string/argz-replace.c

   1 /* String replacement in an argz vector
   2    Copyright (C) 1997-2022 Free Software Foundation, Inc.
   3    This file is part of the GNU C Library.
   4
   5    The GNU C Library is free software; you can redistribute it and/or
   6    modify it under the terms of the GNU Lesser General Public
   7    License as published by the Free Software Foundation; either
   8    version 2.1 of the License, or (at your option) any later version.
   9
  10    The GNU C Library is distributed in the hope that it will be useful,
  11    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13    Lesser General Public License for more details.
  14
  15    You should have received a copy of the GNU Lesser General Public
  16    License along with the GNU C Library; if not, see
  17    <https://www.gnu.org/licenses/>.  */
  18
  19 #include <stdlib.h>
  20 #include <string.h>
  21 #include <argz.h>
  22
  23 /* Append BUF, of length BUF_LEN to *TO, of length *TO_LEN, reallocating and
  24    updating *TO & *TO_LEN appropriately.  If an allocation error occurs,
  25    *TO's old value is freed, and *TO is set to 0.  */
  26 static void
  27 str_append (char **to, size_t *to_len, const char *buf, const size_t buf_len)
  28 {
  29   size_t new_len = *to_len + buf_len;
  30   char *new_to = realloc (*to, new_len + 1);
  31
  32   if (new_to)
  33     {
  34       *((char *) __mempcpy (new_to + *to_len, buf, buf_len)) = '\0';
  35       *to = new_to;
  36       *to_len = new_len;
  37     }
  38   else
  39     {
  40       free (*to);
  41       *to = 0;
  42     }
  43 }
  44
  45 /* Replace any occurrences of the string STR in ARGZ with WITH, reallocating
  46    ARGZ as necessary.  If REPLACE_COUNT is non-zero, *REPLACE_COUNT will be
  47    incremented by number of replacements performed.  */
  48 error_t
  49 __argz_replace (char **argz, size_t *argz_len, const char *str, const char *with,
  50                 unsigned *replace_count)
  51 {
  52   error_t err = 0;
  53
  54   if (str && *str)
  55     {
  56       char *arg = 0;
  57       char *src = *argz;
  58       size_t src_len = *argz_len;
  59       char *dst = 0;
  60       size_t dst_len = 0;
  61       int delayed_copy = 1;     /* True while we've avoided copying anything.  */
  62       size_t str_len = strlen (str), with_len = strlen (with);
  63
  64       while (!err && (arg = argz_next (src, src_len, arg)))
  65         {
  66           char *match = strstr (arg, str);
  67           if (match)
  68             {
  69               char *from = match + str_len;
  70               size_t to_len = match - arg;
  71               char *to = __strndup (arg, to_len);
  72
  73               while (to && from)
  74                 {
  75                   str_append (&to, &to_len, with, with_len);
  76                   if (to)
  77                     {
  78                       match = strstr (from, str);
  79                       if (match)
  80                         {
  81                           str_append (&to, &to_len, from, match - from);
  82                           from = match + str_len;
  83                         }
  84                       else
  85                         {
  86                           str_append (&to, &to_len, from, strlen (from));
  87                           from = 0;
  88                         }
  89                     }
  90                 }
  91
  92               if (to)
  93                 {
  94                   if (delayed_copy)
  95                     /* We avoided copying SRC to DST until we found a match;
  96                        now that we've done so, copy everything from the start
  97                        of SRC.  */
  98                     {
  99                       if (arg > src)
 100                         err = __argz_append (&dst, &dst_len, src, (arg - src));
 101                       delayed_copy = 0;
 102                     }
 103                   if (! err)
 104                     err = __argz_add (&dst, &dst_len, to);
 105                   free (to);
 106                 }
 107               else
 108                 err = ENOMEM;
 109
 110               if (replace_count)
 111                 (*replace_count)++;
 112             }
 113           else if (! delayed_copy)
 114             err = __argz_add (&dst, &dst_len, arg);
 115         }
 116
 117       if (! err)
 118         {
 119           if (! delayed_copy)
 120             /* We never found any instances of str.  */
 121             {
 122               free (src);
 123               *argz = dst;
 124               *argz_len = dst_len;
 125             }
 126         }
 127       else if (dst_len > 0)
 128         free (dst);
 129     }
 130
 131   return err;
 132 }
 133 weak_alias (__argz_replace, argz_replace)