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458f14b7 AM |
1 | /* |
2 | * shvar.c | |
3 | * | |
4 | * Implementation of non-destructively reading/writing files containing | |
5 | * only shell variable declarations and full-line comments. | |
6 | * | |
7 | * Includes explicit inheritance mechanism intended for use with | |
8 | * Red Hat Linux ifcfg-* files. There is no protection against | |
9 | * inheritance loops; they will generally cause stack overflows. | |
10 | * Furthermore, they are only intended for one level of inheritance; | |
11 | * the value setting algorithm assumes this. | |
12 | * | |
aa8f8aa6 | 13 | * Copyright 1999,2000 Red Hat, Inc. |
458f14b7 AM |
14 | * |
15 | * This is free software; you can redistribute it and/or modify it | |
16 | * under the terms of the GNU General Public License as published by | |
17 | * the Free Software Foundation; either version 2 of the License, or | |
18 | * (at your option) any later version. | |
19 | * | |
20 | * This program is distributed in the hope that it will be useful, but | |
21 | * WITHOUT ANY WARRANTY; without even the implied warranty of | |
22 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | |
23 | * General Public License for more details. | |
24 | * | |
25 | * You should have received a copy of the GNU General Public License | |
26 | * along with this program; if not, write to the Free Software | |
27 | * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. | |
28 | * | |
29 | */ | |
30 | ||
458f14b7 AM |
31 | #include <fcntl.h> |
32 | #include <stdio.h> | |
33 | #include <stdlib.h> | |
34 | #include <string.h> | |
35 | #include <sys/types.h> | |
36 | #include <sys/stat.h> | |
37 | #include <unistd.h> | |
38 | ||
39 | #include "shvar.h" | |
40 | ||
aa8f8aa6 AM |
41 | /* Open the file <name>, returning a shvarFile on success and NULL on failure. |
42 | Add a wrinkle to let the caller specify whether or not to create the file | |
43 | (actually, return a structure anyway) if it doesn't exist. */ | |
44 | static shvarFile * | |
45 | svOpenFile(const char *name, gboolean create) | |
458f14b7 AM |
46 | { |
47 | shvarFile *s = NULL; | |
48 | int closefd = 0; | |
49 | ||
aa8f8aa6 | 50 | s = g_malloc0(sizeof(shvarFile)); |
458f14b7 AM |
51 | |
52 | s->fd = open(name, O_RDWR); /* NOT O_CREAT */ | |
53 | if (s->fd == -1) { | |
54 | /* try read-only */ | |
55 | s->fd = open(name, O_RDONLY); /* NOT O_CREAT */ | |
aa8f8aa6 | 56 | if (s->fd != -1) closefd = 1; |
458f14b7 | 57 | } |
aa8f8aa6 | 58 | s->fileName = g_strdup(name); |
458f14b7 AM |
59 | |
60 | if (s->fd != -1) { | |
61 | struct stat buf; | |
aa8f8aa6 | 62 | char *p, *q; |
458f14b7 AM |
63 | |
64 | if (fstat(s->fd, &buf) < 0) goto bail; | |
aa8f8aa6 AM |
65 | s->arena = g_malloc0(buf.st_size + 1); |
66 | ||
458f14b7 | 67 | if (read(s->fd, s->arena, buf.st_size) < 0) goto bail; |
aa8f8aa6 AM |
68 | |
69 | /* we'd use g_strsplit() here, but we want a list, not an array */ | |
70 | for(p = s->arena; (q = strchr(p, '\n')) != NULL; p = q + 1) { | |
71 | s->lineList = g_list_append(s->lineList, g_strndup(p, q - p)); | |
458f14b7 | 72 | } |
aa8f8aa6 AM |
73 | |
74 | /* closefd is set if we opened the file read-only, so go ahead and | |
75 | close it, because we can't write to it anyway */ | |
458f14b7 AM |
76 | if (closefd) { |
77 | close(s->fd); | |
78 | s->fd = -1; | |
79 | } | |
aa8f8aa6 AM |
80 | |
81 | return s; | |
458f14b7 AM |
82 | } |
83 | ||
aa8f8aa6 AM |
84 | if (create) { |
85 | return s; | |
86 | } | |
458f14b7 AM |
87 | |
88 | bail: | |
89 | if (s->fd != -1) close(s->fd); | |
aa8f8aa6 AM |
90 | if (s->arena) g_free (s->arena); |
91 | if (s->fileName) g_free (s->fileName); | |
92 | g_free (s); | |
458f14b7 AM |
93 | return NULL; |
94 | } | |
95 | ||
aa8f8aa6 AM |
96 | /* Open the file <name>, return shvarFile on success, NULL on failure */ |
97 | shvarFile * | |
98 | svNewFile(const char *name) | |
99 | { | |
100 | return svOpenFile(name, FALSE); | |
101 | } | |
102 | ||
103 | /* Create a new file structure, returning actual data if the file exists, | |
104 | * and a suitable starting point if it doesn't. */ | |
105 | shvarFile * | |
106 | svCreateFile(const char *name) | |
107 | { | |
108 | return svOpenFile(name, TRUE); | |
109 | } | |
110 | ||
458f14b7 AM |
111 | /* remove escaped characters in place */ |
112 | static void | |
113 | unescape(char *s) { | |
114 | int len, i; | |
115 | ||
116 | len = strlen(s); | |
117 | if ((s[0] == '"' || s[0] == '\'') && s[0] == s[len-1]) { | |
118 | i = len - 2; | |
119 | memmove(s, s+1, i); | |
120 | s[i+1] = '\0'; | |
121 | len = i; | |
122 | } | |
123 | for (i = 0; i < len; i++) { | |
124 | if (s[i] == '\\') { | |
125 | memmove(s+i, s+i+1, len-(i+1)); | |
126 | len--; | |
127 | } | |
128 | s[len] = '\0'; | |
129 | } | |
130 | } | |
131 | ||
132 | ||
133 | /* create a new string with all necessary characters escaped. | |
134 | * caller must free returned string | |
135 | */ | |
aa8f8aa6 AM |
136 | static const char escapees[] = "\"'\\$~`"; /* must be escaped */ |
137 | static const char spaces[] = " \t|&;()<>"; /* only require "" */ | |
458f14b7 | 138 | static char * |
aa8f8aa6 | 139 | escape(const char *s) { |
458f14b7 AM |
140 | char *new; |
141 | int i, j, mangle = 0, space = 0; | |
142 | int newlen, slen; | |
143 | static int esclen, splen; | |
144 | ||
145 | if (!esclen) esclen = strlen(escapees); | |
146 | if (!splen) splen = strlen(spaces); | |
aa8f8aa6 AM |
147 | slen = strlen(s); |
148 | ||
149 | for (i = 0; i < slen; i++) { | |
150 | if (strchr(escapees, s[i])) mangle++; | |
151 | if (strchr(spaces, s[i])) space++; | |
458f14b7 AM |
152 | } |
153 | if (!mangle && !space) return strdup(s); | |
154 | ||
458f14b7 | 155 | newlen = slen + mangle + 3; /* 3 is extra ""\0 */ |
aa8f8aa6 | 156 | new = g_malloc0(newlen); |
458f14b7 AM |
157 | if (!new) return NULL; |
158 | ||
aa8f8aa6 AM |
159 | j = 0; |
160 | new[j++] = '"'; | |
161 | for (i = 0; i < slen; i++) { | |
458f14b7 AM |
162 | if (strchr(escapees, s[i])) { |
163 | new[j++] = '\\'; | |
164 | } | |
aa8f8aa6 | 165 | new[j++] = s[i]; |
458f14b7 | 166 | } |
aa8f8aa6 AM |
167 | new[j++] = '"'; |
168 | g_assert(j == slen + mangle + 2); /* j is the index of the '\0' */ | |
458f14b7 AM |
169 | |
170 | return new; | |
171 | } | |
172 | ||
173 | /* Get the value associated with the key, and leave the current pointer | |
174 | * pointing at the line containing the value. The char* returned MUST | |
175 | * be freed by the caller. | |
176 | */ | |
177 | char * | |
aa8f8aa6 | 178 | svGetValue(shvarFile *s, const char *key) |
458f14b7 AM |
179 | { |
180 | char *value = NULL; | |
181 | char *line; | |
182 | char *keyString; | |
183 | int len; | |
184 | ||
aa8f8aa6 AM |
185 | g_assert(s); |
186 | g_assert(key); | |
458f14b7 | 187 | |
aa8f8aa6 | 188 | keyString = g_malloc0(strlen(key) + 2); |
458f14b7 AM |
189 | strcpy(keyString, key); |
190 | keyString[strlen(key)] = '='; | |
191 | len = strlen(keyString); | |
192 | ||
193 | for (s->current = s->lineList; s->current; s->current = s->current->next) { | |
194 | line = s->current->data; | |
195 | if (!strncmp(keyString, line, len)) { | |
aa8f8aa6 | 196 | value = g_strdup(line + len); |
458f14b7 AM |
197 | unescape(value); |
198 | break; | |
199 | } | |
200 | } | |
aa8f8aa6 | 201 | g_free(keyString); |
458f14b7 AM |
202 | |
203 | if (value) { | |
204 | if (value[0]) { | |
205 | return value; | |
206 | } else { | |
aa8f8aa6 | 207 | g_free(value); |
458f14b7 AM |
208 | return NULL; |
209 | } | |
210 | } | |
211 | if (s->parent) value = svGetValue(s->parent, key); | |
212 | return value; | |
213 | } | |
214 | ||
215 | /* return 1 if <key> resolves to any truth value (e.g. "yes", "y", "true") | |
216 | * return 0 if <key> resolves to any non-truth value (e.g. "no", "n", "false") | |
217 | * return <default> otherwise | |
218 | */ | |
219 | int | |
aa8f8aa6 | 220 | svTrueValue(shvarFile *s, const char *key, int def) |
458f14b7 AM |
221 | { |
222 | char *tmp; | |
223 | int returnValue = def; | |
224 | ||
225 | tmp = svGetValue(s, key); | |
226 | if (!tmp) return returnValue; | |
227 | ||
228 | if ( (!strcasecmp("yes", tmp)) || | |
229 | (!strcasecmp("true", tmp)) || | |
230 | (!strcasecmp("t", tmp)) || | |
231 | (!strcasecmp("y", tmp)) ) returnValue = 1; | |
232 | else | |
233 | if ( (!strcasecmp("no", tmp)) || | |
234 | (!strcasecmp("false", tmp)) || | |
235 | (!strcasecmp("f", tmp)) || | |
236 | (!strcasecmp("n", tmp)) ) returnValue = 0; | |
237 | ||
aa8f8aa6 | 238 | g_free (tmp); |
458f14b7 AM |
239 | return returnValue; |
240 | } | |
241 | ||
242 | ||
243 | /* Set the variable <key> equal to the value <value>. | |
244 | * If <key> does not exist, and the <current> pointer is set, append | |
245 | * the key=value pair after that line. Otherwise, prepend the pair | |
246 | * to the top of the file. Here's the algorithm, as the C code | |
247 | * seems to be rather dense: | |
248 | * | |
249 | * if (value == NULL), then: | |
250 | * if val2 (parent): change line to key= or append line key= | |
251 | * if val1 (this) : delete line | |
252 | * else noop | |
253 | * else use this table: | |
254 | * val2 | |
255 | * NULL value other | |
256 | * v NULL append line noop append line | |
257 | * a | |
258 | * l value noop noop noop | |
259 | * 1 | |
260 | * other change line delete line change line | |
261 | * | |
262 | * No changes are ever made to the parent config file, only to the | |
263 | * specific file passed on the command line. | |
264 | * | |
265 | */ | |
266 | void | |
aa8f8aa6 | 267 | svSetValue(shvarFile *s, const char *key, const char *value) |
458f14b7 | 268 | { |
aa8f8aa6 | 269 | char *newval = NULL, *val1 = NULL, *val2 = NULL; |
458f14b7 AM |
270 | char *keyValue; |
271 | ||
aa8f8aa6 AM |
272 | g_assert(s); |
273 | g_assert(key); | |
458f14b7 AM |
274 | /* value may be NULL */ |
275 | ||
aa8f8aa6 AM |
276 | if (value) newval = escape(value); |
277 | keyValue = g_strdup_printf("%s=%s", key, newval ? newval : ""); | |
458f14b7 AM |
278 | |
279 | val1 = svGetValue(s, key); | |
aa8f8aa6 | 280 | if (val1 && newval && !strcmp(val1, newval)) goto bail; |
458f14b7 AM |
281 | if (s->parent) val2 = svGetValue(s->parent, key); |
282 | ||
aa8f8aa6 | 283 | if (!newval || !newval[0]) { |
458f14b7 AM |
284 | /* delete value somehow */ |
285 | if (val2) { | |
286 | /* change/append line to get key= */ | |
287 | if (s->current) s->current->data = keyValue; | |
288 | else s->lineList = g_list_append(s->lineList, keyValue); | |
289 | s->freeList = g_list_append(s->freeList, keyValue); | |
290 | s->modified = 1; | |
291 | } else if (val1) { | |
292 | /* delete line */ | |
293 | s->lineList = g_list_remove_link(s->lineList, s->current); | |
294 | g_list_free_1(s->current); | |
295 | s->modified = 1; | |
296 | goto bail; /* do not need keyValue */ | |
297 | } | |
298 | goto end; | |
299 | } | |
300 | ||
301 | if (!val1) { | |
aa8f8aa6 | 302 | if (val2 && !strcmp(val2, newval)) goto end; |
458f14b7 AM |
303 | /* append line */ |
304 | s->lineList = g_list_append(s->lineList, keyValue); | |
305 | s->freeList = g_list_append(s->freeList, keyValue); | |
306 | s->modified = 1; | |
307 | goto end; | |
308 | } | |
309 | ||
310 | /* deal with a whole line of noops */ | |
aa8f8aa6 | 311 | if (val1 && !strcmp(val1, newval)) goto end; |
458f14b7 AM |
312 | |
313 | /* At this point, val1 && val1 != value */ | |
aa8f8aa6 | 314 | if (val2 && !strcmp(val2, newval)) { |
458f14b7 AM |
315 | /* delete line */ |
316 | s->lineList = g_list_remove_link(s->lineList, s->current); | |
317 | g_list_free_1(s->current); | |
318 | s->modified = 1; | |
319 | goto bail; /* do not need keyValue */ | |
320 | } else { | |
321 | /* change line */ | |
322 | if (s->current) s->current->data = keyValue; | |
323 | else s->lineList = g_list_append(s->lineList, keyValue); | |
324 | s->freeList = g_list_append(s->freeList, keyValue); | |
325 | s->modified = 1; | |
326 | } | |
327 | ||
328 | end: | |
aa8f8aa6 | 329 | if (newval) free(newval); |
458f14b7 AM |
330 | if (val1) free(val1); |
331 | if (val2) free(val2); | |
332 | return; | |
333 | ||
334 | bail: | |
335 | if (keyValue) free (keyValue); | |
336 | goto end; | |
337 | } | |
338 | ||
339 | /* Write the current contents iff modified. Returns -1 on error | |
340 | * and 0 on success. Do not write if no values have been modified. | |
341 | * The mode argument is only used if creating the file, not if | |
342 | * re-writing an existing file, and is passed unchanged to the | |
343 | * open() syscall. | |
344 | */ | |
345 | int | |
346 | svWriteFile(shvarFile *s, int mode) | |
347 | { | |
348 | FILE *f; | |
349 | int tmpfd; | |
350 | ||
351 | if (s->modified) { | |
352 | if (s->fd == -1) | |
353 | s->fd = open(s->fileName, O_WRONLY|O_CREAT, mode); | |
354 | if (s->fd == -1) | |
355 | return -1; | |
356 | if (ftruncate(s->fd, 0) < 0) | |
357 | return -1; | |
358 | ||
359 | tmpfd = dup(s->fd); | |
360 | f = fdopen(tmpfd, "w"); | |
361 | fseek(f, 0, SEEK_SET); | |
362 | for (s->current = s->lineList; s->current; s->current = s->current->next) { | |
363 | char *line = s->current->data; | |
364 | fprintf(f, "%s\n", line); | |
365 | } | |
366 | fclose(f); | |
367 | } | |
368 | ||
369 | return 0; | |
370 | } | |
371 | ||
372 | ||
373 | /* Close the file descriptor (if open) and delete the shvarFile. | |
374 | * Returns -1 on error and 0 on success. | |
375 | */ | |
376 | int | |
377 | svCloseFile(shvarFile *s) | |
378 | { | |
379 | ||
aa8f8aa6 | 380 | g_assert(s); |
458f14b7 AM |
381 | |
382 | if (s->fd != -1) close(s->fd); | |
383 | ||
aa8f8aa6 | 384 | g_free(s->arena); |
458f14b7 | 385 | for (s->current = s->freeList; s->current; s->current = s->current->next) { |
aa8f8aa6 | 386 | g_free(s->current->data); |
458f14b7 | 387 | } |
aa8f8aa6 | 388 | g_free(s->fileName); |
458f14b7 AM |
389 | g_list_free(s->freeList); |
390 | g_list_free(s->lineList); /* implicitly frees s->current */ | |
aa8f8aa6 | 391 | g_free(s); |
458f14b7 AM |
392 | return 0; |
393 | } |