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// Protocol Buffers - Google's data interchange format
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// Copyright 2012 Google Inc. All rights reserved.
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// http://code.google.com/p/protobuf/
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// Redistribution and use in source and binary forms, with or without
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// modification, are permitted provided that the following conditions are
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// * Redistributions of source code must retain the above copyright
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// notice, this list of conditions and the following disclaimer.
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// * Redistributions in binary form must reproduce the above
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// copyright notice, this list of conditions and the following disclaimer
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// in the documentation and/or other materials provided with the
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// * Neither the name of Google Inc. nor the names of its
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// contributors may be used to endorse or promote products derived from
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// this software without specific prior written permission.
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// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
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// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
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// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
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// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
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// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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// from google3/base/stringprintf.cc
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#include <google/protobuf/stubs/stringprintf.h>
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#include <stdarg.h> // For va_list and related operations
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#include <stdio.h> // MSVC requires this for _vsnprintf
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#include <google/protobuf/stubs/common.h>
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#include <google/protobuf/testing/googletest.h>
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enum { IS_COMPILER_MSVC = 1 };
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// Define va_copy for MSVC. This is a hack, assuming va_list is simply a
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// pointer into the stack and is safe to copy.
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#define va_copy(dest, src) ((dest) = (src))
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enum { IS_COMPILER_MSVC = 0 };
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void StringAppendV(string* dst, const char* format, va_list ap) {
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// First try with a small fixed size buffer
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static const int kSpaceLength = 1024;
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char space[kSpaceLength];
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// It's possible for methods that use a va_list to invalidate
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// the data in it upon use. The fix is to make a copy
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// of the structure before using it and use that copy instead.
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va_copy(backup_ap, ap);
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int result = vsnprintf(space, kSpaceLength, format, backup_ap);
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if (result < kSpaceLength) {
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// Normal case -- everything fit.
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dst->append(space, result);
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if (IS_COMPILER_MSVC) {
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// Error or MSVC running out of space. MSVC 8.0 and higher
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// can be asked about space needed with the special idiom below:
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va_copy(backup_ap, ap);
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result = vsnprintf(NULL, 0, format, backup_ap);
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// Increase the buffer size to the size requested by vsnprintf,
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// plus one for the closing \0.
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int length = result+1;
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char* buf = new char[length];
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// Restore the va_list before we use it again
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va_copy(backup_ap, ap);
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result = vsnprintf(buf, length, format, backup_ap);
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if (result >= 0 && result < length) {
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dst->append(buf, result);
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string StringPrintf(const char* format, ...) {
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va_start(ap, format);
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StringAppendV(&result, format, ap);
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const string& SStringPrintf(string* dst, const char* format, ...) {
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va_start(ap, format);
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StringAppendV(dst, format, ap);
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void StringAppendF(string* dst, const char* format, ...) {
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va_start(ap, format);
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StringAppendV(dst, format, ap);
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// Max arguments supported by StringPrintVector
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const int kStringPrintfVectorMaxArgs = 32;
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// An empty block of zero for filler arguments. This is const so that if
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// printf tries to write to it (via %n) then the program gets a SIGSEGV
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// and we can fix the problem or protect against an attack.
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static const char string_printf_empty_block[256] = { '\0' };
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string StringPrintfVector(const char* format, const vector<string>& v) {
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GOOGLE_CHECK_LE(v.size(), kStringPrintfVectorMaxArgs)
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<< "StringPrintfVector currently only supports up to "
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<< kStringPrintfVectorMaxArgs << " arguments. "
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<< "Feel free to add support for more if you need it.";
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// Add filler arguments so that bogus format+args have a harder time
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// crashing the program, corrupting the program (%n),
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// or displaying random chunks of memory to users.
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const char* cstr[kStringPrintfVectorMaxArgs];
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for (int i = 0; i < v.size(); ++i) {
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cstr[i] = v[i].c_str();
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for (int i = v.size(); i < GOOGLE_ARRAYSIZE(cstr); ++i) {
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cstr[i] = &string_printf_empty_block[0];
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// I do not know any way to pass kStringPrintfVectorMaxArgs arguments,
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// or any way to build a va_list by hand, or any API for printf
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// that accepts an array of arguments. The best I can do is stick
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// this COMPILE_ASSERT right next to the actual statement.
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GOOGLE_COMPILE_ASSERT(kStringPrintfVectorMaxArgs == 32, arg_count_mismatch);
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return StringPrintf(format,
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cstr[0], cstr[1], cstr[2], cstr[3], cstr[4],
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cstr[5], cstr[6], cstr[7], cstr[8], cstr[9],
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cstr[10], cstr[11], cstr[12], cstr[13], cstr[14],
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cstr[15], cstr[16], cstr[17], cstr[18], cstr[19],
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cstr[20], cstr[21], cstr[22], cstr[23], cstr[24],
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cstr[25], cstr[26], cstr[27], cstr[28], cstr[29],
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} // namespace protobuf
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} // namespace google