| author | Lars Hjemli <hjemli@gmail.com> | 2006-12-11 11:10:12 (UTC) |
|---|---|---|
| committer | Lars Hjemli <hjemli@gmail.com> | 2006-12-11 11:10:12 (UTC) |
| commit | 318d106300102c19d114a4ea89265b0a4060d9cb (patch) (side-by-side diff) | |
| 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
@@ -1,98 +1,107 @@ /* cache.c: cache management * * Copyright (C) 2006 Lars Hjemli * * Licensed under GNU General Public License v2 * (see COPYING for full license text) */ #include "cgit.h" const int NOLOCK = -1; void cache_prepare(struct cacheitem *item) { if (!cgit_query_repo) { item->name = xstrdup(fmt("%s/index.html", cgit_cache_root)); item->ttl = cgit_cache_root_ttl; } else if (!cgit_query_page) { item->name = xstrdup(fmt("%s/%s/index.html", cgit_cache_root, cgit_query_repo)); item->ttl = cgit_cache_repo_ttl; } else { item->name = xstrdup(fmt("%s/%s/%s/%s.html", cgit_cache_root, cgit_query_repo, cgit_query_page, cgit_querystring)); if (cgit_query_has_symref) item->ttl = cgit_cache_dynamic_ttl; else if (cgit_query_has_sha1) item->ttl = cgit_cache_static_ttl; else item->ttl = cgit_cache_repo_ttl; } } int cache_exist(struct cacheitem *item) { if (stat(item->name, &item->st)) { item->st.st_mtime = 0; return 0; } return 1; } int cache_create_dirs() { char *path; if (!cgit_query_repo) return 0; path = fmt("%s/%s", cgit_cache_root, cgit_query_repo); if (mkdir(path, S_IRWXU) && errno!=EEXIST) return 0; if (cgit_query_page) { path = fmt("%s/%s/%s", cgit_cache_root, cgit_query_repo, cgit_query_page); if (mkdir(path, S_IRWXU) && errno!=EEXIST) return 0; } return 1; } +int cache_refill_overdue(const char *lockfile) +{ + struct stat st; + + if (stat(lockfile, &st)) + return 0; + else + return (time(NULL) - st.st_mtime > cgit_cache_max_create_time); +} + int cache_lock(struct cacheitem *item) { - int ret; + int i = 0; char *lockfile = fmt("%s.lock", item->name); - top: - item->fd = open(lockfile, O_WRONLY | O_CREAT | O_EXCL, S_IRUSR|S_IWUSR); + top: + if (++i > cgit_max_lock_attempts) + die("cache_lock: unable to lock %s: %s", + item->name, strerror(errno)); + + item->fd = open(lockfile, O_WRONLY|O_CREAT|O_EXCL, S_IRUSR|S_IWUSR); + if (item->fd == NOLOCK && errno == ENOENT && cache_create_dirs()) goto top; - if (item->fd == NOLOCK && errno == EEXIST) { - struct stat st; - time_t t; - if (stat(lockfile, &st)) - return ret; - t = time(NULL); - if (t-st.st_mtime > cgit_cache_max_create_time && - !unlink(lockfile)) + + if (item->fd == NOLOCK && errno == EEXIST && + cache_refill_overdue(lockfile) && !unlink(lockfile)) goto top; - return 0; - } + return (item->fd > 0); } int cache_unlock(struct cacheitem *item) { close(item->fd); return (rename(fmt("%s.lock", item->name), item->name) == 0); } int cache_expired(struct cacheitem *item) { if (item->ttl < 0) return 0; return item->st.st_mtime + item->ttl * 60 < time(NULL); } @@ -1,129 +1,130 @@ /* cgit.c: cgi for the git scm * * Copyright (C) 2006 Lars Hjemli * * Licensed under GNU General Public License v2 * (see COPYING for full license text) */ #include "cgit.h" const char cgit_version[] = CGIT_VERSION; const char cgit_doctype[] = "<!DOCTYPE html PUBLIC \"-//W3C//DTD XHTML 1.0 Transitional//EN\"\n" " \"http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd\">\n"; const char cgit_error[] = "<div class='error'>%s</div>"; const char cgit_lib_error[] = "<div class='error'>%s: %s</div>"; int htmlfd = 0; char *cgit_root = "/usr/src/git"; char *cgit_root_title = "Git repository browser"; char *cgit_css = "/cgit.css"; char *cgit_logo = "/git-logo.png"; char *cgit_logo_link = "http://www.kernel.org/pub/software/scm/git/docs/"; char *cgit_virtual_root = NULL; char *cgit_cache_root = "/var/cache/cgit"; +int cgit_max_lock_attempts = 5; int cgit_cache_root_ttl = 5; int cgit_cache_repo_ttl = 5; int cgit_cache_dynamic_ttl = 5; int cgit_cache_static_ttl = -1; int cgit_cache_max_create_time = 5; char *cgit_repo_name = NULL; char *cgit_repo_desc = NULL; char *cgit_repo_owner = NULL; int cgit_query_has_symref = 0; int cgit_query_has_sha1 = 0; char *cgit_querystring = NULL; char *cgit_query_repo = NULL; char *cgit_query_page = NULL; char *cgit_query_head = NULL; char *cgit_query_sha1 = NULL; struct cacheitem cacheitem; int cgit_parse_query(char *txt, configfn fn) { char *t, *value = NULL, c; if (!txt) return 0; t = txt = xstrdup(txt); while((c=*t) != '\0') { if (c=='=') { *t = '\0'; value = t+1; } else if (c=='&') { *t = '\0'; (*fn)(txt, value); txt = t+1; value = NULL; } t++; } if (t!=txt) (*fn)(txt, value); return 0; } void cgit_global_config_cb(const char *name, const char *value) { if (!strcmp(name, "root")) cgit_root = xstrdup(value); else if (!strcmp(name, "root-title")) cgit_root_title = xstrdup(value); else if (!strcmp(name, "css")) cgit_css = xstrdup(value); else if (!strcmp(name, "logo")) cgit_logo = xstrdup(value); else if (!strcmp(name, "logo-link")) cgit_logo_link = xstrdup(value); else if (!strcmp(name, "virtual-root")) cgit_virtual_root = xstrdup(value); } void cgit_repo_config_cb(const char *name, const char *value) { if (!strcmp(name, "name")) cgit_repo_name = xstrdup(value); else if (!strcmp(name, "desc")) cgit_repo_desc = xstrdup(value); else if (!strcmp(name, "owner")) cgit_repo_owner = xstrdup(value); } void cgit_querystring_cb(const char *name, const char *value) { if (!strcmp(name,"r")) cgit_query_repo = xstrdup(value); else if (!strcmp(name, "p")) cgit_query_page = xstrdup(value); else if (!strcmp(name, "h")) { cgit_query_head = xstrdup(value); cgit_query_has_symref = 1; } else if (!strcmp(name, "id")) { cgit_query_sha1 = xstrdup(value); cgit_query_has_sha1 = 1; } } char *cgit_repourl(const char *reponame) { if (cgit_virtual_root) { return fmt("%s/%s/", cgit_virtual_root, reponame); } else { return fmt("?r=%s", reponame); } } @@ -372,137 +373,143 @@ static void cgit_print_log(const char *tip, int ofs, int cnt) rev.verbose_header = 1; rev.show_root_diff = 0; setup_revisions(2, argv, &rev, NULL); prepare_revision_walk(&rev); html("<h2>Log</h2>"); html("<table class='list'>"); html("<tr><th>Date</th><th>Message</th><th>Author</th></tr>\n"); while ((commit = get_revision(&rev)) != NULL && n++ < 100) { cgit_print_commit_shortlog(commit); free(commit->buffer); commit->buffer = NULL; free_commit_list(commit->parents); commit->parents = NULL; } html("</table>\n"); } static void cgit_print_repo_summary() { html("<h2>"); html_txt("Repo summary page"); html("</h2>"); cgit_print_branches(); } static void cgit_print_object(char *hex) { unsigned char sha1[20]; //struct object *object; char type[20]; unsigned char *buf; unsigned long size; if (get_sha1_hex(hex, sha1)){ htmlf(cgit_error, "Bad hex value"); return; } if (sha1_object_info(sha1, type, NULL)){ htmlf(cgit_error, "Bad object name"); return; } buf = read_sha1_file(sha1, type, &size); if (!buf) { htmlf(cgit_error, "Error reading object"); return; } buf[size] = '\0'; html("<h2>Object view</h2>"); htmlf("sha1=%s<br/>type=%s<br/>size=%i<br/>", hex, type, size); html("<pre>"); html_txt(buf); html("</pre>"); } static void cgit_print_repo_page() { if (chdir(fmt("%s/%s", cgit_root, cgit_query_repo)) || cgit_read_config("info/cgit", cgit_repo_config_cb)) { char *title = fmt("%s - %s", cgit_root_title, "Bad request"); cgit_print_docstart(title); cgit_print_pageheader(title); htmlf(cgit_lib_error, "Unable to scan repository", strerror(errno)); cgit_print_docend(); return; } setenv("GIT_DIR", fmt("%s/%s", cgit_root, cgit_query_repo), 1); char *title = fmt("%s - %s", cgit_repo_name, cgit_repo_desc); cgit_print_docstart(title); cgit_print_pageheader(title); if (!cgit_query_page) cgit_print_repo_summary(); else if (!strcmp(cgit_query_page, "log")) { cgit_print_log(cgit_query_head, 0, 100); } else if (!strcmp(cgit_query_page, "view")) { cgit_print_object(cgit_query_sha1); } cgit_print_docend(); } static void cgit_fill_cache(struct cacheitem *item) { htmlfd = item->fd; item->st.st_mtime = time(NULL); if (cgit_query_repo) cgit_print_repo_page(); else cgit_print_repolist(); } static void cgit_refresh_cache(struct cacheitem *item) { + int i = 0; + cache_prepare(item); top: + if (++i > cgit_max_lock_attempts) { + die("cgit_refresh_cache: unable to lock %s: %s", + item->name, strerror(errno)); + } if (!cache_exist(item)) { if (!cache_lock(item)) { - sched_yield(); + sleep(1); goto top; } if (!cache_exist(item)) cgit_fill_cache(item); cache_unlock(item); } else if (cache_expired(item) && cache_lock(item)) { if (cache_expired(item)) cgit_fill_cache(item); cache_unlock(item); } } static void cgit_print_cache(struct cacheitem *item) { static char buf[4096]; ssize_t i; int fd = open(item->name, O_RDONLY); if (fd<0) die("Unable to open cached file %s", item->name); while((i=read(fd, buf, sizeof(buf))) > 0) write(STDOUT_FILENO, buf, i); close(fd); } int main(int argc, const char **argv) { cgit_read_config("/etc/cgitrc", cgit_global_config_cb); cgit_querystring = xstrdup(getenv("QUERY_STRING")); cgit_parse_query(cgit_querystring, cgit_querystring_cb); cgit_refresh_cache(&cacheitem); cgit_print_cache(&cacheitem); return 0; } @@ -1,65 +1,66 @@ #ifndef CGIT_H #define CGIT_H #include "git.h" #include <openssl/sha.h> #include <ctype.h> #include <sched.h> typedef void (*configfn)(const char *name, const char *value); struct cacheitem { char *name; struct stat st; int ttl; int fd; }; extern char *cgit_root; extern char *cgit_root_title; extern char *cgit_css; extern char *cgit_logo; extern char *cgit_logo_link; extern char *cgit_virtual_root; extern char *cgit_cache_root; +extern int cgit_max_lock_attempts; extern int cgit_cache_root_ttl; extern int cgit_cache_repo_ttl; extern int cgit_cache_dynamic_ttl; extern int cgit_cache_static_ttl; extern int cgit_cache_max_create_time; extern char *cgit_repo_name; extern char *cgit_repo_desc; extern char *cgit_repo_owner; extern int cgit_query_has_symref; extern int cgit_query_has_sha1; extern char *cgit_querystring; extern char *cgit_query_repo; extern char *cgit_query_page; extern char *cgit_query_head; extern char *cgit_query_sha1; extern int htmlfd; extern char *fmt(const char *format,...); extern void html(const char *txt); extern void htmlf(const char *format,...); extern void html_txt(char *txt); extern void html_attr(char *txt); extern void html_link_open(char *url, char *title, char *class); extern void html_link_close(void); extern int cgit_read_config(const char *filename, configfn fn); extern void cache_prepare(struct cacheitem *item); extern int cache_lock(struct cacheitem *item); extern int cache_unlock(struct cacheitem *item); extern int cache_exist(struct cacheitem *item); extern int cache_expired(struct cacheitem *item); #endif /* CGIT_H */ |