iconv/gconv_parseconfdir.h

   1 /* Handle configuration data.
   2    Copyright (C) 2021-2023 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 <dirent.h>
  20 #include <libc-symbols.h>
  21 #include <locale.h>
  22 #include <sys/types.h>
  23
  24 #if IS_IN (libc)
  25 # include <libio/libioP.h>
  26 # define __getdelim(line, len, c, fp) __getdelim (line, len, c, fp)
  27
  28 # undef isspace
  29 # define isspace(__c) __isspace_l ((__c), _nl_C_locobj_ptr)
  30 # define asprintf __asprintf
  31 # define opendir __opendir
  32 # define readdir64 __readdir64
  33 # define closedir __closedir
  34 # define mempcpy __mempcpy
  35 # define struct_stat64 struct __stat64_t64
  36 # define lstat64 __lstat64_time64
  37 # define feof_unlocked __feof_unlocked
  38 #else
  39 # define struct_stat64 struct stat64
  40 #endif
  41
  42 /* Name of the file containing the module information in the directories
  43    along the path.  */
  44 static const char gconv_conf_filename[] = "gconv-modules";
  45
  46 static void add_alias (char *);
  47 static void add_module (char *, const char *, size_t, int);
  48
  49 /* Read the next configuration file.  */
  50 static bool
  51 read_conf_file (const char *filename, const char *directory, size_t dir_len)
  52 {
  53   /* Note the file is opened with cancellation in the I/O functions
  54      disabled.  */
  55   FILE *fp = fopen (filename, "rce");
  56   char *line = NULL;
  57   size_t line_len = 0;
  58   static int modcounter;
  59
  60   /* Don't complain if a file is not present or readable, simply silently
  61      ignore it.  */
  62   if (fp == NULL)
  63     return false;
  64
  65   /* No threads reading from this stream.  */
  66   __fsetlocking (fp, FSETLOCKING_BYCALLER);
  67
  68   /* Process the known entries of the file.  Comments start with `#' and
  69      end with the end of the line.  Empty lines are ignored.  */
  70   while (!feof_unlocked (fp))
  71     {
  72       char *rp, *endp, *word;
  73       ssize_t n = __getdelim (&line, &line_len, '\n', fp);
  74       if (n < 0)
  75         /* An error occurred.  */
  76         break;
  77
  78       rp = line;
  79       /* Terminate the line (excluding comments or newline) by an NUL byte
  80          to simplify the following code.  */
  81       endp = strchr (rp, '#');
  82       if (endp != NULL)
  83         *endp = '\0';
  84       else
  85         if (rp[n - 1] == '\n')
  86           rp[n - 1] = '\0';
  87
  88       while (isspace (*rp))
  89         ++rp;
  90
  91       /* If this is an empty line go on with the next one.  */
  92       if (rp == endp)
  93         continue;
  94
  95       word = rp;
  96       while (*rp != '\0' && !isspace (*rp))
  97         ++rp;
  98
  99       if (rp - word == sizeof ("alias") - 1
 100           && memcmp (word, "alias", sizeof ("alias") - 1) == 0)
 101         add_alias (rp);
 102       else if (rp - word == sizeof ("module") - 1
 103                && memcmp (word, "module", sizeof ("module") - 1) == 0)
 104         add_module (rp, directory, dir_len, modcounter++);
 105       /* else */
 106         /* Otherwise ignore the line.  */
 107     }
 108
 109   free (line);
 110
 111   fclose (fp);
 112   return true;
 113 }
 114
 115 /* Prefix DIR (with length DIR_LEN) with PREFIX if the latter is non-NULL and
 116    parse configuration in it.  */
 117
 118 static __always_inline bool
 119 gconv_parseconfdir (const char *prefix, const char *dir, size_t dir_len)
 120 {
 121   /* No slash needs to be inserted between dir and gconv_conf_filename; dir
 122      already ends in a slash.  The additional 2 is to accommodate the ".d"
 123      when looking for configuration files in gconv-modules.d.  */
 124   size_t buflen = dir_len + sizeof (gconv_conf_filename) + 2;
 125   char *buf = malloc (buflen + (prefix != NULL ? strlen (prefix) : 0));
 126   char *cp = buf;
 127   bool found = false;
 128
 129   if (buf == NULL)
 130     return false;
 131
 132   if (prefix != NULL)
 133     cp = stpcpy (cp, prefix);
 134
 135   cp = mempcpy (mempcpy (cp, dir, dir_len), gconv_conf_filename,
 136                 sizeof (gconv_conf_filename));
 137
 138   /* Read the gconv-modules configuration file first.  */
 139   found = read_conf_file (buf, dir, dir_len);
 140
 141   /* Next, see if there is a gconv-modules.d directory containing
 142      configuration files and if it is non-empty.  */
 143   cp--;
 144   cp[0] = '.';
 145   cp[1] = 'd';
 146   cp[2] = '\0';
 147
 148   DIR *confdir = opendir (buf);
 149   if (confdir != NULL)
 150     {
 151       struct dirent64 *ent;
 152       while ((ent = readdir64 (confdir)) != NULL)
 153         {
 154           if (ent->d_type != DT_REG && ent->d_type != DT_UNKNOWN)
 155             continue;
 156
 157           size_t len = strlen (ent->d_name);
 158           const char *suffix = ".conf";
 159
 160           if (len > strlen (suffix)
 161               && strcmp (ent->d_name + len - strlen (suffix), suffix) == 0)
 162             {
 163               char *conf;
 164               struct_stat64 st;
 165               if (asprintf (&conf, "%s/%s", buf, ent->d_name) < 0)
 166                 continue;
 167
 168               if (ent->d_type != DT_UNKNOWN
 169                   || (lstat64 (conf, &st) != -1 && S_ISREG (st.st_mode)))
 170                 found |= read_conf_file (conf, dir, dir_len);
 171
 172               free (conf);
 173             }
 174         }
 175       closedir (confdir);
 176     }
 177   free (buf);
 178   return found;
 179 }