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elf: Fix use-after-free in ldconfig [BZ #26779]
[glibc.git] / nss / nss_files / files-parse.c
blobc90e2938021a66ed15a71b6497f50682728aa15b
1 /* Common code for file-based database parsers in nss_files module.
2 Copyright (C) 1996-2022 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 <ctype.h>
20 #include <errno.h>
21 #include <string.h>
22 #include <stdlib.h>
23 #include <stdint.h>
24 #include <nss_files.h>
25
26 /* These symbols are defined by the including source file:
27
28 ENTNAME -- database name of the structure and functions (hostent, pwent).
29 STRUCTURE -- struct name, define only if not ENTNAME (passwd, group).
30 DATABASE -- string of the database file's name ("hosts", "passwd").
31
32 ENTDATA -- if defined, `struct ENTDATA' is used by the parser to store
33 things pointed to by the resultant `struct STRUCTURE'.
34
35 NEED_H_ERRNO - defined iff an arg `int *herrnop' is used.
36
37 EXTRA_ARGS -- defined iff extra parameters must be passed to the parser
38 EXTRA_ARGS_DECL -- declaration for these extra parameters
39 EXTRA_ARGS_VALUE -- values to be passed for these parameters
40
41 Also see files-XXX.c. */
42
43 #ifndef EXTRA_ARGS
44 # define EXTRA_ARGS
45 # define EXTRA_ARGS_DECL
46 # define EXTRA_ARGS_VALUE
47 #endif
48
49 #define CONCAT(a,b) CONCAT1(a,b)
50 #define CONCAT1(a,b) a##b
51
52 #ifndef STRUCTURE
53 # define STRUCTURE ENTNAME
54 #endif
55
56
57 struct parser_data
58 {
59 #ifdef ENTDATA
60 struct ENTDATA entdata;
61 # define ENTDATA_DECL(data) struct ENTDATA *const entdata = &data->entdata;
62 #else
63 # define ENTDATA_DECL(data)
64 #endif
65 char linebuffer[0];
66 };
67
68 #ifdef ENTDATA
69 /* The function can't be exported, because the entdata structure
70 is defined only in files-foo.c. */
71 # define parser_stclass static
72 # define nss_files_parse_hidden_def(name)
73 #else
74 /* Export the line parser function so it can be used in nss_db. */
75 # define parser_stclass /* Global */
76 # define parse_line CONCAT(_nss_files_parse_,ENTNAME)
77 # define nss_files_parse_hidden_def(name) libc_hidden_def (name)
78 #endif
79
80
81 #ifdef EXTERN_PARSER
82
83 /* The parser is defined in a different module. */
84 extern int parse_line (char *line, void *result,
85 struct parser_data *data, size_t datalen, int *errnop
86 EXTRA_ARGS_DECL);
87
88 # define LINE_PARSER(EOLSET, BODY) /* Do nothing */
89
90 #else
91
92 /* Define a line parsing function. */
93
94 # define LINE_PARSER(EOLSET, BODY) \
95 parser_stclass int \
96 parse_line (char *line, void *generic_result, \
97 struct parser_data *data, size_t datalen, int *errnop \
98 EXTRA_ARGS_DECL) \
99 { \
100 struct STRUCTURE *result = generic_result; \
101 ENTDATA_DECL (data) \
102 BUFFER_PREPARE \
103 char *p = strpbrk (line, EOLSET "\n"); \
104 if (p != NULL) \
105 *p = '\0'; \
106 BODY; \
107 TRAILING_LIST_PARSER; \
108 return 1; \
109 } \
110 nss_files_parse_hidden_def (parse_line)
111
112
113 # define STRING_FIELD(variable, terminator_p, swallow) \
114 { \
115 variable = line; \
116 while (*line != '\0' && !terminator_p (*line)) \
117 ++line; \
118 if (*line != '\0') \
119 { \
120 *line = '\0'; \
121 do \
122 ++line; \
123 while (swallow && terminator_p (*line)); \
124 } \
125 }
126
127 # define STRING_LIST(variable, terminator_c) \
128 { \
129 char **list = parse_list (&line, buf_start, buf_end, terminator_c, \
130 errnop); \
131 if (list) \
132 variable = list; \
133 else \
134 return -1; /* -1 indicates we ran out of space. */ \
135 \
136 /* Determine the new end of the buffer. */ \
137 while (*list != NULL) \
138 ++list; \
139 buf_start = (char *) (list + 1); \
140 }
141
142 /* Helper function. */
143 static inline uint32_t
144 __attribute__ ((always_inline))
145 strtou32 (const char *nptr, char **endptr, int base)
146 {
147 unsigned long int val = strtoul (nptr, endptr, base);
148
149 /* Match the 32-bit behavior on 64-bit platforms. */
150 if (sizeof (long int) > 4 && val > 0xffffffff)
151 val = 0xffffffff;
152
153 return val;
154 }
155
156 # define INT_FIELD(variable, terminator_p, swallow, base, convert) \
157 { \
158 char *endp; \
159 variable = convert (strtou32 (line, &endp, base)); \
160 if (endp == line) \
161 return 0; \
162 else if (terminator_p (*endp)) \
163 do \
164 ++endp; \
165 while (swallow && terminator_p (*endp)); \
166 else if (*endp != '\0') \
167 return 0; \
168 line = endp; \
169 }
170
171 # define INT_FIELD_MAYBE_NULL(variable, terminator_p, swallow, base, convert, default) \
172 { \
173 char *endp; \
174 if (*line == '\0') \
175 /* We expect some more input, so don't allow the string to end here. */ \
176 return 0; \
177 variable = convert (strtou32 (line, &endp, base)); \
178 if (endp == line) \
179 variable = default; \
180 if (terminator_p (*endp)) \
181 do \
182 ++endp; \
183 while (swallow && terminator_p (*endp)); \
184 else if (*endp != '\0') \
185 return 0; \
186 line = endp; \
187 }
188
189 # define ISCOLON(c) ((c) == ':')
190
191
192 # ifndef TRAILING_LIST_MEMBER
193 # define BUFFER_PREPARE /* Nothing to do. */
194 # define TRAILING_LIST_PARSER /* Nothing to do. */
195 # else
196
197 # define BUFFER_PREPARE \
198 char *buf_start = NULL; \
199 char *buf_end = (char *) data + datalen; \
200 if (line >= data->linebuffer && line < buf_end) \
201 /* Find the end of the line buffer, we will use the space in \
202 DATA after it for storing the vector of pointers. */ \
203 buf_start = strchr (line, '\0') + 1; \
204 else \
205 /* LINE does not point within DATA->linebuffer, so that space is \
206 not being used for scratch space right now. We can use all of \
207 it for the pointer vector storage. */ \
208 buf_start = data->linebuffer; \
209
210 # define TRAILING_LIST_PARSER \
211 { \
212 if (buf_start == NULL) \
213 { \
214 if (line >= data->linebuffer && line < buf_end) \
215 /* Find the end of the line buffer, we will use the space in \
216 DATA after it for storing the vector of pointers. */ \
217 buf_start = strchr (line, '\0') + 1; \
218 else \
219 /* LINE does not point within DATA->linebuffer, so that space is \
220 not being used for scratch space right now. We can use all of \
221 it for the pointer vector storage. */ \
222 buf_start = data->linebuffer; \
223 } \
224 \
225 char **list = parse_list (&line, buf_start, buf_end, '\0', errnop); \
226 if (list) \
227 result->TRAILING_LIST_MEMBER = list; \
228 else \
229 return -1; /* -1 indicates we ran out of space. */ \
230 }
231
232 static inline char **
233 __attribute ((always_inline))
234 parse_list (char **linep, char *eol, char *buf_end, int terminator_c,
235 int *errnop)
236 {
237 char *line = *linep;
238 char **list, **p;
239
240 /* Adjust the pointer so it is aligned for storing pointers. */
241 eol += __alignof__ (char *) - 1;
242 eol -= (eol - (char *) 0) % __alignof__ (char *);
243 /* We will start the storage here for the vector of pointers. */
244 list = (char **) eol;
245
246 p = list;
247 while (1)
248 {
249 if ((char *) (p + 2) > buf_end)
250 {
251 /* We cannot fit another pointer in the buffer. */
252 *errnop = ERANGE;
253 return NULL;
254 }
255
256 if (*line == '\0')
257 break;
258 if (*line == terminator_c)
259 {
260 ++line;
261 break;
262 }
263
264 /* Skip leading white space. This might not be portable but useful. */
265 while (isspace (*line))
266 ++line;
267
268 char *elt = line;
269 while (1)
270 {
271 if (*line == '\0' || *line == terminator_c
272 || TRAILING_LIST_SEPARATOR_P (*line))
273 {
274 /* End of the next entry. */
275 if (line > elt)
276 /* We really found some data. */
277 *p++ = elt;
278
279 /* Terminate string if necessary. */
280 if (*line != '\0')
281 {
282 char endc = *line;
283 *line++ = '\0';
284 if (endc == terminator_c)
285 goto out;
286 }
287 break;
288 }
289 ++line;
290 }
291 }
292 out:
293 *p = NULL;
294 *linep = line;
295
296 return list;
297 }
298
299 # endif /* TRAILING_LIST_MEMBER */
300 #endif /* EXTERN_PARSER */
301
302
303 #define LOOKUP_NAME(nameelt, aliaselt) \
304 { \
305 char **ap; \
306 if (! strcmp (name, result->nameelt)) \
307 break; \
308 for (ap = result->aliaselt; *ap; ++ap) \
309 if (! strcmp (name, *ap)) \
310 break; \
311 if (*ap) \
312 break; \
313 }
314
315 #define LOOKUP_NAME_CASE(nameelt, aliaselt) \
316 { \
317 char **ap; \
318 if (! __strcasecmp (name, result->nameelt)) \
319 break; \
320 for (ap = result->aliaselt; *ap; ++ap) \
321 if (! __strcasecmp (name, *ap)) \
322 break; \
323 if (*ap) \
324 break; \
325 }
326
327
328 /* This is defined by db-*.c to include "../nss_db/db-XXX.c" instead. */
329 #ifndef GENERIC
330 # define GENERIC "files-XXX.c"
331 #endif
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