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
StringAppendV(std::string * dst,const char * format,va_list ap)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
StringPrintf(const char * fmt,...)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
StringAppendF(std::string * dst,const char * format,...)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