vasnprintf.c
1.91 KB
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/* GNU Mailutils -- a suite of utilities for electronic mail
Copyright (C) 2009-2012 Free Software Foundation, Inc.
This library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 3 of the License, or (at your option) any later version.
This library 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
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General
Public License along with this library. If not, see
<http://www.gnu.org/licenses/>. */
#if HAVE_CONFIG_H
# include <config.h>
#endif
#include <stdlib.h>
#include <stdarg.h>
#include <stdio.h>
#include <errno.h>
#include <string.h>
#include <mailutils/io.h>
int
mu_vasnprintf (char **pbuf, size_t *psize, const char *fmt, va_list ap)
{
char *buf = *pbuf;
size_t buflen = *psize;
int rc = 0;
if (!buf)
{
if (buflen == 0)
buflen = 512; /* Initial allocation */
buf = calloc (1, buflen);
if (buf == NULL)
return ENOMEM;
}
for (;;)
{
ssize_t n;
va_list aq;
va_copy(aq, ap);
n = vsnprintf (buf, buflen, fmt, aq);
va_end(aq);
if (n < 0 || n >= buflen || !memchr (buf, '\0', n + 1))
{
char *newbuf;
size_t newlen = buflen * 2;
if (newlen < buflen)
{
rc = ENOMEM;
break;
}
newbuf = realloc (buf, newlen);
if (newbuf == NULL)
{
rc = ENOMEM;
break;
}
buflen = newlen;
buf = newbuf;
}
else
break;
}
if (rc)
{
if (!*pbuf)
{
/* We made first allocation, now free it */
free (buf);
buf = NULL;
buflen = 0;
}
}
*pbuf = buf;
*psize = buflen;
return rc;
}