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 // 9 // * Redistributions of source code must retain the above copyright 10 // notice, this list of conditions and the following disclaimer. 11 // * Redistributions in binary form must reproduce the above 12 // copyright notice, this list of conditions and the following disclaimer 13 // in the documentation and/or other materials provided with the 14 // distribution. 15 // * Neither the name of Google Inc. nor the names of its 16 // contributors may be used to endorse or promote products derived from 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, 24 // SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT 25 // LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 26 // DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 27 // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 28 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE 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 41 namespace google { 42 namespace protobuf { 43 44 #ifdef _MSC_VER 45 enum { IS_COMPILER_MSVC = 1 }; 46 #ifndef va_copy 47 // Define va_copy for MSVC. This is a hack, assuming va_list is simply a 48 // pointer into the stack and is safe to copy. 49 #define va_copy(dest, src) ((dest) = (src)) 50 #endif 51 #else 52 enum { IS_COMPILER_MSVC = 0 }; 53 #endif 54 55 void StringAppendV(string* dst, const char* format, va_list ap) { 56 // First try with a small fixed size buffer 57 static const int kSpaceLength = 1024; 58 char space[kSpaceLength]; 59 60 // It's possible for methods that use a va_list to invalidate 61 // the data in it upon use. The fix is to make a copy 62 // of the structure before using it and use that copy instead. 63 va_list backup_ap; 64 va_copy(backup_ap, ap); 65 int result = vsnprintf(space, kSpaceLength, format, backup_ap); 66 va_end(backup_ap); 67 68 if (result < kSpaceLength) { 69 if (result >= 0) { 70 // Normal case -- everything fit. 71 dst->append(space, result); 72 return; 73 } 74 75 if (IS_COMPILER_MSVC) { 76 // Error or MSVC running out of space. MSVC 8.0 and higher 77 // can be asked about space needed with the special idiom below: 78 va_copy(backup_ap, ap); 79 result = vsnprintf(NULL, 0, format, backup_ap); 80 va_end(backup_ap); 81 } 82 83 if (result < 0) { 84 // Just an error. 85 return; 86 } 87 } 88 89 // Increase the buffer size to the size requested by vsnprintf, 90 // plus one for the closing \0. 91 int length = result+1; 92 char* buf = new char[length]; 93 94 // Restore the va_list before we use it again 95 va_copy(backup_ap, ap); 96 result = vsnprintf(buf, length, format, backup_ap); 97 va_end(backup_ap); 98 99 if (result >= 0 && result < length) { 100 // It fit 101 dst->append(buf, result); 102 } 103 delete[] buf; 104 } 105 106 107 string StringPrintf(const char* format, ...) { 108 va_list ap; 109 va_start(ap, format); 110 string result; 111 StringAppendV(&result, format, ap); 112 va_end(ap); 113 return result; 114 } 115 116 const string& SStringPrintf(string* dst, const char* format, ...) { 117 va_list ap; 118 va_start(ap, format); 119 dst->clear(); 120 StringAppendV(dst, format, ap); 121 va_end(ap); 122 return *dst; 123 } 124 125 void StringAppendF(string* dst, const char* format, ...) { 126 va_list ap; 127 va_start(ap, format); 128 StringAppendV(dst, format, ap); 129 va_end(ap); 130 } 131 132 // Max arguments supported by StringPrintVector 133 const int kStringPrintfVectorMaxArgs = 32; 134 135 // An empty block of zero for filler arguments. This is const so that if 136 // printf tries to write to it (via %n) then the program gets a SIGSEGV 137 // and we can fix the problem or protect against an attack. 138 static const char string_printf_empty_block[256] = { '\0' }; 139 140 string StringPrintfVector(const char* format, const vector<string>& v) { 141 GOOGLE_CHECK_LE(v.size(), kStringPrintfVectorMaxArgs) 142 << "StringPrintfVector currently only supports up to " 143 << kStringPrintfVectorMaxArgs << " arguments. " 144 << "Feel free to add support for more if you need it."; 145 146 // Add filler arguments so that bogus format+args have a harder time 147 // crashing the program, corrupting the program (%n), 148 // or displaying random chunks of memory to users. 149 150 const char* cstr[kStringPrintfVectorMaxArgs]; 151 for (int i = 0; i < v.size(); ++i) { 152 cstr[i] = v[i].c_str(); 153 } 154 for (int i = v.size(); i < GOOGLE_ARRAYSIZE(cstr); ++i) { 155 cstr[i] = &string_printf_empty_block[0]; 156 } 157 158 // I do not know any way to pass kStringPrintfVectorMaxArgs arguments, 159 // or any way to build a va_list by hand, or any API for printf 160 // that accepts an array of arguments. The best I can do is stick 161 // this COMPILE_ASSERT right next to the actual statement. 162 163 GOOGLE_COMPILE_ASSERT(kStringPrintfVectorMaxArgs == 32, arg_count_mismatch); 164 return StringPrintf(format, 165 cstr[0], cstr[1], cstr[2], cstr[3], cstr[4], 166 cstr[5], cstr[6], cstr[7], cstr[8], cstr[9], 167 cstr[10], cstr[11], cstr[12], cstr[13], cstr[14], 168 cstr[15], cstr[16], cstr[17], cstr[18], cstr[19], 169 cstr[20], cstr[21], cstr[22], cstr[23], cstr[24], 170 cstr[25], cstr[26], cstr[27], cstr[28], cstr[29], 171 cstr[30], cstr[31]); 172 } 173 } // namespace protobuf 174 } // namespace google 175
