Stop overwriting errno in base::StringPrintf, StringAppendV, and StringToDouble

base/stringprintf.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "base/stringprintf.h"
 
 #include <errno.h>
 
+#include "base/scoped_clear_errno.h"
 #include "base/string_util.h"
 #include "base/utf_string_conversions.h"
 
 namespace base {
 
 namespace {
 
 // Overloaded wrappers around vsnprintf and vswprintf. The buf_size parameter
 // is the size of the buffer. These return the number of characters in the
 // formatted string excluding the NUL terminator. If the buffer is not
@@ skipping 24 matching lines @@
                            va_list ap) {
   // First try with a small fixed size buffer.
   // This buffer size should be kept in sync with StringUtilTest.GrowBoundary
   // and StringUtilTest.StringPrintfBounds.
   typename StringType::value_type stack_buf[1024];
 
   va_list ap_copy;
   GG_VA_COPY(ap_copy, ap);
 
 #if !defined(OS_WIN)
-  errno = 0;
+  ScopedClearErrno clear_errno;
 #endif
   int result = vsnprintfT(stack_buf, arraysize(stack_buf), format, ap_copy);
   va_end(ap_copy);
 
   if (result >= 0 && result < static_cast<int>(arraysize(stack_buf))) {
     // It fit.
     dst->append(stack_buf, result);
     return;
   }
 
@@ skipping 112 matching lines @@
   StringAppendVT(dst, format, ap);
 }
 
 #if !defined(OS_ANDROID)
 void StringAppendV(std::wstring* dst, const wchar_t* format, va_list ap) {
   StringAppendVT(dst, format, ap);
 }
 #endif
 
 }  // namespace base