1 // Copyright 2002 The RE2 Authors. All Rights Reserved. 2 // Use of this source code is governed by a BSD-style 3 // license that can be found in the LICENSE file. 4 5 #include "util/util.h" 6 7 #ifndef va_copy 8 #define va_copy(d,s) ((d) = (s)) //KLUGE: for MS compilers 9 #endif 10 11 namespace re2 { 12 13 static void StringAppendV(string* dst, const char* format, va_list ap) { 14 // First try with a small fixed size buffer 15 char space[1024]; 16 17 // It's possible for methods that use a va_list to invalidate 18 // the data in it upon use. The fix is to make a copy 19 // of the structure before using it and use that copy instead. 20 va_list backup_ap; 21 va_copy(backup_ap, ap); 22 int result = vsnprintf(space, sizeof(space), format, backup_ap); 23 va_end(backup_ap); 24 25 if ((result >= 0) && (result < sizeof(space))) { 26 // It fit 27 dst->append(space, result); 28 return; 29 } 30 31 // Repeatedly increase buffer size until it fits 32 int length = sizeof(space); 33 while (true) { 34 if (result < 0) { 35 // Older behavior: just try doubling the buffer size 36 length *= 2; 37 } else { 38 // We need exactly "result+1" characters 39 length = result+1; 40 } 41 char* buf = new char[length]; 42 43 // Restore the va_list before we use it again 44 va_copy(backup_ap, ap); 45 result = vsnprintf(buf, length, format, backup_ap); 46 va_end(backup_ap); 47 48 if ((result >= 0) && (result < length)) { 49 // It fit 50 dst->append(buf, result); 51 delete[] buf; 52 return; 53 } 54 delete[] buf; 55 } 56 } 57 58 string StringPrintf(const char* format, ...) { 59 va_list ap; 60 va_start(ap, format); 61 string result; 62 StringAppendV(&result, format, ap); 63 va_end(ap); 64 return result; 65 } 66 67 void SStringPrintf(string* dst, const char* format, ...) { 68 va_list ap; 69 va_start(ap, format); 70 dst->clear(); 71 StringAppendV(dst, format, ap); 72 va_end(ap); 73 } 74 75 void StringAppendF(string* dst, const char* format, ...) { 76 va_list ap; 77 va_start(ap, format); 78 StringAppendV(dst, format, ap); 79 va_end(ap); 80 } 81 82 } // namespace re2 83
