author | Lars Hjemli <hjemli@gmail.com> | 2008-05-18 21:10:05 (UTC) |
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committer | Lars Hjemli <hjemli@gmail.com> | 2008-05-18 21:10:05 (UTC) |
commit | 6102bcfce46fd357566941d565b95f78510af79b (patch) (unidiff) | |
tree | 95794eda3bdf84e72a6fb32bfa96fb4e0cb147b9 /cache.c | |
parent | c3de425acbc4ae1190ca99e733a72da56c6a082b (diff) | |
download | cgit-6102bcfce46fd357566941d565b95f78510af79b.zip cgit-6102bcfce46fd357566941d565b95f78510af79b.tar.gz cgit-6102bcfce46fd357566941d565b95f78510af79b.tar.bz2 |
cache.c: read(2) returns -1 on error, not 0
Noticed-by: Jim Meyering <jim@meyering.net>
Signed-off-by: Lars Hjemli <hjemli@gmail.com>
-rw-r--r-- | cache.c | 2 |
1 files changed, 1 insertions, 1 deletions
@@ -1,247 +1,247 @@ | |||
1 | /* cache.c: cache management | 1 | /* cache.c: cache management |
2 | * | 2 | * |
3 | * Copyright (C) 2006 Lars Hjemli | 3 | * Copyright (C) 2006 Lars Hjemli |
4 | * | 4 | * |
5 | * Licensed under GNU General Public License v2 | 5 | * Licensed under GNU General Public License v2 |
6 | * (see COPYING for full license text) | 6 | * (see COPYING for full license text) |
7 | * | 7 | * |
8 | * | 8 | * |
9 | * The cache is just a directory structure where each file is a cache slot, | 9 | * The cache is just a directory structure where each file is a cache slot, |
10 | * and each filename is based on the hash of some key (e.g. the cgit url). | 10 | * and each filename is based on the hash of some key (e.g. the cgit url). |
11 | * Each file contains the full key followed by the cached content for that | 11 | * Each file contains the full key followed by the cached content for that |
12 | * key. | 12 | * key. |
13 | * | 13 | * |
14 | */ | 14 | */ |
15 | 15 | ||
16 | #include "cgit.h" | 16 | #include "cgit.h" |
17 | #include "cache.h" | 17 | #include "cache.h" |
18 | 18 | ||
19 | #define CACHE_BUFSIZE (1024 * 4) | 19 | #define CACHE_BUFSIZE (1024 * 4) |
20 | 20 | ||
21 | struct cache_slot { | 21 | struct cache_slot { |
22 | const char *key; | 22 | const char *key; |
23 | int keylen; | 23 | int keylen; |
24 | int ttl; | 24 | int ttl; |
25 | cache_fill_fn fn; | 25 | cache_fill_fn fn; |
26 | void *cbdata; | 26 | void *cbdata; |
27 | int cache_fd; | 27 | int cache_fd; |
28 | int lock_fd; | 28 | int lock_fd; |
29 | const char *cache_name; | 29 | const char *cache_name; |
30 | const char *lock_name; | 30 | const char *lock_name; |
31 | int match; | 31 | int match; |
32 | struct stat cache_st; | 32 | struct stat cache_st; |
33 | struct stat lock_st; | 33 | struct stat lock_st; |
34 | int bufsize; | 34 | int bufsize; |
35 | char buf[CACHE_BUFSIZE]; | 35 | char buf[CACHE_BUFSIZE]; |
36 | }; | 36 | }; |
37 | 37 | ||
38 | /* Open an existing cache slot and fill the cache buffer with | 38 | /* Open an existing cache slot and fill the cache buffer with |
39 | * (part of) the content of the cache file. Return 0 on success | 39 | * (part of) the content of the cache file. Return 0 on success |
40 | * and errno otherwise. | 40 | * and errno otherwise. |
41 | */ | 41 | */ |
42 | static int open_slot(struct cache_slot *slot) | 42 | static int open_slot(struct cache_slot *slot) |
43 | { | 43 | { |
44 | char *bufz; | 44 | char *bufz; |
45 | int bufkeylen = -1; | 45 | int bufkeylen = -1; |
46 | 46 | ||
47 | slot->cache_fd = open(slot->cache_name, O_RDONLY); | 47 | slot->cache_fd = open(slot->cache_name, O_RDONLY); |
48 | if (slot->cache_fd == -1) | 48 | if (slot->cache_fd == -1) |
49 | return errno; | 49 | return errno; |
50 | 50 | ||
51 | if (fstat(slot->cache_fd, &slot->cache_st)) | 51 | if (fstat(slot->cache_fd, &slot->cache_st)) |
52 | return errno; | 52 | return errno; |
53 | 53 | ||
54 | slot->bufsize = read(slot->cache_fd, slot->buf, sizeof(slot->buf)); | 54 | slot->bufsize = read(slot->cache_fd, slot->buf, sizeof(slot->buf)); |
55 | if (slot->bufsize == 0) | 55 | if (slot->bufsize < 0) |
56 | return errno; | 56 | return errno; |
57 | 57 | ||
58 | bufz = memchr(slot->buf, 0, slot->bufsize); | 58 | bufz = memchr(slot->buf, 0, slot->bufsize); |
59 | if (bufz) | 59 | if (bufz) |
60 | bufkeylen = bufz - slot->buf; | 60 | bufkeylen = bufz - slot->buf; |
61 | 61 | ||
62 | slot->match = bufkeylen == slot->keylen && | 62 | slot->match = bufkeylen == slot->keylen && |
63 | !memcmp(slot->key, slot->buf, bufkeylen + 1); | 63 | !memcmp(slot->key, slot->buf, bufkeylen + 1); |
64 | 64 | ||
65 | return 0; | 65 | return 0; |
66 | } | 66 | } |
67 | 67 | ||
68 | /* Close the active cache slot */ | 68 | /* Close the active cache slot */ |
69 | static void close_slot(struct cache_slot *slot) | 69 | static void close_slot(struct cache_slot *slot) |
70 | { | 70 | { |
71 | if (slot->cache_fd > 0) { | 71 | if (slot->cache_fd > 0) { |
72 | close(slot->cache_fd); | 72 | close(slot->cache_fd); |
73 | slot->cache_fd = -1; | 73 | slot->cache_fd = -1; |
74 | } | 74 | } |
75 | } | 75 | } |
76 | 76 | ||
77 | /* Print the content of the active cache slot (but skip the key). */ | 77 | /* Print the content of the active cache slot (but skip the key). */ |
78 | static int print_slot(struct cache_slot *slot) | 78 | static int print_slot(struct cache_slot *slot) |
79 | { | 79 | { |
80 | ssize_t i, j = 0; | 80 | ssize_t i, j = 0; |
81 | 81 | ||
82 | i = lseek(slot->cache_fd, slot->keylen + 1, SEEK_SET); | 82 | i = lseek(slot->cache_fd, slot->keylen + 1, SEEK_SET); |
83 | if (i != slot->keylen + 1) | 83 | if (i != slot->keylen + 1) |
84 | return errno; | 84 | return errno; |
85 | 85 | ||
86 | while((i=read(slot->cache_fd, slot->buf, sizeof(slot->buf))) > 0) | 86 | while((i=read(slot->cache_fd, slot->buf, sizeof(slot->buf))) > 0) |
87 | j = write(STDOUT_FILENO, slot->buf, i); | 87 | j = write(STDOUT_FILENO, slot->buf, i); |
88 | 88 | ||
89 | if (j < 0) | 89 | if (j < 0) |
90 | return errno; | 90 | return errno; |
91 | else | 91 | else |
92 | return 0; | 92 | return 0; |
93 | } | 93 | } |
94 | 94 | ||
95 | /* Check if the slot has expired */ | 95 | /* Check if the slot has expired */ |
96 | static int is_expired(struct cache_slot *slot) | 96 | static int is_expired(struct cache_slot *slot) |
97 | { | 97 | { |
98 | if (slot->ttl < 0) | 98 | if (slot->ttl < 0) |
99 | return 0; | 99 | return 0; |
100 | else | 100 | else |
101 | return slot->cache_st.st_mtime + slot->ttl*60 < time(NULL); | 101 | return slot->cache_st.st_mtime + slot->ttl*60 < time(NULL); |
102 | } | 102 | } |
103 | 103 | ||
104 | /* Check if the slot has been modified since we opened it. | 104 | /* Check if the slot has been modified since we opened it. |
105 | * NB: If stat() fails, we pretend the file is modified. | 105 | * NB: If stat() fails, we pretend the file is modified. |
106 | */ | 106 | */ |
107 | static int is_modified(struct cache_slot *slot) | 107 | static int is_modified(struct cache_slot *slot) |
108 | { | 108 | { |
109 | struct stat st; | 109 | struct stat st; |
110 | 110 | ||
111 | if (stat(slot->cache_name, &st)) | 111 | if (stat(slot->cache_name, &st)) |
112 | return 1; | 112 | return 1; |
113 | return (st.st_ino != slot->cache_st.st_ino || | 113 | return (st.st_ino != slot->cache_st.st_ino || |
114 | st.st_mtime != slot->cache_st.st_mtime || | 114 | st.st_mtime != slot->cache_st.st_mtime || |
115 | st.st_size != slot->cache_st.st_size); | 115 | st.st_size != slot->cache_st.st_size); |
116 | } | 116 | } |
117 | 117 | ||
118 | /* Close an open lockfile */ | 118 | /* Close an open lockfile */ |
119 | static void close_lock(struct cache_slot *slot) | 119 | static void close_lock(struct cache_slot *slot) |
120 | { | 120 | { |
121 | if (slot->lock_fd > 0) { | 121 | if (slot->lock_fd > 0) { |
122 | close(slot->lock_fd); | 122 | close(slot->lock_fd); |
123 | slot->lock_fd = -1; | 123 | slot->lock_fd = -1; |
124 | } | 124 | } |
125 | } | 125 | } |
126 | 126 | ||
127 | /* Create a lockfile used to store the generated content for a cache | 127 | /* Create a lockfile used to store the generated content for a cache |
128 | * slot, and write the slot key + \0 into it. | 128 | * slot, and write the slot key + \0 into it. |
129 | * Returns 0 on success and errno otherwise. | 129 | * Returns 0 on success and errno otherwise. |
130 | */ | 130 | */ |
131 | static int lock_slot(struct cache_slot *slot) | 131 | static int lock_slot(struct cache_slot *slot) |
132 | { | 132 | { |
133 | slot->lock_fd = open(slot->lock_name, O_RDWR|O_CREAT|O_EXCL, | 133 | slot->lock_fd = open(slot->lock_name, O_RDWR|O_CREAT|O_EXCL, |
134 | S_IRUSR|S_IWUSR); | 134 | S_IRUSR|S_IWUSR); |
135 | if (slot->lock_fd == -1) | 135 | if (slot->lock_fd == -1) |
136 | return errno; | 136 | return errno; |
137 | write(slot->lock_fd, slot->key, slot->keylen + 1); | 137 | write(slot->lock_fd, slot->key, slot->keylen + 1); |
138 | return 0; | 138 | return 0; |
139 | } | 139 | } |
140 | 140 | ||
141 | /* Release the current lockfile. If `replace_old_slot` is set the | 141 | /* Release the current lockfile. If `replace_old_slot` is set the |
142 | * lockfile replaces the old cache slot, otherwise the lockfile is | 142 | * lockfile replaces the old cache slot, otherwise the lockfile is |
143 | * just deleted. | 143 | * just deleted. |
144 | */ | 144 | */ |
145 | static int unlock_slot(struct cache_slot *slot, int replace_old_slot) | 145 | static int unlock_slot(struct cache_slot *slot, int replace_old_slot) |
146 | { | 146 | { |
147 | int err; | 147 | int err; |
148 | 148 | ||
149 | if (replace_old_slot) | 149 | if (replace_old_slot) |
150 | err = rename(slot->lock_name, slot->cache_name); | 150 | err = rename(slot->lock_name, slot->cache_name); |
151 | else | 151 | else |
152 | err = unlink(slot->lock_name); | 152 | err = unlink(slot->lock_name); |
153 | return err; | 153 | return err; |
154 | } | 154 | } |
155 | 155 | ||
156 | /* Generate the content for the current cache slot by redirecting | 156 | /* Generate the content for the current cache slot by redirecting |
157 | * stdout to the lock-fd and invoking the callback function | 157 | * stdout to the lock-fd and invoking the callback function |
158 | */ | 158 | */ |
159 | static int fill_slot(struct cache_slot *slot) | 159 | static int fill_slot(struct cache_slot *slot) |
160 | { | 160 | { |
161 | int tmp; | 161 | int tmp; |
162 | 162 | ||
163 | /* Preserve stdout */ | 163 | /* Preserve stdout */ |
164 | tmp = dup(STDOUT_FILENO); | 164 | tmp = dup(STDOUT_FILENO); |
165 | if (tmp == -1) | 165 | if (tmp == -1) |
166 | return errno; | 166 | return errno; |
167 | 167 | ||
168 | /* Redirect stdout to lockfile */ | 168 | /* Redirect stdout to lockfile */ |
169 | if (dup2(slot->lock_fd, STDOUT_FILENO) == -1) | 169 | if (dup2(slot->lock_fd, STDOUT_FILENO) == -1) |
170 | return errno; | 170 | return errno; |
171 | 171 | ||
172 | /* Generate cache content */ | 172 | /* Generate cache content */ |
173 | slot->fn(slot->cbdata); | 173 | slot->fn(slot->cbdata); |
174 | 174 | ||
175 | /* Restore stdout */ | 175 | /* Restore stdout */ |
176 | if (dup2(tmp, STDOUT_FILENO) == -1) | 176 | if (dup2(tmp, STDOUT_FILENO) == -1) |
177 | return errno; | 177 | return errno; |
178 | 178 | ||
179 | /* Close the temporary filedescriptor */ | 179 | /* Close the temporary filedescriptor */ |
180 | close(tmp); | 180 | close(tmp); |
181 | return 0; | 181 | return 0; |
182 | } | 182 | } |
183 | 183 | ||
184 | /* Crude implementation of 32-bit FNV-1 hash algorithm, | 184 | /* Crude implementation of 32-bit FNV-1 hash algorithm, |
185 | * see http://www.isthe.com/chongo/tech/comp/fnv/ for details | 185 | * see http://www.isthe.com/chongo/tech/comp/fnv/ for details |
186 | * about the magic numbers. | 186 | * about the magic numbers. |
187 | */ | 187 | */ |
188 | #define FNV_OFFSET 0x811c9dc5 | 188 | #define FNV_OFFSET 0x811c9dc5 |
189 | #define FNV_PRIME 0x01000193 | 189 | #define FNV_PRIME 0x01000193 |
190 | 190 | ||
191 | unsigned long hash_str(const char *str) | 191 | unsigned long hash_str(const char *str) |
192 | { | 192 | { |
193 | unsigned long h = FNV_OFFSET; | 193 | unsigned long h = FNV_OFFSET; |
194 | unsigned char *s = (unsigned char *)str; | 194 | unsigned char *s = (unsigned char *)str; |
195 | 195 | ||
196 | if (!s) | 196 | if (!s) |
197 | return h; | 197 | return h; |
198 | 198 | ||
199 | while(*s) { | 199 | while(*s) { |
200 | h *= FNV_PRIME; | 200 | h *= FNV_PRIME; |
201 | h ^= *s++; | 201 | h ^= *s++; |
202 | } | 202 | } |
203 | return h; | 203 | return h; |
204 | } | 204 | } |
205 | 205 | ||
206 | static int process_slot(struct cache_slot *slot) | 206 | static int process_slot(struct cache_slot *slot) |
207 | { | 207 | { |
208 | int err; | 208 | int err; |
209 | 209 | ||
210 | err = open_slot(slot); | 210 | err = open_slot(slot); |
211 | if (!err && slot->match) { | 211 | if (!err && slot->match) { |
212 | if (is_expired(slot)) { | 212 | if (is_expired(slot)) { |
213 | if (!lock_slot(slot)) { | 213 | if (!lock_slot(slot)) { |
214 | /* If the cachefile has been replaced between | 214 | /* If the cachefile has been replaced between |
215 | * `open_slot` and `lock_slot`, we'll just | 215 | * `open_slot` and `lock_slot`, we'll just |
216 | * serve the stale content from the original | 216 | * serve the stale content from the original |
217 | * cachefile. This way we avoid pruning the | 217 | * cachefile. This way we avoid pruning the |
218 | * newly generated slot. The same code-path | 218 | * newly generated slot. The same code-path |
219 | * is chosen if fill_slot() fails for some | 219 | * is chosen if fill_slot() fails for some |
220 | * reason. | 220 | * reason. |
221 | * | 221 | * |
222 | * TODO? check if the new slot contains the | 222 | * TODO? check if the new slot contains the |
223 | * same key as the old one, since we would | 223 | * same key as the old one, since we would |
224 | * prefer to serve the newest content. | 224 | * prefer to serve the newest content. |
225 | * This will require us to open yet another | 225 | * This will require us to open yet another |
226 | * file-descriptor and read and compare the | 226 | * file-descriptor and read and compare the |
227 | * key from the new file, so for now we're | 227 | * key from the new file, so for now we're |
228 | * lazy and just ignore the new file. | 228 | * lazy and just ignore the new file. |
229 | */ | 229 | */ |
230 | if (is_modified(slot) || fill_slot(slot)) { | 230 | if (is_modified(slot) || fill_slot(slot)) { |
231 | unlock_slot(slot, 0); | 231 | unlock_slot(slot, 0); |
232 | close_lock(slot); | 232 | close_lock(slot); |
233 | } else { | 233 | } else { |
234 | close_slot(slot); | 234 | close_slot(slot); |
235 | unlock_slot(slot, 1); | 235 | unlock_slot(slot, 1); |
236 | slot->cache_fd = slot->lock_fd; | 236 | slot->cache_fd = slot->lock_fd; |
237 | } | 237 | } |
238 | } | 238 | } |
239 | } | 239 | } |
240 | print_slot(slot); | 240 | print_slot(slot); |
241 | close_slot(slot); | 241 | close_slot(slot); |
242 | return 0; | 242 | return 0; |
243 | } | 243 | } |
244 | 244 | ||
245 | /* If the cache slot does not exist (or its key doesn't match the | 245 | /* If the cache slot does not exist (or its key doesn't match the |
246 | * current key), lets try to create a new cache slot for this | 246 | * current key), lets try to create a new cache slot for this |
247 | * request. If this fails (for whatever reason), lets just generate | 247 | * request. If this fails (for whatever reason), lets just generate |