d11a0bf7 |
1 | /* -*-c-*- |
2 | * |
3 | * $Id: key-file.c,v 1.1 1999/12/22 15:47:48 mdw Exp $ |
4 | * |
5 | * System-dependent key filing operations |
6 | * |
7 | * (c) 1999 Straylight/Edgeware |
8 | */ |
9 | |
10 | /*----- Licensing notice --------------------------------------------------* |
11 | * |
12 | * This file is part of Catacomb. |
13 | * |
14 | * Catacomb is free software; you can redistribute it and/or modify |
15 | * it under the terms of the GNU Library General Public License as |
16 | * published by the Free Software Foundation; either version 2 of the |
17 | * License, or (at your option) any later version. |
18 | * |
19 | * Catacomb is distributed in the hope that it will be useful, |
20 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
21 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
22 | * GNU Library General Public License for more details. |
23 | * |
24 | * You should have received a copy of the GNU Library General Public |
25 | * License along with Catacomb; if not, write to the Free |
26 | * Software Foundation, Inc., 59 Temple Place - Suite 330, Boston, |
27 | * MA 02111-1307, USA. |
28 | */ |
29 | |
30 | /*----- Revision history --------------------------------------------------* |
31 | * |
32 | * $Log: key-file.c,v $ |
33 | * Revision 1.1 1999/12/22 15:47:48 mdw |
34 | * Major key-management revision. |
35 | * |
36 | */ |
37 | |
38 | /*----- Header files ------------------------------------------------------*/ |
39 | |
40 | #include <errno.h> |
41 | #include <stdio.h> |
42 | #include <stdlib.h> |
43 | #include <string.h> |
44 | |
45 | #include <sys/types.h> |
46 | #include <sys/time.h> |
47 | #include <sys/stat.h> |
48 | #include <unistd.h> |
49 | #include <fcntl.h> |
50 | |
51 | #include <mLib/dstr.h> |
52 | #include <mLib/lock.h> |
53 | |
54 | #include "key.h" |
55 | |
56 | /*----- Main code ---------------------------------------------------------*/ |
57 | |
58 | /* --- @fdcopy@ --- * |
59 | * |
60 | * Arguments: @int source@ = source file descriptor |
61 | * @int dest@ = destination file descriptor |
62 | * |
63 | * Returns: Zero if OK, nonzero otherwise. |
64 | * |
65 | * Use: Copies data from one file descriptor to another. |
66 | */ |
67 | |
68 | static int fdcopy(int source, int dest) |
69 | { |
70 | char buf[4096]; |
71 | |
72 | if (lseek(source, 0, SEEK_SET) < 0|| |
73 | lseek(dest, 0, SEEK_SET) < 0 || |
74 | ftruncate(dest, 0) < 0) |
75 | return (-1); |
76 | for (;;) { |
77 | int n = read(source, buf, sizeof(buf)); |
78 | if (n < 0) |
79 | return (-1); |
80 | else if (n == 0) |
81 | break; |
82 | else if (write(dest, buf, n) < 0) |
83 | return (-1); |
84 | } |
85 | return (0); |
86 | } |
87 | |
88 | /* --- @key_save@ --- * |
89 | * |
90 | * Arguments: @key_file *f@ = pointer to key file block |
91 | * |
92 | * Returns: A @KWRITE_@ code indicating how well it worked. |
93 | * |
94 | * Use: Writes a key file's data back to the actual file. This code |
95 | * is extremely careful about error handling. It should usually |
96 | * be able to back out somewhere sensible, but it can tell when |
97 | * it's got itself into a real pickle and starts leaving well |
98 | * alone. |
99 | * |
100 | * Callers, please make sure that you ring alarm bells when this |
101 | * function returns @KWRITE_BROKEN@. |
102 | */ |
103 | |
104 | int key_save(key_file *f) |
105 | { |
106 | dstr n_older = DSTR_INIT, n_old = DSTR_INIT, n_new = DSTR_INIT; |
107 | int rc = KWRITE_FAIL; |
108 | |
109 | if (!(f->f & KF_MODIFIED)) |
110 | return (KWRITE_OK); |
111 | |
112 | /* --- Write a new key file out --- * |
113 | * |
114 | * Check for an error after each key line. This ought to be enough. |
115 | * Checking after each individual byte write and @fprintf@ isn't much fun. |
116 | */ |
117 | |
118 | dstr_putf(&n_new, "%s.new", f->name); |
119 | |
120 | { |
121 | key *k; |
122 | key_iter i; |
123 | FILE *fp; |
124 | |
125 | if ((fp = fopen(n_new.buf, "w")) == 0) |
126 | goto fail_open; |
127 | |
128 | for (key_mkiter(&i, f); (k = key_next(&i)) != 0; ) { |
129 | if (key_extract(f, k, fp, 0)) { |
130 | fclose(fp); |
131 | goto fail_write; |
132 | } |
133 | } |
134 | |
135 | if (fclose(fp)) |
136 | goto fail_write; |
137 | } |
138 | |
139 | /* --- Set up the other filenames --- */ |
140 | |
141 | dstr_putf(&n_older, "%s.older", f->name); |
142 | dstr_putf(&n_old, "%s.old", f->name); |
143 | |
144 | /* --- Move the current backup on one --- * |
145 | * |
146 | * If the `older' file exists, then we're in need of attention. |
147 | */ |
148 | |
149 | { |
150 | struct stat st; |
151 | if (stat(n_older.buf, &st) == 0 || errno != ENOENT) { |
152 | errno = EEXIST; |
153 | rc = KWRITE_BROKEN; |
154 | goto fail_shift; |
155 | } |
156 | if (rename(n_old.buf, n_older.buf) && errno != ENOENT) |
157 | goto fail_shift; |
158 | } |
159 | |
160 | /* --- Copy the current file to the backup --- */ |
161 | |
162 | { |
163 | int fd; |
164 | if ((fd = open(n_old.buf, O_WRONLY | O_CREAT | O_EXCL, 0600)) < 0) |
165 | goto fail_backup; |
166 | if (fdcopy(fileno(f->fp), fd)) { |
167 | close(fd); |
168 | goto fail_backup; |
169 | } |
170 | if (close(fd)) |
171 | goto fail_backup; |
172 | } |
173 | |
174 | /* --- Copy the newly created file to the current one --- * |
175 | * |
176 | * This is the dangerous bit. |
177 | */ |
178 | |
179 | { |
180 | int fd; |
181 | if ((fd = open(n_new.buf, O_RDONLY)) < 0) |
182 | goto fail_update; |
183 | if (fdcopy(fd, fileno(f->fp))) { |
184 | close(fd); |
185 | goto fail_update; |
186 | } |
187 | close(fd); |
188 | if (fsync(fileno(f->fp))) |
189 | goto fail_update; |
190 | } |
191 | |
192 | /* --- Clean up --- * |
193 | * |
194 | * Remove the `new' file and the `older' backup. Then we're done. |
195 | */ |
196 | |
197 | unlink(n_new.buf); |
198 | unlink(n_older.buf); |
199 | return (KWRITE_OK); |
200 | |
201 | /* --- Failure while writing the new key file --- * |
202 | * |
203 | * I need to copy the backup back. If that fails then I'm really stuffed. |
204 | * If not, then I might as well try to get the backups sorted back out |
205 | * again. |
206 | */ |
207 | |
208 | fail_update: |
209 | { |
210 | int fd; |
211 | int e = errno; |
212 | |
213 | if ((fd = open(n_old.buf, O_RDONLY)) < 0) |
214 | rc = KWRITE_BROKEN; |
215 | else if (fdcopy(fd, fileno(f->fp))) { |
216 | close(fd); |
217 | rc = KWRITE_BROKEN; |
218 | } else { |
219 | close(fd); |
220 | if (fsync(fileno(f->fp))) |
221 | rc = KWRITE_BROKEN; |
222 | } |
223 | |
224 | errno = e; |
225 | if (rc == KWRITE_BROKEN) |
226 | goto fail_shift; |
227 | } |
228 | /* Now drop through */ |
229 | |
230 | /* --- Failure while writing the new backup --- * |
231 | * |
232 | * The new backup isn't any use. Try to recover the old one. |
233 | */ |
234 | |
235 | fail_backup: |
236 | { |
237 | int e = errno; |
238 | unlink(n_old.buf); |
239 | if (rename(n_older.buf, n_old.buf) && errno != ENOENT) |
240 | rc = KWRITE_BROKEN; |
241 | errno = e; |
242 | } |
243 | /* Now drop through */ |
244 | |
245 | /* --- Failure while demoting the current backup --- * |
246 | * |
247 | * Leave the completed output file there for the operator in case he wants |
248 | * to clean up. |
249 | */ |
250 | |
251 | fail_shift: |
252 | dstr_destroy(&n_new); |
253 | dstr_destroy(&n_old); |
254 | dstr_destroy(&n_older); |
255 | return (rc); |
256 | |
257 | /* --- Failure during write of new data --- * |
258 | * |
259 | * Clean up the new file and return. These errors can never cause |
260 | * breakage. |
261 | */ |
262 | |
263 | fail_write: |
264 | unlink(n_new.buf); |
265 | fail_open: |
266 | dstr_destroy(&n_new); |
267 | return (rc); |
268 | } |
269 | |
270 | /* --- @key_lockfile@ --- * |
271 | * |
272 | * Arguments: @key_file *f@ = pointer to file structure to initialize |
273 | * @const char *file@ = pointer to the file name |
274 | * @int how@ = opening options (@KOPEN_*@). |
275 | * |
276 | * Returns: Zero if it worked, nonzero otherwise. |
277 | * |
278 | * Use: Opens a keyfile and stores the information needed for |
279 | * continued access in the structure. |
280 | * |
281 | * If the file is opened with @KOPEN_WRITE@, it's created if |
282 | * necessary with read and write permissions for owner only, and |
283 | * locked for update while it's open. |
284 | * |
285 | * This is a system-dependent routine, and only really intended |
286 | * for the private use of @key_open@. |
287 | */ |
288 | |
289 | int key_lockfile(key_file *f, const char *file, int how) |
290 | { |
291 | int of, lf; |
292 | const char *ff; |
293 | int fd; |
294 | |
295 | /* --- Lots of things depend on whether we're writing --- */ |
296 | |
297 | switch (how) { |
298 | case KOPEN_READ: |
299 | of = O_RDONLY; |
300 | lf = LOCK_NONEXCL; |
301 | ff = "r"; |
302 | break; |
303 | case KOPEN_WRITE: |
304 | of = O_RDWR | O_CREAT; |
305 | lf = LOCK_EXCL; |
306 | ff = "r+"; |
307 | break; |
308 | default: |
309 | errno = EINVAL; |
310 | return (-1); |
311 | } |
312 | |
313 | /* --- Open and lock the file --- */ |
314 | |
315 | if ((fd = open(file, of, 0600)) < 0) |
316 | return (-1); |
317 | if (fcntl(fd, F_SETFD, FD_CLOEXEC) < 0 || |
318 | lock_file(fd, lf) < 0 || |
319 | (f->fp = fdopen(fd, ff)) == 0) { |
320 | close(fd); |
321 | return (-1); |
322 | } |
323 | |
324 | return (0); |
325 | } |
326 | |
327 | /*----- That's all, folks -------------------------------------------------*/ |