author | Lars Hjemli <hjemli@gmail.com> | 2006-12-11 21:53:50 (UTC) |
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committer | Lars Hjemli <hjemli@gmail.com> | 2006-12-11 21:53:50 (UTC) |
commit | fbaf1171b4e343929dd43ecac7cd9d1c692b84ec (patch) (unidiff) | |
tree | 40b7007b2e1e85f2e91e052b33555df2e9fb5e14 /cgit.c | |
parent | 44923f8953c66dc9b852316b655ab3b5aec9478e (diff) | |
download | cgit-fbaf1171b4e343929dd43ecac7cd9d1c692b84ec.zip cgit-fbaf1171b4e343929dd43ecac7cd9d1c692b84ec.tar.gz cgit-fbaf1171b4e343929dd43ecac7cd9d1c692b84ec.tar.bz2 |
Don't truncate valid cachefiles
An embarrassing thinko in cgit_check_cache() would truncate valid cachefiles
in the following situation:
1) process A notices a missing/expired cachefile
2) process B gets scheduled, locks, fills and unlocks the cachefile
3) process A gets scheduled, locks the cachefile, notices that the cachefile
now exist/is not expired anymore, and continues to overwrite it with an
empty lockfile.
Thanks to Linus for noticing (again).
Signed-off-by: Lars Hjemli <hjemli@gmail.com>
-rw-r--r-- | cgit.c | 14 |
1 files changed, 10 insertions, 4 deletions
@@ -40,55 +40,61 @@ static void cgit_fill_cache(struct cacheitem *item) | |||
40 | { | 40 | { |
41 | htmlfd = item->fd; | 41 | htmlfd = item->fd; |
42 | item->st.st_mtime = time(NULL); | 42 | item->st.st_mtime = time(NULL); |
43 | if (cgit_query_repo) | 43 | if (cgit_query_repo) |
44 | cgit_print_repo_page(item); | 44 | cgit_print_repo_page(item); |
45 | else | 45 | else |
46 | cgit_print_repolist(item); | 46 | cgit_print_repolist(item); |
47 | } | 47 | } |
48 | 48 | ||
49 | static void cgit_check_cache(struct cacheitem *item) | 49 | static void cgit_check_cache(struct cacheitem *item) |
50 | { | 50 | { |
51 | int i = 0; | 51 | int i = 0; |
52 | 52 | ||
53 | cache_prepare(item); | 53 | cache_prepare(item); |
54 | top: | 54 | top: |
55 | if (++i > cgit_max_lock_attempts) { | 55 | if (++i > cgit_max_lock_attempts) { |
56 | die("cgit_refresh_cache: unable to lock %s: %s", | 56 | die("cgit_refresh_cache: unable to lock %s: %s", |
57 | item->name, strerror(errno)); | 57 | item->name, strerror(errno)); |
58 | } | 58 | } |
59 | if (!cache_exist(item)) { | 59 | if (!cache_exist(item)) { |
60 | if (!cache_lock(item)) { | 60 | if (!cache_lock(item)) { |
61 | sleep(1); | 61 | sleep(1); |
62 | goto top; | 62 | goto top; |
63 | } | 63 | } |
64 | if (!cache_exist(item)) | 64 | if (!cache_exist(item)) { |
65 | cgit_fill_cache(item); | 65 | cgit_fill_cache(item); |
66 | cache_unlock(item); | 66 | cache_unlock(item); |
67 | } else { | ||
68 | cache_cancel_lock(item); | ||
69 | } | ||
67 | } else if (cache_expired(item) && cache_lock(item)) { | 70 | } else if (cache_expired(item) && cache_lock(item)) { |
68 | if (cache_expired(item)) | 71 | if (cache_expired(item)) { |
69 | cgit_fill_cache(item); | 72 | cgit_fill_cache(item); |
70 | cache_unlock(item); | 73 | cache_unlock(item); |
74 | } else { | ||
75 | cache_cancel_lock(item); | ||
76 | } | ||
71 | } | 77 | } |
72 | } | 78 | } |
73 | 79 | ||
74 | static void cgit_print_cache(struct cacheitem *item) | 80 | static void cgit_print_cache(struct cacheitem *item) |
75 | { | 81 | { |
76 | static char buf[4096]; | 82 | static char buf[4096]; |
77 | ssize_t i; | 83 | ssize_t i; |
78 | 84 | ||
79 | int fd = open(item->name, O_RDONLY); | 85 | int fd = open(item->name, O_RDONLY); |
80 | if (fd<0) | 86 | if (fd<0) |
81 | die("Unable to open cached file %s", item->name); | 87 | die("Unable to open cached file %s", item->name); |
82 | 88 | ||
83 | while((i=read(fd, buf, sizeof(buf))) > 0) | 89 | while((i=read(fd, buf, sizeof(buf))) > 0) |
84 | write(STDOUT_FILENO, buf, i); | 90 | write(STDOUT_FILENO, buf, i); |
85 | 91 | ||
86 | close(fd); | 92 | close(fd); |
87 | } | 93 | } |
88 | 94 | ||
89 | int main(int argc, const char **argv) | 95 | int main(int argc, const char **argv) |
90 | { | 96 | { |
91 | struct cacheitem item; | 97 | struct cacheitem item; |
92 | 98 | ||
93 | cgit_read_config("/etc/cgitrc", cgit_global_config_cb); | 99 | cgit_read_config("/etc/cgitrc", cgit_global_config_cb); |
94 | cgit_querystring = xstrdup(getenv("QUERY_STRING")); | 100 | cgit_querystring = xstrdup(getenv("QUERY_STRING")); |