ce4c4d4ad5
It wraps snprintf(3) so that it performs some steps that one might forget, or might be prone to accidents: - It calculates the size of the destination buffer, and makes sure it's an array (otherwise, using sizeof(s) would be very bad). - It calculates if there's truncation or an error, returning -1 if so. BTW, this macro doesn't have any issues of double evaluation, because sizeof() doesn't evaluate its argument (unless it's a VLA, but then the static_assert(3) within NITEMS() makes sure VLAs are not allowed). This macro is very similar to STRTCPY(), defined in <lib/string/strtcpy.h>. Signed-off-by: Alejandro Colomar <alx@kernel.org>
69 lines
1.5 KiB
C
69 lines
1.5 KiB
C
/*
|
|
* SPDX-FileCopyrightText: 2023, Alejandro Colomar <alx@kernel.org>
|
|
* SPDX-License-Identifier: BSD-3-Clause
|
|
*/
|
|
|
|
|
|
#ifndef SHADOW_INCLUDE_LIB_SPRINTF_H_
|
|
#define SHADOW_INCLUDE_LIB_SPRINTF_H_
|
|
|
|
|
|
#include <config.h>
|
|
|
|
#include <stdarg.h>
|
|
#include <stddef.h>
|
|
#include <stdio.h>
|
|
|
|
#include "attr.h"
|
|
#include "defines.h"
|
|
#include "sizeof.h"
|
|
|
|
|
|
#define SNPRINTF(s, fmt, ...) \
|
|
({ \
|
|
size_t sz_, len_; \
|
|
\
|
|
sz_ = NITEMS(s); \
|
|
len_ = snprintf(s, sz_, fmt __VA_OPT__(,) __VA_ARGS__); \
|
|
\
|
|
(len_ >= sz_) ? -1 : len_; \
|
|
})
|
|
|
|
|
|
format_attr(printf, 2, 3)
|
|
inline int xasprintf(char **restrict s, const char *restrict fmt, ...);
|
|
format_attr(printf, 2, 0)
|
|
inline int xvasprintf(char **restrict s, const char *restrict fmt, va_list ap);
|
|
|
|
|
|
inline int
|
|
xasprintf(char **restrict s, const char *restrict fmt, ...)
|
|
{
|
|
int len;
|
|
va_list ap;
|
|
|
|
va_start(ap, fmt);
|
|
len = xvasprintf(s, fmt, ap);
|
|
va_end(ap);
|
|
|
|
return len;
|
|
}
|
|
|
|
|
|
inline int
|
|
xvasprintf(char **restrict s, const char *restrict fmt, va_list ap)
|
|
{
|
|
int len;
|
|
|
|
len = vasprintf(s, fmt, ap);
|
|
if (len == -1) {
|
|
perror("asprintf");
|
|
exit(EXIT_FAILURE);
|
|
}
|
|
|
|
return len;
|
|
}
|
|
|
|
|
|
#endif // include guard
|