1// Protocol Buffers - Google's data interchange format
2// Copyright 2012 Google Inc.  All rights reserved.
3// https://developers.google.com/protocol-buffers/
4//
5// Redistribution and use in source and binary forms, with or without
6// modification, are permitted provided that the following conditions are
7// met:
8//
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10// notice, this list of conditions and the following disclaimer.
11//     * Redistributions in binary form must reproduce the above
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13// in the documentation and/or other materials provided with the
14// distribution.
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17// this software without specific prior written permission.
18//
19// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
20// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
21// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
22// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
23// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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25// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
26// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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29// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
30
31// from google3/base/stringprintf.cc
32
33#include <google/protobuf/stubs/stringprintf.h>
34
35#include <errno.h>
36#include <stdarg.h> // For va_list and related operations
37#include <stdio.h> // MSVC requires this for _vsnprintf
38#include <vector>
39#include <google/protobuf/stubs/common.h>
40#include <google/protobuf/testing/googletest.h>
41
42namespace google {
43namespace protobuf {
44
45#ifdef _MSC_VER
46enum { IS_COMPILER_MSVC = 1 };
47#ifndef va_copy
48// Define va_copy for MSVC. This is a hack, assuming va_list is simply a
49// pointer into the stack and is safe to copy.
50#define va_copy(dest, src) ((dest) = (src))
51#endif
52#else
53enum { IS_COMPILER_MSVC = 0 };
54#endif
55
56void StringAppendV(string* dst, const char* format, va_list ap) {
57  // First try with a small fixed size buffer
58  static const int kSpaceLength = 1024;
59  char space[kSpaceLength];
60
61  // It's possible for methods that use a va_list to invalidate
62  // the data in it upon use.  The fix is to make a copy
63  // of the structure before using it and use that copy instead.
64  va_list backup_ap;
65  va_copy(backup_ap, ap);
66  int result = vsnprintf(space, kSpaceLength, format, backup_ap);
67  va_end(backup_ap);
68
69  if (result < kSpaceLength) {
70    if (result >= 0) {
71      // Normal case -- everything fit.
72      dst->append(space, result);
73      return;
74    }
75
76    if (IS_COMPILER_MSVC) {
77      // Error or MSVC running out of space.  MSVC 8.0 and higher
78      // can be asked about space needed with the special idiom below:
79      va_copy(backup_ap, ap);
80      result = vsnprintf(NULL, 0, format, backup_ap);
81      va_end(backup_ap);
82    }
83
84    if (result < 0) {
85      // Just an error.
86      return;
87    }
88  }
89
90  // Increase the buffer size to the size requested by vsnprintf,
91  // plus one for the closing \0.
92  int length = result+1;
93  char* buf = new char[length];
94
95  // Restore the va_list before we use it again
96  va_copy(backup_ap, ap);
97  result = vsnprintf(buf, length, format, backup_ap);
98  va_end(backup_ap);
99
100  if (result >= 0 && result < length) {
101    // It fit
102    dst->append(buf, result);
103  }
104  delete[] buf;
105}
106
107
108string StringPrintf(const char* format, ...) {
109  va_list ap;
110  va_start(ap, format);
111  string result;
112  StringAppendV(&result, format, ap);
113  va_end(ap);
114  return result;
115}
116
117const string& SStringPrintf(string* dst, const char* format, ...) {
118  va_list ap;
119  va_start(ap, format);
120  dst->clear();
121  StringAppendV(dst, format, ap);
122  va_end(ap);
123  return *dst;
124}
125
126void StringAppendF(string* dst, const char* format, ...) {
127  va_list ap;
128  va_start(ap, format);
129  StringAppendV(dst, format, ap);
130  va_end(ap);
131}
132
133// Max arguments supported by StringPrintVector
134const int kStringPrintfVectorMaxArgs = 32;
135
136// An empty block of zero for filler arguments.  This is const so that if
137// printf tries to write to it (via %n) then the program gets a SIGSEGV
138// and we can fix the problem or protect against an attack.
139static const char string_printf_empty_block[256] = { '\0' };
140
141string StringPrintfVector(const char* format, const vector<string>& v) {
142  GOOGLE_CHECK_LE(v.size(), kStringPrintfVectorMaxArgs)
143      << "StringPrintfVector currently only supports up to "
144      << kStringPrintfVectorMaxArgs << " arguments. "
145      << "Feel free to add support for more if you need it.";
146
147  // Add filler arguments so that bogus format+args have a harder time
148  // crashing the program, corrupting the program (%n),
149  // or displaying random chunks of memory to users.
150
151  const char* cstr[kStringPrintfVectorMaxArgs];
152  for (int i = 0; i < v.size(); ++i) {
153    cstr[i] = v[i].c_str();
154  }
155  for (int i = v.size(); i < GOOGLE_ARRAYSIZE(cstr); ++i) {
156    cstr[i] = &string_printf_empty_block[0];
157  }
158
159  // I do not know any way to pass kStringPrintfVectorMaxArgs arguments,
160  // or any way to build a va_list by hand, or any API for printf
161  // that accepts an array of arguments.  The best I can do is stick
162  // this COMPILE_ASSERT right next to the actual statement.
163
164  GOOGLE_COMPILE_ASSERT(kStringPrintfVectorMaxArgs == 32, arg_count_mismatch);
165  return StringPrintf(format,
166                      cstr[0], cstr[1], cstr[2], cstr[3], cstr[4],
167                      cstr[5], cstr[6], cstr[7], cstr[8], cstr[9],
168                      cstr[10], cstr[11], cstr[12], cstr[13], cstr[14],
169                      cstr[15], cstr[16], cstr[17], cstr[18], cstr[19],
170                      cstr[20], cstr[21], cstr[22], cstr[23], cstr[24],
171                      cstr[25], cstr[26], cstr[27], cstr[28], cstr[29],
172                      cstr[30], cstr[31]);
173}
174}  // namespace protobuf
175}  // namespace google
176