string/argz-replace.c

   1 /* String replacement in an argz vector
   2    Copyright (C) 1997-2020 Free Software Foundation, Inc.
   3    This file is part of the GNU C Library.
   4    Written by Miles Bader <miles@gnu.ai.mit.edu>
   5
   6    The GNU C Library is free software; you can redistribute it and/or
   7    modify it under the terms of the GNU Lesser General Public
   8    License as published by the Free Software Foundation; either
   9    version 2.1 of the License, or (at your option) any later version.
  10
  11    The GNU C Library is distributed in the hope that it will be useful,
  12    but WITHOUT ANY WARRANTY; without even the implied warranty of
  13    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14    Lesser General Public License for more details.
  15
  16    You should have received a copy of the GNU Lesser General Public
  17    License along with the GNU C Library; if not, see
  18    <https://www.gnu.org/licenses/>.  */
  19
  20 #include <stdlib.h>
  21 #include <string.h>
  22 #include <argz.h>
  23
  24 /* Append BUF, of length BUF_LEN to *TO, of length *TO_LEN, reallocating and
  25    updating *TO & *TO_LEN appropriately.  If an allocation error occurs,
  26    *TO's old value is freed, and *TO is set to 0.  */
  27 static void
  28 str_append (char **to, size_t *to_len, const char *buf, const size_t buf_len)
  29 {
  30   size_t new_len = *to_len + buf_len;
  31   char *new_to = realloc (*to, new_len + 1);
  32
  33   if (new_to)
  34     {
  35       *((char *) __mempcpy (new_to + *to_len, buf, buf_len)) = '\0';
  36       *to = new_to;
  37       *to_len = new_len;
  38     }
  39   else
  40     {
  41       free (*to);
  42       *to = 0;
  43     }
  44 }
  45
  46 /* Replace any occurrences of the string STR in ARGZ with WITH, reallocating
  47    ARGZ as necessary.  If REPLACE_COUNT is non-zero, *REPLACE_COUNT will be
  48    incremented by number of replacements performed.  */
  49 error_t
  50 __argz_replace (char **argz, size_t *argz_len, const char *str, const char *with,
  51                 unsigned *replace_count)
  52 {
  53   error_t err = 0;
  54
  55   if (str && *str)
  56     {
  57       char *arg = 0;
  58       char *src = *argz;
  59       size_t src_len = *argz_len;
  60       char *dst = 0;
  61       size_t dst_len = 0;
  62       int delayed_copy = 1;     /* True while we've avoided copying anything.  */
  63       size_t str_len = strlen (str), with_len = strlen (with);
  64
  65       while (!err && (arg = argz_next (src, src_len, arg)))
  66         {
  67           char *match = strstr (arg, str);
  68           if (match)
  69             {
  70               char *from = match + str_len;
  71               size_t to_len = match - arg;
  72               char *to = __strndup (arg, to_len);
  73
  74               while (to && from)
  75                 {
  76                   str_append (&to, &to_len, with, with_len);
  77                   if (to)
  78                     {
  79                       match = strstr (from, str);
  80                       if (match)
  81                         {
  82                           str_append (&to, &to_len, from, match - from);
  83                           from = match + str_len;
  84                         }
  85                       else
  86                         {
  87                           str_append (&to, &to_len, from, strlen (from));
  88                           from = 0;
  89                         }
  90                     }
  91                 }
  92
  93               if (to)
  94                 {
  95                   if (delayed_copy)
  96                     /* We avoided copying SRC to DST until we found a match;
  97                        now that we've done so, copy everything from the start
  98                        of SRC.  */
  99                     {
 100                       if (arg > src)
 101                         err = __argz_append (&dst, &dst_len, src, (arg - src));
 102                       delayed_copy = 0;
 103                     }
 104                   if (! err)
 105                     err = __argz_add (&dst, &dst_len, to);
 106                   free (to);
 107                 }
 108               else
 109                 err = ENOMEM;
 110
 111               if (replace_count)
 112                 (*replace_count)++;
 113             }
 114           else if (! delayed_copy)
 115             err = __argz_add (&dst, &dst_len, arg);
 116         }
 117
 118       if (! err)
 119         {
 120           if (! delayed_copy)
 121             /* We never found any instances of str.  */
 122             {
 123               free (src);
 124               *argz = dst;
 125               *argz_len = dst_len;
 126             }
 127         }
 128       else if (dst_len > 0)
 129         free (dst);
 130     }
 131
 132   return err;
 133 }
 134 weak_alias (__argz_replace, argz_replace)