TestAsyncLogger.cpp

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/* This Source Code Form is subject to the terms of the Mozilla Public

 * License, v. 2.0. If a copy of the MPL was not distributed with this

 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

#include <gtest/gtest.h>

#include <string>

#include "AsyncLogger.h"

namespace mozilla {

TEST(AsyncLogger, AppendCStringExactFitOOBWrite)

  const size_t kBufSize = 16;

  char buf[kBufSize + 1];

  buf[kBufSize] = 0x42;

  StringWriter writer(buf, kBufSize);

  std::string s(kBufSize, 'A');

  size_t idx;

  bool truncated = writer.AppendCString(s.c_str(), &idx);

  EXPECT_TRUE(truncated);

  EXPECT_EQ(idx, 0u);

  EXPECT_EQ(static_cast<unsigned char>(buf[kBufSize]), 0x42u)

      << "off-by-one: null terminator written one byte past end of buffer";

  EXPECT_EQ(buf[kBufSize - 1], 0)

      << "last byte of buffer should be null terminator";

TEST(AsyncLogger, AppendCStringOverflow)

  const size_t kBufSize = 8;

  char buf[kBufSize + 1];

  buf[kBufSize] = 0x42;

  StringWriter writer(buf, kBufSize);

  std::string s(kBufSize * 4, 'B');

  size_t idx;

  bool truncated = writer.AppendCString(s.c_str(), &idx);

  EXPECT_TRUE(truncated);

  EXPECT_EQ(idx, 0u);

  EXPECT_EQ(static_cast<unsigned char>(buf[kBufSize]), 0x42u)

      << "sentinel overwritten on overflow";

  EXPECT_EQ(buf[kBufSize - 1], 0)

      << "last byte of buffer should be null terminator";

  // Truncated content should be kBufSize-1 bytes of 'B'

  EXPECT_EQ(std::string(buf, kBufSize - 1), std::string(kBufSize - 1, 'B'));

TEST(AsyncLogger, AppendCStringFullBufferEarlyReturn)

  const size_t kBufSize = 8;

  char buf[kBufSize + 1];

  buf[kBufSize] = 0x42;

  StringWriter writer(buf, kBufSize);

  // First call: fill the buffer exactly (string of kBufSize chars truncates

  // to kBufSize-1 chars + null terminator, consuming all kBufSize bytes).

  std::string s1(kBufSize, 'C');

  size_t idx1;

  writer.AppendCString(s1.c_str(), &idx1);

  // Second call: buffer is now full, should early-return without writing.

  size_t idx2;

  bool truncated = writer.AppendCString("more", &idx2);

  EXPECT_TRUE(truncated);

  EXPECT_EQ(static_cast<unsigned char>(buf[kBufSize]), 0x42u)

      << "sentinel overwritten on second append to full buffer";

}  // namespace mozilla