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/*-
* Copyright (c) 1996 Peter Wemm <peter@freebsd.org>
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/
#if defined(LIBC_RCS) && !defined(lint)
static char rcsid[] = "$Id: vasprintf.c,v 1.6 1997/07/06 07:54:56 peter Exp $";
#endif /* LIBC_RCS and not lint */
#include <stdio.h>
#include <stdlib.h>
#if __STDC__
#include <stdarg.h>
#else
#include <varargs.h>
#endif
#define CHUNK_SPARE 128 /* how much spare to allocate to avoid realloc calls */
struct bufcookie {
char *base; /* start of buffer */
size_t size;
size_t left;
};
static int writehook __P((void *cookie, const char *, int));
static int
writehook(cookie, buf, len)
void *cookie;
const char *buf;
int len;
{
struct bufcookie *h = (struct bufcookie *)cookie;
char *newbuf;
if (len == 0)
return 0;
if (len > h->left) {
/* grow malloc region */
/*
* XXX this is linearly expanded, which is slow for obscenely
* large strings.
*/
h->left = h->left + len + CHUNK_SPARE;
h->size = h->size + len + CHUNK_SPARE;
newbuf = realloc(h->base, h->size);
if (newbuf == NULL) {
free(h->base);
h->base = NULL;
return (-1);
} else
h->base = newbuf;
}
/* "write" it */
(void)memcpy(h->base + h->size - h->left, buf, (size_t)len);
h->left -= len;
return (len);
}
int
vasprintf(str, fmt, ap)
char **str;
const char *fmt;
va_list ap;
{
int ret;
FILE *f;
struct bufcookie h;
h.base = malloc(CHUNK_SPARE);
if (h.base == NULL)
return (-1);
h.size = CHUNK_SPARE;
h.left = CHUNK_SPARE;
f = funopen(&h, NULL, writehook, NULL, NULL);
if (f == NULL) {
free(h.base);
return (-1);
}
ret = vfprintf(f, fmt, ap);
fclose(f);
/*
* clean up the wreckage. Did writehook fail or did something else
* in stdio explode perhaps?
*/
if (h.base == NULL) /* realloc failed in writehook */
return (-1);
if (ret < 0) { /* something else? */
free(h.base);
return (-1);
}
/*
* At this point, we have a non-null terminated string in a
* buffer. There may not be enough room to null-terminate it
* (h.left == 0) - if realloc failes to expand it, it's fatal.
* If we were merely trying to shrink the buffer, a realloc failure
* is not [yet] fatal. Note that when realloc returns NULL,
* the original buffer is left allocated and valid.
*/
if (h.left == 1) /* exact fit, do not realloc */
*str = h.base;
else {
*str = realloc(h.base, (size_t)(h.size - h.left + 1));
if (*str == NULL) {
/* failed to expand? - fatal */
if (h.left == 0) {
free(h.base);
return (-1);
}
*str = h.base; /* use oversize original buffer */
}
}
(*str)[h.size - h.left] = '\0';
return (ret);
}
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