1// Copyright 2002 and onwards Google Inc.
2
3#include <stdarg.h> // For va_list and related operations
4#include <stdio.h> // MSVC requires this for _vsnprintf
5#include <vector>
6using std::vector;
7
8#include "base/stringprintf.h"
9#include "base/logging.h"
10
11void StringAppendV(string* dst, const char* format, va_list ap) {
12 // First try with a small fixed size buffer
13 char space[1024];
14
15 // It's possible for methods that use a va_list to invalidate
16 // the data in it upon use. The fix is to make a copy
17 // of the structure before using it and use that copy instead.
18 va_list backup_ap;
19 va_copy(backup_ap, ap);
20 int result = vsnprintf(space, sizeof(space), format, backup_ap);
21 va_end(backup_ap);
22
23 if ((result >= 0) && (result < sizeof(space))) {
24 // It fit
25 dst->append(space, result);
26 return;
27 }
28
29 // Repeatedly increase buffer size until it fits
30 int length = sizeof(space);
31 while (true) {
32 if (result < 0) {
33 // Older behavior: just try doubling the buffer size
34 length *= 2;
35 } else {
36 // We need exactly "result+1" characters
37 length = result+1;
38 }
39 char* buf = new char[length];
40
41 // Restore the va_list before we use it again
42 va_copy(backup_ap, ap);
43 result = vsnprintf(buf, length, format, backup_ap);
44 va_end(backup_ap);
45
46 if ((result >= 0) && (result < length)) {
47 // It fit
48 dst->append(buf, result);
49 delete[] buf;
50 return;
51 }
52 delete[] buf;
53 }
54}
55
56string StringPrintf(const char* format, ...) {
57 va_list ap;
58 va_start(ap, format);
59 string result;
60 StringAppendV(&result, format, ap);
61 va_end(ap);
62 return result;
63}
64
65const string& SStringPrintf(string* dst, const char* format, ...) {
66 va_list ap;
67 va_start(ap, format);
68 dst->clear();
69 StringAppendV(dst, format, ap);
70 va_end(ap);
71 return *dst;
72}
73
74void StringAppendF(string* dst, const char* format, ...) {
75 va_list ap;
76 va_start(ap, format);
77 StringAppendV(dst, format, ap);
78 va_end(ap);
79}
80