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// Copyright 2011 Google Inc. All Rights Reserved.
#include "stringprintf.h"
#include <stdio.h>
void StringAppendV(std::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 < int(sizeof(space))) {
if (result >= 0) {
// Normal case -- everything fit.
dst->append(space, result);
return;
}
if (result < 0) {
// Just an error.
return;
}
}
// Increase the buffer size to the size requested by vsnprintf,
// plus one for the closing \0.
int length = result+1;
char* buf = new char[length];
// Restore the va_list before we use it again
va_copy(backup_ap, ap);
result = vsnprintf(buf, length, format, backup_ap);
va_end(backup_ap);
if (result >= 0 && result < length) {
// It fit
dst->append(buf, result);
}
delete[] buf;
}
std::string StringPrintf(const char* fmt, ...) {
va_list ap;
va_start(ap, fmt);
std::string result;
StringAppendV(&result, fmt, ap);
va_end(ap);
return result;
}
void StringAppendF(std::string* dst, const char* format, ...) {
va_list ap;
va_start(ap, format);
StringAppendV(dst, format, ap);
va_end(ap);
}
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