iconv/gconv_parseconfdir.h

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