From 6d92997ec4285caebe94064158a8cc017bbf5caa Mon Sep 17 00:00:00 2001
From: Elliott Hughes <enh@google.com>
Date: Tue, 27 Oct 2015 13:40:35 -0700
Subject: [PATCH] Don't use VLAs in adb.

This makes no measurable difference to the sync time; "adb sync" of
everything on /system for a Nexus 9 still takes 20s.

Change-Id: Ifa2626f7453937e43856b9c4ee06e1f5db0aa273
---
 adb/Android.mk           |  1 +
 adb/file_sync_client.cpp | 23 ++++++++++++-----------
 adb/sysdeps_win32.cpp    |  5 ++---
 3 files changed, 15 insertions(+), 14 deletions(-)

diff --git a/adb/Android.mk b/adb/Android.mk
index 2538e2e3f..c507905db 100644
--- a/adb/Android.mk
+++ b/adb/Android.mk
@@ -14,6 +14,7 @@ ADB_COMMON_CFLAGS := \
     -Wall -Wextra -Werror \
     -Wno-unused-parameter \
     -Wno-missing-field-initializers \
+    -Wvla \
     -DADB_REVISION='"$(adb_version)"' \
 
 # Define windows.h and tchar.h Unicode preprocessor symbols so that
diff --git a/adb/file_sync_client.cpp b/adb/file_sync_client.cpp
index 533994766..1d668bc18 100644
--- a/adb/file_sync_client.cpp
+++ b/adb/file_sync_client.cpp
@@ -29,6 +29,7 @@
 #include <utime.h>
 
 #include <memory>
+#include <vector>
 
 #include "sysdeps.h"
 
@@ -101,14 +102,14 @@ class SyncConnection {
 
         // Sending header and payload in a single write makes a noticeable
         // difference to "adb sync" performance.
-        char buf[sizeof(SyncRequest) + path_length];
-        SyncRequest* req = reinterpret_cast<SyncRequest*>(buf);
+        std::vector<char> buf(sizeof(SyncRequest) + path_length);
+        SyncRequest* req = reinterpret_cast<SyncRequest*>(&buf[0]);
         req->id = id;
         req->path_length = path_length;
         char* data = reinterpret_cast<char*>(req + 1);
         memcpy(data, path_and_mode, path_length);
 
-        return WriteFdExactly(fd, buf, sizeof(buf));
+        return WriteFdExactly(fd, &buf[0], buf.size());
     }
 
     // Sending header, payload, and footer in a single write makes a huge
@@ -123,10 +124,10 @@ class SyncConnection {
             return false;
         }
 
-        char buf[sizeof(SyncRequest) + path_length +
+        std::vector<char> buf(sizeof(SyncRequest) + path_length +
                  sizeof(SyncRequest) + data_length +
-                 sizeof(SyncRequest)];
-        char* p = buf;
+                 sizeof(SyncRequest));
+        char* p = &buf[0];
 
         SyncRequest* req_send = reinterpret_cast<SyncRequest*>(p);
         req_send->id = ID_SEND;
@@ -147,7 +148,7 @@ class SyncConnection {
         req_done->path_length = mtime;
         p += sizeof(SyncRequest);
 
-        if (!WriteFdExactly(fd, buf, (p-buf))) return false;
+        if (!WriteFdExactly(fd, &buf[0], (p - &buf[0]))) return false;
 
         total_bytes += data_length;
         return true;
@@ -172,14 +173,14 @@ class SyncConnection {
     }
 
     bool ReportCopyFailure(const char* from, const char* to, const syncmsg& msg) {
-        char buffer[msg.status.msglen + 1];
-        if (!ReadFdExactly(fd, buffer, msg.status.msglen)) {
+        std::vector<char> buf(msg.status.msglen + 1);
+        if (!ReadFdExactly(fd, &buf[0], msg.status.msglen)) {
             fprintf(stderr, "adb: failed to copy '%s' to '%s'; failed to read reason (!): %s\n",
                     from, to, strerror(errno));
             return false;
         }
-        buffer[msg.status.msglen] = 0;
-        fprintf(stderr, "adb: failed to copy '%s' to '%s': %s\n", from, to, buffer);
+        buf[msg.status.msglen] = 0;
+        fprintf(stderr, "adb: failed to copy '%s' to '%s': %s\n", from, to, &buf[0]);
         return false;
     }
 
diff --git a/adb/sysdeps_win32.cpp b/adb/sysdeps_win32.cpp
index fd753200f..14d137585 100644
--- a/adb/sysdeps_win32.cpp
+++ b/adb/sysdeps_win32.cpp
@@ -567,12 +567,11 @@ char* adb_strerror(int err) {
 
     // Lookup the string for an unknown error.
     char* errmsg = strerror(-1);
-    char unknown_error[(errmsg == nullptr ? 0 : strlen(errmsg)) + 1];
-    strcpy(unknown_error, errmsg == nullptr ? "" : errmsg);
+    const std::string unknown_error = (errmsg == nullptr) ? "" : errmsg;
 
     // Lookup the string for this error to see if the C Runtime has it.
     errmsg = strerror(err);
-    if ((errmsg != nullptr) && strcmp(errmsg, unknown_error)) {
+    if (errmsg != nullptr && unknown_error != errmsg) {
         // The CRT returned an error message and it is different than the error
         // message for an unknown error, so it is probably valid, so use it.
     } else {