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