blob: 4ed4c5dbe2809f3a5b765ebeb045e694ad3550f0 [file] [log] [blame]
/* gmp_vasprintf -- formatted output to an allocated space.
Copyright 2001 Free Software Foundation, Inc.
This file is part of the GNU MP Library.
The GNU MP 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.
The GNU MP 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 the GNU MP Library. If not, see */
#include "config.h"
#include <stdarg.h>
#include <varargs.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include "gmp.h"
#include "gmp-impl.h"
#define vsnprintf __gmp_replacement_vsnprintf
/* vasprintf isn't used since we prefer all GMP allocs to go through
__gmp_allocate_func, and in particular we don't want the -1 return from
vasprintf for out-of-memory, instead __gmp_allocate_func should handle
that. Using vsnprintf unfortunately means we might have to re-run it if
our current space is insufficient.
The initial guess for the needed space is an arbitrary 256 bytes. If
that (and any extra GMP_ASPRINTF_T_NEED might give) isn't enough then an
ISO C99 standard vsnprintf will tell us what we really need.
GLIBC 2.0.x vsnprintf returns either -1 or space-1 to indicate overflow,
without giving any indication how much is really needed. In this case
keep trying with double the space each time.
A return of space-1 is success on a C99 vsnprintf, but we're not
bothering to identify which style vsnprintf we've got, so just take the
pessimistic option and assume it's glibc 2.0.x.
Notice the use of ret+2 for the new space in the C99 case. This ensures
the next vsnprintf return value will be space-2, which is unambiguously
successful. But actually GMP_ASPRINTF_T_NEED() will realloc to even
bigger than that ret+2.
vsnprintf might trash it's given ap, so copy it in case we need to use it
more than once. See comments with gmp_snprintf_format. */
static int
gmp_asprintf_format (struct gmp_asprintf_t *d, const char *fmt,
va_list orig_ap)
int ret;
va_list ap;
size_t space = 256;
for (;;)
space = d->alloc - d->size;
va_copy (ap, orig_ap);
ret = vsnprintf (d->buf + d->size, space, fmt, ap);
if (ret == -1)
ASSERT (strlen (d->buf + d->size) == space-1);
ret = space-1;
/* done if output fits in our space */
if (ret < space-1)
if (ret == space-1)
space *= 2; /* possible glibc 2.0.x, so double */
space = ret+2; /* C99, so now know space required */
d->size += ret;
return ret;
const struct doprnt_funs_t __gmp_asprintf_funs = {
(doprnt_format_t) gmp_asprintf_format,
(doprnt_memory_t) __gmp_asprintf_memory,
(doprnt_reps_t) __gmp_asprintf_reps,
(doprnt_final_t) __gmp_asprintf_final
gmp_vasprintf (char **result, const char *fmt, va_list ap)
struct gmp_asprintf_t d;
GMP_ASPRINTF_T_INIT (d, result);
return __gmp_doprnt (&__gmp_asprintf_funs, &d, fmt, ap);