Add commitdiff between commit and each of it's parent

A link is added next to each parent of a commit, leading to the new
diff-functionality in ui-diff.c.

Also added support for a path-parameter to filelevel diffs accessed via the
diffstat.

Signed-off-by: Lars Hjemli <hjemli@gmail.com>

5 files changed, 63 insertions, 10 deletions

diff --git a/cgit.c b/cgit.c
index aee7ba3..3d85a08 100644
--- a/cgit.c
+++ b/cgit.c
@@ -1,259 +1,259 @@
 /* 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;
 
 
 static struct repoinfo *cgit_get_repoinfo(char *url)
 {
         int i;
         struct repoinfo *repo;
         
         for (i=0; i<cgit_repolist.count; i++) {
                 repo = &cgit_repolist.repos[i];
                 if (!strcmp(repo->url, url))
                         return repo;
         }
         return NULL;
 }
 
 
 static int cgit_prepare_cache(struct cacheitem *item)
 {
         if (!cgit_query_repo) {
                 item->name = xstrdup(fmt("%s/index.html", cgit_cache_root));
                 item->ttl = cgit_cache_root_ttl;
                 return 1;
         }
         cgit_repo = cgit_get_repoinfo(cgit_query_repo);
         if (!cgit_repo) {
                 char *title = fmt("%s - %s", cgit_root_title, "Bad request");
                 cgit_print_docstart(title, item);
                 cgit_print_pageheader(title, 0);
                 cgit_print_error(fmt("Unknown repo: %s", cgit_query_repo));
                 cgit_print_docend();
                 return 0;
         }
 
         if (!cgit_query_page) {
                 item->name = xstrdup(fmt("%s/%s/index.html", cgit_cache_root, 
                            cgit_repo->url));
                 item->ttl = cgit_cache_repo_ttl;
         } else {
                 item->name = xstrdup(fmt("%s/%s/%s/%s.html", cgit_cache_root, 
                            cgit_repo->url, cgit_query_page, 
                            cache_safe_filename(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;
         }
         return 1;
 }
 
 static void cgit_print_repo_page(struct cacheitem *item)
 {
         char *title;
         int show_search;
 
         if (chdir(cgit_repo->path)) {
                 title = fmt("%s - %s", cgit_root_title, "Bad request");
                 cgit_print_docstart(title, item);
                 cgit_print_pageheader(title, 0);
                 cgit_print_error(fmt("Unable to scan repository: %s",
                                      strerror(errno)));
                 cgit_print_docend();
                 return;
         }
 
         title = fmt("%s - %s", cgit_repo->name, cgit_repo->desc);
         show_search = 0;
         setenv("GIT_DIR", cgit_repo->path, 1);
 
         if (cgit_query_page) {
             if (cgit_repo->snapshots && !strcmp(cgit_query_page, "snapshot")) {
                 cgit_print_snapshot(item, cgit_query_sha1, "zip", 
                                     cgit_repo->url, cgit_query_name);
                 return;
             }
             if (!strcmp(cgit_query_page, "blob")) {
                     cgit_print_blob(item, cgit_query_sha1, cgit_query_path);
                     return;
             }
         }
 
         if (cgit_query_page && !strcmp(cgit_query_page, "log"))
                 show_search = 1;
 
         cgit_print_docstart(title, item);
 
 
         if (!cgit_query_page) {
                 cgit_print_pageheader("summary", show_search);
                 cgit_print_summary();
                 cgit_print_docend();
                 return;
         }
 
         cgit_print_pageheader(cgit_query_page, show_search);
 
         if (!strcmp(cgit_query_page, "log")) {
                 cgit_print_log(cgit_query_head, cgit_query_ofs,
                                cgit_max_commit_count, cgit_query_search);
         } else if (!strcmp(cgit_query_page, "tree")) {
                 cgit_print_tree(cgit_query_sha1, cgit_query_path);
         } else if (!strcmp(cgit_query_page, "commit")) {
                 cgit_print_commit(cgit_query_sha1);
         } else if (!strcmp(cgit_query_page, "view")) {
                 cgit_print_view(cgit_query_sha1, cgit_query_path);
         } else if (!strcmp(cgit_query_page, "diff")) {
-                cgit_print_diff(cgit_query_sha1, cgit_query_sha2);
+                cgit_print_diff(cgit_query_sha1, cgit_query_sha2, cgit_query_path);
         } else {
                 cgit_print_error("Invalid request");
         }
         cgit_print_docend();
 }
 
 static void cgit_fill_cache(struct cacheitem *item, int use_cache)
 {
         static char buf[PATH_MAX];
         int stdout2;
 
         getcwd(buf, sizeof(buf));
         item->st.st_mtime = time(NULL);
 
         if (use_cache) {
                 stdout2 = chk_positive(dup(STDOUT_FILENO), 
                                        "Preserving STDOUT");
                 chk_zero(close(STDOUT_FILENO), "Closing STDOUT");
                 chk_positive(dup2(item->fd, STDOUT_FILENO), "Dup2(cachefile)");
         }
 
         if (cgit_query_repo)
                 cgit_print_repo_page(item);
         else
                 cgit_print_repolist(item);
 
         if (use_cache) {
                 chk_zero(close(STDOUT_FILENO), "Close redirected STDOUT");
                 chk_positive(dup2(stdout2, STDOUT_FILENO), 
                              "Restoring original STDOUT");
                 chk_zero(close(stdout2), "Closing temporary STDOUT");
         }
 
         chdir(buf);
 }
 
 static void cgit_check_cache(struct cacheitem *item)
 {
         int i = 0;
 
  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)) {
                         sleep(1);
                         goto top;
                 }
                 if (!cache_exist(item)) {
                         cgit_fill_cache(item, 1);
                         cache_unlock(item);
                 } else {
                         cache_cancel_lock(item);
                 }
         } else if (cache_expired(item) && cache_lock(item)) {
                 if (cache_expired(item)) {
                         cgit_fill_cache(item, 1);
                         cache_unlock(item);
                 } else {
                         cache_cancel_lock(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);
 }
 
 static void cgit_parse_args(int argc, const char **argv)
 {
         int i;
 
         for (i = 1; i < argc; i++) {
                 if (!strncmp(argv[i], "--cache=", 8)) {
                         cgit_cache_root = xstrdup(argv[i]+8);
                 }
                 if (!strcmp(argv[i], "--nocache")) {
                         cgit_nocache = 1;
                 }
                 if (!strncmp(argv[i], "--query=", 8)) {
                         cgit_querystring = xstrdup(argv[i]+8);
                 }
                 if (!strncmp(argv[i], "--repo=", 7)) {
                         cgit_query_repo = xstrdup(argv[i]+7);
                 }
                 if (!strncmp(argv[i], "--page=", 7)) {
                         cgit_query_page = xstrdup(argv[i]+7);
                 }
                 if (!strncmp(argv[i], "--head=", 7)) {
                         cgit_query_head = xstrdup(argv[i]+7);
                         cgit_query_has_symref = 1;
                 }
                 if (!strncmp(argv[i], "--sha1=", 7)) {
                         cgit_query_sha1 = xstrdup(argv[i]+7);
                         cgit_query_has_sha1 = 1;
                 }
                 if (!strncmp(argv[i], "--ofs=", 6)) {
                         cgit_query_ofs = atoi(argv[i]+6);
                 }
         }
 }
 
 int main(int argc, const char **argv)
 {
         struct cacheitem item;
 
         htmlfd = STDOUT_FILENO;
         item.st.st_mtime = time(NULL);
         cgit_repolist.length = 0;
         cgit_repolist.count = 0;
         cgit_repolist.repos = NULL;
 
         cgit_read_config("/etc/cgitrc", cgit_global_config_cb);
         if (getenv("QUERY_STRING"))
                 cgit_querystring = xstrdup(getenv("QUERY_STRING"));
         cgit_parse_args(argc, argv);
         cgit_parse_query(cgit_querystring, cgit_querystring_cb);
         if (!cgit_prepare_cache(&item))
                 return 0;
         if (cgit_nocache) {
                 cgit_fill_cache(&item, 0);
         } else {
                 cgit_check_cache(&item);
                 cgit_print_cache(&item);
         }
         return 0;
 }
diff --git a/cgit.css b/cgit.css
index b736b19..fe0ba50 100644
--- a/cgit.css
+++ b/cgit.css
@@ -1,322 +1,327 @@
 body {
         font-family: arial;
         font-size: 11pt;
         background: white;
 }
 
 body, table {
         padding: 0em;
         margin: 0em;
 }
 
 table {
       border-collapse: collapse;
 }
 
 h2 {
         font-size: 120%;
         font-weight: bold;
         margin-top: 0em;
         margin-bottom: 0.25em;
 }
 
 h3 {
         margin-top: 0em;
         font-size: 100%;
         font-weight: normal;
 }
 
 h4 {
         margin-top: 1.5em;
         margin-bottom: 0.1em;
         font-size: 100%;
         font-weight: bold;
 }
 
 a {
         color: blue;
         text-decoration: none;
 }
 
 a:hover {
         text-decoration: underline;
 }
 
 table.list {
         border: none;
         border-collapse: collapse;
 }
 
 table.list tr {
         background: white;
 }
 
 table.list tr:hover {
         background: #eee;
 }
 
 table.list tr.nohover:hover {
         background: white;
 }
 
 table.list th {
         font-weight: normal;
         border-bottom: solid 1px #777;
         padding: 0.1em 0.5em 0.1em 0.5em;
         vertical-align: baseline;
 }
 
 table.list td {
         border: none;
         padding: 0.1em 0.5em 0.1em 0.5em;
 }
 
 img {
         border: none;
 }
 
 table#layout {
         width: 100%;
         border-collapse: collapse;
         margin: 0px;
 }
 
 td#header, td#logo {
         color: #666;
         background-color: #ddd;
         border-bottom: solid 1px #000;
 }
 
 td#header {
         font-size: 150%;
         font-weight: bold;
         padding: 0.2em 0.5em;
         vertical-align: text-bottom;
 }
 
 td#logo {
         text-align: right;
         vertical-align: middle;
         padding-right: 0.5em;
 }
 
 td#crumb, td#search {
         color: #ccc;
         border-top: solid 3px #555;
         background-color: #666;
         border-bottom: solid 1px #333;
         padding: 2px 1em;
 }
 
 td#crumb {
         font-weight: bold;
 }
 
 td#crumb a {
         color: #ccc;
 }
 
 td#crumb a:hover {
         color: #eee;
 }
 
 td#search {
         text-align: right;
         vertical-align: center;
         padding-right: 0.5em;
 }
 
 td#search form {
         margin: 0px;
         padding: 0px;
 }
 
 td#search input {
         font-size: 9pt;
         padding: 0px;
         width: 10em;
         border: solid 1px #333;
         color: #333;
         background-color: #fff;
 }
 
 td#summary {
         vertical-align: top;
         padding-bottom: 1em;
 }
 
 td#archivelist {
         padding-bottom: 1em;
 }
 
 td#archivelist table {
         float: right;
         border-collapse: collapse;
         border: solid 1px #777;
 }
 
 td#archivelist table th {
         background-color: #ccc;
 }
 
 td#content {
         padding: 1em 0.5em;
 }
 
 div#blob {
         border: solid 1px black;
 }
 
 div.error {
         color: red;
         font-weight: bold;
         margin: 1em 2em;
 }
 
 td.ls-blob, td.ls-dir, td.ls-mod {
         font-family: monospace;
 }
 
 div.ls-dir a {
         font-weight: bold;
 }
 
 th.filesize, td.filesize {
         text-align: right;
 }
 
 td.filesize {
         font-family: monospace;
 }
 
 td.filemode {
         font-family: monospace;
 }
 
 td.blob {
         white-space: pre;
         font-family: monospace;
         background-color: white;
 }
 
 table.nowrap td {
         white-space: nowrap;
 }
 
 table.commit-info {
         border-collapse: collapse;
         margin-top: 1.5em;
 }
 
 table.commit-info th {
         text-align: left;
         font-weight: normal;
         padding: 0.1em 1em 0.1em 0.1em;
 }
 
 table.commit-info td {
         font-weight: normal;
         padding: 0.1em 1em 0.1em 0.1em;
 }
 
 div.commit-subject {
         font-weight: bold;
         font-size: 125%;
         margin: 1.5em 0em 0.5em 0em;
         padding: 0em;
 }
 
 div.commit-msg {
         white-space: pre;
         font-family: monospace;
 }
 
 table.diffstat {
         border-collapse: collapse;
         margin-top: 1.5em;
         width: 100%;
         border: solid 1px #aaa;
 }
 
 table.diffstat tr:hover {
         background-color: #eee;
 }
 
 table.diffstat th {
         font-weight: normal;
         text-align: left;
         text-decoration: underline;
         padding: 0.1em 1em 0.1em 0.1em;
         font-size: 100%;
 }
 
 table.diffstat td {
         padding: 0.2em 0.2em 0.1em 0.1em;
         font-size: 100%;
         border: none;
         border-top: solid 1px #aaa;
         border-bottom: solid 1px #aaa;
 }
 
 table.diffstat td span.modechange {
         padding-left: 1em;
         color: red;
 }
 
 table.diffstat td.add a {
         color: green;
 }
 
 table.diffstat td.del a {
         color: red;
 }
 
 table.diffstat td.upd a {
         color: blue;
 }
 
 table.diffstat td.graph {
         width: 75%;
         vertical-align: center;
 }
 
 table.diffstat td.graph img {
         border: none;
         height: 11pt;
 }
 
 div.diffstat-summary {
         color: #888;
         padding-top: 0.5em;
 }
 
+table.diff th {
+        padding: 1em 0em 0.1em 0.1em;
+        text-align: left;
+}
+
 table.diff td {
         border: solid 1px black;
         font-family: monospace;
         white-space: pre;
 }
 
 table.diff td div.hunk {
         background: #ccc;
 }
 
 table.diff td div.add {
         color: green;
 }
 
 table.diff td div.del {
         color: red;
 }
 
 .sha1 {
         font-family: courier;
         font-size: 90%;
 }
 
 .left {
         text-align: left;
 }
 
 .right {
         text-align: right;
 }
diff --git a/cgit.h b/cgit.h
index 46f3173..93699b5 100644
--- a/cgit.h
+++ b/cgit.h
@@ -1,182 +1,182 @@
 #ifndef CGIT_H
 #define CGIT_H
 
 
 #include <git-compat-util.h>
 #include <cache.h>
 #include <grep.h>
 #include <object.h>
 #include <tree.h>
 #include <commit.h>
 #include <tag.h>
 #include <diff.h>
 #include <diffcore.h>
 #include <refs.h>
 #include <revision.h>
 #include <log-tree.h>
 #include <archive.h>
 #include <xdiff/xdiff.h>
 
 
 typedef void (*configfn)(const char *name, const char *value);
 typedef void (*filepair_fn)(struct diff_filepair *pair);
 typedef void (*linediff_fn)(char *line, int len);
 
 struct cacheitem {
         char *name;
         struct stat st;
         int ttl;
         int fd;
 };
 
 struct repoinfo {
         char *url;
         char *name;
         char *path;
         char *desc;
         char *owner;
         char *module_link;
         int snapshots;
 };
 
 struct repolist {
         int length;
         int count;
         struct repoinfo *repos;
 };
 
 struct commitinfo {
         struct commit *commit;
         char *author;
         char *author_email;
         unsigned long author_date;
         char *committer;
         char *committer_email;
         unsigned long committer_date;
         char *subject;
         char *msg;
 };
 
 struct taginfo {
         char *tagger;
         char *tagger_email;
         int tagger_date;
         char *msg;
 };
 
 extern const char cgit_version[];
 
 extern struct repolist cgit_repolist;
 extern struct repoinfo *cgit_repo;
 
 extern char *cgit_root_title;
 extern char *cgit_css;
 extern char *cgit_logo;
 extern char *cgit_logo_link;
 extern char *cgit_module_link;
 extern char *cgit_virtual_root;
 extern char *cgit_cache_root;
 
 extern int cgit_nocache;
 extern int cgit_snapshots;
 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 int cgit_max_msg_len;
 extern int cgit_max_commit_count;
 
 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_search;
 extern char *cgit_query_head;
 extern char *cgit_query_sha1;
 extern char *cgit_query_sha2;
 extern char *cgit_query_path;
 extern char *cgit_query_name;
 extern int   cgit_query_ofs;
 
 extern int htmlfd;
 
 extern void cgit_global_config_cb(const char *name, const char *value);
 extern void cgit_repo_config_cb(const char *name, const char *value);
 extern void cgit_querystring_cb(const char *name, const char *value);
 
 extern int chk_zero(int result, char *msg);
 extern int chk_positive(int result, char *msg);
 
 extern int hextoint(char c);
 
 extern void *cgit_free_commitinfo(struct commitinfo *info);
 
 extern int cgit_diff_files(const unsigned char *old_sha1,
                            const unsigned char *new_sha1,
                            linediff_fn fn);
 
 extern void cgit_diff_tree(const unsigned char *old_sha1,
                            const unsigned char *new_sha1,
                            filepair_fn fn);
 
 extern void cgit_diff_commit(struct commit *commit, filepair_fn fn);
 
 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_ntxt(int len, char *txt);
 extern void html_attr(char *txt);
 extern void html_hidden(char *name, char *value);
 extern void html_link_open(char *url, char *title, char *class);
 extern void html_link_close(void);
 extern void html_filemode(unsigned short mode);
 
 extern int cgit_read_config(const char *filename, configfn fn);
 extern int cgit_parse_query(char *txt, configfn fn);
 extern struct commitinfo *cgit_parse_commit(struct commit *commit);
 extern struct taginfo *cgit_parse_tag(struct tag *tag);
 
 extern char *cache_safe_filename(const char *unsafe);
 extern int cache_lock(struct cacheitem *item);
 extern int cache_unlock(struct cacheitem *item);
 extern int cache_cancel_lock(struct cacheitem *item);
 extern int cache_exist(struct cacheitem *item);
 extern int cache_expired(struct cacheitem *item);
 
 extern char *cgit_repourl(const char *reponame);
 extern char *cgit_pageurl(const char *reponame, const char *pagename, 
                           const char *query);
 
 extern void cgit_print_error(char *msg);
 extern void cgit_print_date(unsigned long secs);
 extern void cgit_print_docstart(char *title, struct cacheitem *item);
 extern void cgit_print_docend();
 extern void cgit_print_pageheader(char *title, int show_search);
 extern void cgit_print_snapshot_start(const char *mimetype, 
                                       const char *filename, 
                                       struct cacheitem *item);
 
 extern void cgit_print_repolist(struct cacheitem *item);
 extern void cgit_print_summary();
 extern void cgit_print_log(const char *tip, int ofs, int cnt, char *grep);
 extern void cgit_print_view(const char *hex, char *path);
 extern void cgit_print_blob(struct cacheitem *item, const char *hex, char *path);
 extern void cgit_print_tree(const char *hex, char *path);
 extern void cgit_print_commit(const char *hex);
-extern void cgit_print_diff(const char *old_hex, const char *new_hex);
+extern void cgit_print_diff(const char *old_hex, const char *new_hex, char *path);
 extern void cgit_print_snapshot(struct cacheitem *item, const char *hex, 
                                 const char *format, const char *prefix,
                                 const char *filename);
 
 #endif /* CGIT_H */
diff --git a/ui-commit.c b/ui-commit.c
index ce33cf9..b3d1c28 100644
--- a/ui-commit.c
+++ b/ui-commit.c
@@ -1,228 +1,239 @@
 /* ui-commit.c: generate commit view
  *
  * Copyright (C) 2006 Lars Hjemli
  *
  * Licensed under GNU General Public License v2
  *   (see COPYING for full license text)
  */
 
 #include "cgit.h"
 
 int files = 0, slots = 0;
 int total_adds = 0, total_rems = 0, max_changes = 0;
 int lines_added, lines_removed;
 
 struct fileinfo {
         char status;
         unsigned char old_sha1[20];
         unsigned char new_sha1[20];
         unsigned short old_mode;
         unsigned short new_mode;
         char *old_path;
         char *new_path;
         unsigned int added;
         unsigned int removed;
 } *items;
 
 
 void print_fileinfo(struct fileinfo *info)
 {
         char *query, *query2;
         char *class;
         double width;
 
         switch (info->status) {
         case DIFF_STATUS_ADDED:
                 class = "add";
                 break;
         case DIFF_STATUS_COPIED:
                 class = "cpy";
                 break;
         case DIFF_STATUS_DELETED:
                 class = "del";
                 break;
         case DIFF_STATUS_MODIFIED:
                 class = "upd";
                 break;
         case DIFF_STATUS_RENAMED:
                 class = "mov";
                 break;
         case DIFF_STATUS_TYPE_CHANGED:
                 class = "typ";
                 break;
         case DIFF_STATUS_UNKNOWN:
                 class = "unk";
                 break;
         case DIFF_STATUS_UNMERGED:
                 class = "stg";
                 break;
         default:
                 die("bug: unhandled diff status %c", info->status);
         }
 
         html("<tr>");
         htmlf("<td class='mode'>");
         if (is_null_sha1(info->new_sha1)) {
                 html_filemode(info->old_mode);
         } else {
                 html_filemode(info->new_mode);
         }
 
         if (info->old_mode != info->new_mode &&
             !is_null_sha1(info->old_sha1) &&
             !is_null_sha1(info->new_sha1)) {
                 html("<span class='modechange'>[");
                 html_filemode(info->old_mode);
                 html("]</span>");
         }
         htmlf("</td><td class='%s'>", class);
-        query = fmt("id=%s&id2=%s", sha1_to_hex(info->old_sha1),
-                    sha1_to_hex(info->new_sha1));
+        query = fmt("id=%s&id2=%s&path=%s", sha1_to_hex(info->old_sha1),
+                    sha1_to_hex(info->new_sha1), info->new_path);
         html_link_open(cgit_pageurl(cgit_query_repo, "diff", query),
                        NULL, NULL);
         if (info->status == DIFF_STATUS_COPIED ||
             info->status == DIFF_STATUS_RENAMED) {
                 html_txt(info->new_path);
                 htmlf("</a> (%s from ", info->status == DIFF_STATUS_COPIED ?
                       "copied" : "renamed");
                 query2 = fmt("id=%s", sha1_to_hex(info->old_sha1));
                 html_link_open(cgit_pageurl(cgit_query_repo, "view", query2),
                                NULL, NULL);
                 html_txt(info->old_path);
                 html("</a>)");
         } else {
                 html_txt(info->new_path);
                 html("</a>");
         }
         html("</td><td class='right'>");
         htmlf("%d", info->added + info->removed);
 
         html("</td><td class='graph'>");
         width = (info->added + info->removed) * 100.0 / max_changes;
         if (width < 0.1)
                 width = 0.1;
         html_link_open(cgit_pageurl(cgit_query_repo, "diff", query),
                        NULL, NULL);
         htmlf("<img src='/cgit/add.png' style='width: %.1f%%;'/>",
               info->added * width / (info->added + info->removed));
         htmlf("<img src='/cgit/del.png' style='width: %.1f%%;'/>",
               info->removed * width / (info->added + info->removed));
         html("</a></td></tr>\n");
 }
 
 void cgit_count_diff_lines(char *line, int len)
 {
         if (line && (len > 0)) {
                 if (line[0] == '+')
                         lines_added++;
                 else if (line[0] == '-')
                         lines_removed++;
         }
 }
 
 void inspect_filepair(struct diff_filepair *pair)
 {
         files++;
         lines_added = 0;
         lines_removed = 0;
         cgit_diff_files(pair->one->sha1, pair->two->sha1, cgit_count_diff_lines);
         if (files >= slots) {
                 if (slots == 0)
                         slots = 4;
                 else
                         slots = slots * 2;
                 items = xrealloc(items, slots * sizeof(struct fileinfo));
         }
         items[files-1].status = pair->status;
         hashcpy(items[files-1].old_sha1, pair->one->sha1);
         hashcpy(items[files-1].new_sha1, pair->two->sha1);
         items[files-1].old_mode = pair->one->mode;
         items[files-1].new_mode = pair->two->mode;
         items[files-1].old_path = xstrdup(pair->one->path);
         items[files-1].new_path = xstrdup(pair->two->path);
         items[files-1].added = lines_added;
         items[files-1].removed = lines_removed;
         if (lines_added + lines_removed > max_changes)
                 max_changes = lines_added + lines_removed;
         total_adds += lines_added;
         total_rems += lines_removed;
 }
 
 
 void cgit_print_commit(const char *hex)
 {
-        struct commit *commit;
+        struct commit *commit, *parent;
         struct commitinfo *info;
         struct commit_list *p;
         unsigned char sha1[20];
         char *query;
         char *filename;
         int i;
 
         if (get_sha1(hex, sha1)) {
                 cgit_print_error(fmt("Bad object id: %s", hex));
                 return;
         }
         commit = lookup_commit_reference(sha1);
         if (!commit) {
                 cgit_print_error(fmt("Bad commit reference: %s", hex));
                 return;
         }
         info = cgit_parse_commit(commit);
 
         html("<table class='commit-info'>\n");
         html("<tr><th>author</th><td>");
         html_txt(info->author);
         html(" ");
         html_txt(info->author_email);
         html("</td><td class='right'>");
         cgit_print_date(info->author_date);
         html("</td></tr>\n");
         html("<tr><th>committer</th><td>");
         html_txt(info->committer);
         html(" ");
         html_txt(info->committer_email);
         html("</td><td class='right'>");
         cgit_print_date(info->committer_date);
         html("</td></tr>\n");
         html("<tr><th>tree</th><td colspan='2' class='sha1'><a href='");
         query = fmt("id=%s", sha1_to_hex(commit->tree->object.sha1));
         html_attr(cgit_pageurl(cgit_query_repo, "tree", query));
         htmlf("'>%s</a></td></tr>\n", sha1_to_hex(commit->tree->object.sha1));
               for (p = commit->parents; p ; p = p->next) {
+                parent = lookup_commit_reference(p->item->object.sha1);
+                if (!parent) {
+                        html("<tr><td colspan='3'>");
+                        cgit_print_error("Error reading parent commit");
+                        html("</td></tr>");
+                        continue;
+                }
                 html("<tr><th>parent</th>"
                      "<td colspan='2' class='sha1'>"
                      "<a href='");
                 query = fmt("id=%s", sha1_to_hex(p->item->object.sha1));
                 html_attr(cgit_pageurl(cgit_query_repo, "commit", query));
-                htmlf("'>%s</a></td></tr>\n",
+                htmlf("'>%s</a> (<a href='",
                       sha1_to_hex(p->item->object.sha1));
+                query = fmt("id=%s&id2=%s", sha1_to_hex(parent->tree->object.sha1),
+                            sha1_to_hex(commit->tree->object.sha1));
+                html_attr(cgit_pageurl(cgit_query_repo, "diff", query));
+                html("'>diff</a>)</td></tr>");
         }
         if (cgit_repo->snapshots) {
                 htmlf("<tr><th>download</th><td colspan='2' class='sha1'><a href='");
                 filename = fmt("%s-%s.zip", cgit_query_repo, hex);
                 html_attr(cgit_pageurl(cgit_query_repo, "snapshot",
                                        fmt("id=%s&name=%s", hex, filename)));
                 htmlf("'>%s</a></td></tr>", filename);
         }
         html("</table>\n");
         html("<div class='commit-subject'>");
         html_txt(info->subject);
         html("</div>");
         html("<div class='commit-msg'>");
         html_txt(info->msg);
         html("</div>");
         if (!(commit->parents && commit->parents->next && commit->parents->next->next)) {
                 html("<table class='diffstat'>");
                 max_changes = 0;
                 cgit_diff_commit(commit, inspect_filepair);
                 for(i = 0; i<files; i++)
                         print_fileinfo(&items[i]);
                 html("</table>");
                 html("<div class='diffstat-summary'>");
                 htmlf("%d files changed, %d insertions, %d deletions\n",
                       files, total_adds, total_rems);
                 html("</div>");
         }
         cgit_free_commitinfo(info);
 }
diff --git a/ui-diff.c b/ui-diff.c
index 96106af..10330d3 100644
--- a/ui-diff.c
+++ b/ui-diff.c
@@ -1,45 +1,82 @@
 /* ui-diff.c: show diff between two blobs
  *
  * Copyright (C) 2006 Lars Hjemli
  *
  * Licensed under GNU General Public License v2
  *   (see COPYING for full license text)
  */
 
 #include "cgit.h"
 
 
 /*
  * print a single line returned from xdiff
  */
 static void print_line(char *line, int len)
 {
         char *class = "ctx";
         char c = line[len-1];
 
         if (line[0] == '+')
                 class = "add";
         else if (line[0] == '-')
                 class = "del";
         else if (line[0] == '@')
                 class = "hunk";
 
         htmlf("<div class='%s'>", class);
         line[len-1] = '\0';
         html_txt(line);
         html("</div>");
         line[len-1] = c;
 }
 
-void cgit_print_diff(const char *old_hex, const char *new_hex)
+static void filepair_cb(struct diff_filepair *pair)
+{
+        html("<tr><th>");
+        html_txt(pair->two->path);
+        html("</th></tr>");
+        html("<tr><td>");
+        if (cgit_diff_files(pair->one->sha1, pair->two->sha1, print_line))
+                cgit_print_error("Error running diff");
+        html("</tr></td>");
+}
+
+void cgit_print_diff(const char *old_hex, const char *new_hex, char *path)
 {
         unsigned char sha1[20], sha2[20];
+        enum object_type type;
+        unsigned long size;
 
         get_sha1(old_hex, sha1);
         get_sha1(new_hex, sha2);
 
-        html("<table class='diff'><tr><td>");
-        if (cgit_diff_files(sha1, sha2, print_line))
-                cgit_print_error("Error running diff");
+        type = sha1_object_info(sha1, &size);
+        if (type == OBJ_BAD) {
+                type = sha1_object_info(sha2, &size);
+                if (type == OBJ_BAD) {
+                        cgit_print_error(fmt("Bad object names: %s, %s", old_hex, new_hex));
+                        return;
+                }
+        }
+
+        html("<table class='diff'>");
+        switch(type) {
+        case OBJ_BLOB:
+                if (path)
+                        htmlf("<tr><th>%s</th></tr>", path);
+                html("<tr><td>");
+                if (cgit_diff_files(sha1, sha2, print_line))
+                        cgit_print_error("Error running diff");
+                html("</tr></td>");
+                break;
+        case OBJ_TREE:
+                cgit_diff_tree(sha1, sha2, filepair_cb);
+                break;
+        default:
+                cgit_print_error(fmt("Unhandled object type: %s",
+                                     typename(type)));
+                break;
+        }
         html("</td></tr></table>");
 }