adb: Remove most C-style allocations

This change gets rid of most malloc/calloc/free calls. The future is
now!

Bug: None
Test: test_device.py
Change-Id: Iccfe3bd4fe45a0319bd9f23b8cbff4c7070c9f4d
diff --git a/adb/client/commandline.cpp b/adb/client/commandline.cpp
index 80d0dd3..7791895 100644
--- a/adb/client/commandline.cpp
+++ b/adb/client/commandline.cpp
@@ -362,9 +362,8 @@
 }
 
 static void copy_to_file(int inFd, int outFd) {
-    const size_t BUFSIZE = 32 * 1024;
-    char* buf = (char*) malloc(BUFSIZE);
-    if (buf == nullptr) fatal("couldn't allocate buffer for copy_to_file");
+    constexpr size_t BUFSIZE = 32 * 1024;
+    std::vector<char> buf(BUFSIZE);
     int len;
     long total = 0;
     int old_stdin_mode = -1;
@@ -376,9 +375,9 @@
 
     while (true) {
         if (inFd == STDIN_FILENO) {
-            len = unix_read(inFd, buf, BUFSIZE);
+            len = unix_read(inFd, buf.data(), BUFSIZE);
         } else {
-            len = adb_read(inFd, buf, BUFSIZE);
+            len = adb_read(inFd, buf.data(), BUFSIZE);
         }
         if (len == 0) {
             D("copy_to_file() : read 0 bytes; exiting");
@@ -389,10 +388,10 @@
             break;
         }
         if (outFd == STDOUT_FILENO) {
-            fwrite(buf, 1, len, stdout);
+            fwrite(buf.data(), 1, len, stdout);
             fflush(stdout);
         } else {
-            adb_write(outFd, buf, len);
+            adb_write(outFd, buf.data(), len);
         }
         total += len;
     }
@@ -400,7 +399,6 @@
     stdinout_raw_epilogue(inFd, outFd, old_stdin_mode, old_stdout_mode);
 
     D("copy_to_file() finished after %lu bytes", total);
-    free(buf);
 }
 
 static void send_window_size_change(int fd, std::unique_ptr<ShellProtocol>& shell) {
@@ -1142,24 +1140,22 @@
 static void write_zeros(int bytes, int fd) {
     int old_stdin_mode = -1;
     int old_stdout_mode = -1;
-    char* buf = (char*) calloc(1, bytes);
-    if (buf == nullptr) fatal("couldn't allocate buffer for write_zeros");
+    std::vector<char> buf(bytes);
 
     D("write_zeros(%d) -> %d", bytes, fd);
 
     stdinout_raw_prologue(-1, fd, old_stdin_mode, old_stdout_mode);
 
     if (fd == STDOUT_FILENO) {
-        fwrite(buf, 1, bytes, stdout);
+        fwrite(buf.data(), 1, bytes, stdout);
         fflush(stdout);
     } else {
-        adb_write(fd, buf, bytes);
+        adb_write(fd, buf.data(), bytes);
     }
 
     stdinout_raw_prologue(-1, fd, old_stdin_mode, old_stdout_mode);
 
     D("write_zeros() finished");
-    free(buf);
 }
 
 static int backup(int argc, const char** argv) {