diff --git a/adb/Android.bp b/adb/Android.bp
index 9f16c40..00e98fe 100644
--- a/adb/Android.bp
+++ b/adb/Android.bp
@@ -25,6 +25,7 @@
         "-Wvla",
     ],
     rtti: true,
+    cpp_std: "gnu++17",
 
     use_version_lib: true,
 
@@ -314,6 +315,8 @@
         "daemon/auth.cpp",
         "daemon/jdwp_service.cpp",
         "daemon/usb.cpp",
+        "daemon/usb_ffs.cpp",
+        "daemon/usb_legacy.cpp",
     ],
 
     local_include_dirs: [
diff --git a/adb/adb.cpp b/adb/adb.cpp
index 62e8908..9c0eeca 100644
--- a/adb/adb.cpp
+++ b/adb/adb.cpp
@@ -73,39 +73,6 @@
         android::base::GetExecutablePath().c_str());
 }
 
-void fatal(const char *fmt, ...) {
-    va_list ap;
-    va_start(ap, fmt);
-    char buf[1024];
-    vsnprintf(buf, sizeof(buf), fmt, ap);
-
-#if ADB_HOST
-    fprintf(stderr, "error: %s\n", buf);
-#else
-    LOG(ERROR) << "error: " << buf;
-#endif
-
-    va_end(ap);
-    abort();
-}
-
-void fatal_errno(const char* fmt, ...) {
-    int err = errno;
-    va_list ap;
-    va_start(ap, fmt);
-    char buf[1024];
-    vsnprintf(buf, sizeof(buf), fmt, ap);
-
-#if ADB_HOST
-    fprintf(stderr, "error: %s: %s\n", buf, strerror(err));
-#else
-    LOG(ERROR) << "error: " << buf << ": " << strerror(err);
-#endif
-
-    va_end(ap);
-    abort();
-}
-
 uint32_t calculate_apacket_checksum(const apacket* p) {
     uint32_t sum = 0;
     for (size_t i = 0; i < p->msg.data_length; ++i) {
@@ -118,7 +85,7 @@
 {
     apacket* p = new apacket();
     if (p == nullptr) {
-      fatal("failed to allocate an apacket");
+        LOG(FATAL) << "failed to allocate an apacket";
     }
 
     memset(&p->msg, 0, sizeof(p->msg));
diff --git a/adb/adb.h b/adb/adb.h
index f434e2d..e2911e8 100644
--- a/adb/adb.h
+++ b/adb/adb.h
@@ -124,9 +124,6 @@
 
 void print_packet(const char* label, apacket* p);
 
-void fatal(const char* fmt, ...) __attribute__((noreturn, format(__printf__, 1, 2)));
-void fatal_errno(const char* fmt, ...) __attribute__((noreturn, format(__printf__, 1, 2)));
-
 void handle_packet(apacket* p, atransport* t);
 
 int launch_server(const std::string& socket_spec);
diff --git a/adb/adb_utils.cpp b/adb/adb_utils.cpp
index 437720e..bc184c5 100644
--- a/adb/adb_utils.cpp
+++ b/adb/adb_utils.cpp
@@ -57,11 +57,11 @@
 void close_stdin() {
     int fd = unix_open(kNullFileName, O_RDONLY);
     if (fd == -1) {
-        fatal_errno("failed to open %s", kNullFileName);
+        PLOG(FATAL) << "failed to open " << kNullFileName;
     }
 
     if (TEMP_FAILURE_RETRY(dup2(fd, STDIN_FILENO)) == -1) {
-        fatal_errno("failed to redirect stdin to %s", kNullFileName);
+        PLOG(FATAL) << "failed to redirect stdin to " << kNullFileName;
     }
     unix_close(fd);
 }
@@ -316,18 +316,6 @@
     return android_dir;
 }
 
-int syntax_error(const char* fmt, ...) {
-    fprintf(stderr, "adb: usage: ");
-
-    va_list ap;
-    va_start(ap, fmt);
-    vfprintf(stderr, fmt, ap);
-    va_end(ap);
-
-    fprintf(stderr, "\n");
-    return 1;
-}
-
 std::string GetLogFilePath() {
 #if defined(_WIN32)
     const char log_name[] = "adb.log";
@@ -337,13 +325,13 @@
     DWORD nchars = GetTempPathW(arraysize(temp_path), temp_path);
     if (nchars >= arraysize(temp_path) || nchars == 0) {
         // If string truncation or some other error.
-        fatal("cannot retrieve temporary file path: %s\n",
-              android::base::SystemErrorCodeToString(GetLastError()).c_str());
+        LOG(FATAL) << "cannot retrieve temporary file path: "
+                   << android::base::SystemErrorCodeToString(GetLastError());
     }
 
     std::string temp_path_utf8;
     if (!android::base::WideToUTF8(temp_path, &temp_path_utf8)) {
-        fatal_errno("cannot convert temporary file path from UTF-16 to UTF-8");
+        PLOG(FATAL) << "cannot convert temporary file path from UTF-16 to UTF-8";
     }
 
     return temp_path_utf8 + log_name;
diff --git a/adb/adb_utils.h b/adb/adb_utils.h
index ad83302..442ca2b 100644
--- a/adb/adb_utils.h
+++ b/adb/adb_utils.h
@@ -26,8 +26,6 @@
 
 #include "adb.h"
 
-int syntax_error(const char*, ...) __attribute__((__format__(__printf__, 1, 2)));
-
 void close_stdin();
 
 bool getcwd(std::string* cwd);
diff --git a/adb/client/adb_install.cpp b/adb/client/adb_install.cpp
index d69dbef..e1b75b0 100644
--- a/adb/client/adb_install.cpp
+++ b/adb/client/adb_install.cpp
@@ -134,7 +134,7 @@
     // The last argument must be the APK file
     const char* file = argv[argc - 1];
     if (!android::base::EndsWithIgnoreCase(file, ".apk")) {
-        return syntax_error("filename doesn't end .apk: %s", file);
+        error(1, 0, "filename doesn't end .apk: %s", file);
     }
 
     if (use_fastdeploy == true) {
@@ -224,7 +224,7 @@
         }
     }
 
-    if (last_apk == -1) return syntax_error("need APK file on command line");
+    if (last_apk == -1) error(1, 0, "need APK file on command line");
 
     int result = -1;
     std::vector<const char*> apk_file = {argv[last_apk]};
@@ -311,7 +311,7 @@
     }
 
     if (installMode == INSTALL_STREAM && _use_legacy_install() == true) {
-        return syntax_error("Attempting to use streaming install on unsupported deivce.");
+        error(1, 0, "Attempting to use streaming install on unsupported device");
     }
 
     if (use_fastdeploy == true && is_reinstall == false) {
@@ -370,7 +370,7 @@
         }
     }
 
-    if (first_apk == -1) return syntax_error("need APK file on command line");
+    if (first_apk == -1) error(1, 0, "need APK file on command line");
 
     std::string install_cmd;
     if (_use_legacy_install()) {
diff --git a/adb/client/bugreport.cpp b/adb/client/bugreport.cpp
index fe98737..83eb157 100644
--- a/adb/client/bugreport.cpp
+++ b/adb/client/bugreport.cpp
@@ -197,7 +197,7 @@
 };
 
 int Bugreport::DoIt(int argc, const char** argv) {
-    if (argc > 2) return syntax_error("adb bugreport [PATH]");
+    if (argc > 2) error(1, 0, "usage: adb bugreport [PATH]");
 
     // Gets bugreportz version.
     std::string bugz_stdout, bugz_stderr;
diff --git a/adb/client/commandline.cpp b/adb/client/commandline.cpp
index 07b5747..0e03201 100644
--- a/adb/client/commandline.cpp
+++ b/adb/client/commandline.cpp
@@ -71,8 +71,7 @@
 static std::string product_file(const std::string& file) {
     const char* ANDROID_PRODUCT_OUT = getenv("ANDROID_PRODUCT_OUT");
     if (ANDROID_PRODUCT_OUT == nullptr) {
-        fprintf(stderr, "adb: product directory not specified; set $ANDROID_PRODUCT_OUT\n");
-        exit(1);
+        error(1, 0, "product directory not specified; set $ANDROID_PRODUCT_OUT");
     }
     return std::string{ANDROID_PRODUCT_OUT} + OS_PATH_SEPARATOR_STR + file;
 }
@@ -318,7 +317,7 @@
 #ifdef _WIN32
         old_stdin_mode = _setmode(STDIN_FILENO, _O_BINARY);
         if (old_stdin_mode == -1) {
-            fatal_errno("could not set stdin to binary");
+            PLOG(FATAL) << "could not set stdin to binary";
         }
 #endif
     }
@@ -327,7 +326,7 @@
     if (outFd == STDOUT_FILENO) {
         old_stdout_mode = _setmode(STDOUT_FILENO, _O_BINARY);
         if (old_stdout_mode == -1) {
-            fatal_errno("could not set stdout to binary");
+            PLOG(FATAL) << "could not set stdout to binary";
         }
     }
 #endif
@@ -338,7 +337,7 @@
         stdin_raw_restore();
 #ifdef _WIN32
         if (_setmode(STDIN_FILENO, old_stdin_mode) == -1) {
-            fatal_errno("could not restore stdin mode");
+            PLOG(FATAL) << "could not restore stdin mode";
         }
 #endif
     }
@@ -346,7 +345,7 @@
 #ifdef _WIN32
     if (outFd == STDOUT_FILENO) {
         if (_setmode(STDOUT_FILENO, old_stdout_mode) == -1) {
-            fatal_errno("could not restore stdout mode");
+            PLOG(FATAL) << "could not restore stdout mode";
         }
     }
 #endif
@@ -660,9 +659,9 @@
 
 static int adb_shell(int argc, const char** argv) {
     FeatureSet features;
-    std::string error;
-    if (!adb_get_feature_set(&features, &error)) {
-        fprintf(stderr, "error: %s\n", error.c_str());
+    std::string error_message;
+    if (!adb_get_feature_set(&features, &error_message)) {
+        fprintf(stderr, "error: %s\n", error_message.c_str());
         return 1;
     }
 
@@ -685,7 +684,7 @@
         switch (opt) {
             case 'e':
                 if (!(strlen(optarg) == 1 || strcmp(optarg, "none") == 0)) {
-                    return syntax_error("-e requires a single-character argument or 'none'");
+                    error(1, 0, "-e requires a single-character argument or 'none'");
                 }
                 escape_char = (strcmp(optarg, "none") == 0) ? 0 : optarg[0];
                 break;
@@ -933,31 +932,29 @@
  */
 static int ppp(int argc, const char** argv) {
 #if defined(_WIN32)
-    fprintf(stderr, "error: adb %s not implemented on Win32\n", argv[0]);
-    return -1;
+    error(1, 0, "adb %s not implemented on Win32", argv[0]);
+    __builtin_unreachable();
 #else
-    if (argc < 2) return syntax_error("adb %s <adb service name> [ppp opts]", argv[0]);
+    if (argc < 2) error(1, 0, "usage: adb %s <adb service name> [ppp opts]", argv[0]);
 
     const char* adb_service_name = argv[1];
-    std::string error;
-    int fd = adb_connect(adb_service_name, &error);
+    std::string error_message;
+    int fd = adb_connect(adb_service_name, &error_message);
     if (fd < 0) {
-        fprintf(stderr, "adb: could not open adb service %s: %s\n", adb_service_name, error.c_str());
-        return 1;
+        error(1, 0, "could not open adb service %s: %s", adb_service_name, error_message.c_str());
     }
 
     pid_t pid = fork();
+    if (pid == -1) {
+        error(1, errno, "fork failed");
+    }
 
-    if (pid < 0) {
-        perror("from fork()");
-        return 1;
-    } else if (pid == 0) {
-        int err;
+    if (pid == 0) {
+        // child side
         int i;
-        const char **ppp_args;
 
         // copy args
-        ppp_args = (const char **) alloca(sizeof(char *) * argc + 1);
+        const char** ppp_args = (const char**)alloca(sizeof(char*) * argc + 1);
         ppp_args[0] = "pppd";
         for (i = 2 ; i < argc ; i++) {
             //argv[2] and beyond become ppp_args[1] and beyond
@@ -965,25 +962,18 @@
         }
         ppp_args[i-1] = nullptr;
 
-        // child side
-
         dup2(fd, STDIN_FILENO);
         dup2(fd, STDOUT_FILENO);
         adb_close(STDERR_FILENO);
         adb_close(fd);
 
-        err = execvp("pppd", (char * const *)ppp_args);
-
-        if (err < 0) {
-            perror("execing pppd");
-        }
-        exit(-1);
-    } else {
-        // parent side
-
-        adb_close(fd);
-        return 0;
+        execvp("pppd", (char* const*)ppp_args);
+        error(1, errno, "exec pppd failed");
     }
+
+    // parent side
+    adb_close(fd);
+    return 0;
 #endif /* !defined(_WIN32) */
 }
 
@@ -1161,7 +1151,7 @@
     /* find, extract, and use any -f argument */
     for (int i = 1; i < argc; i++) {
         if (!strcmp("-f", argv[i])) {
-            if (i == argc - 1) return syntax_error("backup -f passed with no filename");
+            if (i == argc - 1) error(1, 0, "backup -f passed with no filename");
             filename = argv[i+1];
             for (int j = i+2; j <= argc; ) {
                 argv[i++] = argv[j++];
@@ -1173,7 +1163,7 @@
 
     // Bare "adb backup" or "adb backup -f filename" are not valid invocations ---
     // a list of packages is required.
-    if (argc < 2) return syntax_error("backup either needs a list of packages or -all/-shared");
+    if (argc < 2) error(1, 0, "backup either needs a list of packages or -all/-shared");
 
     adb_unlink(filename);
     int outFd = adb_creat(filename, 0640);
@@ -1209,7 +1199,7 @@
 }
 
 static int restore(int argc, const char** argv) {
-    if (argc != 2) return syntax_error("restore requires an argument");
+    if (argc != 2) error(1, 0, "restore requires an argument");
 
     const char* filename = argv[1];
     int tarFd = adb_open(filename, O_RDONLY);
@@ -1263,8 +1253,7 @@
             } else if (!strcmp(*arg, "--")) {
                 ignore_flags = true;
             } else {
-                syntax_error("unrecognized option '%s'", *arg);
-                exit(1);
+                error(1, 0, "unrecognized option '%s'", *arg);
             }
         }
         ++arg;
@@ -1342,7 +1331,7 @@
             /* this is a special flag used only when the ADB client launches the ADB Server */
             is_daemon = true;
         } else if (!strcmp(argv[0], "--reply-fd")) {
-            if (argc < 2) return syntax_error("--reply-fd requires an argument");
+            if (argc < 2) error(1, 0, "--reply-fd requires an argument");
             const char* reply_fd_str = argv[1];
             argc--;
             argv++;
@@ -1355,7 +1344,7 @@
             if (isdigit(argv[0][2])) {
                 serial = argv[0] + 2;
             } else {
-                if (argc < 2 || argv[0][2] != '\0') return syntax_error("-s requires an argument");
+                if (argc < 2 || argv[0][2] != '\0') error(1, 0, "-s requires an argument");
                 serial = argv[1];
                 argc--;
                 argv++;
@@ -1371,7 +1360,7 @@
             }
             transport_id = strtoll(id, const_cast<char**>(&id), 10);
             if (*id != '\0') {
-                return syntax_error("invalid transport id");
+                error(1, 0, "invalid transport id");
             }
         } else if (!strcmp(argv[0],"-d")) {
             transport_type = kTransportUsb;
@@ -1381,7 +1370,7 @@
             gListenAll = 1;
         } else if (!strncmp(argv[0], "-H", 2)) {
             if (argv[0][2] == '\0') {
-                if (argc < 2) return syntax_error("-H requires an argument");
+                if (argc < 2) error(1, 0, "-H requires an argument");
                 server_host_str = argv[1];
                 argc--;
                 argv++;
@@ -1390,7 +1379,7 @@
             }
         } else if (!strncmp(argv[0], "-P", 2)) {
             if (argv[0][2] == '\0') {
-                if (argc < 2) return syntax_error("-P requires an argument");
+                if (argc < 2) error(1, 0, "-P requires an argument");
                 server_port_str = argv[1];
                 argc--;
                 argv++;
@@ -1398,7 +1387,7 @@
                 server_port_str = argv[0] + 2;
             }
         } else if (!strcmp(argv[0], "-L")) {
-            if (argc < 2) return syntax_error("-L requires an argument");
+            if (argc < 2) error(1, 0, "-L requires an argument");
             server_socket_str = argv[1];
             argc--;
             argv++;
@@ -1411,7 +1400,7 @@
     }
 
     if ((server_host_str || server_port_str) && server_socket_str) {
-        return syntax_error("-L is incompatible with -H or -P");
+        error(1, 0, "-L is incompatible with -H or -P");
     }
 
     // If -L, -H, or -P are specified, ignore environment variables.
@@ -1428,11 +1417,10 @@
         server_port_str = server_port_str ? server_port_str : getenv("ANDROID_ADB_SERVER_PORT");
         if (server_port_str && strlen(server_port_str) > 0) {
             if (!android::base::ParseInt(server_port_str, &server_port, 1, 65535)) {
-                fprintf(stderr,
-                        "adb: Env var ANDROID_ADB_SERVER_PORT must be a positive"
-                        " number less than 65535. Got \"%s\"\n",
-                        server_port_str);
-                exit(1);
+                error(1, 0,
+                      "$ANDROID_ADB_SERVER_PORT must be a positive number less than 65535: "
+                      "got \"%s\"",
+                      server_port_str);
             }
         }
 
@@ -1444,7 +1432,7 @@
             rc = asprintf(&temp, "tcp:%d", server_port);
         }
         if (rc < 0) {
-            fatal("failed to allocate server socket specification");
+            LOG(FATAL) << "failed to allocate server socket specification";
         }
         server_socket_str = temp;
     }
@@ -1506,7 +1494,7 @@
         } else if (argc == 2 && !strcmp(argv[1], "-l")) {
             listopt = argv[1];
         } else {
-            return syntax_error("adb devices [-l]");
+            error(1, 0, "adb devices [-l]");
         }
 
         std::string query = android::base::StringPrintf("host:%s%s", argv[0], listopt);
@@ -1514,13 +1502,13 @@
         return adb_query_command(query);
     }
     else if (!strcmp(argv[0], "connect")) {
-        if (argc != 2) return syntax_error("adb connect <host>[:<port>]");
+        if (argc != 2) error(1, 0, "usage: adb connect <host>[:<port>]");
 
         std::string query = android::base::StringPrintf("host:connect:%s", argv[1]);
         return adb_query_command(query);
     }
     else if (!strcmp(argv[0], "disconnect")) {
-        if (argc > 2) return syntax_error("adb disconnect [<host>[:<port>]]");
+        if (argc > 2) error(1, 0, "usage: adb disconnect [<host>[:<port>]]");
 
         std::string query = android::base::StringPrintf("host:disconnect:%s",
                                                         (argc == 2) ? argv[1] : "");
@@ -1535,7 +1523,7 @@
     else if (!strcmp(argv[0], "exec-in") || !strcmp(argv[0], "exec-out")) {
         int exec_in = !strcmp(argv[0], "exec-in");
 
-        if (argc < 2) return syntax_error("adb %s command", argv[0]);
+        if (argc < 2) error(1, 0, "usage: adb %s command", argv[0]);
 
         std::string cmd = "exec:";
         cmd += argv[1];
@@ -1565,17 +1553,17 @@
         return adb_kill_server() ? 0 : 1;
     }
     else if (!strcmp(argv[0], "sideload")) {
-        if (argc != 2) return syntax_error("sideload requires an argument");
+        if (argc != 2) error(1, 0, "sideload requires an argument");
         if (adb_sideload_host(argv[1])) {
             return 1;
         } else {
             return 0;
         }
     } else if (!strcmp(argv[0], "tcpip")) {
-        if (argc != 2) return syntax_error("tcpip requires an argument");
+        if (argc != 2) error(1, 0, "tcpip requires an argument");
         int port;
         if (!android::base::ParseInt(argv[1], &port, 1, 65535)) {
-            return syntax_error("tcpip: invalid port: %s", argv[1]);
+            error(1, 0, "tcpip: invalid port: %s", argv[1]);
         }
         return adb_connect_command(android::base::StringPrintf("tcpip:%d", port));
     }
@@ -1607,7 +1595,7 @@
     } else if (!strcmp(argv[0], "forward") || !strcmp(argv[0], "reverse")) {
         bool reverse = !strcmp(argv[0], "reverse");
         --argc;
-        if (argc < 1) return syntax_error("%s requires an argument", argv[0]);
+        if (argc < 1) error(1, 0, "%s requires an argument", argv[0]);
         ++argv;
 
         // Determine the <host-prefix> for this command.
@@ -1626,46 +1614,44 @@
             }
         }
 
-        std::string cmd, error;
+        std::string cmd, error_message;
         if (strcmp(argv[0], "--list") == 0) {
-            if (argc != 1) return syntax_error("--list doesn't take any arguments");
+            if (argc != 1) error(1, 0, "--list doesn't take any arguments");
             return adb_query_command(host_prefix + ":list-forward");
         } else if (strcmp(argv[0], "--remove-all") == 0) {
-            if (argc != 1) return syntax_error("--remove-all doesn't take any arguments");
+            if (argc != 1) error(1, 0, "--remove-all doesn't take any arguments");
             cmd = host_prefix + ":killforward-all";
         } else if (strcmp(argv[0], "--remove") == 0) {
             // forward --remove <local>
-            if (argc != 2) return syntax_error("--remove requires an argument");
+            if (argc != 2) error(1, 0, "--remove requires an argument");
             cmd = host_prefix + ":killforward:" + argv[1];
         } else if (strcmp(argv[0], "--no-rebind") == 0) {
             // forward --no-rebind <local> <remote>
-            if (argc != 3) return syntax_error("--no-rebind takes two arguments");
-            if (forward_targets_are_valid(argv[1], argv[2], &error)) {
+            if (argc != 3) error(1, 0, "--no-rebind takes two arguments");
+            if (forward_targets_are_valid(argv[1], argv[2], &error_message)) {
                 cmd = host_prefix + ":forward:norebind:" + argv[1] + ";" + argv[2];
             }
         } else {
             // forward <local> <remote>
-            if (argc != 2) return syntax_error("forward takes two arguments");
-            if (forward_targets_are_valid(argv[0], argv[1], &error)) {
+            if (argc != 2) error(1, 0, "forward takes two arguments");
+            if (forward_targets_are_valid(argv[0], argv[1], &error_message)) {
                 cmd = host_prefix + ":forward:" + argv[0] + ";" + argv[1];
             }
         }
 
-        if (!error.empty()) {
-            fprintf(stderr, "error: %s\n", error.c_str());
-            return 1;
+        if (!error_message.empty()) {
+            error(1, 0, "error: %s", error_message.c_str());
         }
 
-        int fd = adb_connect(cmd, &error);
-        if (fd < 0 || !adb_status(fd, &error)) {
+        int fd = adb_connect(cmd, &error_message);
+        if (fd < 0 || !adb_status(fd, &error_message)) {
             adb_close(fd);
-            fprintf(stderr, "error: %s\n", error.c_str());
-            return 1;
+            error(1, 0, "error: %s", error_message.c_str());
         }
 
         // Server or device may optionally return a resolved TCP port number.
         std::string resolved_port;
-        if (ReadProtocolString(fd, &resolved_port, &error) && !resolved_port.empty()) {
+        if (ReadProtocolString(fd, &resolved_port, &error_message) && !resolved_port.empty()) {
             printf("%s\n", resolved_port.c_str());
         }
 
@@ -1674,7 +1660,7 @@
     }
     /* do_sync_*() commands */
     else if (!strcmp(argv[0], "ls")) {
-        if (argc != 2) return syntax_error("ls requires an argument");
+        if (argc != 2) error(1, 0, "ls requires an argument");
         return do_sync_ls(argv[1]) ? 0 : 1;
     }
     else if (!strcmp(argv[0], "push")) {
@@ -1684,7 +1670,7 @@
         const char* dst = nullptr;
 
         parse_push_pull_args(&argv[1], argc - 1, &srcs, &dst, &copy_attrs, &sync);
-        if (srcs.empty() || !dst) return syntax_error("push requires an argument");
+        if (srcs.empty() || !dst) error(1, 0, "push requires an argument");
         return do_sync_push(srcs, dst, sync) ? 0 : 1;
     }
     else if (!strcmp(argv[0], "pull")) {
@@ -1693,19 +1679,19 @@
         const char* dst = ".";
 
         parse_push_pull_args(&argv[1], argc - 1, &srcs, &dst, &copy_attrs, nullptr);
-        if (srcs.empty()) return syntax_error("pull requires an argument");
+        if (srcs.empty()) error(1, 0, "pull requires an argument");
         return do_sync_pull(srcs, dst, copy_attrs) ? 0 : 1;
     }
     else if (!strcmp(argv[0], "install")) {
-        if (argc < 2) return syntax_error("install requires an argument");
+        if (argc < 2) error(1, 0, "install requires an argument");
         return install_app(argc, argv);
     }
     else if (!strcmp(argv[0], "install-multiple")) {
-        if (argc < 2) return syntax_error("install-multiple requires an argument");
+        if (argc < 2) error(1, 0, "install-multiple requires an argument");
         return install_multiple_app(argc, argv);
     }
     else if (!strcmp(argv[0], "uninstall")) {
-        if (argc < 2) return syntax_error("uninstall requires an argument");
+        if (argc < 2) error(1, 0, "uninstall requires an argument");
         return uninstall_app(argc, argv);
     }
     else if (!strcmp(argv[0], "sync")) {
@@ -1719,7 +1705,7 @@
         } else if (argc == 2) {
             src = argv[1];
         } else {
-            return syntax_error("adb sync [-l] [PARTITION]");
+            error(1, 0, "usage: adb sync [-l] [PARTITION]");
         }
 
         if (src.empty()) src = "all";
@@ -1734,7 +1720,8 @@
                 if (!do_sync_sync(src_dir, "/" + partition, list_only)) return 1;
             }
         }
-        return found ? 0 : syntax_error("don't know how to sync %s partition", src.c_str());
+        if (!found) error(1, 0, "don't know how to sync %s partition", src.c_str());
+        return 0;
     }
     /* passthrough commands */
     else if (!strcmp(argv[0],"get-state") ||
@@ -1765,7 +1752,7 @@
         return restore(argc, argv);
     }
     else if (!strcmp(argv[0], "keygen")) {
-        if (argc != 2) return syntax_error("keygen requires an argument");
+        if (argc != 2) error(1, 0, "keygen requires an argument");
         // Always print key generation information for keygen command.
         adb_trace_enable(AUTH);
         return adb_auth_keygen(argv[1]);
@@ -1780,7 +1767,7 @@
         return adb_connect_command("host:track-devices");
     } else if (!strcmp(argv[0], "raw")) {
         if (argc != 2) {
-            return syntax_error("adb raw SERVICE");
+            error(1, 0, "usage: adb raw SERVICE");
         }
         return adb_connect_command(argv[1]);
     }
@@ -1823,11 +1810,11 @@
                 std::string err;
                 return adb_query_command("host:reconnect-offline");
             } else {
-                return syntax_error("adb reconnect [device|offline]");
+                error(1, 0, "usage: adb reconnect [device|offline]");
             }
         }
     }
 
-    syntax_error("unknown command %s", argv[0]);
-    return 1;
+    error(1, 0, "unknown command %s", argv[0]);
+    __builtin_unreachable();
 }
diff --git a/adb/client/fastdeploy.cpp b/adb/client/fastdeploy.cpp
index 183a1fa..933b913 100644
--- a/adb/client/fastdeploy.cpp
+++ b/adb/client/fastdeploy.cpp
@@ -27,6 +27,7 @@
 #include "client/file_sync_client.h"
 #include "commandline.h"
 #include "fastdeploycallbacks.h"
+#include "sysdeps.h"
 #include "utils/String16.h"
 
 static constexpr long kRequiredAgentVersion = 0x00000001;
@@ -72,13 +73,14 @@
 static std::string get_agent_component_host_path(const char* local_path, const char* sdk_path) {
     std::string adb_dir = android::base::GetExecutableDirectory();
     if (adb_dir.empty()) {
-        fatal("Could not determine location of adb!");
+        error(1, 0, "Could not determine location of adb!");
     }
 
     if (g_use_localagent) {
         const char* product_out = getenv("ANDROID_PRODUCT_OUT");
         if (product_out == nullptr) {
-            fatal("Could not locate %s because $ANDROID_PRODUCT_OUT is not defined", local_path);
+            error(1, 0, "Could not locate %s because $ANDROID_PRODUCT_OUT is not defined",
+                  local_path);
         }
         return android::base::StringPrintf("%s%s", product_out, local_path);
     } else {
@@ -103,10 +105,10 @@
                 android::base::StringPrintf(kChmodCommandPattern, kDeviceAgentPath);
         int ret = send_shell_command(chmodCommand);
         if (ret != 0) {
-            fatal("Error executing %s returncode: %d", chmodCommand.c_str(), ret);
+            error(1, 0, "Error executing %s returncode: %d", chmodCommand.c_str(), ret);
         }
     } else {
-        fatal("Error pushing agent files to device");
+        error(1, 0, "Error pushing agent files to device");
     }
 
     return true;
@@ -136,7 +138,7 @@
 
     agent_version = get_agent_version();
     if (agent_version != kRequiredAgentVersion) {
-        fatal("After update agent version remains incorrect! Expected %ld but version is %ld",
+        error(1, 0, "After update agent version remains incorrect! Expected %ld but version is %ld",
               kRequiredAgentVersion, agent_version);
     }
 }
@@ -153,26 +155,28 @@
 }
 
 static std::string get_packagename_from_apk(const char* apkPath) {
+#undef open
     std::unique_ptr<android::ZipFileRO> zipFile(android::ZipFileRO::open(apkPath));
+#define open ___xxx_unix_open
     if (zipFile == nullptr) {
-        fatal("Could not open %s", apkPath);
+        error(1, errno, "Could not open %s", apkPath);
     }
     android::ZipEntryRO entry = zipFile->findEntryByName("AndroidManifest.xml");
     if (entry == nullptr) {
-        fatal("Could not find AndroidManifest.xml inside %s", apkPath);
+        error(1, 0, "Could not find AndroidManifest.xml inside %s", apkPath);
     }
     uint32_t manifest_len = 0;
     if (!zipFile->getEntryInfo(entry, NULL, &manifest_len, NULL, NULL, NULL, NULL)) {
-        fatal("Could not read AndroidManifest.xml inside %s", apkPath);
+        error(1, 0, "Could not read AndroidManifest.xml inside %s", apkPath);
     }
     std::vector<char> manifest_data(manifest_len);
     if (!zipFile->uncompressEntry(entry, manifest_data.data(), manifest_len)) {
-        fatal("Could not uncompress AndroidManifest.xml inside %s", apkPath);
+        error(1, 0, "Could not uncompress AndroidManifest.xml inside %s", apkPath);
     }
     android::ResXMLTree tree;
     android::status_t setto_status = tree.setTo(manifest_data.data(), manifest_len, true);
     if (setto_status != android::OK) {
-        fatal("Could not parse AndroidManifest.xml inside %s", apkPath);
+        error(1, 0, "Could not parse AndroidManifest.xml inside %s", apkPath);
     }
     android::ResXMLParser::event_code_t code;
     while ((code = tree.next()) != android::ResXMLParser::BAD_DOCUMENT &&
@@ -213,7 +217,8 @@
                 break;
         }
     }
-    fatal("Could not find package name tag in AndroidManifest.xml inside %s", apkPath);
+    error(1, 0, "Could not find package name tag in AndroidManifest.xml inside %s", apkPath);
+    __builtin_unreachable();
 }
 
 void extract_metadata(const char* apkPath, FILE* outputFp) {
@@ -227,7 +232,7 @@
     DeployAgentFileCallback cb(outputFp, &extractErrorBuffer, &statusCode);
     int returnCode = send_shell_command(extractCommand, false, &cb);
     if (returnCode != 0) {
-        fatal("Executing %s returned %d\n", extractCommand.c_str(), returnCode);
+        error(1, 0, "Executing %s returned %d", extractCommand.c_str(), returnCode);
     }
 }
 
@@ -236,8 +241,9 @@
         // This should never happen on a Windows machine
         const char* host_out = getenv("ANDROID_HOST_OUT");
         if (host_out == nullptr) {
-            fatal("Could not locate deploypatchgenerator.jar because $ANDROID_HOST_OUT is not "
-                  "defined");
+            error(1, 0,
+                  "Could not locate deploypatchgenerator.jar because $ANDROID_HOST_OUT "
+                  "is not defined");
         }
         return android::base::StringPrintf("java -jar %s/framework/deploypatchgenerator.jar",
                                            host_out);
@@ -245,7 +251,7 @@
 
     std::string adb_dir = android::base::GetExecutableDirectory();
     if (adb_dir.empty()) {
-        fatal("Could not locate deploypatchgenerator.jar");
+        error(1, 0, "Could not locate deploypatchgenerator.jar");
     }
     return android::base::StringPrintf(R"(java -jar "%s/deploypatchgenerator.jar")",
                                        adb_dir.c_str());
@@ -257,7 +263,7 @@
             patchPath);
     int returnCode = system(generatePatchCommand.c_str());
     if (returnCode != 0) {
-        fatal("Executing %s returned %d\n", generatePatchCommand.c_str(), returnCode);
+        error(1, 0, "Executing %s returned %d", generatePatchCommand.c_str(), returnCode);
     }
 }
 
@@ -276,7 +282,7 @@
     std::vector<const char*> srcs = {patchPath};
     bool push_ok = do_sync_push(srcs, patchDevicePath.c_str(), false);
     if (!push_ok) {
-        fatal("Error pushing %s to %s returned\n", patchPath, patchDevicePath.c_str());
+        error(1, 0, "Error pushing %s to %s returned", patchPath, patchDevicePath.c_str());
     }
 
     std::string applyPatchCommand =
@@ -285,7 +291,7 @@
 
     int returnCode = send_shell_command(applyPatchCommand);
     if (returnCode != 0) {
-        fatal("Executing %s returned %d\n", applyPatchCommand.c_str(), returnCode);
+        error(1, 0, "Executing %s returned %d", applyPatchCommand.c_str(), returnCode);
     }
 }
 
@@ -299,7 +305,7 @@
     std::vector<const char*> srcs{patchPath};
     bool push_ok = do_sync_push(srcs, patchDevicePath.c_str(), false);
     if (!push_ok) {
-        fatal("Error pushing %s to %s returned\n", patchPath, patchDevicePath.c_str());
+        error(1, 0, "Error pushing %s to %s returned", patchPath, patchDevicePath.c_str());
     }
 
     std::vector<unsigned char> applyOutputBuffer;
@@ -316,6 +322,6 @@
                                         patchDevicePath.c_str(), argsString.c_str());
     int returnCode = send_shell_command(applyPatchCommand);
     if (returnCode != 0) {
-        fatal("Executing %s returned %d\n", applyPatchCommand.c_str(), returnCode);
+        error(1, 0, "Executing %s returned %d", applyPatchCommand.c_str(), returnCode);
     }
 }
diff --git a/adb/client/file_sync_client.cpp b/adb/client/file_sync_client.cpp
index cb9bcfa..697d9ea 100644
--- a/adb/client/file_sync_client.cpp
+++ b/adb/client/file_sync_client.cpp
@@ -325,12 +325,12 @@
         memset(st, 0, sizeof(*st));
         if (have_stat_v2_) {
             if (!ReadFdExactly(fd, &msg.stat_v2, sizeof(msg.stat_v2))) {
-                fatal_errno("protocol fault: failed to read stat response");
+                PLOG(FATAL) << "protocol fault: failed to read stat response";
             }
 
             if (msg.stat_v2.id != ID_LSTAT_V2 && msg.stat_v2.id != ID_STAT_V2) {
-                fatal_errno("protocol fault: stat response has wrong message id: %" PRIx32,
-                            msg.stat_v2.id);
+                PLOG(FATAL) << "protocol fault: stat response has wrong message id: "
+                            << msg.stat_v2.id;
             }
 
             if (msg.stat_v2.error != 0) {
@@ -351,12 +351,12 @@
             return true;
         } else {
             if (!ReadFdExactly(fd, &msg.stat_v1, sizeof(msg.stat_v1))) {
-                fatal_errno("protocol fault: failed to read stat response");
+                PLOG(FATAL) << "protocol fault: failed to read stat response";
             }
 
             if (msg.stat_v1.id != ID_LSTAT_V1) {
-                fatal_errno("protocol fault: stat response has wrong message id: %" PRIx32,
-                            msg.stat_v1.id);
+                PLOG(FATAL) << "protocol fault: stat response has wrong message id: "
+                            << msg.stat_v1.id;
             }
 
             if (msg.stat_v1.mode == 0 && msg.stat_v1.size == 0 && msg.stat_v1.time == 0) {
diff --git a/adb/client/main.cpp b/adb/client/main.cpp
index a7e454d..fb581a6 100644
--- a/adb/client/main.cpp
+++ b/adb/client/main.cpp
@@ -42,13 +42,13 @@
     const std::string log_file_path(GetLogFilePath());
     int fd = unix_open(log_file_path.c_str(), O_WRONLY | O_CREAT | O_APPEND, 0640);
     if (fd == -1) {
-        fatal("cannot open '%s': %s", log_file_path.c_str(), strerror(errno));
+        PLOG(FATAL) << "cannot open " << log_file_path;
     }
     if (dup2(fd, STDOUT_FILENO) == -1) {
-        fatal("cannot redirect stdout: %s", strerror(errno));
+        PLOG(FATAL) << "cannot redirect stdout";
     }
     if (dup2(fd, STDERR_FILENO) == -1) {
-        fatal("cannot redirect stderr: %s", strerror(errno));
+        PLOG(FATAL) << "cannot redirect stderr";
     }
     unix_close(fd);
 
@@ -81,10 +81,10 @@
     // This also keeps stderr unbuffered when it is redirected to adb.log.
     if (is_daemon) {
         if (setvbuf(stdout, nullptr, _IONBF, 0) == -1) {
-            fatal("cannot make stdout unbuffered: %s", strerror(errno));
+            PLOG(FATAL) << "cannot make stdout unbuffered";
         }
         if (setvbuf(stderr, nullptr, _IONBF, 0) == -1) {
-            fatal("cannot make stderr unbuffered: %s", strerror(errno));
+            PLOG(FATAL) << "cannot make stderr unbuffered";
         }
     }
 
@@ -137,7 +137,7 @@
     while (install_listener(socket_spec, "*smartsocket*", nullptr, 0, nullptr, &error) !=
            INSTALL_STATUS_OK) {
         if (std::chrono::steady_clock::now() - start > 0.5s) {
-            fatal("could not install *smartsocket* listener: %s", error.c_str());
+            LOG(FATAL) << "could not install *smartsocket* listener: " << error;
         }
 
         std::this_thread::sleep_for(100ms);
@@ -153,7 +153,7 @@
         // setsid will fail with EPERM if it's already been a lead process of new session.
         // Ignore such error.
         if (setsid() == -1 && errno != EPERM) {
-            fatal("setsid() failed: %s", strerror(errno));
+            PLOG(FATAL) << "setsid() failed";
         }
 #endif
 
@@ -171,19 +171,19 @@
             const DWORD bytes_to_write = arraysize(ack) - 1;
             DWORD written = 0;
             if (!WriteFile(ack_reply_handle, ack, bytes_to_write, &written, NULL)) {
-                fatal("adb: cannot write ACK to handle 0x%p: %s", ack_reply_handle,
-                      android::base::SystemErrorCodeToString(GetLastError()).c_str());
+                LOG(FATAL) << "cannot write ACK to handle " << ack_reply_handle
+                           << android::base::SystemErrorCodeToString(GetLastError());
             }
             if (written != bytes_to_write) {
-                fatal("adb: cannot write %lu bytes of ACK: only wrote %lu bytes", bytes_to_write,
-                      written);
+                LOG(FATAL) << "cannot write " << bytes_to_write << " bytes of ACK: only wrote "
+                           << written << " bytes";
             }
             CloseHandle(ack_reply_handle);
 #else
             // TODO(danalbert): Can't use SendOkay because we're sending "OK\n", not
             // "OKAY".
             if (!android::base::WriteStringToFd("OK\n", ack_reply_fd)) {
-                fatal_errno("error writing ACK to fd %d", ack_reply_fd);
+                PLOG(FATAL) << "error writing ACK to fd " << ack_reply_fd;
             }
             unix_close(ack_reply_fd);
 #endif
diff --git a/adb/client/usb_windows.cpp b/adb/client/usb_windows.cpp
index 00aeb9b..cfa5cf4 100644
--- a/adb/client/usb_windows.cpp
+++ b/adb/client/usb_windows.cpp
@@ -212,8 +212,8 @@
     const HINSTANCE instance = GetModuleHandleW(nullptr);
     if (!instance) {
         // This is such a common API call that this should never fail.
-        fatal("GetModuleHandleW failed: %s",
-              android::base::SystemErrorCodeToString(GetLastError()).c_str());
+        LOG(FATAL) << "GetModuleHandleW failed: "
+                   << android::base::SystemErrorCodeToString(GetLastError());
     }
 
     WNDCLASSEXW wndclass;
@@ -223,15 +223,15 @@
     wndclass.hInstance = instance;
     wndclass.lpszClassName = kPowerNotificationWindowClassName;
     if (!RegisterClassExW(&wndclass)) {
-        fatal("RegisterClassExW failed: %s",
-              android::base::SystemErrorCodeToString(GetLastError()).c_str());
+        LOG(FATAL) << "RegisterClassExW failed: "
+                   << android::base::SystemErrorCodeToString(GetLastError());
     }
 
     if (!CreateWindowExW(WS_EX_NOACTIVATE, kPowerNotificationWindowClassName,
                          L"ADB Power Notification Window", WS_POPUP, 0, 0, 0, 0, nullptr, nullptr,
                          instance, nullptr)) {
-        fatal("CreateWindowExW failed: %s",
-              android::base::SystemErrorCodeToString(GetLastError()).c_str());
+        LOG(FATAL) << "CreateWindowExW failed: "
+                   << android::base::SystemErrorCodeToString(GetLastError());
     }
 
     MSG msg;
diff --git a/adb/daemon/framebuffer_service.cpp b/adb/daemon/framebuffer_service.cpp
index 8d28c49..586393e 100644
--- a/adb/daemon/framebuffer_service.cpp
+++ b/adb/daemon/framebuffer_service.cpp
@@ -78,7 +78,7 @@
         const char* command = "screencap";
         const char *args[2] = {command, nullptr};
         execvp(command, (char**)args);
-        exit(1);
+        error(1, errno, "exec screencap failed");
     }
 
     adb_close(fds[1]);
diff --git a/adb/daemon/include/adbd/usb.h b/adb/daemon/include/adbd/usb.h
index 78e4cd5..3213f69 100644
--- a/adb/daemon/include/adbd/usb.h
+++ b/adb/daemon/include/adbd/usb.h
@@ -62,3 +62,5 @@
 };
 
 usb_handle *create_usb_handle(unsigned num_bufs, unsigned io_size);
+bool open_functionfs(android::base::unique_fd* control, android::base::unique_fd* bulk_out,
+                     android::base::unique_fd* bulk_in);
diff --git a/adb/daemon/jdwp_service.cpp b/adb/daemon/jdwp_service.cpp
index fe79acd..1363976 100644
--- a/adb/daemon/jdwp_service.cpp
+++ b/adb/daemon/jdwp_service.cpp
@@ -136,7 +136,7 @@
         this->fde = fdevent_create(socket, jdwp_process_event, this);
 
         if (!this->fde) {
-            fatal("could not create fdevent for new JDWP process");
+            LOG(FATAL) << "could not create fdevent for new JDWP process";
         }
 
         /* start by waiting for the PID */
@@ -200,7 +200,7 @@
     // Message is length-prefixed with 4 hex digits in ASCII.
     static constexpr size_t header_len = 4;
     if (bufferlen < header_len) {
-        fatal("invalid JDWP process list buffer size: %zu", bufferlen);
+        LOG(FATAL) << "invalid JDWP process list buffer size: " << bufferlen;
     }
 
     char head[header_len + 1];
@@ -395,7 +395,7 @@
 
         auto proc = std::make_unique<JdwpProcess>(s);
         if (!proc) {
-            fatal("failed to allocate JdwpProcess");
+            LOG(FATAL) << "failed to allocate JdwpProcess";
         }
 
         _jdwp_list.emplace_back(std::move(proc));
@@ -454,7 +454,7 @@
     JdwpSocket* s = new JdwpSocket();
 
     if (!s) {
-        fatal("failed to allocate JdwpSocket");
+        LOG(FATAL) << "failed to allocate JdwpSocket";
     }
 
     install_local_socket(s);
@@ -531,7 +531,7 @@
 asocket* create_jdwp_tracker_service_socket(void) {
     auto t = std::make_unique<JdwpTracker>();
     if (!t) {
-        fatal("failed to allocate JdwpTracker");
+        LOG(FATAL) << "failed to allocate JdwpTracker";
     }
 
     memset(t.get(), 0, sizeof(asocket));
diff --git a/adb/daemon/usb.cpp b/adb/daemon/usb.cpp
index 9d495b0..f603d13 100644
--- a/adb/daemon/usb.cpp
+++ b/adb/daemon/usb.cpp
@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 2007 The Android Open Source Project
+ * Copyright (C) 2018 The Android Open Source Project
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -18,528 +18,568 @@
 
 #include "sysdeps.h"
 
-#include <dirent.h>
 #include <errno.h>
-#include <linux/usb/ch9.h>
-#include <linux/usb/functionfs.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
 #include <sys/ioctl.h>
-#include <sys/mman.h>
 #include <sys/types.h>
 #include <unistd.h>
 
-#include <algorithm>
-#include <atomic>
-#include <chrono>
-#include <condition_variable>
+#include <linux/usb/functionfs.h>
+#include <sys/eventfd.h>
+
+#include <array>
+#include <future>
+#include <memory>
 #include <mutex>
-#include <thread>
+#include <optional>
+#include <vector>
+
+#include <asyncio/AsyncIO.h>
 
 #include <android-base/logging.h>
+#include <android-base/macros.h>
 #include <android-base/properties.h>
+#include <android-base/thread_annotations.h>
 
-#include "adb.h"
-#include "adbd/usb.h"
+#include <adbd/usb.h>
+
+#include "adb_unique_fd.h"
+#include "adb_utils.h"
+#include "sysdeps/chrono.h"
 #include "transport.h"
+#include "types.h"
 
-using namespace std::chrono_literals;
+using android::base::StringPrintf;
 
-#define MAX_PACKET_SIZE_FS 64
-#define MAX_PACKET_SIZE_HS 512
-#define MAX_PACKET_SIZE_SS 1024
+static constexpr size_t kUsbReadQueueDepth = 16;
+static constexpr size_t kUsbReadSize = 16384;
 
-#define USB_FFS_BULK_SIZE 16384
+static constexpr size_t kUsbWriteQueueDepth = 16;
 
-// Number of buffers needed to fit MAX_PAYLOAD, with an extra for ZLPs.
-#define USB_FFS_NUM_BUFS ((4 * MAX_PAYLOAD / USB_FFS_BULK_SIZE) + 1)
-
-#define cpu_to_le16(x) htole16(x)
-#define cpu_to_le32(x) htole32(x)
-
-static unique_fd& dummy_fd = *new unique_fd();
-
-struct func_desc {
-    struct usb_interface_descriptor intf;
-    struct usb_endpoint_descriptor_no_audio source;
-    struct usb_endpoint_descriptor_no_audio sink;
-} __attribute__((packed));
-
-struct ss_func_desc {
-    struct usb_interface_descriptor intf;
-    struct usb_endpoint_descriptor_no_audio source;
-    struct usb_ss_ep_comp_descriptor source_comp;
-    struct usb_endpoint_descriptor_no_audio sink;
-    struct usb_ss_ep_comp_descriptor sink_comp;
-} __attribute__((packed));
-
-struct desc_v1 {
-    struct usb_functionfs_descs_head_v1 {
-        __le32 magic;
-        __le32 length;
-        __le32 fs_count;
-        __le32 hs_count;
-    } __attribute__((packed)) header;
-    struct func_desc fs_descs, hs_descs;
-} __attribute__((packed));
-
-struct desc_v2 {
-    struct usb_functionfs_descs_head_v2 header;
-    // The rest of the structure depends on the flags in the header.
-    __le32 fs_count;
-    __le32 hs_count;
-    __le32 ss_count;
-    __le32 os_count;
-    struct func_desc fs_descs, hs_descs;
-    struct ss_func_desc ss_descs;
-    struct usb_os_desc_header os_header;
-    struct usb_ext_compat_desc os_desc;
-} __attribute__((packed));
-
-static struct func_desc fs_descriptors = {
-    .intf = {
-        .bLength = sizeof(fs_descriptors.intf),
-        .bDescriptorType = USB_DT_INTERFACE,
-        .bInterfaceNumber = 0,
-        .bNumEndpoints = 2,
-        .bInterfaceClass = ADB_CLASS,
-        .bInterfaceSubClass = ADB_SUBCLASS,
-        .bInterfaceProtocol = ADB_PROTOCOL,
-        .iInterface = 1, /* first string from the provided table */
-    },
-    .source = {
-        .bLength = sizeof(fs_descriptors.source),
-        .bDescriptorType = USB_DT_ENDPOINT,
-        .bEndpointAddress = 1 | USB_DIR_OUT,
-        .bmAttributes = USB_ENDPOINT_XFER_BULK,
-        .wMaxPacketSize = MAX_PACKET_SIZE_FS,
-    },
-    .sink = {
-        .bLength = sizeof(fs_descriptors.sink),
-        .bDescriptorType = USB_DT_ENDPOINT,
-        .bEndpointAddress = 2 | USB_DIR_IN,
-        .bmAttributes = USB_ENDPOINT_XFER_BULK,
-        .wMaxPacketSize = MAX_PACKET_SIZE_FS,
-    },
-};
-
-static struct func_desc hs_descriptors = {
-    .intf = {
-        .bLength = sizeof(hs_descriptors.intf),
-        .bDescriptorType = USB_DT_INTERFACE,
-        .bInterfaceNumber = 0,
-        .bNumEndpoints = 2,
-        .bInterfaceClass = ADB_CLASS,
-        .bInterfaceSubClass = ADB_SUBCLASS,
-        .bInterfaceProtocol = ADB_PROTOCOL,
-        .iInterface = 1, /* first string from the provided table */
-    },
-    .source = {
-        .bLength = sizeof(hs_descriptors.source),
-        .bDescriptorType = USB_DT_ENDPOINT,
-        .bEndpointAddress = 1 | USB_DIR_OUT,
-        .bmAttributes = USB_ENDPOINT_XFER_BULK,
-        .wMaxPacketSize = MAX_PACKET_SIZE_HS,
-    },
-    .sink = {
-        .bLength = sizeof(hs_descriptors.sink),
-        .bDescriptorType = USB_DT_ENDPOINT,
-        .bEndpointAddress = 2 | USB_DIR_IN,
-        .bmAttributes = USB_ENDPOINT_XFER_BULK,
-        .wMaxPacketSize = MAX_PACKET_SIZE_HS,
-    },
-};
-
-static struct ss_func_desc ss_descriptors = {
-    .intf = {
-        .bLength = sizeof(ss_descriptors.intf),
-        .bDescriptorType = USB_DT_INTERFACE,
-        .bInterfaceNumber = 0,
-        .bNumEndpoints = 2,
-        .bInterfaceClass = ADB_CLASS,
-        .bInterfaceSubClass = ADB_SUBCLASS,
-        .bInterfaceProtocol = ADB_PROTOCOL,
-        .iInterface = 1, /* first string from the provided table */
-    },
-    .source = {
-        .bLength = sizeof(ss_descriptors.source),
-        .bDescriptorType = USB_DT_ENDPOINT,
-        .bEndpointAddress = 1 | USB_DIR_OUT,
-        .bmAttributes = USB_ENDPOINT_XFER_BULK,
-        .wMaxPacketSize = MAX_PACKET_SIZE_SS,
-    },
-    .source_comp = {
-        .bLength = sizeof(ss_descriptors.source_comp),
-        .bDescriptorType = USB_DT_SS_ENDPOINT_COMP,
-        .bMaxBurst = 4,
-    },
-    .sink = {
-        .bLength = sizeof(ss_descriptors.sink),
-        .bDescriptorType = USB_DT_ENDPOINT,
-        .bEndpointAddress = 2 | USB_DIR_IN,
-        .bmAttributes = USB_ENDPOINT_XFER_BULK,
-        .wMaxPacketSize = MAX_PACKET_SIZE_SS,
-    },
-    .sink_comp = {
-        .bLength = sizeof(ss_descriptors.sink_comp),
-        .bDescriptorType = USB_DT_SS_ENDPOINT_COMP,
-        .bMaxBurst = 4,
-    },
-};
-
-struct usb_ext_compat_desc os_desc_compat = {
-    .bFirstInterfaceNumber = 0,
-    .Reserved1 = cpu_to_le32(1),
-    .CompatibleID = {0},
-    .SubCompatibleID = {0},
-    .Reserved2 = {0},
-};
-
-static struct usb_os_desc_header os_desc_header = {
-    .interface = cpu_to_le32(1),
-    .dwLength = cpu_to_le32(sizeof(os_desc_header) + sizeof(os_desc_compat)),
-    .bcdVersion = cpu_to_le32(1),
-    .wIndex = cpu_to_le32(4),
-    .bCount = cpu_to_le32(1),
-    .Reserved = cpu_to_le32(0),
-};
-
-#define STR_INTERFACE_ "ADB Interface"
-
-static const struct {
-    struct usb_functionfs_strings_head header;
-    struct {
-        __le16 code;
-        const char str1[sizeof(STR_INTERFACE_)];
-    } __attribute__((packed)) lang0;
-} __attribute__((packed)) strings = {
-    .header = {
-        .magic = cpu_to_le32(FUNCTIONFS_STRINGS_MAGIC),
-        .length = cpu_to_le32(sizeof(strings)),
-        .str_count = cpu_to_le32(1),
-        .lang_count = cpu_to_le32(1),
-    },
-    .lang0 = {
-        cpu_to_le16(0x0409), /* en-us */
-        STR_INTERFACE_,
-    },
-};
-
-static void aio_block_init(aio_block* aiob, unsigned num_bufs) {
-    aiob->iocb.resize(num_bufs);
-    aiob->iocbs.resize(num_bufs);
-    aiob->events.resize(num_bufs);
-    aiob->num_submitted = 0;
-    for (unsigned i = 0; i < num_bufs; i++) {
-        aiob->iocbs[i] = &aiob->iocb[i];
-    }
-    memset(&aiob->ctx, 0, sizeof(aiob->ctx));
-    if (io_setup(num_bufs, &aiob->ctx)) {
-        D("[ aio: got error on io_setup (%d) ]", errno);
+static const char* to_string(enum usb_functionfs_event_type type) {
+    switch (type) {
+        case FUNCTIONFS_BIND:
+            return "FUNCTIONFS_BIND";
+        case FUNCTIONFS_UNBIND:
+            return "FUNCTIONFS_UNBIND";
+        case FUNCTIONFS_ENABLE:
+            return "FUNCTIONFS_ENABLE";
+        case FUNCTIONFS_DISABLE:
+            return "FUNCTIONFS_DISABLE";
+        case FUNCTIONFS_SETUP:
+            return "FUNCTIONFS_SETUP";
+        case FUNCTIONFS_SUSPEND:
+            return "FUNCTIONFS_SUSPEND";
+        case FUNCTIONFS_RESUME:
+            return "FUNCTIONFS_RESUME";
     }
 }
 
-static int getMaxPacketSize(int ffs_fd) {
-    usb_endpoint_descriptor desc;
-    if (ioctl(ffs_fd, FUNCTIONFS_ENDPOINT_DESC, reinterpret_cast<unsigned long>(&desc))) {
-        D("[ could not get endpoint descriptor! (%d) ]", errno);
-        return MAX_PACKET_SIZE_HS;
-    } else {
-        return desc.wMaxPacketSize;
+enum class TransferDirection : uint64_t {
+    READ = 0,
+    WRITE = 1,
+};
+
+struct TransferId {
+    TransferDirection direction : 1;
+    uint64_t id : 63;
+
+    TransferId() : TransferId(TransferDirection::READ, 0) {}
+
+  private:
+    TransferId(TransferDirection direction, uint64_t id) : direction(direction), id(id) {}
+
+  public:
+    explicit operator uint64_t() const {
+        uint64_t result;
+        static_assert(sizeof(*this) == sizeof(result));
+        memcpy(&result, this, sizeof(*this));
+        return result;
     }
-}
 
-static bool init_functionfs(struct usb_handle* h) {
-    LOG(INFO) << "initializing functionfs";
+    static TransferId read(uint64_t id) { return TransferId(TransferDirection::READ, id); }
+    static TransferId write(uint64_t id) { return TransferId(TransferDirection::WRITE, id); }
 
-    ssize_t ret;
-    struct desc_v1 v1_descriptor;
-    struct desc_v2 v2_descriptor;
+    static TransferId from_value(uint64_t value) {
+        TransferId result;
+        memcpy(&result, &value, sizeof(value));
+        return result;
+    }
+};
 
-    v2_descriptor.header.magic = cpu_to_le32(FUNCTIONFS_DESCRIPTORS_MAGIC_V2);
-    v2_descriptor.header.length = cpu_to_le32(sizeof(v2_descriptor));
-    v2_descriptor.header.flags = FUNCTIONFS_HAS_FS_DESC | FUNCTIONFS_HAS_HS_DESC |
-                                 FUNCTIONFS_HAS_SS_DESC | FUNCTIONFS_HAS_MS_OS_DESC;
-    v2_descriptor.fs_count = 3;
-    v2_descriptor.hs_count = 3;
-    v2_descriptor.ss_count = 5;
-    v2_descriptor.os_count = 1;
-    v2_descriptor.fs_descs = fs_descriptors;
-    v2_descriptor.hs_descs = hs_descriptors;
-    v2_descriptor.ss_descs = ss_descriptors;
-    v2_descriptor.os_header = os_desc_header;
-    v2_descriptor.os_desc = os_desc_compat;
+struct IoBlock {
+    bool pending;
+    struct iocb control;
+    Block payload;
 
-    if (h->control < 0) { // might have already done this before
-        LOG(INFO) << "opening control endpoint " << USB_FFS_ADB_EP0;
-        h->control.reset(adb_open(USB_FFS_ADB_EP0, O_WRONLY));
-        if (h->control < 0) {
-            PLOG(ERROR) << "cannot open control endpoint " << USB_FFS_ADB_EP0;
-            goto err;
+    TransferId id() const { return TransferId::from_value(control.aio_data); }
+};
+
+struct ScopedAioContext {
+    ScopedAioContext() = default;
+    ~ScopedAioContext() { reset(); }
+
+    ScopedAioContext(ScopedAioContext&& move) { reset(move.release()); }
+    ScopedAioContext(const ScopedAioContext& copy) = delete;
+
+    ScopedAioContext& operator=(ScopedAioContext&& move) {
+        reset(move.release());
+        return *this;
+    }
+    ScopedAioContext& operator=(const ScopedAioContext& copy) = delete;
+
+    static ScopedAioContext Create(size_t max_events) {
+        aio_context_t ctx = 0;
+        if (io_setup(max_events, &ctx) != 0) {
+            PLOG(FATAL) << "failed to create aio_context_t";
+        }
+        ScopedAioContext result;
+        result.reset(ctx);
+        return result;
+    }
+
+    aio_context_t release() {
+        aio_context_t result = context_;
+        context_ = 0;
+        return result;
+    }
+
+    void reset(aio_context_t new_context = 0) {
+        if (context_ != 0) {
+            io_destroy(context_);
         }
 
-        ret = adb_write(h->control.get(), &v2_descriptor, sizeof(v2_descriptor));
-        if (ret < 0) {
-            v1_descriptor.header.magic = cpu_to_le32(FUNCTIONFS_DESCRIPTORS_MAGIC);
-            v1_descriptor.header.length = cpu_to_le32(sizeof(v1_descriptor));
-            v1_descriptor.header.fs_count = 3;
-            v1_descriptor.header.hs_count = 3;
-            v1_descriptor.fs_descs = fs_descriptors;
-            v1_descriptor.hs_descs = hs_descriptors;
-            D("[ %s: Switching to V1_descriptor format errno=%d ]", USB_FFS_ADB_EP0, errno);
-            ret = adb_write(h->control.get(), &v1_descriptor, sizeof(v1_descriptor));
-            if (ret < 0) {
-                D("[ %s: write descriptors failed: errno=%d ]", USB_FFS_ADB_EP0, errno);
-                goto err;
+        context_ = new_context;
+    }
+
+    aio_context_t get() { return context_; }
+
+  private:
+    aio_context_t context_ = 0;
+};
+
+struct UsbFfsConnection : public Connection {
+    UsbFfsConnection(unique_fd control, unique_fd read, unique_fd write,
+                     std::promise<void> destruction_notifier)
+        : stopped_(false),
+          destruction_notifier_(std::move(destruction_notifier)),
+          control_fd_(std::move(control)),
+          read_fd_(std::move(read)),
+          write_fd_(std::move(write)) {
+        LOG(INFO) << "UsbFfsConnection constructed";
+        event_fd_.reset(eventfd(0, EFD_CLOEXEC));
+        if (event_fd_ == -1) {
+            PLOG(FATAL) << "failed to create eventfd";
+        }
+
+        aio_context_ = ScopedAioContext::Create(kUsbReadQueueDepth + kUsbWriteQueueDepth);
+    }
+
+    ~UsbFfsConnection() {
+        LOG(INFO) << "UsbFfsConnection being destroyed";
+        Stop();
+        monitor_thread_.join();
+        destruction_notifier_.set_value();
+    }
+
+    virtual bool Write(std::unique_ptr<apacket> packet) override final {
+        LOG(DEBUG) << "USB write: " << dump_header(&packet->msg);
+        Block header(sizeof(packet->msg));
+        memcpy(header.data(), &packet->msg, sizeof(packet->msg));
+
+        std::lock_guard<std::mutex> lock(write_mutex_);
+        write_requests_.push_back(CreateWriteBlock(std::move(header), next_write_id_++));
+        if (!packet->payload.empty()) {
+            write_requests_.push_back(
+                    CreateWriteBlock(std::move(packet->payload), next_write_id_++));
+        }
+        SubmitWrites();
+        return true;
+    }
+
+    virtual void Start() override final { StartMonitor(); }
+
+    virtual void Stop() override final {
+        if (stopped_.exchange(true)) {
+            return;
+        }
+        stopped_ = true;
+        uint64_t notify = 1;
+        ssize_t rc = adb_write(event_fd_.get(), &notify, sizeof(notify));
+        if (rc < 0) {
+            PLOG(FATAL) << "failed to notify eventfd to stop UsbFfsConnection";
+        }
+        CHECK_EQ(static_cast<size_t>(rc), sizeof(notify));
+    }
+
+  private:
+    void StartMonitor() {
+        // This is a bit of a mess.
+        // It's possible for io_submit to end up blocking, if we call it as the endpoint
+        // becomes disabled. Work around this by having a monitor thread to listen for functionfs
+        // lifecycle events. If we notice an error condition (either we've become disabled, or we
+        // were never enabled in the first place), we send interruption signals to the worker thread
+        // until it dies, and then report failure to the transport via HandleError, which will
+        // eventually result in the transport being destroyed, which will result in UsbFfsConnection
+        // being destroyed, which unblocks the open thread and restarts this entire process.
+        static constexpr int kInterruptionSignal = SIGUSR1;
+        static std::once_flag handler_once;
+        std::call_once(handler_once, []() { signal(kInterruptionSignal, [](int) {}); });
+
+        monitor_thread_ = std::thread([this]() {
+            adb_thread_setname("UsbFfs-monitor");
+
+            bool bound = false;
+            bool started = false;
+            bool running = true;
+            while (running) {
+                if (!bound || !started) {
+                    adb_pollfd pfd = {.fd = control_fd_.get(), .events = POLLIN, .revents = 0};
+                    int rc = TEMP_FAILURE_RETRY(adb_poll(&pfd, 1, 5000 /*ms*/));
+                    if (rc == -1) {
+                        PLOG(FATAL) << "poll on USB control fd failed";
+                    } else if (rc == 0) {
+                        // Something in the kernel presumably went wrong.
+                        // Close our endpoints, wait for a bit, and then try again.
+                        aio_context_.reset();
+                        read_fd_.reset();
+                        write_fd_.reset();
+                        control_fd_.reset();
+                        std::this_thread::sleep_for(5s);
+                        HandleError("didn't receive FUNCTIONFS_ENABLE, retrying");
+                        return;
+                    }
+                }
+
+                struct usb_functionfs_event event;
+                if (TEMP_FAILURE_RETRY(adb_read(control_fd_.get(), &event, sizeof(event))) !=
+                    sizeof(event)) {
+                    PLOG(FATAL) << "failed to read functionfs event";
+                }
+
+                LOG(INFO) << "USB event: "
+                          << to_string(static_cast<usb_functionfs_event_type>(event.type));
+
+                switch (event.type) {
+                    case FUNCTIONFS_BIND:
+                        CHECK(!started) << "received FUNCTIONFS_ENABLE while already bound?";
+                        bound = true;
+                        break;
+
+                    case FUNCTIONFS_ENABLE:
+                        CHECK(!started) << "received FUNCTIONFS_ENABLE while already running?";
+                        started = true;
+                        StartWorker();
+                        break;
+
+                    case FUNCTIONFS_DISABLE:
+                        running = false;
+                        break;
+                }
+            }
+
+            pthread_t worker_thread_handle = worker_thread_.native_handle();
+            while (true) {
+                int rc = pthread_kill(worker_thread_handle, kInterruptionSignal);
+                if (rc != 0) {
+                    LOG(ERROR) << "failed to send interruption signal to worker: " << strerror(rc);
+                    break;
+                }
+
+                std::this_thread::sleep_for(100ms);
+
+                rc = pthread_kill(worker_thread_handle, 0);
+                if (rc == 0) {
+                    continue;
+                } else if (rc == ESRCH) {
+                    break;
+                } else {
+                    LOG(ERROR) << "failed to send interruption signal to worker: " << strerror(rc);
+                }
+            }
+
+            worker_thread_.join();
+
+            aio_context_.reset();
+            read_fd_.reset();
+            write_fd_.reset();
+        });
+    }
+
+    void StartWorker() {
+        worker_thread_ = std::thread([this]() {
+            adb_thread_setname("UsbFfs-worker");
+            for (size_t i = 0; i < kUsbReadQueueDepth; ++i) {
+                read_requests_[i] = CreateReadBlock(next_read_id_++);
+                SubmitRead(&read_requests_[i]);
+            }
+
+            while (!stopped_) {
+                uint64_t dummy;
+                ssize_t rc = adb_read(event_fd_.get(), &dummy, sizeof(dummy));
+                if (rc == -1) {
+                    PLOG(FATAL) << "failed to read from eventfd";
+                } else if (rc == 0) {
+                    LOG(FATAL) << "hit EOF on eventfd";
+                }
+
+                WaitForEvents();
+            }
+        });
+    }
+
+    void PrepareReadBlock(IoBlock* block, uint64_t id) {
+        block->pending = false;
+        block->payload.resize(kUsbReadSize);
+        block->control.aio_data = static_cast<uint64_t>(TransferId::read(id));
+        block->control.aio_buf = reinterpret_cast<uintptr_t>(block->payload.data());
+        block->control.aio_nbytes = block->payload.size();
+    }
+
+    IoBlock CreateReadBlock(uint64_t id) {
+        IoBlock block;
+        PrepareReadBlock(&block, id);
+        block.control.aio_rw_flags = 0;
+        block.control.aio_lio_opcode = IOCB_CMD_PREAD;
+        block.control.aio_reqprio = 0;
+        block.control.aio_fildes = read_fd_.get();
+        block.control.aio_offset = 0;
+        block.control.aio_flags = IOCB_FLAG_RESFD;
+        block.control.aio_resfd = event_fd_.get();
+        return block;
+    }
+
+    void WaitForEvents() {
+        static constexpr size_t kMaxEvents = kUsbReadQueueDepth + kUsbWriteQueueDepth;
+        struct io_event events[kMaxEvents];
+        struct timespec timeout = {.tv_sec = 0, .tv_nsec = 0};
+        int rc = io_getevents(aio_context_.get(), 0, kMaxEvents, events, &timeout);
+        if (rc == -1) {
+            HandleError(StringPrintf("io_getevents failed while reading: %s", strerror(errno)));
+            return;
+        }
+
+        for (int event_idx = 0; event_idx < rc; ++event_idx) {
+            auto& event = events[event_idx];
+            TransferId id = TransferId::from_value(event.data);
+
+            if (event.res < 0) {
+                std::string error =
+                        StringPrintf("%s %" PRIu64 " failed with error %s",
+                                     id.direction == TransferDirection::READ ? "read" : "write",
+                                     id.id, strerror(-event.res));
+                HandleError(error);
+                return;
+            }
+
+            if (id.direction == TransferDirection::READ) {
+                HandleRead(id, event.res);
+            } else {
+                HandleWrite(id);
+            }
+        }
+    }
+
+    void HandleRead(TransferId id, int64_t size) {
+        uint64_t read_idx = id.id % kUsbReadQueueDepth;
+        IoBlock* block = &read_requests_[read_idx];
+        block->pending = false;
+        block->payload.resize(size);
+
+        // Notification for completed reads can be received out of order.
+        if (block->id().id != needed_read_id_) {
+            LOG(VERBOSE) << "read " << block->id().id << " completed while waiting for "
+                         << needed_read_id_;
+            return;
+        }
+
+        for (uint64_t id = needed_read_id_;; ++id) {
+            size_t read_idx = id % kUsbReadQueueDepth;
+            IoBlock* current_block = &read_requests_[read_idx];
+            if (current_block->pending) {
+                break;
+            }
+            ProcessRead(current_block);
+            ++needed_read_id_;
+        }
+    }
+
+    void ProcessRead(IoBlock* block) {
+        if (!block->payload.empty()) {
+            if (!incoming_header_.has_value()) {
+                CHECK_EQ(sizeof(amessage), block->payload.size());
+                amessage msg;
+                memcpy(&msg, block->payload.data(), sizeof(amessage));
+                LOG(DEBUG) << "USB read:" << dump_header(&msg);
+                incoming_header_ = msg;
+            } else {
+                size_t bytes_left = incoming_header_->data_length - incoming_payload_.size();
+                Block payload = std::move(block->payload);
+                CHECK_LE(payload.size(), bytes_left);
+                incoming_payload_.append(std::make_unique<Block>(std::move(payload)));
+            }
+
+            if (incoming_header_->data_length == incoming_payload_.size()) {
+                auto packet = std::make_unique<apacket>();
+                packet->msg = *incoming_header_;
+
+                // TODO: Make apacket contain an IOVector so we don't have to coalesce.
+                packet->payload = incoming_payload_.coalesce();
+                read_callback_(this, std::move(packet));
+
+                incoming_header_.reset();
+                incoming_payload_.clear();
             }
         }
 
-        ret = adb_write(h->control.get(), &strings, sizeof(strings));
-        if (ret < 0) {
-            D("[ %s: writing strings failed: errno=%d]", USB_FFS_ADB_EP0, errno);
-            goto err;
+        PrepareReadBlock(block, block->id().id + kUsbReadQueueDepth);
+        SubmitRead(block);
+    }
+
+    void SubmitRead(IoBlock* block) {
+        block->pending = true;
+        struct iocb* iocb = &block->control;
+        if (io_submit(aio_context_.get(), 1, &iocb) != 1) {
+            HandleError(StringPrintf("failed to submit read: %s", strerror(errno)));
+            return;
         }
-        //Signal only when writing the descriptors to ffs
-        android::base::SetProperty("sys.usb.ffs.ready", "1");
     }
 
-    h->bulk_out.reset(adb_open(USB_FFS_ADB_OUT, O_RDONLY));
-    if (h->bulk_out < 0) {
-        PLOG(ERROR) << "cannot open bulk-out endpoint " << USB_FFS_ADB_OUT;
-        goto err;
+    void HandleWrite(TransferId id) {
+        std::lock_guard<std::mutex> lock(write_mutex_);
+        auto it =
+                std::find_if(write_requests_.begin(), write_requests_.end(), [id](const auto& req) {
+                    return static_cast<uint64_t>(req->id()) == static_cast<uint64_t>(id);
+                });
+        CHECK(it != write_requests_.end());
+
+        write_requests_.erase(it);
+        size_t outstanding_writes = --writes_submitted_;
+        LOG(DEBUG) << "USB write: reaped, down to " << outstanding_writes;
+
+        SubmitWrites();
     }
 
-    h->bulk_in.reset(adb_open(USB_FFS_ADB_IN, O_WRONLY));
-    if (h->bulk_in < 0) {
-        PLOG(ERROR) << "cannot open bulk-in endpoint " << USB_FFS_ADB_IN;
-        goto err;
+    std::unique_ptr<IoBlock> CreateWriteBlock(Block payload, uint64_t id) {
+        auto block = std::make_unique<IoBlock>();
+        block->payload = std::move(payload);
+        block->control.aio_data = static_cast<uint64_t>(TransferId::write(id));
+        block->control.aio_rw_flags = 0;
+        block->control.aio_lio_opcode = IOCB_CMD_PWRITE;
+        block->control.aio_reqprio = 0;
+        block->control.aio_fildes = write_fd_.get();
+        block->control.aio_buf = reinterpret_cast<uintptr_t>(block->payload.data());
+        block->control.aio_nbytes = block->payload.size();
+        block->control.aio_offset = 0;
+        block->control.aio_flags = IOCB_FLAG_RESFD;
+        block->control.aio_resfd = event_fd_.get();
+        return block;
     }
 
-    h->read_aiob.fd = h->bulk_out;
-    h->write_aiob.fd = h->bulk_in;
-    h->reads_zero_packets = true;
-    return true;
+    void SubmitWrites() REQUIRES(write_mutex_) {
+        if (writes_submitted_ == kUsbWriteQueueDepth) {
+            return;
+        }
 
-err:
-    h->bulk_in.reset();
-    h->bulk_out.reset();
-    h->control.reset();
-    return false;
-}
+        ssize_t writes_to_submit = std::min(kUsbWriteQueueDepth - writes_submitted_,
+                                            write_requests_.size() - writes_submitted_);
+        CHECK_GE(writes_to_submit, 0);
+        if (writes_to_submit == 0) {
+            return;
+        }
 
-static void usb_ffs_open_thread(usb_handle *usb) {
+        struct iocb* iocbs[kUsbWriteQueueDepth];
+        for (int i = 0; i < writes_to_submit; ++i) {
+            CHECK(!write_requests_[writes_submitted_ + i]->pending);
+            write_requests_[writes_submitted_ + i]->pending = true;
+            iocbs[i] = &write_requests_[writes_submitted_ + i]->control;
+            LOG(VERBOSE) << "submitting write_request " << static_cast<void*>(iocbs[i]);
+        }
+
+        int rc = io_submit(aio_context_.get(), writes_to_submit, iocbs);
+        if (rc == -1) {
+            HandleError(StringPrintf("failed to submit write requests: %s", strerror(errno)));
+            return;
+        } else if (rc != writes_to_submit) {
+            LOG(FATAL) << "failed to submit all writes: wanted to submit " << writes_to_submit
+                       << ", actually submitted " << rc;
+        }
+
+        writes_submitted_ += rc;
+    }
+
+    void HandleError(const std::string& error) {
+        std::call_once(error_flag_, [&]() {
+            error_callback_(this, error);
+            if (!stopped_) {
+                Stop();
+            }
+        });
+    }
+
+    std::thread monitor_thread_;
+    std::thread worker_thread_;
+
+    std::atomic<bool> stopped_;
+    std::promise<void> destruction_notifier_;
+    std::once_flag error_flag_;
+
+    unique_fd event_fd_;
+
+    ScopedAioContext aio_context_;
+    unique_fd control_fd_;
+    unique_fd read_fd_;
+    unique_fd write_fd_;
+
+    std::optional<amessage> incoming_header_;
+    IOVector incoming_payload_;
+
+    std::array<IoBlock, kUsbReadQueueDepth> read_requests_;
+    IOVector read_data_;
+
+    // ID of the next request that we're going to send out.
+    size_t next_read_id_ = 0;
+
+    // ID of the next packet we're waiting for.
+    size_t needed_read_id_ = 0;
+
+    std::mutex write_mutex_;
+    std::deque<std::unique_ptr<IoBlock>> write_requests_ GUARDED_BY(write_mutex_);
+    size_t next_write_id_ GUARDED_BY(write_mutex_) = 0;
+    size_t writes_submitted_ GUARDED_BY(write_mutex_) = 0;
+};
+
+static void usb_ffs_open_thread() {
     adb_thread_setname("usb ffs open");
 
     while (true) {
-        // wait until the USB device needs opening
-        std::unique_lock<std::mutex> lock(usb->lock);
-        while (!usb->open_new_connection) {
-            usb->notify.wait(lock);
-        }
-        usb->open_new_connection = false;
-        lock.unlock();
-
-        while (true) {
-            if (init_functionfs(usb)) {
-                LOG(INFO) << "functionfs successfully initialized";
-                break;
-            }
+        unique_fd control;
+        unique_fd bulk_out;
+        unique_fd bulk_in;
+        if (!open_functionfs(&control, &bulk_out, &bulk_in)) {
             std::this_thread::sleep_for(1s);
-        }
-
-        LOG(INFO) << "registering usb transport";
-        register_usb_transport(usb, nullptr, nullptr, 1);
-    }
-
-    // never gets here
-    abort();
-}
-
-static int usb_ffs_write(usb_handle* h, const void* data, int len) {
-    D("about to write (fd=%d, len=%d)", h->bulk_in.get(), len);
-
-    const char* buf = static_cast<const char*>(data);
-    int orig_len = len;
-    while (len > 0) {
-        int write_len = std::min(USB_FFS_BULK_SIZE, len);
-        int n = adb_write(h->bulk_in, buf, write_len);
-        if (n < 0) {
-            D("ERROR: fd = %d, n = %d: %s", h->bulk_in.get(), n, strerror(errno));
-            return -1;
-        }
-        buf += n;
-        len -= n;
-    }
-
-    D("[ done fd=%d ]", h->bulk_in.get());
-    return orig_len;
-}
-
-static int usb_ffs_read(usb_handle* h, void* data, int len) {
-    D("about to read (fd=%d, len=%d)", h->bulk_out.get(), len);
-
-    char* buf = static_cast<char*>(data);
-    int orig_len = len;
-    while (len > 0) {
-        int read_len = std::min(USB_FFS_BULK_SIZE, len);
-        int n = adb_read(h->bulk_out, buf, read_len);
-        if (n < 0) {
-            D("ERROR: fd = %d, n = %d: %s", h->bulk_out.get(), n, strerror(errno));
-            return -1;
-        }
-        buf += n;
-        len -= n;
-    }
-
-    D("[ done fd=%d ]", h->bulk_out.get());
-    return orig_len;
-}
-
-static int usb_ffs_do_aio(usb_handle* h, const void* data, int len, bool read) {
-    aio_block* aiob = read ? &h->read_aiob : &h->write_aiob;
-    bool zero_packet = false;
-
-    int num_bufs = len / h->io_size + (len % h->io_size == 0 ? 0 : 1);
-    const char* cur_data = reinterpret_cast<const char*>(data);
-    int packet_size = getMaxPacketSize(aiob->fd);
-
-    if (posix_madvise(const_cast<void*>(data), len, POSIX_MADV_SEQUENTIAL | POSIX_MADV_WILLNEED) <
-        0) {
-        D("[ Failed to madvise: %d ]", errno);
-    }
-
-    for (int i = 0; i < num_bufs; i++) {
-        int buf_len = std::min(len, static_cast<int>(h->io_size));
-        io_prep(&aiob->iocb[i], aiob->fd, cur_data, buf_len, 0, read);
-
-        len -= buf_len;
-        cur_data += buf_len;
-
-        if (len == 0 && buf_len % packet_size == 0 && read) {
-            // adb does not expect the device to send a zero packet after data transfer,
-            // but the host *does* send a zero packet for the device to read.
-            zero_packet = h->reads_zero_packets;
-        }
-    }
-    if (zero_packet) {
-        io_prep(&aiob->iocb[num_bufs], aiob->fd, reinterpret_cast<const void*>(cur_data),
-                packet_size, 0, read);
-        num_bufs += 1;
-    }
-
-    while (true) {
-        if (TEMP_FAILURE_RETRY(io_submit(aiob->ctx, num_bufs, aiob->iocbs.data())) < num_bufs) {
-            PLOG(ERROR) << "aio: got error submitting " << (read ? "read" : "write");
-            return -1;
-        }
-        if (TEMP_FAILURE_RETRY(io_getevents(aiob->ctx, num_bufs, num_bufs, aiob->events.data(),
-                                            nullptr)) < num_bufs) {
-            PLOG(ERROR) << "aio: got error waiting " << (read ? "read" : "write");
-            return -1;
-        }
-        if (num_bufs == 1 && aiob->events[0].res == -EINTR) {
             continue;
         }
-        int ret = 0;
-        for (int i = 0; i < num_bufs; i++) {
-            if (aiob->events[i].res < 0) {
-                errno = -aiob->events[i].res;
-                PLOG(ERROR) << "aio: got error event on " << (read ? "read" : "write")
-                            << " total bufs " << num_bufs;
-                return -1;
-            }
-            ret += aiob->events[i].res;
-        }
-        return ret;
+
+        atransport* transport = new atransport();
+        transport->serial = "UsbFfs";
+        std::promise<void> destruction_notifier;
+        std::future<void> future = destruction_notifier.get_future();
+        transport->SetConnection(std::make_unique<UsbFfsConnection>(
+                std::move(control), std::move(bulk_out), std::move(bulk_in),
+                std::move(destruction_notifier)));
+        register_transport(transport);
+        future.wait();
     }
 }
 
-static int usb_ffs_aio_read(usb_handle* h, void* data, int len) {
-    return usb_ffs_do_aio(h, data, len, true);
-}
-
-static int usb_ffs_aio_write(usb_handle* h, const void* data, int len) {
-    return usb_ffs_do_aio(h, data, len, false);
-}
-
-static void usb_ffs_kick(usb_handle* h) {
-    int err;
-
-    err = ioctl(h->bulk_in.get(), FUNCTIONFS_CLEAR_HALT);
-    if (err < 0) {
-        D("[ kick: source (fd=%d) clear halt failed (%d) ]", h->bulk_in.get(), errno);
-    }
-
-    err = ioctl(h->bulk_out.get(), FUNCTIONFS_CLEAR_HALT);
-    if (err < 0) {
-        D("[ kick: sink (fd=%d) clear halt failed (%d) ]", h->bulk_out.get(), errno);
-    }
-
-    // don't close ep0 here, since we may not need to reinitialize it with
-    // the same descriptors again. if however ep1/ep2 fail to re-open in
-    // init_functionfs, only then would we close and open ep0 again.
-    // Ditto the comment in usb_adb_kick.
-    h->kicked = true;
-    TEMP_FAILURE_RETRY(dup2(dummy_fd.get(), h->bulk_out.get()));
-    TEMP_FAILURE_RETRY(dup2(dummy_fd.get(), h->bulk_in.get()));
-}
-
-static void usb_ffs_close(usb_handle* h) {
-    LOG(INFO) << "closing functionfs transport";
-
-    h->kicked = false;
-    h->bulk_out.reset();
-    h->bulk_in.reset();
-
-    // Notify usb_adb_open_thread to open a new connection.
-    h->lock.lock();
-    h->open_new_connection = true;
-    h->lock.unlock();
-    h->notify.notify_one();
-}
-
-usb_handle *create_usb_handle(unsigned num_bufs, unsigned io_size) {
-    usb_handle* h = new usb_handle();
-
-    if (android::base::GetBoolProperty("sys.usb.ffs.aio_compat", false)) {
-        // Devices on older kernels (< 3.18) will not have aio support for ffs
-        // unless backported. Fall back on the non-aio functions instead.
-        h->write = usb_ffs_write;
-        h->read = usb_ffs_read;
-    } else {
-        h->write = usb_ffs_aio_write;
-        h->read = usb_ffs_aio_read;
-        aio_block_init(&h->read_aiob, num_bufs);
-        aio_block_init(&h->write_aiob, num_bufs);
-    }
-    h->io_size = io_size;
-    h->kick = usb_ffs_kick;
-    h->close = usb_ffs_close;
-    return h;
-}
-
+void usb_init_legacy();
 void usb_init() {
-    D("[ usb_init - using FunctionFS ]");
-    dummy_fd.reset(adb_open("/dev/null", O_WRONLY | O_CLOEXEC));
-    CHECK_NE(-1, dummy_fd.get());
-
-    std::thread(usb_ffs_open_thread, create_usb_handle(USB_FFS_NUM_BUFS, USB_FFS_BULK_SIZE)).detach();
-}
-
-int usb_write(usb_handle* h, const void* data, int len) {
-    return h->write(h, data, len);
-}
-
-int usb_read(usb_handle* h, void* data, int len) {
-    return h->read(h, data, len);
-}
-
-int usb_close(usb_handle* h) {
-    h->close(h);
-    return 0;
-}
-
-void usb_kick(usb_handle* h) {
-    h->kick(h);
+    if (!android::base::GetBoolProperty("persist.adb.nonblocking_ffs", false)) {
+        usb_init_legacy();
+    } else {
+        std::thread(usb_ffs_open_thread).detach();
+    }
 }
diff --git a/adb/daemon/usb_ffs.cpp b/adb/daemon/usb_ffs.cpp
new file mode 100644
index 0000000..07b4ba8
--- /dev/null
+++ b/adb/daemon/usb_ffs.cpp
@@ -0,0 +1,278 @@
+/*
+ * Copyright (C) 2018 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#define TRACE_TAG USB
+
+#include "sysdeps.h"
+
+#include <linux/usb/ch9.h>
+#include <linux/usb/functionfs.h>
+
+#include <android-base/logging.h>
+#include <android-base/properties.h>
+#include <android-base/unique_fd.h>
+
+#include "adb.h"
+#include "adbd/usb.h"
+
+#define MAX_PACKET_SIZE_FS 64
+#define MAX_PACKET_SIZE_HS 512
+#define MAX_PACKET_SIZE_SS 1024
+
+#define USB_FFS_BULK_SIZE 16384
+
+// Number of buffers needed to fit MAX_PAYLOAD, with an extra for ZLPs.
+#define USB_FFS_NUM_BUFS ((4 * MAX_PAYLOAD / USB_FFS_BULK_SIZE) + 1)
+
+#define cpu_to_le16(x) htole16(x)
+#define cpu_to_le32(x) htole32(x)
+
+struct func_desc {
+    struct usb_interface_descriptor intf;
+    struct usb_endpoint_descriptor_no_audio source;
+    struct usb_endpoint_descriptor_no_audio sink;
+} __attribute__((packed));
+
+struct ss_func_desc {
+    struct usb_interface_descriptor intf;
+    struct usb_endpoint_descriptor_no_audio source;
+    struct usb_ss_ep_comp_descriptor source_comp;
+    struct usb_endpoint_descriptor_no_audio sink;
+    struct usb_ss_ep_comp_descriptor sink_comp;
+} __attribute__((packed));
+
+struct desc_v1 {
+    struct usb_functionfs_descs_head_v1 {
+        __le32 magic;
+        __le32 length;
+        __le32 fs_count;
+        __le32 hs_count;
+    } __attribute__((packed)) header;
+    struct func_desc fs_descs, hs_descs;
+} __attribute__((packed));
+
+struct desc_v2 {
+    struct usb_functionfs_descs_head_v2 header;
+    // The rest of the structure depends on the flags in the header.
+    __le32 fs_count;
+    __le32 hs_count;
+    __le32 ss_count;
+    __le32 os_count;
+    struct func_desc fs_descs, hs_descs;
+    struct ss_func_desc ss_descs;
+    struct usb_os_desc_header os_header;
+    struct usb_ext_compat_desc os_desc;
+} __attribute__((packed));
+
+// clang-format off
+static struct func_desc fs_descriptors = {
+    .intf = {
+        .bLength = sizeof(fs_descriptors.intf),
+        .bDescriptorType = USB_DT_INTERFACE,
+        .bInterfaceNumber = 0,
+        .bNumEndpoints = 2,
+        .bInterfaceClass = ADB_CLASS,
+        .bInterfaceSubClass = ADB_SUBCLASS,
+        .bInterfaceProtocol = ADB_PROTOCOL,
+        .iInterface = 1, /* first string from the provided table */
+    },
+    .source = {
+        .bLength = sizeof(fs_descriptors.source),
+        .bDescriptorType = USB_DT_ENDPOINT,
+        .bEndpointAddress = 1 | USB_DIR_OUT,
+        .bmAttributes = USB_ENDPOINT_XFER_BULK,
+        .wMaxPacketSize = MAX_PACKET_SIZE_FS,
+    },
+    .sink = {
+        .bLength = sizeof(fs_descriptors.sink),
+        .bDescriptorType = USB_DT_ENDPOINT,
+        .bEndpointAddress = 2 | USB_DIR_IN,
+        .bmAttributes = USB_ENDPOINT_XFER_BULK,
+        .wMaxPacketSize = MAX_PACKET_SIZE_FS,
+    },
+};
+
+static struct func_desc hs_descriptors = {
+    .intf = {
+        .bLength = sizeof(hs_descriptors.intf),
+        .bDescriptorType = USB_DT_INTERFACE,
+        .bInterfaceNumber = 0,
+        .bNumEndpoints = 2,
+        .bInterfaceClass = ADB_CLASS,
+        .bInterfaceSubClass = ADB_SUBCLASS,
+        .bInterfaceProtocol = ADB_PROTOCOL,
+        .iInterface = 1, /* first string from the provided table */
+    },
+    .source = {
+        .bLength = sizeof(hs_descriptors.source),
+        .bDescriptorType = USB_DT_ENDPOINT,
+        .bEndpointAddress = 1 | USB_DIR_OUT,
+        .bmAttributes = USB_ENDPOINT_XFER_BULK,
+        .wMaxPacketSize = MAX_PACKET_SIZE_HS,
+    },
+    .sink = {
+        .bLength = sizeof(hs_descriptors.sink),
+        .bDescriptorType = USB_DT_ENDPOINT,
+        .bEndpointAddress = 2 | USB_DIR_IN,
+        .bmAttributes = USB_ENDPOINT_XFER_BULK,
+        .wMaxPacketSize = MAX_PACKET_SIZE_HS,
+    },
+};
+
+static struct ss_func_desc ss_descriptors = {
+    .intf = {
+        .bLength = sizeof(ss_descriptors.intf),
+        .bDescriptorType = USB_DT_INTERFACE,
+        .bInterfaceNumber = 0,
+        .bNumEndpoints = 2,
+        .bInterfaceClass = ADB_CLASS,
+        .bInterfaceSubClass = ADB_SUBCLASS,
+        .bInterfaceProtocol = ADB_PROTOCOL,
+        .iInterface = 1, /* first string from the provided table */
+    },
+    .source = {
+        .bLength = sizeof(ss_descriptors.source),
+        .bDescriptorType = USB_DT_ENDPOINT,
+        .bEndpointAddress = 1 | USB_DIR_OUT,
+        .bmAttributes = USB_ENDPOINT_XFER_BULK,
+        .wMaxPacketSize = MAX_PACKET_SIZE_SS,
+    },
+    .source_comp = {
+        .bLength = sizeof(ss_descriptors.source_comp),
+        .bDescriptorType = USB_DT_SS_ENDPOINT_COMP,
+        .bMaxBurst = 4,
+    },
+    .sink = {
+        .bLength = sizeof(ss_descriptors.sink),
+        .bDescriptorType = USB_DT_ENDPOINT,
+        .bEndpointAddress = 2 | USB_DIR_IN,
+        .bmAttributes = USB_ENDPOINT_XFER_BULK,
+        .wMaxPacketSize = MAX_PACKET_SIZE_SS,
+    },
+    .sink_comp = {
+        .bLength = sizeof(ss_descriptors.sink_comp),
+        .bDescriptorType = USB_DT_SS_ENDPOINT_COMP,
+        .bMaxBurst = 4,
+    },
+};
+
+struct usb_ext_compat_desc os_desc_compat = {
+    .bFirstInterfaceNumber = 0,
+    .Reserved1 = cpu_to_le32(1),
+    .CompatibleID = {0},
+    .SubCompatibleID = {0},
+    .Reserved2 = {0},
+};
+
+static struct usb_os_desc_header os_desc_header = {
+    .interface = cpu_to_le32(1),
+    .dwLength = cpu_to_le32(sizeof(os_desc_header) + sizeof(os_desc_compat)),
+    .bcdVersion = cpu_to_le32(1),
+    .wIndex = cpu_to_le32(4),
+    .bCount = cpu_to_le32(1),
+    .Reserved = cpu_to_le32(0),
+};
+
+#define STR_INTERFACE_ "ADB Interface"
+
+static const struct {
+    struct usb_functionfs_strings_head header;
+    struct {
+        __le16 code;
+        const char str1[sizeof(STR_INTERFACE_)];
+    } __attribute__((packed)) lang0;
+} __attribute__((packed)) strings = {
+    .header = {
+        .magic = cpu_to_le32(FUNCTIONFS_STRINGS_MAGIC),
+        .length = cpu_to_le32(sizeof(strings)),
+        .str_count = cpu_to_le32(1),
+        .lang_count = cpu_to_le32(1),
+    },
+    .lang0 = {
+        cpu_to_le16(0x0409), /* en-us */
+        STR_INTERFACE_,
+    },
+};
+// clang-format on
+
+bool open_functionfs(android::base::unique_fd* out_control, android::base::unique_fd* out_bulk_out,
+                     android::base::unique_fd* out_bulk_in) {
+    unique_fd control, bulk_out, bulk_in;
+    struct desc_v1 v1_descriptor = {};
+    struct desc_v2 v2_descriptor = {};
+
+    v2_descriptor.header.magic = cpu_to_le32(FUNCTIONFS_DESCRIPTORS_MAGIC_V2);
+    v2_descriptor.header.length = cpu_to_le32(sizeof(v2_descriptor));
+    v2_descriptor.header.flags = FUNCTIONFS_HAS_FS_DESC | FUNCTIONFS_HAS_HS_DESC |
+                                 FUNCTIONFS_HAS_SS_DESC | FUNCTIONFS_HAS_MS_OS_DESC;
+    v2_descriptor.fs_count = 3;
+    v2_descriptor.hs_count = 3;
+    v2_descriptor.ss_count = 5;
+    v2_descriptor.os_count = 1;
+    v2_descriptor.fs_descs = fs_descriptors;
+    v2_descriptor.hs_descs = hs_descriptors;
+    v2_descriptor.ss_descs = ss_descriptors;
+    v2_descriptor.os_header = os_desc_header;
+    v2_descriptor.os_desc = os_desc_compat;
+
+    if (out_control->get() < 0) {  // might have already done this before
+        LOG(INFO) << "opening control endpoint " << USB_FFS_ADB_EP0;
+        control.reset(adb_open(USB_FFS_ADB_EP0, O_RDWR));
+        if (control < 0) {
+            PLOG(ERROR) << "cannot open control endpoint " << USB_FFS_ADB_EP0;
+            return false;
+        }
+
+        if (adb_write(control.get(), &v2_descriptor, sizeof(v2_descriptor)) < 0) {
+            D("[ %s: Switching to V1_descriptor format errno=%s ]", USB_FFS_ADB_EP0,
+              strerror(errno));
+            v1_descriptor.header.magic = cpu_to_le32(FUNCTIONFS_DESCRIPTORS_MAGIC);
+            v1_descriptor.header.length = cpu_to_le32(sizeof(v1_descriptor));
+            v1_descriptor.header.fs_count = 3;
+            v1_descriptor.header.hs_count = 3;
+            v1_descriptor.fs_descs = fs_descriptors;
+            v1_descriptor.hs_descs = hs_descriptors;
+            if (adb_write(control.get(), &v1_descriptor, sizeof(v1_descriptor)) < 0) {
+                PLOG(ERROR) << "failed to write USB descriptors";
+                return false;
+            }
+        }
+
+        if (adb_write(control.get(), &strings, sizeof(strings)) < 0) {
+            PLOG(ERROR) << "failed to write USB strings";
+            return false;
+        }
+        // Signal only when writing the descriptors to ffs
+        android::base::SetProperty("sys.usb.ffs.ready", "1");
+    }
+
+    bulk_out.reset(adb_open(USB_FFS_ADB_OUT, O_RDONLY));
+    if (bulk_out < 0) {
+        PLOG(ERROR) << "cannot open bulk-out endpoint " << USB_FFS_ADB_OUT;
+        return false;
+    }
+
+    bulk_in.reset(adb_open(USB_FFS_ADB_IN, O_WRONLY));
+    if (bulk_in < 0) {
+        PLOG(ERROR) << "cannot open bulk-in endpoint " << USB_FFS_ADB_IN;
+        return false;
+    }
+
+    *out_control = std::move(control);
+    *out_bulk_in = std::move(bulk_in);
+    *out_bulk_out = std::move(bulk_out);
+    return true;
+}
diff --git a/adb/daemon/usb_legacy.cpp b/adb/daemon/usb_legacy.cpp
new file mode 100644
index 0000000..7ace59d
--- /dev/null
+++ b/adb/daemon/usb_legacy.cpp
@@ -0,0 +1,312 @@
+/*
+ * Copyright (C) 2007 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#define TRACE_TAG USB
+
+#include "sysdeps.h"
+
+#include <dirent.h>
+#include <errno.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/ioctl.h>
+#include <sys/mman.h>
+#include <sys/types.h>
+#include <unistd.h>
+
+#include <linux/usb/ch9.h>
+#include <linux/usb/functionfs.h>
+
+#include <algorithm>
+#include <atomic>
+#include <chrono>
+#include <condition_variable>
+#include <mutex>
+#include <thread>
+
+#include <android-base/logging.h>
+#include <android-base/properties.h>
+
+#include "adb.h"
+#include "adbd/usb.h"
+#include "transport.h"
+
+using namespace std::chrono_literals;
+
+#define MAX_PACKET_SIZE_FS 64
+#define MAX_PACKET_SIZE_HS 512
+#define MAX_PACKET_SIZE_SS 1024
+
+#define USB_FFS_BULK_SIZE 16384
+
+// Number of buffers needed to fit MAX_PAYLOAD, with an extra for ZLPs.
+#define USB_FFS_NUM_BUFS ((4 * MAX_PAYLOAD / USB_FFS_BULK_SIZE) + 1)
+
+static unique_fd& dummy_fd = *new unique_fd();
+
+static void aio_block_init(aio_block* aiob, unsigned num_bufs) {
+    aiob->iocb.resize(num_bufs);
+    aiob->iocbs.resize(num_bufs);
+    aiob->events.resize(num_bufs);
+    aiob->num_submitted = 0;
+    for (unsigned i = 0; i < num_bufs; i++) {
+        aiob->iocbs[i] = &aiob->iocb[i];
+    }
+    memset(&aiob->ctx, 0, sizeof(aiob->ctx));
+    if (io_setup(num_bufs, &aiob->ctx)) {
+        D("[ aio: got error on io_setup (%d) ]", errno);
+    }
+}
+
+static int getMaxPacketSize(int ffs_fd) {
+    usb_endpoint_descriptor desc;
+    if (ioctl(ffs_fd, FUNCTIONFS_ENDPOINT_DESC, reinterpret_cast<unsigned long>(&desc))) {
+        D("[ could not get endpoint descriptor! (%d) ]", errno);
+        return MAX_PACKET_SIZE_HS;
+    } else {
+        return desc.wMaxPacketSize;
+    }
+}
+
+static bool init_functionfs(struct usb_handle* h) {
+    LOG(INFO) << "initializing functionfs";
+    if (!open_functionfs(&h->control, &h->bulk_out, &h->bulk_in)) {
+        return false;
+    }
+
+    h->read_aiob.fd = h->bulk_out.get();
+    h->write_aiob.fd = h->bulk_in.get();
+    h->reads_zero_packets = true;
+    return true;
+}
+
+static void usb_legacy_ffs_open_thread(usb_handle* usb) {
+    adb_thread_setname("usb legacy ffs open");
+
+    while (true) {
+        // wait until the USB device needs opening
+        std::unique_lock<std::mutex> lock(usb->lock);
+        while (!usb->open_new_connection) {
+            usb->notify.wait(lock);
+        }
+        usb->open_new_connection = false;
+        lock.unlock();
+
+        while (true) {
+            if (init_functionfs(usb)) {
+                LOG(INFO) << "functionfs successfully initialized";
+                break;
+            }
+            std::this_thread::sleep_for(1s);
+        }
+
+        LOG(INFO) << "registering usb transport";
+        register_usb_transport(usb, nullptr, nullptr, 1);
+    }
+
+    // never gets here
+    abort();
+}
+
+static int usb_ffs_write(usb_handle* h, const void* data, int len) {
+    D("about to write (fd=%d, len=%d)", h->bulk_in.get(), len);
+
+    const char* buf = static_cast<const char*>(data);
+    int orig_len = len;
+    while (len > 0) {
+        int write_len = std::min(USB_FFS_BULK_SIZE, len);
+        int n = adb_write(h->bulk_in, buf, write_len);
+        if (n < 0) {
+            D("ERROR: fd = %d, n = %d: %s", h->bulk_in.get(), n, strerror(errno));
+            return -1;
+        }
+        buf += n;
+        len -= n;
+    }
+
+    D("[ done fd=%d ]", h->bulk_in.get());
+    return orig_len;
+}
+
+static int usb_ffs_read(usb_handle* h, void* data, int len) {
+    D("about to read (fd=%d, len=%d)", h->bulk_out.get(), len);
+
+    char* buf = static_cast<char*>(data);
+    int orig_len = len;
+    while (len > 0) {
+        int read_len = std::min(USB_FFS_BULK_SIZE, len);
+        int n = adb_read(h->bulk_out, buf, read_len);
+        if (n < 0) {
+            D("ERROR: fd = %d, n = %d: %s", h->bulk_out.get(), n, strerror(errno));
+            return -1;
+        }
+        buf += n;
+        len -= n;
+    }
+
+    D("[ done fd=%d ]", h->bulk_out.get());
+    return orig_len;
+}
+
+static int usb_ffs_do_aio(usb_handle* h, const void* data, int len, bool read) {
+    aio_block* aiob = read ? &h->read_aiob : &h->write_aiob;
+    bool zero_packet = false;
+
+    int num_bufs = len / h->io_size + (len % h->io_size == 0 ? 0 : 1);
+    const char* cur_data = reinterpret_cast<const char*>(data);
+    int packet_size = getMaxPacketSize(aiob->fd);
+
+    if (posix_madvise(const_cast<void*>(data), len, POSIX_MADV_SEQUENTIAL | POSIX_MADV_WILLNEED) <
+        0) {
+        D("[ Failed to madvise: %d ]", errno);
+    }
+
+    for (int i = 0; i < num_bufs; i++) {
+        int buf_len = std::min(len, static_cast<int>(h->io_size));
+        io_prep(&aiob->iocb[i], aiob->fd, cur_data, buf_len, 0, read);
+
+        len -= buf_len;
+        cur_data += buf_len;
+
+        if (len == 0 && buf_len % packet_size == 0 && read) {
+            // adb does not expect the device to send a zero packet after data transfer,
+            // but the host *does* send a zero packet for the device to read.
+            zero_packet = h->reads_zero_packets;
+        }
+    }
+    if (zero_packet) {
+        io_prep(&aiob->iocb[num_bufs], aiob->fd, reinterpret_cast<const void*>(cur_data),
+                packet_size, 0, read);
+        num_bufs += 1;
+    }
+
+    while (true) {
+        if (TEMP_FAILURE_RETRY(io_submit(aiob->ctx, num_bufs, aiob->iocbs.data())) < num_bufs) {
+            PLOG(ERROR) << "aio: got error submitting " << (read ? "read" : "write");
+            return -1;
+        }
+        if (TEMP_FAILURE_RETRY(io_getevents(aiob->ctx, num_bufs, num_bufs, aiob->events.data(),
+                                            nullptr)) < num_bufs) {
+            PLOG(ERROR) << "aio: got error waiting " << (read ? "read" : "write");
+            return -1;
+        }
+        if (num_bufs == 1 && aiob->events[0].res == -EINTR) {
+            continue;
+        }
+        int ret = 0;
+        for (int i = 0; i < num_bufs; i++) {
+            if (aiob->events[i].res < 0) {
+                errno = -aiob->events[i].res;
+                PLOG(ERROR) << "aio: got error event on " << (read ? "read" : "write")
+                            << " total bufs " << num_bufs;
+                return -1;
+            }
+            ret += aiob->events[i].res;
+        }
+        return ret;
+    }
+}
+
+static int usb_ffs_aio_read(usb_handle* h, void* data, int len) {
+    return usb_ffs_do_aio(h, data, len, true);
+}
+
+static int usb_ffs_aio_write(usb_handle* h, const void* data, int len) {
+    return usb_ffs_do_aio(h, data, len, false);
+}
+
+static void usb_ffs_kick(usb_handle* h) {
+    int err;
+
+    err = ioctl(h->bulk_in.get(), FUNCTIONFS_CLEAR_HALT);
+    if (err < 0) {
+        D("[ kick: source (fd=%d) clear halt failed (%d) ]", h->bulk_in.get(), errno);
+    }
+
+    err = ioctl(h->bulk_out.get(), FUNCTIONFS_CLEAR_HALT);
+    if (err < 0) {
+        D("[ kick: sink (fd=%d) clear halt failed (%d) ]", h->bulk_out.get(), errno);
+    }
+
+    // don't close ep0 here, since we may not need to reinitialize it with
+    // the same descriptors again. if however ep1/ep2 fail to re-open in
+    // init_functionfs, only then would we close and open ep0 again.
+    // Ditto the comment in usb_adb_kick.
+    h->kicked = true;
+    TEMP_FAILURE_RETRY(dup2(dummy_fd.get(), h->bulk_out.get()));
+    TEMP_FAILURE_RETRY(dup2(dummy_fd.get(), h->bulk_in.get()));
+}
+
+static void usb_ffs_close(usb_handle* h) {
+    LOG(INFO) << "closing functionfs transport";
+
+    h->kicked = false;
+    h->bulk_out.reset();
+    h->bulk_in.reset();
+
+    // Notify usb_adb_open_thread to open a new connection.
+    h->lock.lock();
+    h->open_new_connection = true;
+    h->lock.unlock();
+    h->notify.notify_one();
+}
+
+usb_handle* create_usb_handle(unsigned num_bufs, unsigned io_size) {
+    usb_handle* h = new usb_handle();
+
+    if (android::base::GetBoolProperty("sys.usb.ffs.aio_compat", false)) {
+        // Devices on older kernels (< 3.18) will not have aio support for ffs
+        // unless backported. Fall back on the non-aio functions instead.
+        h->write = usb_ffs_write;
+        h->read = usb_ffs_read;
+    } else {
+        h->write = usb_ffs_aio_write;
+        h->read = usb_ffs_aio_read;
+        aio_block_init(&h->read_aiob, num_bufs);
+        aio_block_init(&h->write_aiob, num_bufs);
+    }
+    h->io_size = io_size;
+    h->kick = usb_ffs_kick;
+    h->close = usb_ffs_close;
+    return h;
+}
+
+void usb_init_legacy() {
+    D("[ usb_init - using legacy FunctionFS ]");
+    dummy_fd.reset(adb_open("/dev/null", O_WRONLY | O_CLOEXEC));
+    CHECK_NE(-1, dummy_fd.get());
+
+    std::thread(usb_legacy_ffs_open_thread, create_usb_handle(USB_FFS_NUM_BUFS, USB_FFS_BULK_SIZE))
+            .detach();
+}
+
+int usb_write(usb_handle* h, const void* data, int len) {
+    return h->write(h, data, len);
+}
+
+int usb_read(usb_handle* h, void* data, int len) {
+    return h->read(h, data, len);
+}
+
+int usb_close(usb_handle* h) {
+    h->close(h);
+    return 0;
+}
+
+void usb_kick(usb_handle* h) {
+    h->kick(h);
+}
diff --git a/adb/fdevent_test.h b/adb/fdevent_test.h
index 5a417e0..8d853c3 100644
--- a/adb/fdevent_test.h
+++ b/adb/fdevent_test.h
@@ -20,6 +20,7 @@
 #include <mutex>
 #include <thread>
 
+#include "adb_io.h"
 #include "socket.h"
 #include "sysdeps.h"
 #include "sysdeps/chrono.h"
diff --git a/adb/sockets.cpp b/adb/sockets.cpp
index 1534792..8b07f74 100644
--- a/adb/sockets.cpp
+++ b/adb/sockets.cpp
@@ -78,7 +78,7 @@
 
     // Socket ids should never be 0.
     if (local_socket_next_id == 0) {
-        fatal("local socket id overflow");
+        LOG(FATAL) << "local socket id overflow";
     }
 
     local_socket_list.push_back(s);
@@ -451,7 +451,7 @@
 // Returns a new non-NULL asocket handle.
 asocket* create_remote_socket(unsigned id, atransport* t) {
     if (id == 0) {
-        fatal("invalid remote socket id (0)");
+        LOG(FATAL) << "invalid remote socket id (0)";
     }
     asocket* s = new asocket();
     s->id = id;
@@ -477,9 +477,7 @@
     p->payload.assign(destination, destination + strlen(destination) + 1);
     p->msg.data_length = p->payload.size();
 
-    if (p->msg.data_length > s->get_max_payload()) {
-        fatal("destination oversized");
-    }
+    CHECK_LE(p->msg.data_length, s->get_max_payload());
 
     send_packet(p, s->transport);
 }
diff --git a/adb/sysdeps.h b/adb/sysdeps.h
index b8d7e06..bebf4e6 100644
--- a/adb/sysdeps.h
+++ b/adb/sysdeps.h
@@ -25,6 +25,7 @@
 #endif
 
 #include <errno.h>
+#include <error.h>
 
 #include <string>
 #include <vector>
@@ -69,6 +70,8 @@
 #define OS_PATH_SEPARATOR_STR "\\"
 #define ENV_PATH_SEPARATOR_STR ";"
 
+void error(int status, int error, const char* fmt, ...) __attribute__((__format__(printf, 3, 4)));
+
 static __inline__ bool adb_is_separator(char c) {
     return c == '\\' || c == '/';
 }
diff --git a/adb/sysdeps_win32.cpp b/adb/sysdeps_win32.cpp
index 0a08fbb..af15241 100644
--- a/adb/sysdeps_win32.cpp
+++ b/adb/sysdeps_win32.cpp
@@ -35,6 +35,7 @@
 #include <cutils/sockets.h>
 
 #include <android-base/errors.h>
+#include <android-base/file.h>
 #include <android-base/logging.h>
 #include <android-base/macros.h>
 #include <android-base/stringprintf.h>
@@ -46,8 +47,6 @@
 
 #include "sysdeps/uio.h"
 
-extern void fatal(const char *fmt, ...);
-
 /* forward declarations */
 
 typedef const struct FHClassRec_* FHClass;
@@ -98,11 +97,6 @@
 #undef assert
 #endif
 
-#define assert(cond)                                                                       \
-    do {                                                                                   \
-        if (!(cond)) fatal("assertion failed '%s' on %s:%d\n", #cond, __FILE__, __LINE__); \
-    } while (0)
-
 void handle_deleter::operator()(HANDLE h) {
     // CreateFile() is documented to return INVALID_HANDLE_FILE on error,
     // implying that NULL is a valid handle, but this is probably impossible.
@@ -730,8 +724,8 @@
         WSADATA wsaData;
         int rc = WSAStartup(MAKEWORD(2, 2), &wsaData);
         if (rc != 0) {
-            fatal("adb: could not initialize Winsock: %s",
-                  android::base::SystemErrorCodeToString(rc).c_str());
+            LOG(FATAL) << "could not initialize Winsock: "
+                       << android::base::SystemErrorCodeToString(rc);
         }
 
         // Note that we do not call atexit() to register WSACleanup to be called
@@ -1287,11 +1281,11 @@
         }
 
         if (read_count == 0) {   // should be impossible
-            fatal("ReadConsoleInputA returned 0");
+            LOG(FATAL) << "ReadConsoleInputA returned 0";
         }
 
         if (read_count != 1) {   // should be impossible
-            fatal("ReadConsoleInputA did not return one input record");
+            LOG(FATAL) << "ReadConsoleInputA did not return one input record";
         }
 
         // If the console window is resized, emulate SIGWINCH by breaking out
@@ -1309,8 +1303,7 @@
         if ((input_record->EventType == KEY_EVENT) &&
             (input_record->Event.KeyEvent.bKeyDown)) {
             if (input_record->Event.KeyEvent.wRepeatCount == 0) {
-                fatal("ReadConsoleInputA returned a key event with zero repeat"
-                      " count");
+                LOG(FATAL) << "ReadConsoleInputA returned a key event with zero repeat count";
             }
 
             // Got an interesting INPUT_RECORD, so return
@@ -2193,7 +2186,7 @@
     for (int i = 0; i < argc; ++i) {
         std::string arg_narrow;
         if (!android::base::WideToUTF8(argv[i], &arg_narrow)) {
-            fatal_errno("cannot convert argument from UTF-16 to UTF-8");
+            PLOG(FATAL) << "cannot convert argument from UTF-16 to UTF-8";
         }
         narrow_args[i] = strdup(arg_narrow.c_str());
     }
@@ -2644,7 +2637,7 @@
         // If _wenviron is null, then -municode probably wasn't used. That
         // linker flag will cause the entry point to setup _wenviron. It will
         // also require an implementation of wmain() (which we provide above).
-        fatal("_wenviron is not set, did you link with -municode?");
+        LOG(FATAL) << "_wenviron is not set, did you link with -municode?";
     }
 
     // Read name/value pairs from UTF-16 _wenviron and write new name/value
@@ -2763,3 +2756,24 @@
 
     return 0;
 }
+
+void error(int status, int error, const char* fmt, ...) {
+    fflush(stdout);
+    fprintf(stderr, "%s: ", android::base::Basename(android::base::GetExecutablePath()).c_str());
+
+    va_list ap;
+    va_start(ap, fmt);
+    vfprintf(stderr, fmt, ap);
+    va_end(ap);
+
+    if (error != 0) {
+        fprintf(stderr, ": %s", strerror(error));
+    }
+
+    putc('\n', stderr);
+    fflush(stderr);
+
+    if (status != 0) {
+        exit(status);
+    }
+}
diff --git a/adb/transport.cpp b/adb/transport.cpp
index d41f9c8..0fbeec6 100644
--- a/adb/transport.cpp
+++ b/adb/transport.cpp
@@ -52,7 +52,6 @@
 #include "fdevent.h"
 #include "sysdeps/chrono.h"
 
-static void register_transport(atransport* transport);
 static void remove_transport(atransport* transport);
 static void transport_unref(atransport* transport);
 
@@ -420,7 +419,7 @@
     VLOG(TRANSPORT) << dump_packet(t->serial.c_str(), "to remote", p);
 
     if (t == nullptr) {
-        fatal("Transport is null");
+        LOG(FATAL) << "Transport is null";
     }
 
     if (t->Write(p) != 0) {
@@ -526,7 +525,7 @@
 
 asocket* create_device_tracker(bool long_output) {
     device_tracker* tracker = new device_tracker();
-    if (tracker == nullptr) fatal("cannot allocate device tracker");
+    if (tracker == nullptr) LOG(FATAL) << "cannot allocate device tracker";
 
     D("device tracker %p created", tracker);
 
@@ -632,7 +631,7 @@
     }
 
     if (transport_read_action(_fd, &m)) {
-        fatal_errno("cannot read transport registration socket");
+        PLOG(FATAL) << "cannot read transport registration socket";
     }
 
     t = m.transport;
@@ -671,7 +670,7 @@
             return true;
         });
         t->connection()->SetErrorCallback([t](Connection*, const std::string& error) {
-            D("%s: connection terminated: %s", t->serial.c_str(), error.c_str());
+            LOG(INFO) << t->serial_name() << ": connection terminated: " << error;
             fdevent_run_on_main_thread([t]() {
                 handle_offline(t);
                 transport_unref(t);
@@ -706,7 +705,7 @@
     int s[2];
 
     if (adb_socketpair(s)) {
-        fatal_errno("cannot open transport registration socketpair");
+        PLOG(FATAL) << "cannot open transport registration socketpair";
     }
     D("socketpair: (%d,%d)", s[0], s[1]);
 
@@ -730,13 +729,13 @@
 }
 
 /* the fdevent select pump is single threaded */
-static void register_transport(atransport* transport) {
+void register_transport(atransport* transport) {
     tmsg m;
     m.transport = transport;
     m.action = 1;
     D("transport: %s registered", transport->serial.c_str());
     if (transport_write_action(transport_registration_send, &m)) {
-        fatal_errno("cannot write transport registration socket\n");
+        PLOG(FATAL) << "cannot write transport registration socket";
     }
 }
 
@@ -746,7 +745,7 @@
     m.action = 0;
     D("transport: %s removed", transport->serial.c_str());
     if (transport_write_action(transport_registration_send, &m)) {
-        fatal_errno("cannot write transport registration socket\n");
+        PLOG(FATAL) << "cannot write transport registration socket";
     }
 }
 
@@ -758,6 +757,7 @@
     CHECK_GT(t->ref_count, 0u);
     t->ref_count--;
     if (t->ref_count == 0) {
+        LOG(INFO) << "destroying transport " << t->serial_name();
         t->connection()->Stop();
 #if ADB_HOST
         if (t->IsTcpDevice() && !t->kicked()) {
@@ -1293,6 +1293,7 @@
     register_transport(t);
 }
 
+#if ADB_HOST
 // This should only be used for transports with connection_state == kCsNoPerm.
 void unregister_usb_transport(usb_handle* usb) {
     std::lock_guard<std::recursive_mutex> lock(transport_lock);
@@ -1304,6 +1305,7 @@
         return false;
     });
 }
+#endif
 
 bool check_header(apacket* p, atransport* t) {
     if (p->msg.magic != (p->msg.command ^ 0xffffffff)) {
diff --git a/adb/transport.h b/adb/transport.h
index f854ce5..1350e63 100644
--- a/adb/transport.h
+++ b/adb/transport.h
@@ -362,6 +362,7 @@
 void kick_all_tcp_devices();
 void kick_all_transports();
 
+void register_transport(atransport* transport);
 void register_usb_transport(usb_handle* h, const char* serial,
                             const char* devpath, unsigned writeable);
 
diff --git a/adb/transport_test.cpp b/adb/transport_test.cpp
index 8c628d8..b66f8fa 100644
--- a/adb/transport_test.cpp
+++ b/adb/transport_test.cpp
@@ -19,13 +19,16 @@
 #include <gtest/gtest.h>
 
 #include "adb.h"
+#include "fdevent_test.h"
+
+struct TransportTest : public FdeventTest {};
 
 static void DisconnectFunc(void* arg, atransport*) {
     int* count = reinterpret_cast<int*>(arg);
     ++*count;
 }
 
-TEST(transport, RunDisconnects) {
+TEST_F(TransportTest, RunDisconnects) {
     atransport t;
     // RunDisconnects() can be called with an empty atransport.
     t.RunDisconnects();
@@ -49,7 +52,7 @@
     ASSERT_EQ(0, count);
 }
 
-TEST(transport, SetFeatures) {
+TEST_F(TransportTest, SetFeatures) {
     atransport t;
     ASSERT_EQ(0U, t.features().size());
 
@@ -77,8 +80,7 @@
     ASSERT_EQ(0U, t.features().size());
 }
 
-TEST(transport, parse_banner_no_features) {
-    set_main_thread();
+TEST_F(TransportTest, parse_banner_no_features) {
     atransport t;
 
     parse_banner("host::", &t);
@@ -91,7 +93,7 @@
     ASSERT_EQ(std::string(), t.device);
 }
 
-TEST(transport, parse_banner_product_features) {
+TEST_F(TransportTest, parse_banner_product_features) {
     atransport t;
 
     const char banner[] =
@@ -107,9 +109,8 @@
     ASSERT_EQ(std::string("baz"), t.device);
 }
 
-TEST(transport, parse_banner_features) {
+TEST_F(TransportTest, parse_banner_features) {
     atransport t;
-
     const char banner[] =
         "host::ro.product.name=foo;ro.product.model=bar;ro.product.device=baz;"
         "features=woodly,doodly";
@@ -126,7 +127,7 @@
     ASSERT_EQ(std::string("baz"), t.device);
 }
 
-TEST(transport, test_matches_target) {
+TEST_F(TransportTest, test_matches_target) {
     std::string serial = "foo";
     std::string devpath = "/path/to/bar";
     std::string product = "test_product";
@@ -157,7 +158,7 @@
     }
 }
 
-TEST(transport, test_matches_target_local) {
+TEST_F(TransportTest, test_matches_target_local) {
     std::string serial = "100.100.100.100:5555";
 
     atransport t;
diff --git a/base/logging.cpp b/base/logging.cpp
index d60d91d..bd09069 100644
--- a/base/logging.cpp
+++ b/base/logging.cpp
@@ -53,6 +53,7 @@
 #include <unistd.h>
 #endif
 
+#include <android-base/file.h>
 #include <android-base/macros.h>
 #include <android-base/parseint.h>
 #include <android-base/strings.h>
@@ -71,14 +72,8 @@
   static char progname[MAX_PATH] = {};
 
   if (first) {
-    CHAR longname[MAX_PATH];
-    DWORD nchars = GetModuleFileNameA(nullptr, longname, arraysize(longname));
-    if ((nchars >= arraysize(longname)) || (nchars == 0)) {
-      // String truncation or some other error.
-      strcpy(progname, "<unknown>");
-    } else {
-      strcpy(progname, basename(longname));
-    }
+    snprintf(progname, sizeof(progname), "%s",
+             android::base::Basename(android::base::GetExecutablePath()).c_str());
     first = false;
   }
 
diff --git a/fs_mgr/tests/adb-remount-test.sh b/fs_mgr/tests/adb-remount-test.sh
new file mode 100755
index 0000000..d4ca574
--- /dev/null
+++ b/fs_mgr/tests/adb-remount-test.sh
@@ -0,0 +1,264 @@
+#! /bin/bash
+#
+# adb remount tests (overlayfs focus)
+#
+# Conditions:
+#  - Must be a userdebug build.
+#  - Must be in adb mode.
+#  - Kernel must have overlayfs enabled and patched to support override_creds.
+#  - Must have either squashfs, ext4-dedupe or right-sized partitions.
+#  - Minimum expectation system and vender are overlayfs covered partitions.
+#
+
+# Helper Variables
+
+SPACE=" "
+# A _real_ embedded tab character
+TAB="`echo | tr '\n' '\t'`"
+# A _real_ embedded escape character
+ESCAPE="`echo | tr '\n' '\033'`"
+GREEN="${ESCAPE}[38;5;40m"
+RED="${ESCAPE}[38;5;196m"
+ORANGE="${ESCAPE}[38;5;255:165:0m"
+NORMAL="${ESCAPE}[0m"
+
+# Helper functions
+
+[ "USAGE: inFastboot
+
+Returns: true if device is in fastboot mode" ]
+inFastboot() {
+  fastboot devices | grep "^${ANDROID_SERIAL}[${SPACE}${TAB}]" > /dev/null
+}
+
+[ "USAGE: inAdb
+
+Returns: true if device is in adb mode" ]
+inAdb() {
+  adb devices | grep -v 'List of devices attached' | grep "^${ANDROID_SERIAL}[${SPACE}${TAB}]" > /dev/null
+}
+
+[ "USAGE: adb_sh <commands>
+
+Returns: true if the command succeeded" ]
+adb_sh() {
+  adb shell "${@}"
+}
+
+[ "USAGE: get_property <prop>
+
+Returns the property value" ]
+get_property() {
+  adb_sh getprop ${1} 2>&1 </dev/null
+}
+
+[ "USAGE: isDebuggable
+
+Returns: true if device is (likely) a debug build" ]
+isDebuggable() {
+  if inAdb && [ 1 -ne `get_property ro.debuggable` ]; then
+    false
+  fi
+}
+
+[ "USAGE: adb_su <commands>
+
+Returns: true if the command running as root succeeded" ]
+adb_su() {
+  adb_sh su root "${@}"
+}
+
+[ "USAGE: adb_cat <file> >stdout
+
+Returns: content of file to stdout with carriage returns skipped,
+         true of the file exists" ]
+adb_cat() {
+    OUTPUT="`adb_sh cat ${1} </dev/null 2>&1`"
+    retval=${?}
+    echo "${OUTPUT}" | tr -d '\r'
+    return ${retval}
+}
+
+[ "USAGE: adb_reboot
+
+Returns: true if the reboot command succeeded" ]
+adb_reboot() {
+  adb reboot remount-test
+}
+
+[ "USAGE: adb_wait
+
+Returns: waits until the device has returned" ]
+adb_wait() {
+  adb wait-for-device
+}
+
+[ "USAGE: adb_root
+
+Returns: true if device in root state" ]
+adb_root() {
+  adb root >/dev/null </dev/null 2>&1 &&
+  sleep 1 &&
+  adb_wait &&
+  sleep 1
+}
+
+die() {
+  echo "${RED}[  FAILED  ]${NORMAL} ${@}" >&2
+  exit 1
+}
+
+[ "USAGE: EXPECT_EQ <lval> <rval> [message]
+
+Returns true if (regex) lval matches rval" ]
+EXPECT_EQ() {
+  lval="${1}"
+  rval="${2}"
+  shift 2
+  if ! ( echo X"${rval}" | grep '^X'"${lval}"'$' >/dev/null 2>/dev/null ); then
+    if [ `echo ${lval}${rval}${*} | wc -c` -gt 50 -o "${rval}" != "${rval%
+*}" ]; then
+      echo "ERROR: expected \"${lval}\"" >&2
+      echo "       got \"${rval}\"" |
+        sed ': again
+             N
+             s/\(\n\)\([^ ]\)/\1             \2/
+             t again' >&2
+      if [ -n "${*}" ] ; then
+        echo "       ${*}" >&2
+      fi
+    else
+      echo "ERROR: expected \"${lval}\" got \"${rval}\" ${*}" >&2
+    fi
+    return 1
+  fi
+  if [ -n "${*}" ] ; then
+    if [ X"${lval}" != X"${rval}" ]; then
+      if [ `echo ${lval}${rval}${*} | wc -c` -gt 60 -o "${rval}" != "${rval% *}" ]; then
+        echo "INFO: ok \"${lval}\"" >&2
+        echo "       = \"${rval}\"" |
+          sed ': again
+               N
+               s/\(\n\)\([^ ]\)/\1          \2/
+               t again' >&2
+        if [ -n "${*}" ] ; then
+          echo "      ${*}" >&2
+        fi
+      else
+        echo "INFO: ok \"${lval}\" = \"${rval}\" ${*}" >&2
+      fi
+    else
+      echo "INFO: ok \"${lval}\" ${*}" >&2
+    fi
+  fi
+  return 0
+}
+
+[ "USAGE: check_eq <lval> <rval> [message]
+
+Exits if (regex) lval mismatches rval" ]
+check_eq() {
+  left="${1}"
+  right="${2}"
+  shift 2
+  EXPECT_EQ "${left}" "${right}" ||
+    die "${@}"
+}
+
+[ "USAGE: skip_administrative_mounts
+
+Filters out all administrative (eg: sysfs) mounts" ]
+skip_administrative_mounts() {
+  grep -v -e "^\(overlay\|tmpfs\|none\|sysfs\|proc\|selinuxfs\|debugfs\|bpf\|cg2_bpf\|pstore\|tracefs\|adb\|mtp\|ptp\|devpts\|/data/media\) " -e " /\(cache\|mnt/scratch\|mnt/vendor/persist\|metadata\|data\) "
+}
+
+if [ X"-s" = X"${1}" -a -n "${2}" ]; then
+  export ANDROID_SERIAL="${2}"
+  shift 2
+fi
+
+inFastboot && die "device in fastboot mode"
+inAdb || die "device not in adb mode"
+isDebuggable || die "device not a debug build"
+
+# Do something
+adb_wait || die "wait for device failed"
+adb_sh ls -d /sys/module/overlay </dev/null || die "overlay module not present"
+adb_su ls /sys/module/overlay/parameters/override_creds </dev/null ||
+  die "overlay module can not be used on ANDROID"
+adb_root &&
+  adb_wait &&
+  D=`adb disable-verity 2>&1` ||
+    die "setup for overlay"
+echo "${D}"
+if [ X"${D}" != X"${D##*using overlayfs}" ]; then
+  echo "${GREEN}[       OK ]${NORMAL} using overlayfs" >&2
+fi
+if adb_sh ls -d /data/overlay </dev/null >/dev/null 2>&1; then
+  echo "/data/overlay setup, clearing out" >&2
+  adb_sh rm -rf /data/overlay </dev/null ||
+    die "/data/overlay removal"
+fi
+adb_sh ls -d /cache/overlay </dev/null >/dev/null 2>&1 ||
+  adb_sh ls -d /mnt/scratch/overlay </dev/null >/dev/null 2>&1 ||
+  die "overlay directory setup"
+adb_reboot &&
+  adb_wait &&
+  adb_sh df -k </dev/null | head -1 &&
+  adb_sh df -k </dev/null | grep "^overlay " &&
+  adb_sh df -k </dev/null | grep "^overlay .* /system\$" >/dev/null ||
+  echo "${ORANGE}[  WARNING ]${NORMAL} overlay takeover before remount not complete" >&2
+
+adb_root &&
+  adb_wait &&
+  adb remount &&
+  adb_sh df -k </dev/null | head -1 &&
+  adb_sh df -k </dev/null | grep "^overlay " &&
+  adb_sh df -k </dev/null | grep "^overlay .* /system\$" >/dev/null ||
+  die  "overlay takeover after remount"
+!(adb_sh grep "^overlay " /proc/mounts </dev/null | grep " overlay ro,") &&
+  !(adb_sh grep " rw," /proc/mounts </dev/null |
+  skip_administrative_mounts) ||
+    die "remount overlayfs missed a spot"
+
+adb_su "sed -n '1,/overlay \\/system/p' /proc/mounts" </dev/null |
+  skip_administrative_mounts |
+  grep -v ' \(squashfs\|ext4\|f2fs\) ' &&
+  echo "${ORANGE}[  WARNING ]${NORMAL} overlay takeover after first stage init" >&2 ||
+  echo "${GREEN}[       OK ]${NORMAL} overlay takeover in first stage init" >&2
+
+# Check something
+A="Hello World! $(date)"
+echo "${A}" | adb_sh "cat - > /system/hello"
+echo "${A}" | adb_sh "cat - > /vendor/hello"
+B="`adb_cat /system/hello`" ||
+  die "sytem hello"
+check_eq "${A}" "${B}" system before reboot
+B="`adb_cat /vendor/hello`" ||
+  die "vendor hello"
+check_eq "${A}" "${B}" vendor before reboot
+adb_reboot &&
+  adb_wait &&
+  B="`adb_cat /system/hello`" ||
+  die "re-read system hello after reboot"
+check_eq "${A}" "${B}" system after reboot
+# Only root can read vendor if sepolicy permissions are as expected
+B="`adb_cat /vendor/hello`" &&
+  die "re-read vendor hello after reboot w/o root"
+check_eq "cat: /vendor/hello: Permission denied" "${B}" vendor after reboot w/o root
+adb_root &&
+  adb_wait &&
+  B="`adb_cat /vendor/hello`" ||
+  die "re-read vendor hello after reboot"
+check_eq "${A}" "${B}" vendor after reboot
+adb remount &&
+  adb_sh rm /system/hello /vendor/hello </dev/null ||
+  die "cleanup hello"
+B="`adb_cat /system/hello`" &&
+  die "re-read system hello after rm"
+check_eq "cat: /system/hello: No such file or directory" "${B}" after flash rm
+B="`adb_cat /vendor/hello`" &&
+  die "re-read vendor hello after rm"
+check_eq "cat: /vendor/hello: No such file or directory" "${B}" after flash rm
+
+echo "${GREEN}[  PASSED  ]${NORMAL} adb remount" >&2
diff --git a/logcat/logcat.cpp b/logcat/logcat.cpp
index 115b1a3..87bc6ae 100644
--- a/logcat/logcat.cpp
+++ b/logcat/logcat.cpp
@@ -478,10 +478,10 @@
                     "  -G <size>, --buffer-size=<size>\n"
                     "                  Set size of log ring buffer, may suffix with K or M.\n"
                     "  -L, --last      Dump logs from prior to last reboot\n"
-                    // Leave security (Device Owner only installations) and
-                    // kernel (userdebug and eng) buffers undocumented.
                     "  -b <buffer>, --buffer=<buffer>         Request alternate ring buffer, 'main',\n"
                     "                  'system', 'radio', 'events', 'crash', 'default' or 'all'.\n"
+                    "                  Additionally, 'kernel' for userdebug and eng builds, and\n"
+                    "                  'security' for Device Owner installations.\n"
                     "                  Multiple -b parameters or comma separated list of buffers are\n"
                     "                  allowed. Buffers interleaved. Default -b main,system,crash.\n"
                     "  -B, --binary    Output the log in binary.\n"