blob: e60cca445f3651b0465975761493807fa975af56
1 | /* vi: set sw=4 ts=4: */ |
2 | /* |
3 | * save.c - write the cache struct to disk |
4 | * |
5 | * Copyright (C) 2001 by Andreas Dilger |
6 | * Copyright (C) 2003 Theodore Ts'o |
7 | * |
8 | * %Begin-Header% |
9 | * This file may be redistributed under the terms of the |
10 | * GNU Lesser General Public License. |
11 | * %End-Header% |
12 | */ |
13 | |
14 | #include <stdio.h> |
15 | #include <string.h> |
16 | #include <stdlib.h> |
17 | #include <unistd.h> |
18 | #include <sys/types.h> |
19 | #ifdef HAVE_SYS_STAT_H |
20 | #include <sys/stat.h> |
21 | #endif |
22 | #ifdef HAVE_SYS_MKDEV_H |
23 | #include <sys/mkdev.h> |
24 | #endif |
25 | #ifdef HAVE_ERRNO_H |
26 | #include <errno.h> |
27 | #endif |
28 | #include "blkidP.h" |
29 | |
30 | static int save_dev(blkid_dev dev, FILE *file) |
31 | { |
32 | struct list_head *p; |
33 | |
34 | if (!dev || dev->bid_name[0] != '/') |
35 | return 0; |
36 | |
37 | DBG(DEBUG_SAVE, |
38 | printf("device %s, type %s\n", dev->bid_name, dev->bid_type)); |
39 | |
40 | fprintf(file, |
41 | "<device DEVNO=\"0x%04lx\" TIME=\"%lu\"", |
42 | (unsigned long) dev->bid_devno, dev->bid_time); |
43 | if (dev->bid_pri) |
44 | fprintf(file, " PRI=\"%d\"", dev->bid_pri); |
45 | list_for_each(p, &dev->bid_tags) { |
46 | blkid_tag tag = list_entry(p, struct blkid_struct_tag, bit_tags); |
47 | fprintf(file, " %s=\"%s\"", tag->bit_name,tag->bit_val); |
48 | } |
49 | fprintf(file, ">%s</device>\n", dev->bid_name); |
50 | |
51 | return 0; |
52 | } |
53 | |
54 | /* |
55 | * Write out the cache struct to the cache file on disk. |
56 | */ |
57 | int blkid_flush_cache(blkid_cache cache) |
58 | { |
59 | struct list_head *p; |
60 | char *tmp = NULL; |
61 | const char *opened = NULL; |
62 | const char *filename; |
63 | FILE *file = NULL; |
64 | int fd, ret = 0; |
65 | struct stat st; |
66 | |
67 | if (!cache) |
68 | return -BLKID_ERR_PARAM; |
69 | |
70 | if (list_empty(&cache->bic_devs) || |
71 | !(cache->bic_flags & BLKID_BIC_FL_CHANGED)) { |
72 | DBG(DEBUG_SAVE, printf("skipping cache file write\n")); |
73 | return 0; |
74 | } |
75 | |
76 | filename = cache->bic_filename ? cache->bic_filename: BLKID_CACHE_FILE; |
77 | |
78 | /* If we can't write to the cache file, then don't even try */ |
79 | if (((ret = stat(filename, &st)) < 0 && errno != ENOENT) || |
80 | (ret == 0 && access(filename, W_OK) < 0)) { |
81 | DBG(DEBUG_SAVE, |
82 | printf("can't write to cache file %s\n", filename)); |
83 | return 0; |
84 | } |
85 | |
86 | /* |
87 | * Try and create a temporary file in the same directory so |
88 | * that in case of error we don't overwrite the cache file. |
89 | * If the cache file doesn't yet exist, it isn't a regular |
90 | * file (e.g. /dev/null or a socket), or we couldn't create |
91 | * a temporary file then we open it directly. |
92 | */ |
93 | if (ret == 0 && S_ISREG(st.st_mode)) { |
94 | tmp = xmalloc(strlen(filename) + 8); |
95 | sprintf(tmp, "%s-XXXXXX", filename); |
96 | fd = mkstemp(tmp); |
97 | if (fd >= 0) { |
98 | file = xfdopen_for_write(fd); |
99 | opened = tmp; |
100 | } |
101 | fchmod(fd, 0644); |
102 | } |
103 | |
104 | if (!file) { |
105 | file = fopen_for_write(filename); |
106 | opened = filename; |
107 | } |
108 | |
109 | DBG(DEBUG_SAVE, |
110 | printf("writing cache file %s (really %s)\n", |
111 | filename, opened)); |
112 | |
113 | if (!file) { |
114 | ret = errno; |
115 | goto errout; |
116 | } |
117 | |
118 | list_for_each(p, &cache->bic_devs) { |
119 | blkid_dev dev = list_entry(p, struct blkid_struct_dev, bid_devs); |
120 | if (!dev->bid_type) |
121 | continue; |
122 | if ((ret = save_dev(dev, file)) < 0) |
123 | break; |
124 | } |
125 | |
126 | if (ret >= 0) { |
127 | cache->bic_flags &= ~BLKID_BIC_FL_CHANGED; |
128 | ret = 1; |
129 | } |
130 | |
131 | fclose(file); |
132 | if (opened != filename) { |
133 | if (ret < 0) { |
134 | unlink(opened); |
135 | DBG(DEBUG_SAVE, |
136 | printf("unlinked temp cache %s\n", opened)); |
137 | } else { |
138 | char *backup; |
139 | |
140 | backup = xmalloc(strlen(filename) + 5); |
141 | sprintf(backup, "%s.old", filename); |
142 | unlink(backup); |
143 | link(filename, backup); |
144 | free(backup); |
145 | rename(opened, filename); |
146 | DBG(DEBUG_SAVE, |
147 | printf("moved temp cache %s\n", opened)); |
148 | } |
149 | } |
150 | |
151 | errout: |
152 | free(tmp); |
153 | return ret; |
154 | } |
155 | |
156 | #ifdef TEST_PROGRAM |
157 | int main(int argc, char **argv) |
158 | { |
159 | blkid_cache cache = NULL; |
160 | int ret; |
161 | |
162 | blkid_debug_mask = DEBUG_ALL; |
163 | if (argc > 2) { |
164 | fprintf(stderr, "Usage: %s [filename]\n" |
165 | "Test loading/saving a cache (filename)\n", argv[0]); |
166 | exit(1); |
167 | } |
168 | |
169 | if ((ret = blkid_get_cache(&cache, bb_dev_null)) != 0) { |
170 | fprintf(stderr, "%s: error creating cache (%d)\n", |
171 | argv[0], ret); |
172 | exit(1); |
173 | } |
174 | if ((ret = blkid_probe_all(cache)) < 0) { |
175 | fprintf(stderr, "error (%d) probing devices\n", ret); |
176 | exit(1); |
177 | } |
178 | cache->bic_filename = blkid_strdup(argv[1]); |
179 | |
180 | if ((ret = blkid_flush_cache(cache)) < 0) { |
181 | fprintf(stderr, "error (%d) saving cache\n", ret); |
182 | exit(1); |
183 | } |
184 | |
185 | blkid_put_cache(cache); |
186 | |
187 | return ret; |
188 | } |
189 | #endif |
190 |