YugabyteDB (2.13.0.0-b42, bfc6a6643e7399ac8a0e81d06a3ee6d6571b33ab)

// Copyright 2002 and onwards Google Inc.

//

// The following only applies to changes made to this file as part of YugaByte development.

//

// Portions Copyright (c) YugaByte, Inc.

//

// Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except

// in compliance with the License.  You may obtain a copy of the License at

//

// http://www.apache.org/licenses/LICENSE-2.0

//

// Unless required by applicable law or agreed to in writing, software distributed under the License

// is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express

// or implied.  See the License for the specific language governing permissions and limitations

// under the License.

//

#include "yb/gutil/stringprintf.h"

#include <errno.h>

#include <stdarg.h> // For va_list and related operations

#include <stdio.h> // MSVC requires this for _vsnprintf

#include <vector>

#include <glog/logging.h>

#include "yb/gutil/macros.h"

using std::vector;

#ifdef _MSC_VER

enum { IS__MSC_VER = 1 };

#else

enum { IS__MSC_VER = 0 };

#endif

void StringAppendV(string* dst, const char* format, va_list ap) {

  // First try with a small fixed size buffer

  static const int kSpaceLength = 1024;

  char space[kSpaceLength];

  // It's possible for methods that use a va_list to invalidate

  // the data in it upon use.  The fix is to make a copy

  // of the structure before using it and use that copy instead.

  va_list backup_ap;

  va_copy(backup_ap, ap);

  int result = vsnprintf(space, kSpaceLength, format, backup_ap);

  va_end(backup_ap);

  if (result < kSpaceLength) {

    if (result >= 0) {

      // Normal case -- everything fit.

      dst->append(space, result);

      return;

    }

    if (IS__MSC_VER) {

      // Error or MSVC running out of space.  MSVC 8.0 and higher

      // can be asked about space needed with the special idiom below:

      va_copy(backup_ap, ap);

      result = vsnprintf(nullptr, 0, format, backup_ap);

      va_end(backup_ap);

    }

    if (result < 0) {

      // Just an error.

      return;

    }

  }

  // Increase the buffer size to the size requested by vsnprintf,

  // plus one for the closing \0.

  int length = result+1;

  auto buf = new char[length];

  // Restore the va_list before we use it again

  va_copy(backup_ap, ap);

  result = vsnprintf(buf, length, format, backup_ap);

  va_end(backup_ap);

  if (result >= 0 && result < length) {

    // It fit

    dst->append(buf, result);

  }

  delete[] buf;

}

string StringPrintf(const char* format, ...) {

  va_list ap;

  va_start(ap, format);

  string result;

  StringAppendV(&result, format, ap);

  va_end(ap);

  return result;

}

const string& SStringPrintf(string* dst, const char* format, ...) {

  va_list ap;

  va_start(ap, format);

  dst->clear();

  StringAppendV(dst, format, ap);

  va_end(ap);

  return *dst;

}

void StringAppendF(string* dst, const char* format, ...) {

  va_list ap;

  va_start(ap, format);

  StringAppendV(dst, format, ap);

  va_end(ap);

}

// Max arguments supported by StringPrintVector

const int kStringPrintfVectorMaxArgs = 32;

// An empty block of zero for filler arguments.  This is const so that if

// printf tries to write to it (via %n) then the program gets a SIGSEGV

// and we can fix the problem or protect against an attack.

static const char string_printf_empty_block[256] = { '\0' };

string StringPrintfVector(const char* format, const vector<string>& v) {

  CHECK_LE(v.size(), kStringPrintfVectorMaxArgs)

      << "StringPrintfVector currently only supports up to "

      << kStringPrintfVectorMaxArgs << " arguments. "

      << "Feel free to add support for more if you need it.";

  // Add filler arguments so that bogus format+args have a harder time

  // crashing the program, corrupting the program (%n),

  // or displaying random chunks of memory to users.

  const char* cstr[kStringPrintfVectorMaxArgs];

  for (size_t i = 0; i < v.size(); ++i) {

    cstr[i] = v[i].c_str();

  }

  for (size_t i = v.size(); i < arraysize(cstr); ++i) {

    cstr[i] = &string_printf_empty_block[0];

  }

  // I do not know any way to pass kStringPrintfVectorMaxArgs arguments,

  // or any way to build a va_list by hand, or any API for printf

  // that accepts an array of arguments.  The best I can do is stick

  // this COMPILE_ASSERT right next to the actual statement.

  COMPILE_ASSERT(kStringPrintfVectorMaxArgs == 32, arg_count_mismatch);

  // Getting these warnings from clang static analyzer:

  // warning: {2nd,3rd,4th,5th} function call argument is an uninitialized value

  return StringPrintf(format,

                      cstr[0], cstr[1], cstr[2], cstr[3], cstr[4],

                      cstr[5], cstr[6], cstr[7], cstr[8], cstr[9],

                      cstr[10], cstr[11], cstr[12], cstr[13], cstr[14],

                      cstr[15], cstr[16], cstr[17], cstr[18], cstr[19],

                      cstr[20], cstr[21], cstr[22], cstr[23], cstr[24],

                      cstr[25], cstr[26], cstr[27], cstr[28], cstr[29],

                      cstr[30], cstr[31]);

}