author | Lars Hjemli <hjemli@gmail.com> | 2006-12-11 11:10:12 (UTC) |
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committer | Lars Hjemli <hjemli@gmail.com> | 2006-12-11 11:10:12 (UTC) |
commit | 318d106300102c19d114a4ea89265b0a4060d9cb (patch) (unidiff) | |
tree | 3752575abec74ee0a2b544e36e3cc8f9cdfa1e66 | |
parent | a581ed8d6c15b0734b082fbadf0a907c2b170423 (diff) | |
download | cgit-318d106300102c19d114a4ea89265b0a4060d9cb.zip cgit-318d106300102c19d114a4ea89265b0a4060d9cb.tar.gz cgit-318d106300102c19d114a4ea89265b0a4060d9cb.tar.bz2 |
Avoid infinite loops in caching layer
Add a global variable, cgit_max_lock_attemps, to avoid the possibility of
infinite loops when failing to acquire a lockfile. This could happen on
broken setups or under crazy server load.
Incidentally, this also fixes a lurking bug in cache_lock() where an
uninitialized returnvalue was used.
Signed-off-by: Lars Hjemli <hjemli@gmail.com>
-rw-r--r-- | cache.c | 35 | ||||
-rw-r--r-- | cgit.c | 9 | ||||
-rw-r--r-- | cgit.h | 1 |
3 files changed, 31 insertions, 14 deletions
@@ -52,44 +52,53 @@ int cache_create_dirs() | |||
52 | if (mkdir(path, S_IRWXU) && errno!=EEXIST) | 52 | if (mkdir(path, S_IRWXU) && errno!=EEXIST) |
53 | return 0; | 53 | return 0; |
54 | 54 | ||
55 | if (cgit_query_page) { | 55 | if (cgit_query_page) { |
56 | path = fmt("%s/%s/%s", cgit_cache_root, cgit_query_repo, | 56 | path = fmt("%s/%s/%s", cgit_cache_root, cgit_query_repo, |
57 | cgit_query_page); | 57 | cgit_query_page); |
58 | if (mkdir(path, S_IRWXU) && errno!=EEXIST) | 58 | if (mkdir(path, S_IRWXU) && errno!=EEXIST) |
59 | return 0; | 59 | return 0; |
60 | } | 60 | } |
61 | return 1; | 61 | return 1; |
62 | } | 62 | } |
63 | 63 | ||
64 | int cache_refill_overdue(const char *lockfile) | ||
65 | { | ||
66 | struct stat st; | ||
67 | |||
68 | if (stat(lockfile, &st)) | ||
69 | return 0; | ||
70 | else | ||
71 | return (time(NULL) - st.st_mtime > cgit_cache_max_create_time); | ||
72 | } | ||
73 | |||
64 | int cache_lock(struct cacheitem *item) | 74 | int cache_lock(struct cacheitem *item) |
65 | { | 75 | { |
66 | int ret; | 76 | int i = 0; |
67 | char *lockfile = fmt("%s.lock", item->name); | 77 | char *lockfile = fmt("%s.lock", item->name); |
68 | 78 | ||
69 | top: | 79 | top: |
70 | item->fd = open(lockfile, O_WRONLY | O_CREAT | O_EXCL, S_IRUSR|S_IWUSR); | 80 | if (++i > cgit_max_lock_attempts) |
81 | die("cache_lock: unable to lock %s: %s", | ||
82 | item->name, strerror(errno)); | ||
83 | |||
84 | item->fd = open(lockfile, O_WRONLY|O_CREAT|O_EXCL, S_IRUSR|S_IWUSR); | ||
85 | |||
71 | if (item->fd == NOLOCK && errno == ENOENT && cache_create_dirs()) | 86 | if (item->fd == NOLOCK && errno == ENOENT && cache_create_dirs()) |
72 | goto top; | 87 | goto top; |
73 | if (item->fd == NOLOCK && errno == EEXIST) { | 88 | |
74 | struct stat st; | 89 | if (item->fd == NOLOCK && errno == EEXIST && |
75 | time_t t; | 90 | cache_refill_overdue(lockfile) && !unlink(lockfile)) |
76 | if (stat(lockfile, &st)) | ||
77 | return ret; | ||
78 | t = time(NULL); | ||
79 | if (t-st.st_mtime > cgit_cache_max_create_time && | ||
80 | !unlink(lockfile)) | ||
81 | goto top; | 91 | goto top; |
82 | return 0; | 92 | |
83 | } | ||
84 | return (item->fd > 0); | 93 | return (item->fd > 0); |
85 | } | 94 | } |
86 | 95 | ||
87 | int cache_unlock(struct cacheitem *item) | 96 | int cache_unlock(struct cacheitem *item) |
88 | { | 97 | { |
89 | close(item->fd); | 98 | close(item->fd); |
90 | return (rename(fmt("%s.lock", item->name), item->name) == 0); | 99 | return (rename(fmt("%s.lock", item->name), item->name) == 0); |
91 | } | 100 | } |
92 | 101 | ||
93 | int cache_expired(struct cacheitem *item) | 102 | int cache_expired(struct cacheitem *item) |
94 | { | 103 | { |
95 | if (item->ttl < 0) | 104 | if (item->ttl < 0) |
@@ -22,24 +22,25 @@ const char cgit_lib_error[] = | |||
22 | 22 | ||
23 | int htmlfd = 0; | 23 | int htmlfd = 0; |
24 | 24 | ||
25 | char *cgit_root = "/usr/src/git"; | 25 | char *cgit_root = "/usr/src/git"; |
26 | char *cgit_root_title = "Git repository browser"; | 26 | char *cgit_root_title = "Git repository browser"; |
27 | char *cgit_css = "/cgit.css"; | 27 | char *cgit_css = "/cgit.css"; |
28 | char *cgit_logo = "/git-logo.png"; | 28 | char *cgit_logo = "/git-logo.png"; |
29 | char *cgit_logo_link = "http://www.kernel.org/pub/software/scm/git/docs/"; | 29 | char *cgit_logo_link = "http://www.kernel.org/pub/software/scm/git/docs/"; |
30 | char *cgit_virtual_root = NULL; | 30 | char *cgit_virtual_root = NULL; |
31 | 31 | ||
32 | char *cgit_cache_root = "/var/cache/cgit"; | 32 | char *cgit_cache_root = "/var/cache/cgit"; |
33 | 33 | ||
34 | int cgit_max_lock_attempts = 5; | ||
34 | int cgit_cache_root_ttl = 5; | 35 | int cgit_cache_root_ttl = 5; |
35 | int cgit_cache_repo_ttl = 5; | 36 | int cgit_cache_repo_ttl = 5; |
36 | int cgit_cache_dynamic_ttl = 5; | 37 | int cgit_cache_dynamic_ttl = 5; |
37 | int cgit_cache_static_ttl = -1; | 38 | int cgit_cache_static_ttl = -1; |
38 | int cgit_cache_max_create_time = 5; | 39 | int cgit_cache_max_create_time = 5; |
39 | 40 | ||
40 | char *cgit_repo_name = NULL; | 41 | char *cgit_repo_name = NULL; |
41 | char *cgit_repo_desc = NULL; | 42 | char *cgit_repo_desc = NULL; |
42 | char *cgit_repo_owner = NULL; | 43 | char *cgit_repo_owner = NULL; |
43 | 44 | ||
44 | int cgit_query_has_symref = 0; | 45 | int cgit_query_has_symref = 0; |
45 | int cgit_query_has_sha1 = 0; | 46 | int cgit_query_has_sha1 = 0; |
@@ -456,29 +457,35 @@ static void cgit_print_repo_page() | |||
456 | static void cgit_fill_cache(struct cacheitem *item) | 457 | static void cgit_fill_cache(struct cacheitem *item) |
457 | { | 458 | { |
458 | htmlfd = item->fd; | 459 | htmlfd = item->fd; |
459 | item->st.st_mtime = time(NULL); | 460 | item->st.st_mtime = time(NULL); |
460 | if (cgit_query_repo) | 461 | if (cgit_query_repo) |
461 | cgit_print_repo_page(); | 462 | cgit_print_repo_page(); |
462 | else | 463 | else |
463 | cgit_print_repolist(); | 464 | cgit_print_repolist(); |
464 | } | 465 | } |
465 | 466 | ||
466 | static void cgit_refresh_cache(struct cacheitem *item) | 467 | static void cgit_refresh_cache(struct cacheitem *item) |
467 | { | 468 | { |
469 | int i = 0; | ||
470 | |||
468 | cache_prepare(item); | 471 | cache_prepare(item); |
469 | top: | 472 | top: |
473 | if (++i > cgit_max_lock_attempts) { | ||
474 | die("cgit_refresh_cache: unable to lock %s: %s", | ||
475 | item->name, strerror(errno)); | ||
476 | } | ||
470 | if (!cache_exist(item)) { | 477 | if (!cache_exist(item)) { |
471 | if (!cache_lock(item)) { | 478 | if (!cache_lock(item)) { |
472 | sched_yield(); | 479 | sleep(1); |
473 | goto top; | 480 | goto top; |
474 | } | 481 | } |
475 | if (!cache_exist(item)) | 482 | if (!cache_exist(item)) |
476 | cgit_fill_cache(item); | 483 | cgit_fill_cache(item); |
477 | cache_unlock(item); | 484 | cache_unlock(item); |
478 | } else if (cache_expired(item) && cache_lock(item)) { | 485 | } else if (cache_expired(item) && cache_lock(item)) { |
479 | if (cache_expired(item)) | 486 | if (cache_expired(item)) |
480 | cgit_fill_cache(item); | 487 | cgit_fill_cache(item); |
481 | cache_unlock(item); | 488 | cache_unlock(item); |
482 | } | 489 | } |
483 | } | 490 | } |
484 | 491 | ||
@@ -14,24 +14,25 @@ struct cacheitem { | |||
14 | int ttl; | 14 | int ttl; |
15 | int fd; | 15 | int fd; |
16 | }; | 16 | }; |
17 | 17 | ||
18 | extern char *cgit_root; | 18 | extern char *cgit_root; |
19 | extern char *cgit_root_title; | 19 | extern char *cgit_root_title; |
20 | extern char *cgit_css; | 20 | extern char *cgit_css; |
21 | extern char *cgit_logo; | 21 | extern char *cgit_logo; |
22 | extern char *cgit_logo_link; | 22 | extern char *cgit_logo_link; |
23 | extern char *cgit_virtual_root; | 23 | extern char *cgit_virtual_root; |
24 | extern char *cgit_cache_root; | 24 | extern char *cgit_cache_root; |
25 | 25 | ||
26 | extern int cgit_max_lock_attempts; | ||
26 | extern int cgit_cache_root_ttl; | 27 | extern int cgit_cache_root_ttl; |
27 | extern int cgit_cache_repo_ttl; | 28 | extern int cgit_cache_repo_ttl; |
28 | extern int cgit_cache_dynamic_ttl; | 29 | extern int cgit_cache_dynamic_ttl; |
29 | extern int cgit_cache_static_ttl; | 30 | extern int cgit_cache_static_ttl; |
30 | extern int cgit_cache_max_create_time; | 31 | extern int cgit_cache_max_create_time; |
31 | 32 | ||
32 | extern char *cgit_repo_name; | 33 | extern char *cgit_repo_name; |
33 | extern char *cgit_repo_desc; | 34 | extern char *cgit_repo_desc; |
34 | extern char *cgit_repo_owner; | 35 | extern char *cgit_repo_owner; |
35 | 36 | ||
36 | extern int cgit_query_has_symref; | 37 | extern int cgit_query_has_symref; |
37 | extern int cgit_query_has_sha1; | 38 | extern int cgit_query_has_sha1; |