1 /* 2 * Copyright (C) 2011 The Android Open Source Project 3 * 4 * Licensed under the Apache License, Version 2.0 (the "License"); 5 * you may not use this file except in compliance with the License. 6 * You may obtain a copy of the License at 7 * 8 * http://www.apache.org/licenses/LICENSE-2.0 9 * 10 * Unless required by applicable law or agreed to in writing, software 11 * distributed under the License is distributed on an "AS IS" BASIS, 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 * See the License for the specific language governing permissions and 14 * limitations under the License. 15 */ 16 17 #include "android-base/stringprintf.h" 18 19 #include <stdio.h> 20 21 #include <string> 22 23 namespace android { 24 namespace base { 25 26 void StringAppendV(std::string* dst, const char* format, va_list ap) { 27 // First try with a small fixed size buffer 28 char space[1024]; 29 30 // It's possible for methods that use a va_list to invalidate 31 // the data in it upon use. The fix is to make a copy 32 // of the structure before using it and use that copy instead. 33 va_list backup_ap; 34 va_copy(backup_ap, ap); 35 int result = vsnprintf(space, sizeof(space), format, backup_ap); 36 va_end(backup_ap); 37 38 if (result < static_cast<int>(sizeof(space))) { 39 if (result >= 0) { 40 // Normal case -- everything fit. 41 dst->append(space, result); 42 return; 43 } 44 45 if (result < 0) { 46 // Just an error. 47 return; 48 } 49 } 50 51 // Increase the buffer size to the size requested by vsnprintf, 52 // plus one for the closing \0. 53 int length = result + 1; 54 char* buf = new char[length]; 55 56 // Restore the va_list before we use it again 57 va_copy(backup_ap, ap); 58 result = vsnprintf(buf, length, format, backup_ap); 59 va_end(backup_ap); 60 61 if (result >= 0 && result < length) { 62 // It fit 63 dst->append(buf, result); 64 } 65 delete[] buf; 66 } 67 68 std::string StringPrintf(const char* fmt, ...) { 69 va_list ap; 70 va_start(ap, fmt); 71 std::string result; 72 StringAppendV(&result, fmt, ap); 73 va_end(ap); 74 return result; 75 } 76 77 void StringAppendF(std::string* dst, const char* format, ...) { 78 va_list ap; 79 va_start(ap, format); 80 StringAppendV(dst, format, ap); 81 va_end(ap); 82 } 83 84 } // namespace base 85 } // namespace android 86
