kc3-lang/angle/src/common/angleutils.cpp

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• Hash : a8ccb95b
  Author :
  Date : 2016-12-16T15:12:57
  

  FormatString: avoid an UB when we need to grow the buffer
  
  A va_list is undefined after it has been used by vsnprtinf. This was
  causing crashes in the GL backend when the driver was returning big
  info logs.
  
  BUG=chromium:668223
  
  Change-Id: I444194ecce2846960c8a27f20f322f7099c651e5
  Reviewed-on: https://chromium-review.googlesource.com/421271
  Reviewed-by: Jamie Madill <jmadill@chromium.org>
  Reviewed-by: Geoff Lang <geofflang@chromium.org>
  Commit-Queue: Corentin Wallez <cwallez@chromium.org>
  

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• src/common/angleutils.cpp

• //
  // Copyright (c) 2014 The ANGLE Project 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 "common/angleutils.h"
  #include "common/debug.h"
  
  #include <stdio.h>
  
  #include <limits>
  #include <vector>
  
  namespace angle
  {
  const uintptr_t DirtyPointer = std::numeric_limits<uintptr_t>::max();
  }
  
  size_t FormatStringIntoVector(const char *fmt, va_list vararg, std::vector<char>& outBuffer)
  {
      // The state of the va_list passed to vsnprintf is undefined after the call, do a copy in case
      // we need to grow the buffer.
      va_list varargCopy;
      va_copy(varargCopy, vararg);
  
      // Attempt to just print to the current buffer
      int len = vsnprintf(&(outBuffer.front()), outBuffer.size(), fmt, varargCopy);
      va_end(varargCopy);
  
      if (len < 0 || static_cast<size_t>(len) >= outBuffer.size())
      {
          // Buffer was not large enough, calculate the required size and resize the buffer
          len = vsnprintf(NULL, 0, fmt, vararg);
          outBuffer.resize(len + 1);
  
          // Print again
          va_copy(varargCopy, vararg);
          len = vsnprintf(&(outBuffer.front()), outBuffer.size(), fmt, varargCopy);
          va_end(varargCopy);
      }
      ASSERT(len >= 0);
      return static_cast<size_t>(len);
  }
  
  std::string FormatString(const char *fmt, va_list vararg)
  {
      static std::vector<char> buffer(512);
  
      size_t len = FormatStringIntoVector(fmt, vararg, buffer);
      return std::string(&buffer[0], len);
  }
  
  std::string FormatString(const char *fmt, ...)
  {
      va_list vararg;
      va_start(vararg, fmt);
      std::string result = FormatString(fmt, vararg);
      va_end(vararg);
      return result;
  }
  

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