string/argz-replace.c

   1 /* String replacement in an argz vector
   2    Copyright (C) 1997, 1998, 2006 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, write to the Free
  18    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
  19    02111-1307 USA.  */
  20
  21 #include <stdlib.h>
  22 #include <string.h>
  23 #include <argz.h>
  24
  25 /* Append BUF, of length BUF_LEN to *TO, of length *TO_LEN, reallocating and
  26    updating *TO & *TO_LEN appropriately.  If an allocation error occurs,
  27    *TO's old value is freed, and *TO is set to 0.  */
  28 static void
  29 str_append (char **to, size_t *to_len, const char *buf, const size_t buf_len)
  30 {
  31   size_t new_len = *to_len + buf_len;
  32   char *new_to = realloc (*to, new_len + 1);
  33
  34   if (new_to)
  35     {
  36       *((char *) __mempcpy (new_to + *to_len, buf, buf_len)) = '\0';
  37       *to = new_to;
  38       *to_len = new_len;
  39     }
  40   else
  41     {
  42       free (*to);
  43       *to = 0;
  44     }
  45 }
  46
  47 /* Replace any occurrences of the string STR in ARGZ with WITH, reallocating
  48    ARGZ as necessary.  If REPLACE_COUNT is non-zero, *REPLACE_COUNT will be
  49    incremented by number of replacements performed.  */
  50 error_t
  51 __argz_replace (char **argz, size_t *argz_len, const char *str, const char *with,
  52                 unsigned *replace_count)
  53 {
  54   error_t err = 0;
  55
  56   if (str && *str)
  57     {
  58       char *arg = 0;
  59       char *src = *argz;
  60       size_t src_len = *argz_len;
  61       char *dst = 0;
  62       size_t dst_len = 0;
  63       int delayed_copy = 1;     /* True while we've avoided copying anything.  */
  64       size_t str_len = strlen (str), with_len = strlen (with);
  65
  66       while (!err && (arg = argz_next (src, src_len, arg)))
  67         {
  68           char *match = strstr (arg, str);
  69           if (match)
  70             {
  71               char *from = match + str_len;
  72               size_t to_len = match - arg;
  73               char *to = __strndup (arg, to_len);
  74
  75               while (to && from)
  76                 {
  77                   str_append (&to, &to_len, with, with_len);
  78                   if (to)
  79                     {
  80                       match = strstr (from, str);
  81                       if (match)
  82                         {
  83                           str_append (&to, &to_len, from, match - from);
  84                           from = match + str_len;
  85                         }
  86                       else
  87                         {
  88                           str_append (&to, &to_len, from, strlen (from));
  89                           from = 0;
  90                         }
  91                     }
  92                 }
  93
  94               if (to)
  95                 {
  96                   if (delayed_copy)
  97                     /* We avoided copying SRC to DST until we found a match;
  98                        now that we've done so, copy everything from the start
  99                        of SRC.  */
 100                     {
 101                       if (arg > src)
 102                         err = __argz_append (&dst, &dst_len, src, (arg - src));
 103                       delayed_copy = 0;
 104                     }
 105                   if (! err)
 106                     err = __argz_add (&dst, &dst_len, to);
 107                   free (to);
 108                 }
 109               else
 110                 err = ENOMEM;
 111
 112               if (replace_count)
 113                 (*replace_count)++;
 114             }
 115           else if (! delayed_copy)
 116             err = __argz_add (&dst, &dst_len, arg);
 117         }
 118
 119       if (! err)
 120         {
 121           if (! delayed_copy)
 122             /* We never found any instances of str.  */
 123             {
 124               free (src);
 125               *argz = dst;
 126               *argz_len = dst_len;
 127             }
 128         }
 129       else if (dst_len > 0)
 130         free (dst);
 131     }
 132
 133   return err;
 134 }
 135 weak_alias (__argz_replace, argz_replace)