diff --git a/adb/adb.cpp b/adb/adb.cpp
index 65fa2e7..702a5a2 100644
--- a/adb/adb.cpp
+++ b/adb/adb.cpp
@@ -257,7 +257,7 @@
                    << connection_str.length() << ")";
     }
 
-    cp->payload = std::move(connection_str);
+    cp->payload.assign(connection_str.begin(), connection_str.end());
     cp->msg.data_length = cp->payload.size();
 
     send_packet(cp, t);
@@ -329,7 +329,8 @@
     handle_offline(t);
 
     t->update_version(p->msg.arg0, p->msg.arg1);
-    parse_banner(p->payload, t);
+    std::string banner(p->payload.begin(), p->payload.end());
+    parse_banner(banner, t);
 
 #if ADB_HOST
     handle_online(t);
@@ -369,8 +370,10 @@
                 send_auth_response(p->payload.data(), p->msg.data_length, t);
                 break;
 #else
-            case ADB_AUTH_SIGNATURE:
-                if (adbd_auth_verify(t->token, sizeof(t->token), p->payload)) {
+            case ADB_AUTH_SIGNATURE: {
+                // TODO: Switch to string_view.
+                std::string signature(p->payload.begin(), p->payload.end());
+                if (adbd_auth_verify(t->token, sizeof(t->token), signature)) {
                     adbd_auth_verified(t);
                     t->failed_auth_attempts = 0;
                 } else {
@@ -378,6 +381,7 @@
                     send_auth_request(t);
                 }
                 break;
+            }
 
             case ADB_AUTH_RSAPUBLICKEY:
                 adbd_auth_confirm_key(p->payload.data(), p->msg.data_length, t);
@@ -392,7 +396,9 @@
 
     case A_OPEN: /* OPEN(local-id, 0, "destination") */
         if (t->online && p->msg.arg0 != 0 && p->msg.arg1 == 0) {
-            asocket* s = create_local_service_socket(p->payload.c_str(), t);
+            // TODO: Switch to string_view.
+            std::string address(p->payload.begin(), p->payload.end());
+            asocket* s = create_local_service_socket(address.c_str(), t);
             if (s == nullptr) {
                 send_close(0, p->msg.arg0, t);
             } else {
diff --git a/adb/adb.h b/adb/adb.h
index c74fa99..86da43c 100644
--- a/adb/adb.h
+++ b/adb/adb.h
@@ -28,6 +28,7 @@
 #include "adb_trace.h"
 #include "fdevent.h"
 #include "socket.h"
+#include "types.h"
 #include "usb.h"
 
 constexpr size_t MAX_PAYLOAD_V1 = 4 * 1024;
@@ -63,20 +64,6 @@
 using TransportId = uint64_t;
 class atransport;
 
-struct amessage {
-    uint32_t command;     /* command identifier constant      */
-    uint32_t arg0;        /* first argument                   */
-    uint32_t arg1;        /* second argument                  */
-    uint32_t data_length; /* length of payload (0 is allowed) */
-    uint32_t data_check;  /* checksum of data payload         */
-    uint32_t magic;       /* command ^ 0xffffffff             */
-};
-
-struct apacket {
-    amessage msg;
-    std::string payload;
-};
-
 uint32_t calculate_apacket_checksum(const apacket* packet);
 
 /* the adisconnect structure is used to record a callback that
diff --git a/adb/client/auth.cpp b/adb/client/auth.cpp
index c3aef16..ade2623 100644
--- a/adb/client/auth.cpp
+++ b/adb/client/auth.cpp
@@ -454,10 +454,8 @@
     p->msg.command = A_AUTH;
     p->msg.arg0 = ADB_AUTH_RSAPUBLICKEY;
 
-    p->payload = std::move(key);
-
     // adbd expects a null-terminated string.
-    p->payload.push_back('\0');
+    p->payload.assign(key.data(), key.data() + key.size() + 1);
     p->msg.data_length = p->payload.size();
     send_packet(p, t);
 }
@@ -482,7 +480,7 @@
 
     p->msg.command = A_AUTH;
     p->msg.arg0 = ADB_AUTH_SIGNATURE;
-    p->payload = std::move(result);
+    p->payload.assign(result.begin(), result.end());
     p->msg.data_length = p->payload.size();
     send_packet(p, t);
 }
diff --git a/adb/daemon/jdwp_service.cpp b/adb/daemon/jdwp_service.cpp
index 9761558..89577cb 100644
--- a/adb/daemon/jdwp_service.cpp
+++ b/adb/daemon/jdwp_service.cpp
@@ -459,7 +459,7 @@
     delete s;
 }
 
-static int jdwp_socket_enqueue(asocket* s, std::string) {
+static int jdwp_socket_enqueue(asocket* s, apacket::payload_type) {
     /* you can't write to this asocket */
     D("LS(%d): JDWP socket received data?", s->id);
     s->peer->close(s->peer);
@@ -474,7 +474,7 @@
      * on the second one, close the connection
      */
     if (!jdwp->pass) {
-        std::string data;
+        apacket::payload_type data;
         data.resize(s->get_max_payload());
         size_t len = jdwp_process_list(&data[0], data.size());
         data.resize(len);
@@ -521,7 +521,8 @@
     for (auto& t : _jdwp_trackers) {
         if (t->peer) {
             // The tracker might not have been connected yet.
-            t->peer->enqueue(t->peer, data);
+            apacket::payload_type payload(data.begin(), data.end());
+            t->peer->enqueue(t->peer, std::move(payload));
         }
     }
 }
@@ -547,7 +548,7 @@
     JdwpTracker* t = (JdwpTracker*)s;
 
     if (t->need_initial) {
-        std::string data;
+        apacket::payload_type data;
         data.resize(s->get_max_payload());
         data.resize(jdwp_process_list_msg(&data[0], data.size()));
         t->need_initial = false;
@@ -555,7 +556,7 @@
     }
 }
 
-static int jdwp_tracker_enqueue(asocket* s, std::string) {
+static int jdwp_tracker_enqueue(asocket* s, apacket::payload_type) {
     /* you can't write to this socket */
     D("LS(%d): JDWP tracker received data?", s->id);
     s->peer->close(s->peer);
diff --git a/adb/range.h b/adb/range.h
deleted file mode 100644
index 7a0b822..0000000
--- a/adb/range.h
+++ /dev/null
@@ -1,65 +0,0 @@
-#pragma once
-
-/*
- * 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.
- */
-
-#include <string>
-
-#include <android-base/logging.h>
-
-struct Range {
-    explicit Range(std::string data) : data_(std::move(data)) {}
-
-    Range(const Range& copy) = delete;
-    Range& operator=(const Range& copy) = delete;
-
-    Range(Range&& move) = default;
-    Range& operator=(Range&& move) = default;
-
-    bool empty() const {
-        return size() == 0;
-    }
-
-    size_t size() const {
-        return data_.size() - begin_offset_ - end_offset_;
-    };
-
-    void drop_front(size_t n) {
-        CHECK_GE(size(), n);
-        begin_offset_ += n;
-    }
-
-    void drop_end(size_t n) {
-        CHECK_GE(size(), n);
-        end_offset_ += n;
-    }
-
-    char* data() {
-        return &data_[0] + begin_offset_;
-    }
-
-    std::string::iterator begin() {
-        return data_.begin() + begin_offset_;
-    }
-
-    std::string::iterator end() {
-        return data_.end() - end_offset_;
-    }
-
-    std::string data_;
-    size_t begin_offset_ = 0;
-    size_t end_offset_ = 0;
-};
diff --git a/adb/socket.h b/adb/socket.h
index 2f09080..e8cb58b 100644
--- a/adb/socket.h
+++ b/adb/socket.h
@@ -24,9 +24,8 @@
 #include <string>
 
 #include "fdevent.h"
-#include "range.h"
+#include "types.h"
 
-struct apacket;
 class atransport;
 
 /* An asocket represents one half of a connection between a local and
@@ -73,7 +72,7 @@
      * peer->ready() when we once again are ready to
      * receive data.
      */
-    int (*enqueue)(asocket* s, std::string data) = nullptr;
+    int (*enqueue)(asocket* s, apacket::payload_type data) = nullptr;
 
     /* ready is called by the peer when it is ready for
      * us to send data via enqueue again
diff --git a/adb/socket_test.cpp b/adb/socket_test.cpp
index 6c4a8b2..04214a2 100644
--- a/adb/socket_test.cpp
+++ b/adb/socket_test.cpp
@@ -118,7 +118,7 @@
         // each write to give the underlying implementation time to flush.
         bool socket_filled = false;
         for (int i = 0; i < 128; ++i) {
-            std::string data;
+            apacket::payload_type data;
             data.resize(MAX_PAYLOAD);
             arg->bytes_written += data.size();
             int ret = s->enqueue(s, std::move(data));
diff --git a/adb/sockets.cpp b/adb/sockets.cpp
index 0887e6f..f3fce27 100644
--- a/adb/sockets.cpp
+++ b/adb/sockets.cpp
@@ -37,8 +37,8 @@
 
 #include "adb.h"
 #include "adb_io.h"
-#include "range.h"
 #include "transport.h"
+#include "types.h"
 
 static std::recursive_mutex& local_socket_list_lock = *new std::recursive_mutex();
 static unsigned local_socket_next_id = 1;
@@ -147,7 +147,7 @@
 // Returns false if the socket has been closed and destroyed as a side-effect of this function.
 static bool local_socket_flush_outgoing(asocket* s) {
     const size_t max_payload = s->get_max_payload();
-    std::string data;
+    apacket::payload_type data;
     data.resize(max_payload);
     char* x = &data[0];
     size_t avail = max_payload;
@@ -214,7 +214,7 @@
     return true;
 }
 
-static int local_socket_enqueue(asocket* s, std::string data) {
+static int local_socket_enqueue(asocket* s, apacket::payload_type data) {
     D("LS(%d): enqueue %zu", s->id, data.size());
 
     Range r(std::move(data));
@@ -394,7 +394,7 @@
 }
 #endif /* ADB_HOST */
 
-static int remote_socket_enqueue(asocket* s, std::string data) {
+static int remote_socket_enqueue(asocket* s, apacket::payload_type data) {
     D("entered remote_socket_enqueue RS(%d) WRITE fd=%d peer.fd=%d", s->id, s->fd, s->peer->fd);
     apacket* p = get_apacket();
 
@@ -476,8 +476,7 @@
     p->msg.arg0 = s->id;
 
     // adbd expects a null-terminated string.
-    p->payload = destination;
-    p->payload.push_back('\0');
+    p->payload.assign(destination, destination + strlen(destination) + 1);
     p->msg.data_length = p->payload.size();
 
     if (p->msg.data_length > s->get_max_payload()) {
@@ -612,7 +611,7 @@
 
 #endif  // ADB_HOST
 
-static int smart_socket_enqueue(asocket* s, std::string data) {
+static int smart_socket_enqueue(asocket* s, apacket::payload_type data) {
 #if ADB_HOST
     char* service = nullptr;
     char* serial = nullptr;
@@ -623,7 +622,8 @@
     D("SS(%d): enqueue %zu", s->id, data.size());
 
     if (s->smart_socket_data.empty()) {
-        s->smart_socket_data = std::move(data);
+        // TODO: Make this a BlockChain?
+        s->smart_socket_data.assign(data.begin(), data.end());
     } else {
         std::copy(data.begin(), data.end(), std::back_inserter(s->smart_socket_data));
     }
diff --git a/adb/sysdeps/uio.h b/adb/sysdeps/uio.h
new file mode 100644
index 0000000..d06ef89
--- /dev/null
+++ b/adb/sysdeps/uio.h
@@ -0,0 +1,39 @@
+/*
+ * 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.
+ */
+
+#pragma once
+
+#include <sys/types.h>
+
+#if defined(_WIN32)
+
+// Layout of this struct must match struct WSABUF (verified via static assert in sysdeps_win32.cpp)
+struct adb_iovec {
+    size_t iov_len;
+    void* iov_base;
+};
+
+ssize_t adb_writev(int fd, const adb_iovec* iov, int iovcnt);
+
+#else
+
+#include <sys/uio.h>
+using adb_iovec = struct iovec;
+#define adb_writev writev
+
+#endif
+
+#pragma GCC poison writev
diff --git a/adb/sysdeps_win32.cpp b/adb/sysdeps_win32.cpp
index 7d35fb6..bfac342 100644
--- a/adb/sysdeps_win32.cpp
+++ b/adb/sysdeps_win32.cpp
@@ -36,6 +36,7 @@
 
 #include <android-base/errors.h>
 #include <android-base/logging.h>
+#include <android-base/macros.h>
 #include <android-base/stringprintf.h>
 #include <android-base/strings.h>
 #include <android-base/utf8.h>
@@ -43,6 +44,8 @@
 #include "adb.h"
 #include "adb_utils.h"
 
+#include "sysdeps/uio.h"
+
 extern void fatal(const char *fmt, ...);
 
 /* forward declarations */
@@ -57,6 +60,7 @@
     int (*_fh_lseek)(FH, int, int);
     int (*_fh_read)(FH, void*, int);
     int (*_fh_write)(FH, const void*, int);
+    int (*_fh_writev)(FH, const adb_iovec*, int);
 } FHClassRec;
 
 static void _fh_file_init(FH);
@@ -64,6 +68,7 @@
 static int _fh_file_lseek(FH, int, int);
 static int _fh_file_read(FH, void*, int);
 static int _fh_file_write(FH, const void*, int);
+static int _fh_file_writev(FH, const adb_iovec*, int);
 
 static const FHClassRec _fh_file_class = {
     _fh_file_init,
@@ -71,6 +76,7 @@
     _fh_file_lseek,
     _fh_file_read,
     _fh_file_write,
+    _fh_file_writev,
 };
 
 static void _fh_socket_init(FH);
@@ -78,6 +84,7 @@
 static int _fh_socket_lseek(FH, int, int);
 static int _fh_socket_read(FH, void*, int);
 static int _fh_socket_write(FH, const void*, int);
+static int _fh_socket_writev(FH, const adb_iovec*, int);
 
 static const FHClassRec _fh_socket_class = {
     _fh_socket_init,
@@ -85,6 +92,7 @@
     _fh_socket_lseek,
     _fh_socket_read,
     _fh_socket_write,
+    _fh_socket_writev,
 };
 
 #define assert(cond)                                                                       \
@@ -248,57 +256,88 @@
 /**************************************************************************/
 /**************************************************************************/
 
-static void _fh_file_init( FH  f ) {
+static void _fh_file_init(FH f) {
     f->fh_handle = INVALID_HANDLE_VALUE;
 }
 
-static int _fh_file_close( FH  f ) {
-    CloseHandle( f->fh_handle );
+static int _fh_file_close(FH f) {
+    CloseHandle(f->fh_handle);
     f->fh_handle = INVALID_HANDLE_VALUE;
     return 0;
 }
 
-static int _fh_file_read( FH  f,  void*  buf, int   len ) {
-    DWORD  read_bytes;
+static int _fh_file_read(FH f, void* buf, int len) {
+    DWORD read_bytes;
 
-    if ( !ReadFile( f->fh_handle, buf, (DWORD)len, &read_bytes, NULL ) ) {
-        D( "adb_read: could not read %d bytes from %s", len, f->name );
+    if (!ReadFile(f->fh_handle, buf, (DWORD)len, &read_bytes, NULL)) {
+        D("adb_read: could not read %d bytes from %s", len, f->name);
         errno = EIO;
         return -1;
     } else if (read_bytes < (DWORD)len) {
         f->eof = 1;
     }
-    return (int)read_bytes;
+    return read_bytes;
 }
 
-static int _fh_file_write( FH  f,  const void*  buf, int   len ) {
-    DWORD  wrote_bytes;
+static int _fh_file_write(FH f, const void* buf, int len) {
+    DWORD wrote_bytes;
 
-    if ( !WriteFile( f->fh_handle, buf, (DWORD)len, &wrote_bytes, NULL ) ) {
-        D( "adb_file_write: could not write %d bytes from %s", len, f->name );
+    if (!WriteFile(f->fh_handle, buf, (DWORD)len, &wrote_bytes, NULL)) {
+        D("adb_file_write: could not write %d bytes from %s", len, f->name);
         errno = EIO;
         return -1;
     } else if (wrote_bytes < (DWORD)len) {
         f->eof = 1;
     }
-    return  (int)wrote_bytes;
+    return wrote_bytes;
 }
 
-static int _fh_file_lseek( FH  f, int  pos, int  origin ) {
-    DWORD  method;
-    DWORD  result;
+static int _fh_file_writev(FH f, const adb_iovec* iov, int iovcnt) {
+    if (iovcnt <= 0) {
+        errno = EINVAL;
+        return -1;
+    }
 
-    switch (origin)
-    {
-        case SEEK_SET:  method = FILE_BEGIN; break;
-        case SEEK_CUR:  method = FILE_CURRENT; break;
-        case SEEK_END:  method = FILE_END; break;
+    DWORD wrote_bytes = 0;
+
+    for (int i = 0; i < iovcnt; ++i) {
+        ssize_t rc = _fh_file_write(f, iov[i].iov_base, iov[i].iov_len);
+        if (rc == -1) {
+            return wrote_bytes > 0 ? wrote_bytes : -1;
+        } else if (rc == 0) {
+            return wrote_bytes;
+        }
+
+        wrote_bytes += rc;
+
+        if (static_cast<size_t>(rc) < iov[i].iov_len) {
+            return wrote_bytes;
+        }
+    }
+
+    return wrote_bytes;
+}
+
+static int _fh_file_lseek(FH f, int pos, int origin) {
+    DWORD method;
+    DWORD result;
+
+    switch (origin) {
+        case SEEK_SET:
+            method = FILE_BEGIN;
+            break;
+        case SEEK_CUR:
+            method = FILE_CURRENT;
+            break;
+        case SEEK_END:
+            method = FILE_END;
+            break;
         default:
             errno = EINVAL;
             return -1;
     }
 
-    result = SetFilePointer( f->fh_handle, pos, NULL, method );
+    result = SetFilePointer(f->fh_handle, pos, NULL, method);
     if (result == INVALID_SET_FILE_POINTER) {
         errno = EIO;
         return -1;
@@ -308,7 +347,6 @@
     return (int)result;
 }
 
-
 /**************************************************************************/
 /**************************************************************************/
 /*****                                                                *****/
@@ -317,12 +355,11 @@
 /**************************************************************************/
 /**************************************************************************/
 
-int  adb_open(const char*  path, int  options)
-{
-    FH  f;
+int adb_open(const char* path, int options) {
+    FH f;
 
-    DWORD  desiredAccess       = 0;
-    DWORD  shareMode           = FILE_SHARE_READ | FILE_SHARE_WRITE;
+    DWORD desiredAccess = 0;
+    DWORD shareMode = FILE_SHARE_READ | FILE_SHARE_WRITE;
 
     switch (options) {
         case O_RDONLY:
@@ -340,8 +377,8 @@
             return -1;
     }
 
-    f = _fh_alloc( &_fh_file_class );
-    if ( !f ) {
+    f = _fh_alloc(&_fh_file_class);
+    if (!f) {
         return -1;
     }
 
@@ -349,21 +386,21 @@
     if (!android::base::UTF8ToWide(path, &path_wide)) {
         return -1;
     }
-    f->fh_handle = CreateFileW( path_wide.c_str(), desiredAccess, shareMode,
-                                NULL, OPEN_EXISTING, 0, NULL );
+    f->fh_handle =
+        CreateFileW(path_wide.c_str(), desiredAccess, shareMode, NULL, OPEN_EXISTING, 0, NULL);
 
-    if ( f->fh_handle == INVALID_HANDLE_VALUE ) {
+    if (f->fh_handle == INVALID_HANDLE_VALUE) {
         const DWORD err = GetLastError();
         _fh_close(f);
-        D( "adb_open: could not open '%s': ", path );
+        D("adb_open: could not open '%s': ", path);
         switch (err) {
             case ERROR_FILE_NOT_FOUND:
-                D( "file not found" );
+                D("file not found");
                 errno = ENOENT;
                 return -1;
 
             case ERROR_PATH_NOT_FOUND:
-                D( "path not found" );
+                D("path not found");
                 errno = ENOTDIR;
                 return -1;
 
@@ -374,18 +411,17 @@
         }
     }
 
-    snprintf( f->name, sizeof(f->name), "%d(%s)", _fh_to_int(f), path );
-    D( "adb_open: '%s' => fd %d", path, _fh_to_int(f) );
+    snprintf(f->name, sizeof(f->name), "%d(%s)", _fh_to_int(f), path);
+    D("adb_open: '%s' => fd %d", path, _fh_to_int(f));
     return _fh_to_int(f);
 }
 
 /* ignore mode on Win32 */
-int  adb_creat(const char*  path, int  mode)
-{
-    FH  f;
+int adb_creat(const char* path, int mode) {
+    FH f;
 
-    f = _fh_alloc( &_fh_file_class );
-    if ( !f ) {
+    f = _fh_alloc(&_fh_file_class);
+    if (!f) {
         return -1;
     }
 
@@ -393,23 +429,21 @@
     if (!android::base::UTF8ToWide(path, &path_wide)) {
         return -1;
     }
-    f->fh_handle = CreateFileW( path_wide.c_str(), GENERIC_WRITE,
-                                FILE_SHARE_READ | FILE_SHARE_WRITE,
-                                NULL, CREATE_ALWAYS, FILE_ATTRIBUTE_NORMAL,
-                                NULL );
+    f->fh_handle = CreateFileW(path_wide.c_str(), GENERIC_WRITE, FILE_SHARE_READ | FILE_SHARE_WRITE,
+                               NULL, CREATE_ALWAYS, FILE_ATTRIBUTE_NORMAL, NULL);
 
-    if ( f->fh_handle == INVALID_HANDLE_VALUE ) {
+    if (f->fh_handle == INVALID_HANDLE_VALUE) {
         const DWORD err = GetLastError();
         _fh_close(f);
-        D( "adb_creat: could not open '%s': ", path );
+        D("adb_creat: could not open '%s': ", path);
         switch (err) {
             case ERROR_FILE_NOT_FOUND:
-                D( "file not found" );
+                D("file not found");
                 errno = ENOENT;
                 return -1;
 
             case ERROR_PATH_NOT_FOUND:
-                D( "path not found" );
+                D("path not found");
                 errno = ENOTDIR;
                 return -1;
 
@@ -419,57 +453,64 @@
                 return -1;
         }
     }
-    snprintf( f->name, sizeof(f->name), "%d(%s)", _fh_to_int(f), path );
-    D( "adb_creat: '%s' => fd %d", path, _fh_to_int(f) );
+    snprintf(f->name, sizeof(f->name), "%d(%s)", _fh_to_int(f), path);
+    D("adb_creat: '%s' => fd %d", path, _fh_to_int(f));
     return _fh_to_int(f);
 }
 
-
-int  adb_read(int  fd, void* buf, int len)
-{
-    FH     f = _fh_from_int(fd, __func__);
+int adb_read(int fd, void* buf, int len) {
+    FH f = _fh_from_int(fd, __func__);
 
     if (f == NULL) {
+        errno = EBADF;
         return -1;
     }
 
-    return f->clazz->_fh_read( f, buf, len );
+    return f->clazz->_fh_read(f, buf, len);
 }
 
-
-int  adb_write(int  fd, const void*  buf, int  len)
-{
-    FH     f = _fh_from_int(fd, __func__);
+int adb_write(int fd, const void* buf, int len) {
+    FH f = _fh_from_int(fd, __func__);
 
     if (f == NULL) {
+        errno = EBADF;
         return -1;
     }
 
     return f->clazz->_fh_write(f, buf, len);
 }
 
+ssize_t adb_writev(int fd, const adb_iovec* iov, int iovcnt) {
+    FH f = _fh_from_int(fd, __func__);
 
-int  adb_lseek(int  fd, int  pos, int  where)
-{
-    FH     f = _fh_from_int(fd, __func__);
+    if (f == NULL) {
+        errno = EBADF;
+        return -1;
+    }
+
+    return f->clazz->_fh_writev(f, iov, iovcnt);
+}
+
+int adb_lseek(int fd, int pos, int where) {
+    FH f = _fh_from_int(fd, __func__);
 
     if (!f) {
+        errno = EBADF;
         return -1;
     }
 
     return f->clazz->_fh_lseek(f, pos, where);
 }
 
-
-int  adb_close(int  fd)
-{
-    FH   f = _fh_from_int(fd, __func__);
+int adb_close(int fd) {
+    FH f = _fh_from_int(fd, __func__);
 
     if (!f) {
+        errno = EBADF;
         return -1;
     }
 
-    D( "adb_close: %s", f->name);
+    D("adb_close: %s", f->name);
     _fh_close(f);
     return 0;
 }
@@ -582,7 +623,7 @@
     f->fh_socket = INVALID_SOCKET;
 }
 
-static int _fh_socket_close( FH  f ) {
+static int _fh_socket_close(FH f) {
     if (f->fh_socket != INVALID_SOCKET) {
         /* gently tell any peer that we're closing the socket */
         if (shutdown(f->fh_socket, SD_BOTH) == SOCKET_ERROR) {
@@ -603,13 +644,13 @@
     return 0;
 }
 
-static int _fh_socket_lseek( FH  f, int pos, int origin ) {
+static int _fh_socket_lseek(FH f, int pos, int origin) {
     errno = EPIPE;
     return -1;
 }
 
 static int _fh_socket_read(FH f, void* buf, int len) {
-    int  result = recv(f->fh_socket, reinterpret_cast<char*>(buf), len, 0);
+    int result = recv(f->fh_socket, reinterpret_cast<char*>(buf), len, 0);
     if (result == SOCKET_ERROR) {
         const DWORD err = WSAGetLastError();
         // WSAEWOULDBLOCK is normal with a non-blocking socket, so don't trace
@@ -621,11 +662,11 @@
         _socket_set_errno(err);
         result = -1;
     }
-    return  result;
+    return result;
 }
 
 static int _fh_socket_write(FH f, const void* buf, int len) {
-    int  result = send(f->fh_socket, reinterpret_cast<const char*>(buf), len, 0);
+    int result = send(f->fh_socket, reinterpret_cast<const char*>(buf), len, 0);
     if (result == SOCKET_ERROR) {
         const DWORD err = WSAGetLastError();
         // WSAEWOULDBLOCK is normal with a non-blocking socket, so don't trace
@@ -639,13 +680,44 @@
     } else {
         // According to https://code.google.com/p/chromium/issues/detail?id=27870
         // Winsock Layered Service Providers may cause this.
-        CHECK_LE(result, len) << "Tried to write " << len << " bytes to "
-                              << f->name << ", but " << result
-                              << " bytes reportedly written";
+        CHECK_LE(result, len) << "Tried to write " << len << " bytes to " << f->name << ", but "
+                              << result << " bytes reportedly written";
     }
     return result;
 }
 
+// Make sure that adb_iovec is compatible with WSABUF.
+static_assert(sizeof(adb_iovec) == sizeof(WSABUF), "");
+static_assert(SIZEOF_MEMBER(adb_iovec, iov_len) == SIZEOF_MEMBER(WSABUF, len), "");
+static_assert(offsetof(adb_iovec, iov_len) == offsetof(WSABUF, len), "");
+
+static_assert(SIZEOF_MEMBER(adb_iovec, iov_base) == SIZEOF_MEMBER(WSABUF, buf), "");
+static_assert(offsetof(adb_iovec, iov_base) == offsetof(WSABUF, buf), "");
+
+static int _fh_socket_writev(FH f, const adb_iovec* iov, int iovcnt) {
+    if (iovcnt <= 0) {
+        errno = EINVAL;
+        return -1;
+    }
+
+    WSABUF* wsabuf = reinterpret_cast<WSABUF*>(const_cast<adb_iovec*>(iov));
+    DWORD bytes_written = 0;
+    int result = WSASend(f->fh_socket, wsabuf, iovcnt, &bytes_written, 0, nullptr, nullptr);
+    if (result == SOCKET_ERROR) {
+        const DWORD err = WSAGetLastError();
+        // WSAEWOULDBLOCK is normal with a non-blocking socket, so don't trace
+        // that to reduce spam and confusion.
+        if (err != WSAEWOULDBLOCK) {
+            D("send fd %d failed: %s", _fh_to_int(f),
+              android::base::SystemErrorCodeToString(err).c_str());
+        }
+        _socket_set_errno(err);
+        result = -1;
+    }
+    CHECK_GE(static_cast<DWORD>(std::numeric_limits<int>::max()), bytes_written);
+    return static_cast<int>(bytes_written);
+}
+
 /**************************************************************************/
 /**************************************************************************/
 /*****                                                                *****/
@@ -654,23 +726,15 @@
 /**************************************************************************/
 /**************************************************************************/
 
-#include <winsock2.h>
-
-static int  _winsock_init;
-
-static void
-_init_winsock( void )
-{
-    // TODO: Multiple threads calling this may potentially cause multiple calls
-    // to WSAStartup() which offers no real benefit.
-    if (!_winsock_init) {
-        WSADATA  wsaData;
-        int      rc = WSAStartup( MAKEWORD(2,2), &wsaData);
+static int _init_winsock(void) {
+    static std::once_flag once;
+    std::call_once(once, []() {
+        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());
         }
-        _winsock_init = 1;
 
         // Note that we do not call atexit() to register WSACleanup to be called
         // at normal process termination because:
@@ -685,9 +749,12 @@
         //    setupapi.dll which tries to load wintrust.dll which tries to load
         //    crypt32.dll which calls atexit() which tries to acquire the C
         //    Runtime lock that the other thread holds.
-    }
+    });
+    return 0;
 }
 
+static int _winsock_init = _init_winsock();
+
 // Map a socket type to an explicit socket protocol instead of using the socket
 // protocol of 0. Explicit socket protocols are used by most apps and we should
 // do the same to reduce the chance of exercising uncommon code-paths that might
@@ -715,8 +782,6 @@
         return -1;
     }
 
-    if (!_winsock_init) _init_winsock();
-
     memset(&addr, 0, sizeof(addr));
     addr.sin_family = AF_INET;
     addr.sin_port = htons(port);
@@ -765,8 +830,6 @@
         return -1;
     }
 
-    if (!_winsock_init) _init_winsock();
-
     memset(&addr, 0, sizeof(addr));
     addr.sin_family = AF_INET;
     addr.sin_port = htons(port);
@@ -843,8 +906,6 @@
         return -1;
     }
 
-    if (!_winsock_init) _init_winsock();
-
     struct addrinfo hints;
     memset(&hints, 0, sizeof(hints));
     hints.ai_family = AF_UNSPEC;
@@ -912,52 +973,49 @@
     return fd;
 }
 
-int  adb_register_socket(SOCKET s) {
-    FH f = _fh_alloc( &_fh_socket_class );
+int adb_register_socket(SOCKET s) {
+    FH f = _fh_alloc(&_fh_socket_class);
     f->fh_socket = s;
     return _fh_to_int(f);
 }
 
 #undef accept
-int  adb_socket_accept(int  serverfd, struct sockaddr*  addr, socklen_t  *addrlen)
-{
-    FH   serverfh = _fh_from_int(serverfd, __func__);
+int adb_socket_accept(int serverfd, struct sockaddr* addr, socklen_t* addrlen) {
+    FH serverfh = _fh_from_int(serverfd, __func__);
 
-    if ( !serverfh || serverfh->clazz != &_fh_socket_class ) {
+    if (!serverfh || serverfh->clazz != &_fh_socket_class) {
         D("adb_socket_accept: invalid fd %d", serverfd);
         errno = EBADF;
         return -1;
     }
 
-    unique_fh fh(_fh_alloc( &_fh_socket_class ));
+    unique_fh fh(_fh_alloc(&_fh_socket_class));
     if (!fh) {
         PLOG(ERROR) << "adb_socket_accept: failed to allocate accepted socket "
                        "descriptor";
         return -1;
     }
 
-    fh->fh_socket = accept( serverfh->fh_socket, addr, addrlen );
+    fh->fh_socket = accept(serverfh->fh_socket, addr, addrlen);
     if (fh->fh_socket == INVALID_SOCKET) {
         const DWORD err = WSAGetLastError();
-        LOG(ERROR) << "adb_socket_accept: accept on fd " << serverfd <<
-                      " failed: " + android::base::SystemErrorCodeToString(err);
-        _socket_set_errno( err );
+        LOG(ERROR) << "adb_socket_accept: accept on fd " << serverfd
+                   << " failed: " + android::base::SystemErrorCodeToString(err);
+        _socket_set_errno(err);
         return -1;
     }
 
     const int fd = _fh_to_int(fh.get());
-    snprintf( fh->name, sizeof(fh->name), "%d(accept:%s)", fd, serverfh->name );
-    D( "adb_socket_accept on fd %d returns fd %d", serverfd, fd );
+    snprintf(fh->name, sizeof(fh->name), "%d(accept:%s)", fd, serverfh->name);
+    D("adb_socket_accept on fd %d returns fd %d", serverfd, fd);
     fh.release();
-    return  fd;
+    return fd;
 }
 
+int adb_setsockopt(int fd, int level, int optname, const void* optval, socklen_t optlen) {
+    FH fh = _fh_from_int(fd, __func__);
 
-int  adb_setsockopt( int  fd, int  level, int  optname, const void*  optval, socklen_t  optlen )
-{
-    FH   fh = _fh_from_int(fd, __func__);
-
-    if ( !fh || fh->clazz != &_fh_socket_class ) {
+    if (!fh || fh->clazz != &_fh_socket_class) {
         D("adb_setsockopt: invalid fd %d", fd);
         errno = EBADF;
         return -1;
@@ -967,13 +1025,13 @@
     // to set SOL_SOCKET, SO_SNDBUF/SO_RCVBUF, ignore it since the OS has
     // auto-tuning.
 
-    int result = setsockopt( fh->fh_socket, level, optname,
-                             reinterpret_cast<const char*>(optval), optlen );
-    if ( result == SOCKET_ERROR ) {
+    int result =
+        setsockopt(fh->fh_socket, level, optname, reinterpret_cast<const char*>(optval), optlen);
+    if (result == SOCKET_ERROR) {
         const DWORD err = WSAGetLastError();
-        D("adb_setsockopt: setsockopt on fd %d level %d optname %d failed: %s\n",
-          fd, level, optname, android::base::SystemErrorCodeToString(err).c_str());
-        _socket_set_errno( err );
+        D("adb_setsockopt: setsockopt on fd %d level %d optname %d failed: %s\n", fd, level,
+          optname, android::base::SystemErrorCodeToString(err).c_str());
+        _socket_set_errno(err);
         result = -1;
     }
     return result;
diff --git a/adb/transport.cpp b/adb/transport.cpp
index 2867d38..92c52e2 100644
--- a/adb/transport.cpp
+++ b/adb/transport.cpp
@@ -335,7 +335,7 @@
     delete tracker;
 }
 
-static int device_tracker_enqueue(asocket* socket, std::string) {
+static int device_tracker_enqueue(asocket* socket, apacket::payload_type) {
     /* you can't read from a device tracker, close immediately */
     device_tracker_close(socket);
     return -1;
@@ -344,7 +344,7 @@
 static int device_tracker_send(device_tracker* tracker, const std::string& string) {
     asocket* peer = tracker->socket.peer;
 
-    std::string data;
+    apacket::payload_type data;
     data.resize(4 + string.size());
     char buf[5];
     snprintf(buf, sizeof(buf), "%04x", static_cast<int>(string.size()));
diff --git a/adb/types.h b/adb/types.h
new file mode 100644
index 0000000..dd3e063
--- /dev/null
+++ b/adb/types.h
@@ -0,0 +1,163 @@
+/*
+ * 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.
+ */
+
+#pragma once
+
+#include <algorithm>
+#include <utility>
+
+#include <android-base/logging.h>
+
+#include "sysdeps/memory.h"
+
+// Essentially std::vector<char>, except without zero initialization or reallocation.
+struct Block {
+    using iterator = char*;
+
+    Block() {}
+
+    explicit Block(size_t size) { allocate(size); }
+
+    template <typename Iterator>
+    Block(Iterator begin, Iterator end) : Block(end - begin) {
+        std::copy(begin, end, data_);
+    }
+
+    Block(const Block& copy) = delete;
+    Block(Block&& move) {
+        std::swap(data_, move.data_);
+        std::swap(capacity_, move.capacity_);
+        std::swap(size_, move.size_);
+    }
+
+    Block& operator=(const Block& copy) = delete;
+    Block& operator=(Block&& move) {
+        clear();
+
+        std::swap(data_, move.data_);
+        std::swap(capacity_, move.capacity_);
+        std::swap(size_, move.size_);
+
+        return *this;
+    }
+
+    ~Block() { clear(); }
+
+    void resize(size_t new_size) {
+        if (!data_) {
+            allocate(new_size);
+        } else {
+            CHECK_GE(capacity_, new_size);
+            size_ = new_size;
+        }
+    }
+
+    template <typename InputIt>
+    void assign(InputIt begin, InputIt end) {
+        clear();
+        allocate(end - begin);
+        std::copy(begin, end, data_);
+    }
+
+    void clear() {
+        free(data_);
+        capacity_ = 0;
+        size_ = 0;
+    }
+
+    size_t capacity() const { return capacity_; }
+    size_t size() const { return size_; }
+    bool empty() const { return size() == 0; }
+
+    char* data() { return data_; }
+    const char* data() const { return data_; }
+
+    char* begin() { return data_; }
+    const char* begin() const { return data_; }
+
+    char* end() { return data() + size_; }
+    const char* end() const { return data() + size_; }
+
+    char& operator[](size_t idx) { return data()[idx]; }
+    const char& operator[](size_t idx) const { return data()[idx]; }
+
+    bool operator==(const Block& rhs) const {
+        return size() == rhs.size() && memcmp(data(), rhs.data(), size()) == 0;
+    }
+
+  private:
+    void allocate(size_t size) {
+        CHECK(data_ == nullptr);
+        CHECK_EQ(0ULL, capacity_);
+        CHECK_EQ(0ULL, size_);
+        if (size != 0) {
+            data_ = static_cast<char*>(malloc(size));
+            capacity_ = size;
+            size_ = size;
+        }
+    }
+
+    char* data_ = nullptr;
+    size_t capacity_ = 0;
+    size_t size_ = 0;
+};
+
+struct amessage {
+    uint32_t command;     /* command identifier constant      */
+    uint32_t arg0;        /* first argument                   */
+    uint32_t arg1;        /* second argument                  */
+    uint32_t data_length; /* length of payload (0 is allowed) */
+    uint32_t data_check;  /* checksum of data payload         */
+    uint32_t magic;       /* command ^ 0xffffffff             */
+};
+
+struct apacket {
+    using payload_type = Block;
+    amessage msg;
+    payload_type payload;
+};
+
+struct Range {
+    explicit Range(apacket::payload_type data) : data_(std::move(data)) {}
+
+    Range(const Range& copy) = delete;
+    Range& operator=(const Range& copy) = delete;
+
+    Range(Range&& move) = default;
+    Range& operator=(Range&& move) = default;
+
+    size_t size() const { return data_.size() - begin_offset_ - end_offset_; };
+    bool empty() const { return size() == 0; }
+
+    void drop_front(size_t n) {
+        CHECK_GE(size(), n);
+        begin_offset_ += n;
+    }
+
+    void drop_end(size_t n) {
+        CHECK_GE(size(), n);
+        end_offset_ += n;
+    }
+
+    char* data() { return &data_[0] + begin_offset_; }
+
+    apacket::payload_type::iterator begin() { return data_.begin() + begin_offset_; }
+    apacket::payload_type::iterator end() { return data_.end() - end_offset_; }
+
+    apacket::payload_type data_;
+    size_t begin_offset_ = 0;
+    size_t end_offset_ = 0;
+};