blob: 766f184e1ab704d882a73e0114462059dc27f447 [file] [log] [blame]
// Copyright 2002 The RE2 Authors. All Rights Reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
#include <stdarg.h>
#include "util/util.h"
namespace re2 {
static void StringAppendV(string* dst, const char* format, va_list ap) {
// First try with a small fixed size buffer
char space[1024];
// It's possible for methods that use a va_list to invalidate
// the data in it upon use. The fix is to make a copy
// of the structure before using it and use that copy instead.
va_list backup_ap;
va_copy(backup_ap, ap);
int result = vsnprintf(space, sizeof(space), format, backup_ap);
va_end(backup_ap);
if ((result >= 0) && (static_cast<unsigned long>(result) < sizeof(space))) {
// It fit
dst->append(space, result);
return;
}
// Repeatedly increase buffer size until it fits
int length = sizeof(space);
while (true) {
if (result < 0) {
// Older behavior: just try doubling the buffer size
length *= 2;
} else {
// We need exactly "result+1" characters
length = result+1;
}
char* buf = new char[length];
// Restore the va_list before we use it again
va_copy(backup_ap, ap);
#if !defined(_WIN32)
result = vsnprintf(buf, length, format, backup_ap);
#else
// On Windows, the function takes five arguments, not four. With an array,
// the buffer size will be inferred, but not with a pointer. C'est la vie.
// (See https://github.com/google/re2/issues/40 for more details.)
result = vsnprintf(buf, length, _TRUNCATE, format, backup_ap);
#endif
va_end(backup_ap);
if ((result >= 0) && (result < length)) {
// It fit
dst->append(buf, result);
delete[] buf;
return;
}
delete[] buf;
}
}
string StringPrintf(const char* format, ...) {
va_list ap;
va_start(ap, format);
string result;
StringAppendV(&result, format, ap);
va_end(ap);
return result;
}
void SStringPrintf(string* dst, const char* format, ...) {
va_list ap;
va_start(ap, format);
dst->clear();
StringAppendV(dst, format, ap);
va_end(ap);
}
void StringAppendF(string* dst, const char* format, ...) {
va_list ap;
va_start(ap, format);
StringAppendV(dst, format, ap);
va_end(ap);
}
} // namespace re2