mirror of
https://github.com/git/git.git
synced 2024-11-13 20:53:02 +01:00
a9bfbc5b69
If you define SNPRINTF_RETURNS_BOGUS, we use a special git_vsnprintf wrapper assumes that vsnprintf returns "-1" instead of the number of characters that you would need to store the result. To do this, it invokes vsnprintf multiple times, growing a heap buffer until we have enough space to hold the result. However, this means we evaluate the va_list parameter multiple times, which is generally a bad thing (it may be modified by calls to vsnprintf, yielding undefined behavior). Instead, we must va_copy it and hand the copy to vsnprintf, so we always have a pristine va_list. Signed-off-by: Jeff King <peff@peff.net> Signed-off-by: Junio C Hamano <gitster@pobox.com>
69 lines
1.5 KiB
C
69 lines
1.5 KiB
C
#include "../git-compat-util.h"
|
|
|
|
/*
|
|
* The size parameter specifies the available space, i.e. includes
|
|
* the trailing NUL byte; but Windows's vsnprintf uses the entire
|
|
* buffer and avoids the trailing NUL, should the buffer be exactly
|
|
* big enough for the result. Defining SNPRINTF_SIZE_CORR to 1 will
|
|
* therefore remove 1 byte from the reported buffer size, so we
|
|
* always have room for a trailing NUL byte.
|
|
*/
|
|
#ifndef SNPRINTF_SIZE_CORR
|
|
#if defined(WIN32) && (!defined(__GNUC__) || __GNUC__ < 4)
|
|
#define SNPRINTF_SIZE_CORR 1
|
|
#else
|
|
#define SNPRINTF_SIZE_CORR 0
|
|
#endif
|
|
#endif
|
|
|
|
#undef vsnprintf
|
|
int git_vsnprintf(char *str, size_t maxsize, const char *format, va_list ap)
|
|
{
|
|
va_list cp;
|
|
char *s;
|
|
int ret = -1;
|
|
|
|
if (maxsize > 0) {
|
|
va_copy(cp, ap);
|
|
ret = vsnprintf(str, maxsize-SNPRINTF_SIZE_CORR, format, cp);
|
|
va_end(cp);
|
|
if (ret == maxsize-1)
|
|
ret = -1;
|
|
/* Windows does not NUL-terminate if result fills buffer */
|
|
str[maxsize-1] = 0;
|
|
}
|
|
if (ret != -1)
|
|
return ret;
|
|
|
|
s = NULL;
|
|
if (maxsize < 128)
|
|
maxsize = 128;
|
|
|
|
while (ret == -1) {
|
|
maxsize *= 4;
|
|
str = realloc(s, maxsize);
|
|
if (! str)
|
|
break;
|
|
s = str;
|
|
va_copy(cp, ap);
|
|
ret = vsnprintf(str, maxsize-SNPRINTF_SIZE_CORR, format, cp);
|
|
va_end(cp);
|
|
if (ret == maxsize-1)
|
|
ret = -1;
|
|
}
|
|
free(s);
|
|
return ret;
|
|
}
|
|
|
|
int git_snprintf(char *str, size_t maxsize, const char *format, ...)
|
|
{
|
|
va_list ap;
|
|
int ret;
|
|
|
|
va_start(ap, format);
|
|
ret = git_vsnprintf(str, maxsize, format, ap);
|
|
va_end(ap);
|
|
|
|
return ret;
|
|
}
|
|
|