116 lines
3.7 KiB
C
116 lines
3.7 KiB
C
/* gmp_vasprintf -- formatted output to an allocated space.
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Copyright 2001 Free Software Foundation, Inc.
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This file is part of the GNU MP Library.
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The GNU MP Library is free software; you can redistribute it and/or modify
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it under the terms of the GNU Lesser General Public License as published by
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the Free Software Foundation; either version 2.1 of the License, or (at your
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option) any later version.
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The GNU MP Library is distributed in the hope that it will be useful, but
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WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
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or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
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License for more details.
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You should have received a copy of the GNU Lesser General Public License
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along with the GNU MP Library; see the file COPYING.LIB. If not, write to
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the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
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MA 02110-1301, USA. */
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#include "config.h"
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#if HAVE_STDARG
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#include <stdarg.h>
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#else
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#include <varargs.h>
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#endif
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include "gmp.h"
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#include "gmp-impl.h"
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#if ! HAVE_VSNPRINTF
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#define vsnprintf __gmp_replacement_vsnprintf
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#endif
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/* vasprintf isn't used since we prefer all GMP allocs to go through
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__gmp_allocate_func, and in particular we don't want the -1 return from
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vasprintf for out-of-memory, instead __gmp_allocate_func should handle
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that. Using vsnprintf unfortunately means we might have to re-run it if
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our current space is insufficient.
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The initial guess for the needed space is an arbitrary 256 bytes. If
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that (and any extra GMP_ASPRINTF_T_NEED might give) isn't enough then an
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ISO C99 standard vsnprintf will tell us what we really need.
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GLIBC 2.0.x vsnprintf returns either -1 or space-1 to indicate overflow,
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without giving any indication how much is really needed. In this case
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keep trying with double the space each time.
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A return of space-1 is success on a C99 vsnprintf, but we're not
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bothering to identify which style vsnprintf we've got, so just take the
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pessimistic option and assume it's glibc 2.0.x.
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Notice the use of ret+2 for the new space in the C99 case. This ensures
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the next vsnprintf return value will be space-2, which is unambiguously
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successful. But actually GMP_ASPRINTF_T_NEED() will realloc to even
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bigger than that ret+2.
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vsnprintf might trash it's given ap, so copy it in case we need to use it
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more than once. See comments with gmp_snprintf_format. */
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static int
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gmp_asprintf_format (struct gmp_asprintf_t *d, const char *fmt,
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va_list orig_ap)
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{
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int ret;
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va_list ap;
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size_t space = 256;
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for (;;)
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{
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GMP_ASPRINTF_T_NEED (d, space);
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space = d->alloc - d->size;
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va_copy (ap, orig_ap);
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ret = vsnprintf (d->buf + d->size, space, fmt, ap);
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if (ret == -1)
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{
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ASSERT (strlen (d->buf + d->size) == space-1);
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ret = space-1;
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}
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/* done if output fits in our space */
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if (ret < space-1)
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break;
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if (ret == space-1)
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space *= 2; /* possible glibc 2.0.x, so double */
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else
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space = ret+2; /* C99, so now know space required */
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}
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d->size += ret;
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return ret;
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}
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const struct doprnt_funs_t __gmp_asprintf_funs = {
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(doprnt_format_t) gmp_asprintf_format,
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(doprnt_memory_t) __gmp_asprintf_memory,
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(doprnt_reps_t) __gmp_asprintf_reps,
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(doprnt_final_t) __gmp_asprintf_final
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};
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int
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gmp_vasprintf (char **result, const char *fmt, va_list ap)
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{
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struct gmp_asprintf_t d;
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GMP_ASPRINTF_T_INIT (d, result);
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return __gmp_doprnt (&__gmp_asprintf_funs, &d, fmt, ap);
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}
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