9 files changed, 353 insertions, 28 deletions

diff --git a/.gitignore b/.gitignore
index 4eaec97..c4c9ac3 100644
--- a/.gitignore
+++ b/.gitignore
@@ -2,2 +2,3 @@
 cgit
 *.o
+*~
diff --git a/Makefile b/Makefile
index 4e72b07..243f590 100644
--- a/Makefile
+++ b/Makefile
@@ -4,5 +4,7 @@ INSTALL_CSS = /var/www/htdocs/cgit.css
 
 EXTLIBS = ../git/libgit.a ../git/xdiff/lib.a -lz -lcrypto
-OBJECTS = cgit.o config.o html.o
+OBJECTS = cgit.o config.o html.o cache.o
+
+CFLAGS += -Wall
 
 all: cgit
@@ -16,5 +18,5 @@ clean:
 
 cgit: $(OBJECTS)
-        $(CC) -o cgit $(OBJECTS) $(EXTLIBS)
+        $(CC) $(CFLAGS) -o cgit $(OBJECTS) $(EXTLIBS)
 
 $(OBJECTS): cgit.h git.h
diff --git a/README b/README
new file mode 100644
index 0000000..5917c37
--- a/dev/null
+++ b/README
@@ -0,0 +1,54 @@
+Cache algorithm
+===============
+
+Cgit normally returns cached pages when invoked. If there is no cache file, or
+the cache file has expired, it is regenerated. Finally, the cache file is 
+printed on stdout.
+
+When it is decided that a cache file needs to be regenerated, an attempt is 
+made to create a corresponding lockfile. If this fails, the process gives up
+and uses the expired cache file instead.
+
+When there is no cache file for a request, an attempt is made to create a 
+corresponding lockfile. If this fails, the process calls sched_yield(2) before
+restarting the request handling.
+
+In pseudocode:
+
+        name = generate_cache_name(request);
+top:
+        if (!exists(name)) {
+                if (lock_cache(name)) {
+                        generate_cache(request, name);
+                        unlock_cache(name);
+                } else {
+                        sched_yield();
+                        goto top;
+                }
+        } else if (expired(name)) {
+                if (lock_cache(name)) {
+                        generate_cache(request, name);
+                        unlock_cache(name);
+                }
+        }
+        print_file(name);
+
+
+The following options can be set in /etc/cgitrc to control cache behaviour:
+  cache-root:        root directory for cache files
+  cache-root-ttl:    TTL for the repo listing page
+  cache-repo-ttl:    TTL for any repos summary page
+  cache-dynamic-ttl: TTL for pages with symbolic references (not SHA1)
+  cache-static-ttl:  TTL for pages with sha1 references
+
+TTL is specified in minutes, -1 meaning "infinite caching". 
+
+
+Naming of cache files
+---------------------
+Repository listing:  <cachedir>/index.html
+Repository summary:  <cachedir>/<repo>/index.html
+Repository subpage:  <cachedir>/<repo>/<page>/<querystring>.html
+
+The corresponding lock files have a ".lock" suffix.
+
diff --git a/cache.c b/cache.c
new file mode 100644
index 0000000..1be1ea4
--- a/dev/null
+++ b/cache.c
@@ -0,0 +1,86 @@
+#include "cgit.h"
+
+const int NOLOCK = -1;
+
+int cache_lookup(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;
+        }
+        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 4c14f77..09c857c 100644
--- a/cgit.c
+++ b/cgit.c
@@ -11,6 +11,7 @@ static const char cgit_lib_error[] =
 "<div class='error'>%s: %s</div>";
 
+int htmlfd = 0;
 
-char *cgit_root         = "/var/git";
+char *cgit_root         = "/usr/src/git";
 char *cgit_root_title   = "Git repository browser";
 char *cgit_css          = "/cgit.css";
@@ -19,19 +20,36 @@ 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 = txt, *value = NULL, c;
+        char *t, *value = NULL, c;
 
         if (!txt)
                 return 0;
 
+        t = txt = xstrdup(txt);
+ 
         while((c=*t) != '\0') {
                 if (c=='=') {
@@ -83,6 +101,11 @@ void cgit_querystring_cb(const char *name, const char *value)
         else if (!strcmp(name, "p"))
                 cgit_query_page = xstrdup(value);
-        else if (!strcmp(name, "h"))
+        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;
+        }
 }
 
@@ -137,7 +160,30 @@ static int cgit_print_branch_cb(const char *refname, const unsigned char *sha1,
 }
 
+/* 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);
@@ -176,4 +222,5 @@ static void cgit_print_repolist()
         char *name;
 
+        chdir(cgit_root);
         cgit_print_docstart(cgit_root_title);
         cgit_print_pageheader(cgit_root_title);
@@ -198,5 +245,5 @@ static void cgit_print_repolist()
 
                 cgit_repo_name = cgit_repo_desc = cgit_repo_owner = NULL;
-                name = fmt("%s/.git/info/cgit", de->d_name);
+                name = fmt("%s/info/cgit", de->d_name);
                 if (cgit_read_config(name, cgit_repo_config_cb))
                         continue;
@@ -292,5 +339,5 @@ static void cgit_print_commit_shortlog(struct commit *commit)
         html_txt(buf);
         html("</td><td>");
-        char *qry = fmt("h=%s", sha1_to_hex(commit->object.sha1));
+        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);
@@ -372,6 +419,6 @@ static void cgit_print_object(char *hex)
 static void cgit_print_repo_page()
 {
-        if (chdir(cgit_query_repo) || 
-            cgit_read_config(".git/info/cgit", cgit_repo_config_cb)) {
+        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);
@@ -382,5 +429,5 @@ static void cgit_print_repo_page()
                 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);
@@ -391,20 +438,60 @@ static void cgit_print_repo_page()
                 cgit_print_log(cgit_query_head, 0, 100);
         } else if (!strcmp(cgit_query_page, "view")) {
-                cgit_print_object(cgit_query_head);
+                cgit_print_object(cgit_query_sha1);
         }
         cgit_print_docend();
 }
 
-int main(int argc, const char **argv)
+static void cgit_fill_cache(struct cacheitem *item)
 {
-        if (cgit_read_config("/etc/cgitrc", cgit_global_config_cb))
-                die("Error reading config: %d %s", errno, strerror(errno));
-
-        chdir(cgit_root);
-        cgit_parse_query(getenv("QUERY_STRING"), cgit_querystring_cb);
+        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)
+{
+ top:
+        if (!cache_lookup(item)) {
+                if (cache_lock(item)) {
+                        cgit_fill_cache(item);
+                        cache_unlock(item);
+                } else {
+                        sched_yield();
+                        goto top;
+                }
+        } else if (cache_expired(item)) {
+                if (cache_lock(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 19f7ba7..1e084d4 100644
--- a/cgit.h
+++ b/cgit.h
@@ -4,4 +4,44 @@
 #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,...);
@@ -11,11 +51,14 @@ 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);
 
-typedef void (*configfn)(const char *name, const char *value);
 
 extern int cgit_read_config(const char *filename, configfn fn);
 
+extern int cache_lookup(struct cacheitem *item);
+extern int cache_lock(struct cacheitem *item);
+extern int cache_unlock(struct cacheitem *item);
+extern int cache_expired(struct cacheitem *item);
+
 #endif /* CGIT_H */
diff --git a/config.c b/config.c
index 858ab69..ee49b62 100644
--- a/config.c
+++ b/config.c
@@ -33,5 +33,5 @@ int read_config_line(FILE *f, char *line, const char **value, int bufsize)
                         continue;
                 }
-                if (!isname && isblank(c))
+                if (!isname && isspace(c))
                         continue;
 
@@ -65,5 +65,5 @@ int cgit_read_config(const char *filename, configfn fn)
                 return -1;
 
-        while(len = read_config_line(f, line, &value, sizeof(line)))
+        while((len = read_config_line(f, line, &value, sizeof(line))) > 0)
                 (*fn)(line, value);
 
diff --git a/git.h b/git.h
index 443f216..dfa3542 100644
--- a/git.h
+++ b/git.h
@@ -34,4 +34,24 @@
 
 
+/* On most systems <limits.h> would have given us this, but
+ * not on some systems (e.g. GNU/Hurd).
+ */
+#ifndef PATH_MAX
+#define PATH_MAX 4096
+#endif
+
+#ifdef __GNUC__
+#define NORETURN __attribute__((__noreturn__))
+#else
+#define NORETURN
+#ifndef __attribute__
+#define __attribute__(x)
+#endif
+#endif
+
+
+extern void die(const char *err, ...) NORETURN __attribute__((format (printf, 1, 2)));
+
+
 static inline char* xstrdup(const char *str)
 {
@@ -109,7 +129,11 @@ static inline ssize_t xwrite(int fd, const void *buf, size_t len)
 #define DEFAULT_ABBREV 7
 
+extern int sha1_object_info(const unsigned char *, char *, unsigned long *);
 
 extern void * read_sha1_file(const unsigned char *sha1, char *type, unsigned long *size);
 
+extern int get_sha1(const char *str, unsigned char *sha1);
+extern int get_sha1_hex(const char *hex, unsigned char *sha1);
+        extern char *sha1_to_hex(const unsigned char *sha1);/* static buffer result! */
 
 
@@ -184,4 +208,19 @@ struct commit {
 
 
+struct commit *lookup_commit(const unsigned char *sha1);
+struct commit *lookup_commit_reference(const unsigned char *sha1);
+struct commit *lookup_commit_reference_gently(const unsigned char *sha1,
+                                              int quiet);
+
+int parse_commit_buffer(struct commit *item, void *buffer, unsigned long size);
+int parse_commit(struct commit *item);
+
+struct commit_list * commit_list_insert(struct commit *item, struct commit_list **list_p);
+struct commit_list * insert_by_date(struct commit *item, struct commit_list **list);
+
+void free_commit_list(struct commit_list *list);
+
+void sort_by_date(struct commit_list **list);
+
 /* Commit formats */
 enum cmit_fmt {
@@ -198,11 +237,7 @@ enum cmit_fmt {
 };
 
+extern unsigned long pretty_print_commit(enum cmit_fmt fmt, const struct commit *, unsigned long len, char *buf, unsigned long space, int abbrev, const char *subject, const char *after_subject, int relative_date);
 
 
-struct commit *lookup_commit(const unsigned char *sha1);
-struct commit *lookup_commit_reference(const unsigned char *sha1);
-struct commit *lookup_commit_reference_gently(const unsigned char *sha1,
-                                              int quiet);
-
 typedef void (*topo_sort_set_fn_t)(struct commit*, void *data);
 typedef void* (*topo_sort_get_fn_t)(struct commit*);
@@ -307,4 +342,14 @@ enum color_diff {
 
 
+/*
+ * from git:refs.g
+ */
+
+typedef int each_ref_fn(const char *refname, const unsigned char *sha1, int flags, void *cb_data);
+extern int head_ref(each_ref_fn, void *);
+extern int for_each_ref(each_ref_fn, void *);
+extern int for_each_tag_ref(each_ref_fn, void *);
+extern int for_each_branch_ref(each_ref_fn, void *);
+extern int for_each_remote_ref(each_ref_fn, void *);
 
 
@@ -392,4 +437,9 @@ struct rev_info {
 
 
+extern void init_revisions(struct rev_info *revs, const char *prefix);
+extern int setup_revisions(int argc, const char **argv, struct rev_info *revs, const char *def);
+extern int handle_revision_arg(const char *arg, struct rev_info *revs,int flags,int cant_be_filename);
+
+extern void prepare_revision_walk(struct rev_info *revs);
 extern struct commit *get_revision(struct rev_info *revs);
 
diff --git a/html.c b/html.c
index 5780dc1..bf1490f 100644
--- a/html.c
+++ b/html.c
@@ -21,14 +21,16 @@ char *fmt(const char *format, ...)
 void html(const char *txt)
 {
-        fputs(txt, stdout);
+        write(htmlfd, txt, strlen(txt));
 }
 
 void htmlf(const char *format, ...)
 {
+        static char buf[65536];
         va_list args;
 
         va_start(args, format);
-        vprintf(format, args);
+        vsnprintf(buf, sizeof(buf), format, args);
         va_end(args);
+        html(buf);
 }