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safe_asprintf.c
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safe_asprintf.c
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/*
* Copyright (C) 2010 Michael R. Elkins <me@mutt.org>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
*/
#include <stdio.h>
#include "lib.h"
/* NOTE: Currently there is no check in configure.ac for vasprintf(3). the
* undefined behavior of the error condition makes it difficult to write a safe
* version using it.
*/
#ifdef HAVE_VASPRINTF
int safe_asprintf (char **strp, const char *fmt, ...)
{
va_list ap;
int n;
va_start (ap, fmt);
n = vasprintf (strp, fmt, ap);
va_end (ap);
/* GNU libc man page for vasprintf(3) states that the value of *strp
* is undefined when the return code is -1.
*/
if (n < 0)
{
mutt_error _("Out of memory!");
sleep (1);
mutt_exit (1);
}
if (n == 0)
{
/* Mutt convention is to use NULL for 0-length strings */
FREE (strp); /* __FREE_CHECKED__ */
}
return n;
}
#else
/* Allocate a C-string large enough to contain the formatted string.
* This is essentially malloc+sprintf in one.
*/
int safe_asprintf (char **strp, const char *fmt, ...)
{
int rlen = STRING;
int n;
*strp = safe_malloc (rlen);
for (;;)
{
va_list ap;
va_start (ap, fmt);
n = vsnprintf (*strp, rlen, fmt, ap);
va_end (ap);
if (n < 0)
{
FREE (strp); /* __FREE_CHECKED__ */
return n;
}
if (n < rlen)
{
/* reduce space to just that which was used. note that 'n' does not
* include the terminal nul char.
*/
if (n == 0) /* convention is to use NULL for zero-length strings. */
FREE (strp); /* __FREE_CHECKED__ */
else if (n != rlen - 1)
safe_realloc (strp, n + 1);
return n;
}
/* increase size and try again */
rlen = n + 1;
safe_realloc (strp, rlen);
}
/* not reached */
}
#endif /* HAVE_ASPRINTF */