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 7Copyright 2001, 2002, 2018 Free Software Foundation, Inc. 8 9This file is part of the GNU MP Library. 10 11The GNU MP Library is free software; you can redistribute it and/or modify 12it 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 18or 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 24or both in parallel, as here. 25 26The GNU MP Library is distributed in the hope that it will be useful, but 27WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY 28or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 29for more details. 30 31You should have received copies of the GNU General Public License and the 32GNU Lesser General Public License along with the GNU MP Library. If not, 33see https://www.gnu.org/licenses/. */ 34 35#include <stdarg.h> 36#include <stdio.h> 37#include <string.h> 38 39#include "gmp-impl.h" 40 41 42#if ! HAVE_VSNPRINTF 43#define vsnprintf __gmp_replacement_vsnprintf 44#endif 45 46 47/* glibc 2.0.x vsnprintf returns either -1 or size-1 for an overflow, with 48 no indication how big the output would have been. It's necessary to 49 re-run to determine that size. 50 51 "size-1" would mean success from a C99 vsnprintf, and the re-run is 52 unnecessary in this case, but we don't bother to try to detect what sort 53 of vsnprintf we've got. size-1 should occur rarely in normal 54 circumstances. 55 56 vsnprintf might trash it's given ap (it does for instance in glibc 2.1.3 57 on powerpc), so copy it in case we need to use it to probe for the size 58 output that would have been produced. Note there's no need to preserve 59 it for our callers, just for ourselves. */ 60 61static int 62gmp_snprintf_format (struct gmp_snprintf_t *d, const char *fmt, 63 va_list orig_ap) 64{ 65 int ret; 66 size_t 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 return ret; 79 80 step = MIN (ret, avail-1); 81 d->size -= step; 82 d->buf += step; 83 84 if (ret != avail-1) 85 return ret; 86 87 /* probably glibc 2.0.x truncated output, probe for actual size */ 88 alloc = MAX (128, ret); 89 } 90 else 91 { 92 /* no space to write anything, just probe for size */ 93 alloc = 128; 94 } 95 96 do 97 { 98 alloc *= 2; 99 p = __GMP_ALLOCATE_FUNC_TYPE (alloc, char); 100 va_copy (ap, orig_ap); 101 ret = vsnprintf (p, alloc, fmt, ap); 102 __GMP_FREE_FUNC_TYPE (p, alloc, char); 103 } 104 while (ret == alloc-1); 105 106 return ret; 107} 108 109static int 110gmp_snprintf_memory (struct gmp_snprintf_t *d, const char *str, size_t len) 111{ 112 size_t n; 113 114 ASSERT (d->size >= 0); 115 116 if (d->size > 1) 117 { 118 n = MIN (d->size-1, len); 119 memcpy (d->buf, str, n); 120 d->buf += n; 121 d->size -= n; 122 } 123 return len; 124} 125 126static int 127gmp_snprintf_reps (struct gmp_snprintf_t *d, int c, int reps) 128{ 129 size_t n; 130 131 ASSERT (reps >= 0); 132 ASSERT (d->size >= 0); 133 134 if (d->size > 1) 135 { 136 n = MIN (d->size-1, reps); 137 memset (d->buf, c, n); 138 d->buf += n; 139 d->size -= n; 140 } 141 return reps; 142} 143 144static int 145gmp_snprintf_final (struct gmp_snprintf_t *d) 146{ 147 if (d->size >= 1) 148 d->buf[0] = '\0'; 149 return 0; 150} 151 152const struct doprnt_funs_t __gmp_snprintf_funs = { 153 (doprnt_format_t) gmp_snprintf_format, 154 (doprnt_memory_t) gmp_snprintf_memory, 155 (doprnt_reps_t) gmp_snprintf_reps, 156 (doprnt_final_t) gmp_snprintf_final 157}; 158