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 }