1 | /* Common code for file-based databases in nss_files module. |
2 | Copyright (C) 1996-2017 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 | <http://www.gnu.org/licenses/>. */ |
18 | |
19 | #include <stdio.h> |
20 | #include <ctype.h> |
21 | #include <errno.h> |
22 | #include <fcntl.h> |
23 | #include <libc-lock.h> |
24 | #include "nsswitch.h" |
25 | |
26 | #include <kernel-features.h> |
27 | |
28 | /* These symbols are defined by the including source file: |
29 | |
30 | ENTNAME -- database name of the structure and functions (hostent, pwent). |
31 | STRUCTURE -- struct name, define only if not ENTNAME (passwd, group). |
32 | DATABASE -- string of the database file's name ("hosts", "passwd"). |
33 | |
34 | NEED_H_ERRNO - defined iff an arg `int *herrnop' is used. |
35 | |
36 | Also see files-parse.c. |
37 | */ |
38 | |
39 | #define ENTNAME_r CONCAT(ENTNAME,_r) |
40 | |
41 | #define DATAFILE "/etc/" DATABASE |
42 | |
43 | #ifdef NEED_H_ERRNO |
44 | # include <netdb.h> |
45 | # define H_ERRNO_PROTO , int *herrnop |
46 | # define H_ERRNO_ARG , herrnop |
47 | # define H_ERRNO_SET(val) (*herrnop = (val)) |
48 | #else |
49 | # define H_ERRNO_PROTO |
50 | # define H_ERRNO_ARG |
51 | # define H_ERRNO_SET(val) ((void) 0) |
52 | #endif |
53 | |
54 | #ifndef EXTRA_ARGS |
55 | # define EXTRA_ARGS |
56 | # define EXTRA_ARGS_DECL |
57 | # define EXTRA_ARGS_VALUE |
58 | #endif |
59 | |
60 | /* Locks the static variables in this file. */ |
61 | __libc_lock_define_initialized (static, lock) |
62 | |
63 | /* Maintenance of the stream open on the database file. For getXXent |
64 | operations the stream needs to be held open across calls, the other |
65 | getXXbyYY operations all use their own stream. */ |
66 | |
67 | static FILE *stream; |
68 | |
69 | /* Open database file if not already opened. */ |
70 | static enum nss_status |
71 | internal_setent (FILE **stream) |
72 | { |
73 | enum nss_status status = NSS_STATUS_SUCCESS; |
74 | |
75 | if (*stream == NULL) |
76 | { |
77 | *stream = fopen (DATAFILE, "rce" ); |
78 | |
79 | if (*stream == NULL) |
80 | status = errno == EAGAIN ? NSS_STATUS_TRYAGAIN : NSS_STATUS_UNAVAIL; |
81 | else |
82 | { |
83 | #if !defined O_CLOEXEC || !defined __ASSUME_O_CLOEXEC |
84 | # ifdef O_CLOEXEC |
85 | if (__have_o_cloexec <= 0) |
86 | # endif |
87 | { |
88 | /* We have to make sure the file is `closed on exec'. */ |
89 | int result; |
90 | int flags; |
91 | |
92 | result = flags = fcntl (fileno (*stream), F_GETFD, 0); |
93 | if (result >= 0) |
94 | { |
95 | # ifdef O_CLOEXEC |
96 | if (__have_o_cloexec == 0) |
97 | __have_o_cloexec = (flags & FD_CLOEXEC) == 0 ? -1 : 1; |
98 | if (__have_o_cloexec < 0) |
99 | # endif |
100 | { |
101 | flags |= FD_CLOEXEC; |
102 | result = fcntl (fileno (*stream), F_SETFD, flags); |
103 | } |
104 | } |
105 | if (result < 0) |
106 | { |
107 | /* Something went wrong. Close the stream and return a |
108 | failure. */ |
109 | fclose (*stream); |
110 | *stream = NULL; |
111 | status = NSS_STATUS_UNAVAIL; |
112 | } |
113 | } |
114 | #endif |
115 | } |
116 | } |
117 | else |
118 | rewind (*stream); |
119 | |
120 | return status; |
121 | } |
122 | |
123 | |
124 | /* Thread-safe, exported version of that. */ |
125 | enum nss_status |
126 | CONCAT(_nss_files_set,ENTNAME) (int stayopen) |
127 | { |
128 | enum nss_status status; |
129 | |
130 | __libc_lock_lock (lock); |
131 | |
132 | status = internal_setent (&stream); |
133 | |
134 | __libc_lock_unlock (lock); |
135 | |
136 | return status; |
137 | } |
138 | |
139 | |
140 | /* Close the database file. */ |
141 | static void |
142 | internal_endent (FILE **stream) |
143 | { |
144 | if (*stream != NULL) |
145 | { |
146 | fclose (*stream); |
147 | *stream = NULL; |
148 | } |
149 | } |
150 | |
151 | |
152 | /* Thread-safe, exported version of that. */ |
153 | enum nss_status |
154 | CONCAT(_nss_files_end,ENTNAME) (void) |
155 | { |
156 | __libc_lock_lock (lock); |
157 | |
158 | internal_endent (&stream); |
159 | |
160 | __libc_lock_unlock (lock); |
161 | |
162 | return NSS_STATUS_SUCCESS; |
163 | } |
164 | |
165 | |
166 | typedef enum |
167 | { |
168 | gcr_ok = 0, |
169 | gcr_error = -1, |
170 | gcr_overflow = -2 |
171 | } get_contents_ret; |
172 | |
173 | /* Hack around the fact that fgets only accepts int sizes. */ |
174 | static get_contents_ret |
175 | get_contents (char *linebuf, size_t len, FILE *stream) |
176 | { |
177 | size_t remaining_len = len; |
178 | char *curbuf = linebuf; |
179 | |
180 | do |
181 | { |
182 | int curlen = ((remaining_len > (size_t) INT_MAX) ? INT_MAX |
183 | : remaining_len); |
184 | |
185 | /* Terminate the line so that we can test for overflow. */ |
186 | ((unsigned char *) curbuf)[curlen - 1] = 0xff; |
187 | |
188 | char *p = fgets_unlocked (curbuf, curlen, stream); |
189 | |
190 | /* EOF or read error. */ |
191 | if (p == NULL) |
192 | return gcr_error; |
193 | |
194 | /* Done reading in the line. */ |
195 | if (((unsigned char *) curbuf)[curlen - 1] == 0xff) |
196 | return gcr_ok; |
197 | |
198 | /* Drop the terminating '\0'. */ |
199 | remaining_len -= curlen - 1; |
200 | curbuf += curlen - 1; |
201 | } |
202 | /* fgets copies one less than the input length. Our last iteration is of |
203 | REMAINING_LEN and once that is done, REMAINING_LEN is decremented by |
204 | REMAINING_LEN - 1, leaving the result as 1. */ |
205 | while (remaining_len > 1); |
206 | |
207 | /* This means that the current buffer was not large enough. */ |
208 | return gcr_overflow; |
209 | } |
210 | |
211 | /* Parsing the database file into `struct STRUCTURE' data structures. */ |
212 | static enum nss_status |
213 | internal_getent (FILE *stream, struct STRUCTURE *result, |
214 | char *buffer, size_t buflen, int *errnop H_ERRNO_PROTO |
215 | EXTRA_ARGS_DECL) |
216 | { |
217 | char *p; |
218 | struct parser_data *data = (void *) buffer; |
219 | size_t linebuflen = buffer + buflen - data->linebuffer; |
220 | int parse_result; |
221 | |
222 | if (buflen < sizeof *data + 2) |
223 | { |
224 | *errnop = ERANGE; |
225 | H_ERRNO_SET (NETDB_INTERNAL); |
226 | return NSS_STATUS_TRYAGAIN; |
227 | } |
228 | |
229 | do |
230 | { |
231 | get_contents_ret r = get_contents (data->linebuffer, linebuflen, stream); |
232 | |
233 | if (r == gcr_error) |
234 | { |
235 | /* End of file or read error. */ |
236 | H_ERRNO_SET (HOST_NOT_FOUND); |
237 | return NSS_STATUS_NOTFOUND; |
238 | } |
239 | |
240 | if (r == gcr_overflow) |
241 | { |
242 | /* The line is too long. Give the user the opportunity to |
243 | enlarge the buffer. */ |
244 | *errnop = ERANGE; |
245 | H_ERRNO_SET (NETDB_INTERNAL); |
246 | return NSS_STATUS_TRYAGAIN; |
247 | } |
248 | |
249 | /* Everything OK. Now skip leading blanks. */ |
250 | p = data->linebuffer; |
251 | while (isspace (*p)) |
252 | ++p; |
253 | } |
254 | while (*p == '\0' || *p == '#' /* Ignore empty and comment lines. */ |
255 | /* Parse the line. If it is invalid, loop to get the next |
256 | line of the file to parse. */ |
257 | || ! (parse_result = parse_line (p, result, data, buflen, errnop |
258 | EXTRA_ARGS))); |
259 | |
260 | if (__glibc_unlikely (parse_result == -1)) |
261 | { |
262 | H_ERRNO_SET (NETDB_INTERNAL); |
263 | return NSS_STATUS_TRYAGAIN; |
264 | } |
265 | |
266 | /* Filled in RESULT with the next entry from the database file. */ |
267 | return NSS_STATUS_SUCCESS; |
268 | } |
269 | |
270 | |
271 | /* Return the next entry from the database file, doing locking. */ |
272 | enum nss_status |
273 | CONCAT(_nss_files_get,ENTNAME_r) (struct STRUCTURE *result, char *buffer, |
274 | size_t buflen, int *errnop H_ERRNO_PROTO) |
275 | { |
276 | /* Return next entry in host file. */ |
277 | enum nss_status status = NSS_STATUS_SUCCESS; |
278 | |
279 | __libc_lock_lock (lock); |
280 | |
281 | /* Be prepared that the set*ent function was not called before. */ |
282 | if (stream == NULL) |
283 | { |
284 | int save_errno = errno; |
285 | |
286 | status = internal_setent (&stream); |
287 | |
288 | __set_errno (save_errno); |
289 | } |
290 | |
291 | if (status == NSS_STATUS_SUCCESS) |
292 | status = internal_getent (stream, result, buffer, buflen, errnop |
293 | H_ERRNO_ARG EXTRA_ARGS_VALUE); |
294 | |
295 | __libc_lock_unlock (lock); |
296 | |
297 | return status; |
298 | } |
299 | |
300 | /* Macro for defining lookup functions for this file-based database. |
301 | |
302 | NAME is the name of the lookup; e.g. `hostbyname'. |
303 | |
304 | DB_CHAR, KEYPATTERN, KEYSIZE are ignored here but used by db-XXX.c |
305 | e.g. `1 + sizeof (id) * 4'. |
306 | |
307 | PROTO is the potentially empty list of other parameters. |
308 | |
309 | BREAK_IF_MATCH is a block of code which compares `struct STRUCTURE *result' |
310 | to the lookup key arguments and does `break;' if they match. */ |
311 | |
312 | #define DB_LOOKUP(name, db_char, keysize, keypattern, break_if_match, proto...)\ |
313 | enum nss_status \ |
314 | _nss_files_get##name##_r (proto, \ |
315 | struct STRUCTURE *result, char *buffer, \ |
316 | size_t buflen, int *errnop H_ERRNO_PROTO) \ |
317 | { \ |
318 | enum nss_status status; \ |
319 | FILE *stream = NULL; \ |
320 | \ |
321 | /* Open file. */ \ |
322 | status = internal_setent (&stream); \ |
323 | \ |
324 | if (status == NSS_STATUS_SUCCESS) \ |
325 | { \ |
326 | while ((status = internal_getent (stream, result, buffer, buflen, errnop \ |
327 | H_ERRNO_ARG EXTRA_ARGS_VALUE)) \ |
328 | == NSS_STATUS_SUCCESS) \ |
329 | { break_if_match } \ |
330 | \ |
331 | internal_endent (&stream); \ |
332 | } \ |
333 | \ |
334 | return status; \ |
335 | } |
336 | |