source/libs/gmp/gmp-src/printf/snprntffuns.c

   1 /* __gmp_snprintf_funs -- support for gmp_snprintf and gmp_vsnprintf.
   2
   3    THE FUNCTIONS IN THIS FILE ARE FOR INTERNAL USE ONLY.  THEY'RE ALMOST
   4    CERTAIN TO BE SUBJECT TO INCOMPATIBLE CHANGES OR DISAPPEAR COMPLETELY IN
   5    FUTURE GNU MP RELEASES.
   6
   7 Copyright 2001, 2002 Free Software Foundation, Inc.
   8
   9 This file is part of the GNU MP Library.
  10
  11 The GNU MP Library is free software; you can redistribute it and/or modify
  12 it under the terms of either:
  13
  14   * the GNU Lesser General Public License as published by the Free
  15     Software Foundation; either version 3 of the License, or (at your
  16     option) any later version.
  17
  18 or
  19
  20   * the GNU General Public License as published by the Free Software
  21     Foundation; either version 2 of the License, or (at your option) any
  22     later version.
  23
  24 or both in parallel, as here.
  25
  26 The GNU MP Library is distributed in the hope that it will be useful, but
  27 WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
  28 or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  29 for more details.
  30
  31 You should have received copies of the GNU General Public License and the
  32 GNU Lesser General Public License along with the GNU MP Library.  If not,
  33 see https://www.gnu.org/licenses/.  */
  34
  35 #include <stdarg.h>
  36 #include <stdio.h>
  37 #include <string.h>
  38
  39 #include "gmp.h"
  40 #include "gmp-impl.h"
  41
  42
  43 #if ! HAVE_VSNPRINTF
  44 #define vsnprintf  __gmp_replacement_vsnprintf
  45 #endif
  46
  47
  48 /* glibc 2.0.x vsnprintf returns either -1 or size-1 for an overflow, with
  49    no indication how big the output would have been.  It's necessary to
  50    re-run to determine that size.
  51
  52    "size-1" would mean success from a C99 vsnprintf, and the re-run is
  53    unnecessary in this case, but we don't bother to try to detect what sort
  54    of vsnprintf we've got.  size-1 should occur rarely in normal
  55    circumstances.
  56
  57    vsnprintf might trash it's given ap (it does for instance in glibc 2.1.3
  58    on powerpc), so copy it in case we need to use it to probe for the size
  59    output that would have been produced.  Note there's no need to preserve
  60    it for our callers, just for ourselves.  */
  61
  62 static int
  63 gmp_snprintf_format (struct gmp_snprintf_t *d, const char *fmt,
  64                      va_list orig_ap)
  65 {
  66   int      ret, step, alloc, avail;
  67   va_list  ap;
  68   char     *p;
  69
  70   ASSERT (d->size >= 0);
  71
  72   avail = d->size;
  73   if (avail > 1)
  74     {
  75       va_copy (ap, orig_ap);
  76       ret = vsnprintf (d->buf, avail, fmt, ap);
  77       if (ret == -1)
  78         {
  79           ASSERT (strlen (d->buf) == avail-1);
  80           ret = avail-1;
  81         }
  82
  83       step = MIN (ret, avail-1);
  84       d->size -= step;
  85       d->buf += step;
  86
  87       if (ret != avail-1)
  88         return ret;
  89
  90       /* probably glibc 2.0.x truncated output, probe for actual size */
  91       alloc = MAX (128, ret);
  92     }
  93   else
  94     {
  95       /* no space to write anything, just probe for size */
  96       alloc = 128;
  97     }
  98
  99   do
 100     {
 101       alloc *= 2;
 102       p = __GMP_ALLOCATE_FUNC_TYPE (alloc, char);
 103       va_copy (ap, orig_ap);
 104       ret = vsnprintf (p, alloc, fmt, ap);
 105       (*__gmp_free_func) (p, alloc);
 106     }
 107   while (ret == alloc-1 || ret == -1);
 108
 109   return ret;
 110 }
 111
 112 static int
 113 gmp_snprintf_memory (struct gmp_snprintf_t *d, const char *str, size_t len)
 114 {
 115   size_t n;
 116
 117   ASSERT (d->size >= 0);
 118
 119   if (d->size > 1)
 120     {
 121       n = MIN (d->size-1, len);
 122       memcpy (d->buf, str, n);
 123       d->buf += n;
 124       d->size -= n;
 125     }
 126   return len;
 127 }
 128
 129 static int
 130 gmp_snprintf_reps (struct gmp_snprintf_t *d, int c, int reps)
 131 {
 132   size_t n;
 133
 134   ASSERT (reps >= 0);
 135   ASSERT (d->size >= 0);
 136
 137   if (d->size > 1)
 138     {
 139       n = MIN (d->size-1, reps);
 140       memset (d->buf, c, n);
 141       d->buf += n;
 142       d->size -= n;
 143     }
 144   return reps;
 145 }
 146
 147 static int
 148 gmp_snprintf_final (struct gmp_snprintf_t *d)
 149 {
 150   if (d->size >= 1)
 151     d->buf[0] = '\0';
 152   return 0;
 153 }
 154
 155 const struct doprnt_funs_t  __gmp_snprintf_funs = {
 156   (doprnt_format_t) gmp_snprintf_format,
 157   (doprnt_memory_t) gmp_snprintf_memory,
 158   (doprnt_reps_t)   gmp_snprintf_reps,
 159   (doprnt_final_t)  gmp_snprintf_final
 160 };