Return to vasprintf.c CVS log

Up to [local] / OpenXM_contrib / gmp / printf

Annotation of OpenXM_contrib/gmp/printf/vasprintf.c, Revision 1.1.1.1

1.1       ohara       1: /* gmp_vasprintf -- formatted output to an allocated space.
                      2:
                      3: Copyright 2001 Free Software Foundation, Inc.
                      4:
                      5: This file is part of the GNU MP Library.
                      6:
                      7: The GNU MP Library is free software; you can redistribute it and/or modify
                      8: it under the terms of the GNU Lesser General Public License as published by
                      9: the Free Software Foundation; either version 2.1 of the License, or (at your
                     10: option) any later version.
                     11:
                     12: The GNU MP Library is distributed in the hope that it will be useful, but
                     13: WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
                     14: or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Lesser General Public
                     15: License for more details.
                     16:
                     17: You should have received a copy of the GNU Lesser General Public License
                     18: along with the GNU MP Library; see the file COPYING.LIB.  If not, write to
                     19: the Free Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
                     20: MA 02111-1307, USA. */
                     21:
                     22: #include "config.h"
                     23:
                     24: #if HAVE_STDARG
                     25: #include <stdarg.h>
                     26: #else
                     27: #include <varargs.h>
                     28: #endif
                     29:
                     30: #include <stdio.h>
                     31: #include <stdlib.h>
                     32: #include <string.h>
                     33:
                     34: #include "gmp.h"
                     35: #include "gmp-impl.h"
                     36:
                     37: #if ! HAVE_VSNPRINTF
                     38: #define vsnprintf  __gmp_replacement_vsnprintf
                     39: #endif
                     40:
                     41:
                     42: /* vasprintf isn't used since we prefer all GMP allocs to go through
                     43:    __gmp_allocate_func, and in particular we don't want the -1 return from
                     44:    vasprintf for out-of-memory, instead __gmp_allocate_func should handle
                     45:    that.  Using vsnprintf unfortunately means we might have to re-run it if
                     46:    our current space is insufficient.
                     47:
                     48:    The initial guess for the needed space is an arbitrary 256 bytes.  If
                     49:    that (and any extra GMP_ASPRINTF_T_NEED might give) isn't enough then an
                     50:    ISO C99 standard vsnprintf will tell us what we really need.
                     51:
                     52:    GLIBC 2.0.x vsnprintf returns either -1 or space-1 to indicate overflow,
                     53:    without giving any indication how much is really needed.  In this case
                     54:    keep trying with double the space each time.
                     55:
                     56:    A return of space-1 is success on a C99 vsnprintf, but we're not
                     57:    bothering to identify which style vsnprintf we've got, so just take the
                     58:    pessimistic option and assume it's glibc 2.0.x.
                     59:
                     60:    Notice the use of ret+2 for the new space in the C99 case.  This ensures
                     61:    the next vsnprintf return value will be space-2, which is unambiguously
                     62:    successful.  But actually GMP_ASPRINTF_T_NEED() will realloc to even
                     63:    bigger than that ret+2.
                     64:
                     65:    vsnprintf might trash it's given ap, so copy it in case we need to use it
                     66:    more than once.  See comments with gmp_snprintf_format.  */
                     67:
                     68: static int
                     69: gmp_asprintf_format (struct gmp_asprintf_t *d, const char *fmt,
                     70:                      va_list orig_ap)
                     71: {
                     72:   int      ret;
                     73:   va_list  ap;
                     74:   size_t   space = 256;
                     75:
                     76:   for (;;)
                     77:     {
                     78:       GMP_ASPRINTF_T_NEED (d, space);
                     79:       space = d->alloc - d->size;
                     80:       va_copy (ap, orig_ap);
                     81:       ret = vsnprintf (d->buf + d->size, space, fmt, ap);
                     82:       if (ret == -1)
                     83:         {
                     84:           ASSERT (strlen (d->buf + d->size) == space-1);
                     85:           ret = space-1;
                     86:         }
                     87:
                     88:       /* done if output fits in our space */
                     89:       if (ret < space-1)
                     90:         break;
                     91:
                     92:       if (ret == space-1)
                     93:         space *= 2;     /* possible glibc 2.0.x, so double */
                     94:       else
                     95:         space = ret+2;  /* C99, so now know space required */
                     96:     }
                     97:
                     98:   d->size += ret;
                     99:   return ret;
                    100: }
                    101:
                    102: const struct doprnt_funs_t  __gmp_asprintf_funs = {
                    103:   (doprnt_format_t) gmp_asprintf_format,
                    104:   (doprnt_memory_t) __gmp_asprintf_memory,
                    105:   (doprnt_reps_t)   __gmp_asprintf_reps,
                    106:   (doprnt_final_t)  __gmp_asprintf_final
                    107: };
                    108:
                    109: int
                    110: gmp_vasprintf (char **result, const char *fmt, va_list ap)
                    111: {
                    112:   struct gmp_asprintf_t  d;
                    113:   GMP_ASPRINTF_T_INIT (d, result);
                    114:   return __gmp_doprnt (&__gmp_asprintf_funs, &d, fmt, ap);
                    115: }