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, 61 insertions, 8 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
@@ -101,222 +101,227 @@ td#logo {
 }
 
 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>");
+	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>");
 }