iconv/gconv_parseconfdir.h

   1 /* Handle configuration data.
   2    Copyright (C) 2021-2022 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 <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 readdir __readdir
  33 # define closedir __closedir
  34 # define mempcpy __mempcpy
  35 # define lstat64 __lstat64
  36 # define feof_unlocked __feof_unlocked
  37 #endif
  38
  39 /* Name of the file containing the module information in the directories
  40    along the path.  */
  41 static const char gconv_conf_filename[] = "gconv-modules";
  42
  43 static void add_alias (char *);
  44 static void add_module (char *, const char *, size_t, int);
  45
  46 /* Read the next configuration file.  */
  47 static bool
  48 read_conf_file (const char *filename, const char *directory, size_t dir_len)
  49 {
  50   /* Note the file is opened with cancellation in the I/O functions
  51      disabled.  */
  52   FILE *fp = fopen (filename, "rce");
  53   char *line = NULL;
  54   size_t line_len = 0;
  55   static int modcounter;
  56
  57   /* Don't complain if a file is not present or readable, simply silently
  58      ignore it.  */
  59   if (fp == NULL)
  60     return false;
  61
  62   /* No threads reading from this stream.  */
  63   __fsetlocking (fp, FSETLOCKING_BYCALLER);
  64
  65   /* Process the known entries of the file.  Comments start with `#' and
  66      end with the end of the line.  Empty lines are ignored.  */
  67   while (!feof_unlocked (fp))
  68     {
  69       char *rp, *endp, *word;
  70       ssize_t n = __getdelim (&line, &line_len, '\n', fp);
  71       if (n < 0)
  72         /* An error occurred.  */
  73         break;
  74
  75       rp = line;
  76       /* Terminate the line (excluding comments or newline) by an NUL byte
  77          to simplify the following code.  */
  78       endp = strchr (rp, '#');
  79       if (endp != NULL)
  80         *endp = '\0';
  81       else
  82         if (rp[n - 1] == '\n')
  83           rp[n - 1] = '\0';
  84
  85       while (isspace (*rp))
  86         ++rp;
  87
  88       /* If this is an empty line go on with the next one.  */
  89       if (rp == endp)
  90         continue;
  91
  92       word = rp;
  93       while (*rp != '\0' && !isspace (*rp))
  94         ++rp;
  95
  96       if (rp - word == sizeof ("alias") - 1
  97           && memcmp (word, "alias", sizeof ("alias") - 1) == 0)
  98         add_alias (rp);
  99       else if (rp - word == sizeof ("module") - 1
 100                && memcmp (word, "module", sizeof ("module") - 1) == 0)
 101         add_module (rp, directory, dir_len, modcounter++);
 102       /* else */
 103         /* Otherwise ignore the line.  */
 104     }
 105
 106   free (line);
 107
 108   fclose (fp);
 109   return true;
 110 }
 111
 112 /* Prefix DIR (with length DIR_LEN) with PREFIX if the latter is non-NULL and
 113    parse configuration in it.  */
 114
 115 static __always_inline bool
 116 gconv_parseconfdir (const char *prefix, const char *dir, size_t dir_len)
 117 {
 118   /* No slash needs to be inserted between dir and gconv_conf_filename; dir
 119      already ends in a slash.  The additional 2 is to accommodate the ".d"
 120      when looking for configuration files in gconv-modules.d.  */
 121   size_t buflen = dir_len + sizeof (gconv_conf_filename) + 2;
 122   char *buf = malloc (buflen + (prefix != NULL ? strlen (prefix) : 0));
 123   char *cp = buf;
 124   bool found = false;
 125
 126   if (buf == NULL)
 127     return false;
 128
 129   if (prefix != NULL)
 130     cp = stpcpy (cp, prefix);
 131
 132   cp = mempcpy (mempcpy (cp, dir, dir_len), gconv_conf_filename,
 133                 sizeof (gconv_conf_filename));
 134
 135   /* Read the gconv-modules configuration file first.  */
 136   found = read_conf_file (buf, dir, dir_len);
 137
 138   /* Next, see if there is a gconv-modules.d directory containing
 139      configuration files and if it is non-empty.  */
 140   cp--;
 141   cp[0] = '.';
 142   cp[1] = 'd';
 143   cp[2] = '\0';
 144
 145   DIR *confdir = opendir (buf);
 146   if (confdir != NULL)
 147     {
 148       struct dirent *ent;
 149       while ((ent = readdir (confdir)) != NULL)
 150         {
 151           if (ent->d_type != DT_REG && ent->d_type != DT_UNKNOWN)
 152             continue;
 153
 154           size_t len = strlen (ent->d_name);
 155           const char *suffix = ".conf";
 156
 157           if (len > strlen (suffix)
 158               && strcmp (ent->d_name + len - strlen (suffix), suffix) == 0)
 159             {
 160               char *conf;
 161               struct stat64 st;
 162               if (asprintf (&conf, "%s/%s", buf, ent->d_name) < 0)
 163                 continue;
 164
 165               if (ent->d_type != DT_UNKNOWN
 166                   || (lstat64 (conf, &st) != -1 && S_ISREG (st.st_mode)))
 167                 found |= read_conf_file (conf, dir, dir_len);
 168
 169               free (conf);
 170             }
 171         }
 172       closedir (confdir);
 173     }
 174   free (buf);
 175   return found;
 176 }