Fix cache algorithm loophole

This closes the door for unneccessary calls to cgit_fill_cache(). Noticed by Linus. Signed-off-by: Lars Hjemli <hjemli@gmail.com>
author: Lars Hjemli <hjemli@gmail.com> 2006-12-11 08:57:58 (UTC)
committer: Lars Hjemli <hjemli@gmail.com> 2006-12-11 08:57:58 (UTC)
commit: f5069d88dff7a7ed2f4665904b03e906cca75a7c (patch) (unidiff)
tree: 4c9bfa3aaf931af4a345ffb9563b19825c38b628
parent: 76827d8679d1d2bd46e8cddf7da2ce4178e1d676 (diff)
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cgit-f5069d88dff7a7ed2f4665904b03e906cca75a7c.tar.gz
cgit-f5069d88dff7a7ed2f4665904b03e906cca75a7c.tar.bz2
3 files changed, 16 insertions, 11 deletions
diff --git a/cache.c b/cache.c
index b034c48..0ffa502 100644
--- a/cache.c
+++ b/cache.c
@@ -1,94 +1,98 @@
 /* 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;
-int cache_lookup(struct cacheitem *item)
+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_lock(struct cacheitem *item)
 {
        int ret;
        char *lockfile = fmt("%s.lock", item->name);
 top:  
               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))
                        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);
 }
diff --git a/cgit.c b/cgit.c
index 110face..7f14016 100644
--- a/cgit.c
+++ b/cgit.c
@@ -1,508 +1,508 @@
 /* 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_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);
        }
 }
 char *cgit_pageurl(const char *reponame, const char *pagename, 
                   const char *query)
 {
        if (cgit_virtual_root) {
                return fmt("%s/%s/%s/?%s", cgit_virtual_root, reponame, 
                           pagename, query);
        } else {
                return fmt("?r=%s&p=%s&%s", reponame, pagename, query);
        }
 }
 static int cgit_print_branch_cb(const char *refname, const unsigned char *sha1,
                                int flags, void *cb_data)
 {
        struct commit *commit;
        char buf[256], *url;
        commit = lookup_commit(sha1);
        if (commit && !parse_commit(commit)){
                html("<tr><td>");
                url = cgit_pageurl(cgit_query_repo, "log", 
                                   fmt("h=%s", refname));
                html_link_open(url, NULL, NULL);
                strncpy(buf, refname, sizeof(buf));
                html_txt(buf);
                html_link_close();
                html("</td><td>");
                pretty_print_commit(CMIT_FMT_ONELINE, commit, ~0, buf,
                                    sizeof(buf), 0, NULL, NULL, 0);
                html_txt(buf);
                html("</td></tr>\n");
        } else {
                html("<tr><td>");
                html_txt(buf);
                html("</td><td>");
                htmlf("*** bad ref %s", sha1_to_hex(sha1));
                html("</td></tr>\n");
        }
        return 0;
 }
 /* Sun, 06 Nov 1994 08:49:37 GMT */
 static char *http_date(time_t t)
 {
        static char day[][4] = {"Sun", "Mon", "Tue", "Wed", "Thu", "Fri", "Sat"};
        static char month[][4] = {"Jan", "Feb", "Mar", "Apr", "May", "Jun",
                                  "Jul", "Aug", "Sep", "Oct", "Now", "Dec"};
        struct tm *tm = gmtime(&t);
        return fmt("%s, %02d %s %04d %02d:%02d:%02d GMT", day[tm->tm_wday],
                   tm->tm_mday, month[tm->tm_mon], 1900+tm->tm_year,
                   tm->tm_hour, tm->tm_min, tm->tm_sec);
 }
 static int ttl_seconds(int ttl)
 {
        if (ttl<0)
                return 60 * 60 * 24 * 365;
        else 
                return ttl * 60;
 }
 static void cgit_print_docstart(char *title)
 {
        html("Content-Type: text/html; charset=utf-8\n");
        htmlf("Last-Modified: %s\n", http_date(cacheitem.st.st_mtime));
        htmlf("Expires: %s\n", http_date(cacheitem.st.st_mtime + 
                                         ttl_seconds(cacheitem.ttl)));
        html("\n");
        html(cgit_doctype);
        html("<html>\n");
        html("<head>\n");
        html("<title>");
        html_txt(title);
        html("</title>\n");
        htmlf("<meta name='generator' content='cgit v%s'/>\n", cgit_version);
        html("<link rel='stylesheet' type='text/css' href='");
        html_attr(cgit_css);
        html("'/>\n");
        html("</head>\n");
        html("<body>\n");
 }
 static void cgit_print_docend()
 {
        html("</body>\n</html>\n");
 }
 static void cgit_print_pageheader(char *title)
 {
        html("<div id='header'>");
        htmlf("<a href='%s'>", cgit_logo_link);
        htmlf("<img id='logo' src='%s'/>\n", cgit_logo);
        htmlf("</a>");
        html_txt(title);
        html("</div>");
 }
 static void cgit_print_repolist()
 {
        DIR *d;
        struct dirent *de;
        struct stat st;
        char *name;
        chdir(cgit_root);
        cgit_print_docstart(cgit_root_title);
        cgit_print_pageheader(cgit_root_title);
        if (!(d = opendir("."))) {
                htmlf(cgit_lib_error, "Unable to scan repository directory",
                      strerror(errno));
                cgit_print_docend();
                return;
        }
        html("<h2>Repositories</h2>\n");
        html("<table class='list'>");
        html("<tr><th>Name</th><th>Description</th><th>Owner</th></tr>\n");
        while ((de = readdir(d)) != NULL) {
                if (de->d_name[0] == '.')
                        continue;
                if (stat(de->d_name, &st) < 0)
                        continue;
                if (!S_ISDIR(st.st_mode))
                        continue;
                cgit_repo_name = cgit_repo_desc = cgit_repo_owner = NULL;
                name = fmt("%s/info/cgit", de->d_name);
                if (cgit_read_config(name, cgit_repo_config_cb))
                        continue;
                html("<tr><td>");
                html_link_open(cgit_repourl(de->d_name), NULL, NULL);
                html_txt(cgit_repo_name);
                html_link_close();
                html("</td><td>");
                html_txt(cgit_repo_desc);
                html("</td><td>");
                html_txt(cgit_repo_owner);
                html("</td></tr>\n");
        }
        closedir(d);
        html("</table>");
        cgit_print_docend();
 }
 static void cgit_print_branches()
 {
        html("<table class='list'>");
        html("<tr><th>Branch name</th><th>Head commit</th></tr>\n");
        for_each_branch_ref(cgit_print_branch_cb, NULL);
        html("</table>");
 }
 static int get_one_line(char *txt)
 {
        char *t;
        for(t=txt; *t != '\n' && t != '\0'; t++)
                ;
        *t = '\0';
        return t-txt-1;
 }
 static void cgit_print_commit_shortlog(struct commit *commit)
 {
        char *h, *t, *p; 
        char *tree = NULL, *author = NULL, *subject = NULL;
        int len;
        time_t sec;
        struct tm *time;
        char buf[32];
        h = t = commit->buffer;
        
        if (strncmp(h, "tree ", 5))
                die("Bad commit format: %s", 
                    sha1_to_hex(commit->object.sha1));
        
        len = get_one_line(h);
        tree = h+5;
        h += len + 2;
        while (!strncmp(h, "parent ", 7))
                h += get_one_line(h) + 2;
        
        if (!strncmp(h, "author ", 7)) {
                author = h+7;
                h += get_one_line(h) + 2;
                t = author;
                while(t!=h && *t!='<') 
                        t++;
                *t='\0';
                p = t;
                while(--t!=author && *t==' ')
                        *t='\0';
                while(++p!=h && *p!='>')
                        ;
                while(++p!=h && !isdigit(*p))
                        ;
                t = p;
                while(++p && isdigit(*p))
                        ;
                *p = '\0';
                sec = atoi(t);
                time = gmtime(&sec);
        }
        while((len = get_one_line(h)) > 0)
                h += len+2;
        h++;
        len = get_one_line(h);
        subject = h;
        html("<tr><td>");
        strftime(buf, sizeof(buf), "%Y-%m-%d %H:%M:%S", time);
        html_txt(buf);
        html("</td><td>");
        char *qry = fmt("id=%s", sha1_to_hex(commit->object.sha1));
        char *url = cgit_pageurl(cgit_query_repo, "view", qry);
        html_link_open(url, NULL, NULL);
        html_txt(subject);
        html_link_close();
        html("</td><td>");
        html_txt(author);
        html("</td></tr>\n");
 }
 static void cgit_print_log(const char *tip, int ofs, int cnt)
 {
        struct rev_info rev;
        struct commit *commit;
        const char *argv[2] = {NULL, tip};
        int n = 0;
        
        init_revisions(&rev, NULL);
        rev.abbrev = DEFAULT_ABBREV;
        rev.commit_format = CMIT_FMT_DEFAULT;
        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)
 {
+        cache_prepare(item);
 top:
-        if (!cache_lookup(item)) {
+        if (!cache_exist(item)) {
-                if (cache_lock(item)) {
+                if (!cache_lock(item)) {
-                        cgit_fill_cache(item);
-                        cache_unlock(item);
-                } else {
                        sched_yield();
                        goto top;
                }
-        } else if (cache_expired(item)) {
+                if (!cache_exist(item))
-                if (cache_lock(item)) {
                        cgit_fill_cache(item);
-                        cache_unlock(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;
 }
diff --git a/cgit.h b/cgit.h
index 1e084d4..3b0994a 100644
--- a/cgit.h
+++ b/cgit.h
@@ -1,64 +1,65 @@
 #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_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 int cache_lookup(struct cacheitem *item);
+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 */
author	Lars Hjemli <hjemli@gmail.com>	2006-12-11 08:57:58 (UTC)
committer	Lars Hjemli <hjemli@gmail.com>	2006-12-11 08:57:58 (UTC)
commit	f5069d88dff7a7ed2f4665904b03e906cca75a7c (patch) (unidiff)
tree	4c9bfa3aaf931af4a345ffb9563b19825c38b628
parent	76827d8679d1d2bd46e8cddf7da2ce4178e1d676 (diff)
download	cgit-f5069d88dff7a7ed2f4665904b03e906cca75a7c.zip cgit-f5069d88dff7a7ed2f4665904b03e906cca75a7c.tar.gz cgit-f5069d88dff7a7ed2f4665904b03e906cca75a7c.tar.bz2