Add possibility to switch between unidiff and side-by-side-diff.

A new config option side-by-side-diffs added, defaulting to 0,
meaning unidiff. Also a query option (ss) is used toggle this.

In the commit page you can switch between the two diff formats by
clicking on the link on the "commit"-row, to the right of (patch).

In the diff page you can switch by using the link at the start
of the page.

All commit-links and diff-links will remember the choice.

Signed-off-by: Ragnar Ouchterlony <ragnar@lysator.liu.se>
Signed-off-by: Lars Hjemli <hjemli@gmail.com>

9 files changed, 73 insertions, 16 deletions

diff --git a/cgit.c b/cgit.c
index bd37788..ff678fb 100644
--- a/cgit.c
+++ b/cgit.c
@@ -153,161 +153,166 @@ void config_cb(const char *name, const char *value)
                 ctx.cfg.cache_scanrc_ttl = atoi(value);
         else if (!strcmp(name, "cache-static-ttl"))
                 ctx.cfg.cache_static_ttl = atoi(value);
         else if (!strcmp(name, "cache-dynamic-ttl"))
                 ctx.cfg.cache_dynamic_ttl = atoi(value);
         else if (!strcmp(name, "about-filter"))
                 ctx.cfg.about_filter = new_filter(value, 0);
         else if (!strcmp(name, "commit-filter"))
                 ctx.cfg.commit_filter = new_filter(value, 0);
         else if (!strcmp(name, "embedded"))
                 ctx.cfg.embedded = atoi(value);
         else if (!strcmp(name, "max-message-length"))
                 ctx.cfg.max_msg_len = atoi(value);
         else if (!strcmp(name, "max-repodesc-length"))
                 ctx.cfg.max_repodesc_len = atoi(value);
         else if (!strcmp(name, "max-repo-count"))
                 ctx.cfg.max_repo_count = atoi(value);
         else if (!strcmp(name, "max-commit-count"))
                 ctx.cfg.max_commit_count = atoi(value);
         else if (!strcmp(name, "scan-path"))
                 if (!ctx.cfg.nocache && ctx.cfg.cache_size)
                         process_cached_repolist(value);
                 else
                         scan_tree(value, repo_config);
         else if (!strcmp(name, "source-filter"))
                 ctx.cfg.source_filter = new_filter(value, 1);
         else if (!strcmp(name, "summary-log"))
                 ctx.cfg.summary_log = atoi(value);
         else if (!strcmp(name, "summary-branches"))
                 ctx.cfg.summary_branches = atoi(value);
         else if (!strcmp(name, "summary-tags"))
                 ctx.cfg.summary_tags = atoi(value);
+        else if (!strcmp(name, "side-by-side-diffs"))
+                ctx.cfg.ssdiff = atoi(value);
         else if (!strcmp(name, "agefile"))
                 ctx.cfg.agefile = xstrdup(value);
         else if (!strcmp(name, "renamelimit"))
                 ctx.cfg.renamelimit = atoi(value);
         else if (!strcmp(name, "robots"))
                 ctx.cfg.robots = xstrdup(value);
         else if (!strcmp(name, "clone-prefix"))
                 ctx.cfg.clone_prefix = xstrdup(value);
         else if (!strcmp(name, "local-time"))
                 ctx.cfg.local_time = atoi(value);
         else if (!prefixcmp(name, "mimetype."))
                 add_mimetype(name + 9, value);
         else if (!strcmp(name, "include"))
                 parse_configfile(value, config_cb);
 }
 
 static void querystring_cb(const char *name, const char *value)
 {
         if (!value)
                 value = "";
 
         if (!strcmp(name,"r")) {
                 ctx.qry.repo = xstrdup(value);
                 ctx.repo = cgit_get_repoinfo(value);
         } else if (!strcmp(name, "p")) {
                 ctx.qry.page = xstrdup(value);
         } else if (!strcmp(name, "url")) {
                 ctx.qry.url = xstrdup(value);
                 cgit_parse_url(value);
         } else if (!strcmp(name, "qt")) {
                 ctx.qry.grep = xstrdup(value);
         } else if (!strcmp(name, "q")) {
                 ctx.qry.search = xstrdup(value);
         } else if (!strcmp(name, "h")) {
                 ctx.qry.head = xstrdup(value);
                 ctx.qry.has_symref = 1;
         } else if (!strcmp(name, "id")) {
                 ctx.qry.sha1 = xstrdup(value);
                 ctx.qry.has_sha1 = 1;
         } else if (!strcmp(name, "id2")) {
                 ctx.qry.sha2 = xstrdup(value);
                 ctx.qry.has_sha1 = 1;
         } else if (!strcmp(name, "ofs")) {
                 ctx.qry.ofs = atoi(value);
         } else if (!strcmp(name, "path")) {
                 ctx.qry.path = trim_end(value, '/');
         } else if (!strcmp(name, "name")) {
                 ctx.qry.name = xstrdup(value);
         } else if (!strcmp(name, "mimetype")) {
                 ctx.qry.mimetype = xstrdup(value);
         } else if (!strcmp(name, "s")){
                 ctx.qry.sort = xstrdup(value);
         } else if (!strcmp(name, "showmsg")) {
                 ctx.qry.showmsg = atoi(value);
         } else if (!strcmp(name, "period")) {
                 ctx.qry.period = xstrdup(value);
+        } else if (!strcmp(name, "ss")) {
+                ctx.qry.ssdiff = atoi(value);
         }
 }
 
 char *xstrdupn(const char *str)
 {
         return (str ? xstrdup(str) : NULL);
 }
 
 static void prepare_context(struct cgit_context *ctx)
 {
         memset(ctx, 0, sizeof(ctx));
         ctx->cfg.agefile = "info/web/last-modified";
         ctx->cfg.nocache = 0;
         ctx->cfg.cache_size = 0;
         ctx->cfg.cache_dynamic_ttl = 5;
         ctx->cfg.cache_max_create_time = 5;
         ctx->cfg.cache_repo_ttl = 5;
         ctx->cfg.cache_root = CGIT_CACHE_ROOT;
         ctx->cfg.cache_root_ttl = 5;
         ctx->cfg.cache_scanrc_ttl = 15;
         ctx->cfg.cache_static_ttl = -1;
         ctx->cfg.css = "/cgit.css";
         ctx->cfg.logo = "/cgit.png";
         ctx->cfg.local_time = 0;
         ctx->cfg.enable_tree_linenumbers = 1;
         ctx->cfg.max_repo_count = 50;
         ctx->cfg.max_commit_count = 50;
         ctx->cfg.max_lock_attempts = 5;
         ctx->cfg.max_msg_len = 80;
         ctx->cfg.max_repodesc_len = 80;
         ctx->cfg.max_stats = 0;
         ctx->cfg.module_link = "./?repo=%s&page=commit&id=%s";
         ctx->cfg.renamelimit = -1;
         ctx->cfg.robots = "index, nofollow";
         ctx->cfg.root_title = "Git repository browser";
         ctx->cfg.root_desc = "a fast webinterface for the git dscm";
         ctx->cfg.script_name = CGIT_SCRIPT_NAME;
         ctx->cfg.section = "";
         ctx->cfg.summary_branches = 10;
         ctx->cfg.summary_log = 10;
         ctx->cfg.summary_tags = 10;
+        ctx->cfg.ssdiff = 0;
         ctx->env.cgit_config = xstrdupn(getenv("CGIT_CONFIG"));
         ctx->env.http_host = xstrdupn(getenv("HTTP_HOST"));
         ctx->env.https = xstrdupn(getenv("HTTPS"));
         ctx->env.no_http = xstrdupn(getenv("NO_HTTP"));
         ctx->env.path_info = xstrdupn(getenv("PATH_INFO"));
         ctx->env.query_string = xstrdupn(getenv("QUERY_STRING"));
         ctx->env.request_method = xstrdupn(getenv("REQUEST_METHOD"));
         ctx->env.script_name = xstrdupn(getenv("SCRIPT_NAME"));
         ctx->env.server_name = xstrdupn(getenv("SERVER_NAME"));
         ctx->env.server_port = xstrdupn(getenv("SERVER_PORT"));
         ctx->page.mimetype = "text/html";
         ctx->page.charset = PAGE_ENCODING;
         ctx->page.filename = NULL;
         ctx->page.size = 0;
         ctx->page.modified = time(NULL);
         ctx->page.expires = ctx->page.modified;
         ctx->page.etag = NULL;
         memset(&ctx->cfg.mimetypes, 0, sizeof(struct string_list));
         if (ctx->env.script_name)
                 ctx->cfg.script_name = ctx->env.script_name;
         if (ctx->env.query_string)
                 ctx->qry.raw = ctx->env.query_string;
         if (!ctx->env.cgit_config)
                 ctx->env.cgit_config = CGIT_CONFIG;
 }
 
 struct refmatch {
         char *req_ref;
         char *first_ref;
         int match;
 };
 
diff --git a/cgit.h b/cgit.h
index 6c6c460..b7b0adb 100644
--- a/cgit.h
+++ b/cgit.h
@@ -114,115 +114,117 @@ struct refinfo {
         union {
                 struct taginfo *tag;
                 struct commitinfo *commit;
         };
 };
 
 struct reflist {
         struct refinfo **refs;
         int alloc;
         int count;
 };
 
 struct cgit_query {
         int has_symref;
         int has_sha1;
         char *raw;
         char *repo;
         char *page;
         char *search;
         char *grep;
         char *head;
         char *sha1;
         char *sha2;
         char *path;
         char *name;
         char *mimetype;
         char *url;
         char *period;
         int   ofs;
         int nohead;
         char *sort;
         int showmsg;
+        int ssdiff;
 };
 
 struct cgit_config {
         char *agefile;
         char *cache_root;
         char *clone_prefix;
         char *css;
         char *favicon;
         char *footer;
         char *head_include;
         char *header;
         char *index_header;
         char *index_info;
         char *logo;
         char *logo_link;
         char *module_link;
         char *robots;
         char *root_title;
         char *root_desc;
         char *root_readme;
         char *script_name;
         char *section;
         char *virtual_root;
         int cache_size;
         int cache_dynamic_ttl;
         int cache_max_create_time;
         int cache_repo_ttl;
         int cache_root_ttl;
         int cache_scanrc_ttl;
         int cache_static_ttl;
         int embedded;
         int enable_filter_overrides;
         int enable_index_links;
         int enable_log_filecount;
         int enable_log_linecount;
         int enable_tree_linenumbers;
         int local_time;
         int max_repo_count;
         int max_commit_count;
         int max_lock_attempts;
         int max_msg_len;
         int max_repodesc_len;
         int max_stats;
         int nocache;
         int noplainemail;
         int noheader;
         int renamelimit;
         int snapshots;
         int summary_branches;
         int summary_log;
         int summary_tags;
+        int ssdiff;
         struct string_list mimetypes;
         struct cgit_filter *about_filter;
         struct cgit_filter *commit_filter;
         struct cgit_filter *source_filter;
 };
 
 struct cgit_page {
         time_t modified;
         time_t expires;
         size_t size;
         char *mimetype;
         char *charset;
         char *filename;
         char *etag;
         char *title;
         int status;
         char *statusmsg;
 };
 
 struct cgit_environment {
         char *cgit_config;
         char *http_host;
         char *https;
         char *no_http;
         char *path_info;
         char *query_string;
         char *request_method;
         char *script_name;
         char *server_name;
         char *server_port;
 };
 
diff --git a/cgitrc.5.txt b/cgitrc.5.txt
index 4dc383d..252d546 100644
--- a/cgitrc.5.txt
+++ b/cgitrc.5.txt
@@ -209,64 +209,68 @@ renamelimit::
 
 repo.group::
         Legacy alias for "section". This option is deprecated and will not be
         supported in cgit-1.0.
 
 robots::
         Text used as content for the "robots" meta-tag. Default value:
         "index, nofollow".
 
 root-desc::
         Text printed below the heading on the repository index page. Default
         value: "a fast webinterface for the git dscm".
 
 root-readme::
         The content of the file specified with this option will be included
         verbatim below the "about" link on the repository index page. Default
         value: none.
 
 root-title::
         Text printed as heading on the repository index page. Default value:
         "Git Repository Browser".
 
 scan-path::
         A path which will be scanned for repositories. If caching is enabled,
         the result will be cached as a cgitrc include-file in the cache
         directory. Default value: none. See also: cache-scanrc-ttl.
 
 section::
         The name of the current repository section - all repositories defined
         after this option will inherit the current section name. Default value:
         none.
 
+side-by-side-diffs::
+        If set to "1" shows side-by-side diffs instead of unidiffs per
+        default. Default value: "0".
+
 snapshots::
         Text which specifies the default set of snapshot formats generated by
         cgit. The value is a space-separated list of zero or more of the
         values "tar", "tar.gz", "tar.bz2" and "zip". Default value: none.
 
 source-filter::
         Specifies a command which will be invoked to format plaintext blobs
         in the tree view. The command will get the blob content on its STDIN
         and the name of the blob as its only command line argument. The STDOUT
         from the command will be included verbatim as the blob contents, i.e.
         this can be used to implement e.g. syntax highlighting. Default value:
         none.
 
 summary-branches::
         Specifies the number of branches to display in the repository "summary"
         view. Default value: "10".
 
 summary-log::
         Specifies the number of log entries to display in the repository
         "summary" view. Default value: "10".
 
 summary-tags::
         Specifies the number of tags to display in the repository "summary"
         view. Default value: "10".
 
 virtual-root::
         Url which, if specified, will be used as root for all cgit links. It
         will also cause cgit to generate 'virtual urls', i.e. urls like
         '/cgit/tree/README' as opposed to '?r=cgit&p=tree&path=README'. Default
         value: none.
         NOTE: cgit has recently learned how to use PATH_INFO to achieve the
         same kind of virtual urls, so this option will probably be deprecated.
diff --git a/ui-commit.c b/ui-commit.c
index f5b0ae5..b5e3c01 100644
--- a/ui-commit.c
+++ b/ui-commit.c
@@ -29,88 +29,93 @@ void cgit_print_commit(char *hex)
                 return;
         }
         commit = lookup_commit_reference(sha1);
         if (!commit) {
                 cgit_print_error(fmt("Bad commit reference: %s", hex));
                 return;
         }
         info = cgit_parse_commit(commit);
 
         load_ref_decorations(DECORATE_FULL_REFS);
 
         html("<table summary='commit info' class='commit-info'>\n");
         html("<tr><th>author</th><td>");
         html_txt(info->author);
         if (!ctx.cfg.noplainemail) {
                 html(" ");
                 html_txt(info->author_email);
         }
         html("</td><td class='right'>");
         cgit_print_date(info->author_date, FMT_LONGDATE, ctx.cfg.local_time);
         html("</td></tr>\n");
         html("<tr><th>committer</th><td>");
         html_txt(info->committer);
         if (!ctx.cfg.noplainemail) {
                 html(" ");
                 html_txt(info->committer_email);
         }
         html("</td><td class='right'>");
         cgit_print_date(info->committer_date, FMT_LONGDATE, ctx.cfg.local_time);
         html("</td></tr>\n");
         html("<tr><th>commit</th><td colspan='2' class='sha1'>");
         tmp = sha1_to_hex(commit->object.sha1);
-        cgit_commit_link(tmp, NULL, NULL, ctx.qry.head, tmp);
+        cgit_commit_link(tmp, NULL, NULL, ctx.qry.head, tmp, 0);
         html(" (");
         cgit_patch_link("patch", NULL, NULL, NULL, tmp);
+        html(") (");
+        if ((ctx.qry.ssdiff && !ctx.cfg.ssdiff) || (!ctx.qry.ssdiff && ctx.cfg.ssdiff))
+                cgit_commit_link("unidiff", NULL, NULL, ctx.qry.head, tmp, 1);
+        else
+                cgit_commit_link("side-by-side diff", NULL, NULL, ctx.qry.head, tmp, 1);
         html(")</td></tr>\n");
         html("<tr><th>tree</th><td colspan='2' class='sha1'>");
         tmp = xstrdup(hex);
         cgit_tree_link(sha1_to_hex(commit->tree->object.sha1), NULL, NULL,
                        ctx.qry.head, tmp, NULL);
         html("</td></tr>\n");
               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'>");
                 cgit_commit_link(sha1_to_hex(p->item->object.sha1), NULL, NULL,
-                                 ctx.qry.head, sha1_to_hex(p->item->object.sha1));
+                                 ctx.qry.head, sha1_to_hex(p->item->object.sha1), 0);
                 html(" (");
                 cgit_diff_link("diff", NULL, NULL, ctx.qry.head, hex,
-                               sha1_to_hex(p->item->object.sha1), NULL);
+                               sha1_to_hex(p->item->object.sha1), NULL, 0);
                 html(")</td></tr>");
                 parents++;
         }
         if (ctx.repo->snapshots) {
                 html("<tr><th>download</th><td colspan='2' class='sha1'>");
                 cgit_print_snapshot_links(ctx.qry.repo, ctx.qry.head,
                                           hex, ctx.repo->snapshots);
                 html("</td></tr>");
         }
         html("</table>\n");
         html("<div class='commit-subject'>");
         if (ctx.repo->commit_filter)
                 cgit_open_filter(ctx.repo->commit_filter);
         html_txt(info->subject);
         if (ctx.repo->commit_filter)
                 cgit_close_filter(ctx.repo->commit_filter);
         show_commit_decorations(commit);
         html("</div>");
         html("<div class='commit-msg'>");
         if (ctx.repo->commit_filter)
                 cgit_open_filter(ctx.repo->commit_filter);
         html_txt(info->msg);
         if (ctx.repo->commit_filter)
                 cgit_close_filter(ctx.repo->commit_filter);
         html("</div>");
         if (parents < 3) {
                 if (parents)
                         tmp = sha1_to_hex(commit->parents->item->object.sha1);
                 else
                         tmp = NULL;
                 cgit_print_diff(ctx.qry.sha1, tmp, NULL);
         }
diff --git a/ui-diff.c b/ui-diff.c
index 0c6f8d7..42e81ac 100644
--- a/ui-diff.c
+++ b/ui-diff.c
@@ -56,65 +56,65 @@ static void print_fileinfo(struct fileinfo *info)
                 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)) {
                 cgit_print_filemode(info->old_mode);
         } else {
                 cgit_print_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'>[");
                 cgit_print_filemode(info->old_mode);
                 html("]</span>");
         }
         htmlf("</td><td class='%s'>", class);
         cgit_diff_link(info->new_path, NULL, NULL, ctx.qry.head, ctx.qry.sha1,
-                       ctx.qry.sha2, info->new_path);
+                       ctx.qry.sha2, info->new_path, 0);
         if (info->status == DIFF_STATUS_COPIED || info->status == DIFF_STATUS_RENAMED)
                 htmlf(" (%s from %s)",
                       info->status == DIFF_STATUS_COPIED ? "copied" : "renamed",
                       info->old_path);
         html("</td><td class='right'>");
         if (info->binary) {
                 htmlf("bin</td><td class='graph'>%d -> %d bytes",
                       info->old_size, info->new_size);
                 return;
         }
         htmlf("%d", info->added + info->removed);
         html("</td><td class='graph'>");
         htmlf("<table summary='file diffstat' width='%d%%'><tr>", (max_changes > 100 ? 100 : max_changes));
         htmlf("<td class='add' style='width: %.1f%%;'/>",
               info->added * 100.0 / max_changes);
         htmlf("<td class='rem' style='width: %.1f%%;'/>",
               info->removed * 100.0 / max_changes);
         htmlf("<td class='none' style='width: %.1f%%;'/>",
               (max_changes - info->removed - info->added) * 100.0 / max_changes);
         html("</tr></table></td></tr>\n");
 }
 
 static void count_diff_lines(char *line, int len)
 {
         if (line && (len > 0)) {
                 if (line[0] == '+')
                         lines_added++;
                 else if (line[0] == '-')
                         lines_removed++;
         }
 }
 
@@ -131,65 +131,65 @@ static void inspect_filepair(struct diff_filepair *pair)
         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;
         items[files-1].old_size = old_size;
         items[files-1].new_size = new_size;
         items[files-1].binary = binary;
         if (lines_added + lines_removed > max_changes)
                 max_changes = lines_added + lines_removed;
         total_adds += lines_added;
         total_rems += lines_removed;
 }
 
 void cgit_print_diffstat(const unsigned char *old_sha1,
                          const unsigned char *new_sha1)
 {
         int i;
 
         html("<div class='diffstat-header'>");
         cgit_diff_link("Diffstat", NULL, NULL, ctx.qry.head, ctx.qry.sha1,
-                       ctx.qry.sha2, NULL);
+                       ctx.qry.sha2, NULL, 0);
         html("</div>");
         html("<table summary='diffstat' class='diffstat'>");
         max_changes = 0;
         cgit_diff_tree(old_sha1, new_sha1, inspect_filepair, NULL);
         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",
               files, total_adds, total_rems);
         html("</div>");
 }
 
 
 /*
  * 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);
@@ -221,104 +221,122 @@ static void header(unsigned char *sha1, char *path1, int mode1,
         if (mode2 == 0)
                 htmlf("<br/>deleted file mode %.6o", mode1);
 
         if (!subproject) {
                 abbrev1 = xstrdup(find_unique_abbrev(sha1, DEFAULT_ABBREV));
                 abbrev2 = xstrdup(find_unique_abbrev(sha2, DEFAULT_ABBREV));
                 htmlf("<br/>index %s..%s", abbrev1, abbrev2);
                 free(abbrev1);
                 free(abbrev2);
                 if (mode1 != 0 && mode2 != 0) {
                         htmlf(" %.6o", mode1);
                         if (mode2 != mode1)
                                 htmlf("..%.6o", mode2);
                 }
                 html("<br/>--- a/");
                 if (mode1 != 0)
                         cgit_tree_link(path1, NULL, NULL, ctx.qry.head,
                                        sha1_to_hex(old_rev_sha1), path1);
                 else
                         html_txt(path1);
                 html("<br/>+++ b/");
                 if (mode2 != 0)
                         cgit_tree_link(path2, NULL, NULL, ctx.qry.head,
                                        sha1_to_hex(new_rev_sha1), path2);
                 else
                         html_txt(path2);
         }
         html("</div>");
         if (use_ssdiff)
                 cgit_ssdiff_header();
 }
 
+static void print_ssdiff_link()
+{
+        if (!strcmp(ctx.qry.page, "diff")) {
+                if (use_ssdiff)
+                        cgit_diff_link("Unidiff", NULL, NULL, ctx.qry.head,
+                                       ctx.qry.sha1, ctx.qry.sha2, NULL, 1);
+                else
+                        cgit_diff_link("Side-by-side diff", NULL, NULL,
+                                       ctx.qry.head, ctx.qry.sha1,
+                                       ctx.qry.sha2, NULL, 1);
+        }
+}
+
 static void filepair_cb(struct diff_filepair *pair)
 {
         unsigned long old_size = 0;
         unsigned long new_size = 0;
         int binary = 0;
         linediff_fn print_line_fn = print_line;
 
         header(pair->one->sha1, pair->one->path, pair->one->mode,
                pair->two->sha1, pair->two->path, pair->two->mode);
         if (use_ssdiff) {
                 cgit_ssdiff_header();
                 print_line_fn = cgit_ssdiff_line_cb;
         }
         if (S_ISGITLINK(pair->one->mode) || S_ISGITLINK(pair->two->mode)) {
                 if (S_ISGITLINK(pair->one->mode))
                         print_line(fmt("-Subproject %s", sha1_to_hex(pair->one->sha1)), 52);
                 if (S_ISGITLINK(pair->two->mode))
                         print_line(fmt("+Subproject %s", sha1_to_hex(pair->two->sha1)), 52);
                 return;
         }
         if (cgit_diff_files(pair->one->sha1, pair->two->sha1, &old_size,
                             &new_size, &binary, print_line_fn))
                 cgit_print_error("Error running diff");
         if (binary)
                 html("Binary files differ");
         if (use_ssdiff)
                 cgit_ssdiff_footer();
 }
 
 void cgit_print_diff(const char *new_rev, const char *old_rev, const char *prefix)
 {
         enum object_type type;
         unsigned long size;
         struct commit *commit, *commit2;
 
         if (!new_rev)
                 new_rev = ctx.qry.head;
         get_sha1(new_rev, new_rev_sha1);
         type = sha1_object_info(new_rev_sha1, &size);
         if (type == OBJ_BAD) {
                 cgit_print_error(fmt("Bad object name: %s", new_rev));
                 return;
         }
         commit = lookup_commit_reference(new_rev_sha1);
         if (!commit || parse_commit(commit))
                 cgit_print_error(fmt("Bad commit: %s", sha1_to_hex(new_rev_sha1)));
 
         if (old_rev)
                 get_sha1(old_rev, old_rev_sha1);
         else if (commit->parents && commit->parents->item)
                 hashcpy(old_rev_sha1, commit->parents->item->object.sha1);
         else
                 hashclr(old_rev_sha1);
 
         if (!is_null_sha1(old_rev_sha1)) {
                 type = sha1_object_info(old_rev_sha1, &size);
                 if (type == OBJ_BAD) {
                         cgit_print_error(fmt("Bad object name: %s", sha1_to_hex(old_rev_sha1)));
                         return;
                 }
                 commit2 = lookup_commit_reference(old_rev_sha1);
                 if (!commit2 || parse_commit(commit2))
                         cgit_print_error(fmt("Bad commit: %s", sha1_to_hex(old_rev_sha1)));
         }
+
+        if ((ctx.qry.ssdiff && !ctx.cfg.ssdiff) || (!ctx.qry.ssdiff && ctx.cfg.ssdiff))
+                use_ssdiff = 1;
+
+        print_ssdiff_link();
         cgit_print_diffstat(old_rev_sha1, new_rev_sha1);
 
         html("<table summary='diff' class='diff'>");
         html("<tr><td>");
         cgit_diff_tree(old_rev_sha1, new_rev_sha1, filepair_cb, prefix);
         html("</td></tr>");
         html("</table>");
 }
diff --git a/ui-log.c b/ui-log.c
index f3132c9..0947604 100644
--- a/ui-log.c
+++ b/ui-log.c
@@ -37,88 +37,88 @@ void inspect_files(struct diff_filepair *pair)
 }
 
 void show_commit_decorations(struct commit *commit)
 {
         struct name_decoration *deco;
         static char buf[1024];
 
         buf[sizeof(buf) - 1] = 0;
         deco = lookup_decoration(&name_decoration, &commit->object);
         while (deco) {
                 if (!prefixcmp(deco->name, "refs/heads/")) {
                         strncpy(buf, deco->name + 11, sizeof(buf) - 1);
                         cgit_log_link(buf, NULL, "branch-deco", buf, NULL, NULL,
                                 0, NULL, NULL, ctx.qry.showmsg);
                 }
                 else if (!prefixcmp(deco->name, "tag: refs/tags/")) {
                         strncpy(buf, deco->name + 15, sizeof(buf) - 1);
                         cgit_tag_link(buf, NULL, "tag-deco", ctx.qry.head, buf);
                 }
                 else if (!prefixcmp(deco->name, "refs/tags/")) {
                         strncpy(buf, deco->name + 10, sizeof(buf) - 1);
                         cgit_tag_link(buf, NULL, "tag-deco", ctx.qry.head, buf);
                 }
                 else if (!prefixcmp(deco->name, "refs/remotes/")) {
                         strncpy(buf, deco->name + 13, sizeof(buf) - 1);
                         cgit_log_link(buf, NULL, "remote-deco", NULL,
                                 sha1_to_hex(commit->object.sha1), NULL,
                                 0, NULL, NULL, ctx.qry.showmsg);
                 }
                 else {
                         strncpy(buf, deco->name, sizeof(buf) - 1);
                         cgit_commit_link(buf, NULL, "deco", ctx.qry.head,
-                                sha1_to_hex(commit->object.sha1));
+                                sha1_to_hex(commit->object.sha1), 0);
                 }
                 deco = deco->next;
         }
 }
 
 void print_commit(struct commit *commit)
 {
         struct commitinfo *info;
         char *tmp;
         int cols = 2;
 
         info = cgit_parse_commit(commit);
         htmlf("<tr%s><td>",
                 ctx.qry.showmsg ? " class='logheader'" : "");
         tmp = fmt("id=%s", sha1_to_hex(commit->object.sha1));
         tmp = cgit_pageurl(ctx.repo->url, "commit", tmp);
         html_link_open(tmp, NULL, NULL);
         cgit_print_age(commit->date, TM_WEEK * 2, FMT_SHORTDATE);
         html_link_close();
         htmlf("</td><td%s>",
                 ctx.qry.showmsg ? " class='logsubject'" : "");
         cgit_commit_link(info->subject, NULL, NULL, ctx.qry.head,
-                         sha1_to_hex(commit->object.sha1));
+                         sha1_to_hex(commit->object.sha1), 0);
         show_commit_decorations(commit);
         html("</td><td>");
         html_txt(info->author);
         if (ctx.repo->enable_log_filecount) {
                 files = 0;
                 add_lines = 0;
                 rem_lines = 0;
                 cgit_diff_commit(commit, inspect_files);
                 html("</td><td>");
                 htmlf("%d", files);
                 if (ctx.repo->enable_log_linecount) {
                         html("</td><td>");
                         htmlf("-%d/+%d", rem_lines, add_lines);
                 }
         }
         html("</td></tr>\n");
         if (ctx.qry.showmsg) {
                 if (ctx.repo->enable_log_filecount) {
                         cols++;
                         if (ctx.repo->enable_log_linecount)
                                 cols++;
                 }
                 htmlf("<tr class='nohover'><td/><td colspan='%d' class='logmsg'>",
                         cols);
                 html_txt(info->msg);
                 html("</td></tr>\n");
         }
         cgit_free_commitinfo(info);
 }
 
 static const char *disambiguate_ref(const char *ref)
 {
diff --git a/ui-refs.c b/ui-refs.c
index d3b4f6e..33d9bec 100644
--- a/ui-refs.c
+++ b/ui-refs.c
@@ -45,65 +45,65 @@ static int cmp_branch_age(const void *a, const void *b)
 static int cmp_tag_age(const void *a, const void *b)
 {
         struct refinfo *r1 = *(struct refinfo **)a;
         struct refinfo *r2 = *(struct refinfo **)b;
         int r1date, r2date;
 
         if (r1->object->type != OBJ_COMMIT)
                 r1date = r1->tag->tagger_date;
         else
                 r1date = r1->commit->committer_date;
 
         if (r2->object->type != OBJ_COMMIT)
                 r2date = r2->tag->tagger_date;
         else
                 r2date = r2->commit->committer_date;
 
         return cmp_age(r1date, r2date);
 }
 
 static int print_branch(struct refinfo *ref)
 {
         struct commitinfo *info = ref->commit;
         char *name = (char *)ref->refname;
 
         if (!info)
                 return 1;
         html("<tr><td>");
         cgit_log_link(name, NULL, NULL, name, NULL, NULL, 0, NULL, NULL,
                       ctx.qry.showmsg);
         html("</td><td>");
 
         if (ref->object->type == OBJ_COMMIT) {
-                cgit_commit_link(info->subject, NULL, NULL, name, NULL);
+                cgit_commit_link(info->subject, NULL, NULL, name, NULL, 0);
                 html("</td><td>");
                 html_txt(info->author);
                 html("</td><td colspan='2'>");
                 cgit_print_age(info->commit->date, -1, NULL);
         } else {
                 html("</td><td></td><td>");
                 cgit_object_link(ref->object);
         }
         html("</td></tr>\n");
         return 0;
 }
 
 static void print_tag_header()
 {
         html("<tr class='nohover'><th class='left'>Tag</th>"
              "<th class='left'>Download</th>"
              "<th class='left'>Author</th>"
              "<th class='left' colspan='2'>Age</th></tr>\n");
         header = 1;
 }
 
 static void print_tag_downloads(const struct cgit_repo *repo, const char *ref)
 {
         const struct cgit_snapshot_format* f;
             char *filename;
         const char *basename;
 
         if (!ref || strlen(ref) < 2)
                 return;
 
         basename = cgit_repobasename(repo->url);
         if (prefixcmp(ref, basename) != 0) {
diff --git a/ui-shared.c b/ui-shared.c
index 07d5dd4..de55eff 100644
--- a/ui-shared.c
+++ b/ui-shared.c
@@ -288,131 +288,153 @@ void cgit_log_link(char *name, char *title, char *class, char *head,
         delim = repolink(title, class, "log", head, path);
         if (rev && strcmp(rev, ctx.qry.head)) {
                 html(delim);
                 html("id=");
                 html_url_arg(rev);
                 delim = "&";
         }
         if (grep && pattern) {
                 html(delim);
                 html("qt=");
                 html_url_arg(grep);
                 delim = "&";
                 html(delim);
                 html("q=");
                 html_url_arg(pattern);
         }
         if (ofs > 0) {
                 html(delim);
                 html("ofs=");
                 htmlf("%d", ofs);
                 delim = "&";
         }
         if (showmsg) {
                 html(delim);
                 html("showmsg=1");
         }
         html("'>");
         html_txt(name);
         html("</a>");
 }
 
 void cgit_commit_link(char *name, char *title, char *class, char *head,
-                      char *rev)
+                      char *rev, int toggle_ssdiff)
 {
         if (strlen(name) > ctx.cfg.max_msg_len && ctx.cfg.max_msg_len >= 15) {
                 name[ctx.cfg.max_msg_len] = '\0';
                 name[ctx.cfg.max_msg_len - 1] = '.';
                 name[ctx.cfg.max_msg_len - 2] = '.';
                 name[ctx.cfg.max_msg_len - 3] = '.';
         }
-        reporevlink("commit", name, title, class, head, rev, NULL);
+
+        char *delim;
+
+        delim = repolink(title, class, "commit", head, NULL);
+        if (rev && strcmp(rev, ctx.qry.head)) {
+                html(delim);
+                html("id=");
+                html_url_arg(rev);
+                delim = "&amp;";
+        }
+        if ((ctx.qry.ssdiff && !toggle_ssdiff) || (!ctx.qry.ssdiff && toggle_ssdiff)) {
+                html(delim);
+                html("ss=1");
+        }
+        html("'>");
+        html_txt(name);
+        html("</a>");
 }
 
 void cgit_refs_link(char *name, char *title, char *class, char *head,
                     char *rev, char *path)
 {
         reporevlink("refs", name, title, class, head, rev, path);
 }
 
 void cgit_snapshot_link(char *name, char *title, char *class, char *head,
                         char *rev, char *archivename)
 {
         reporevlink("snapshot", name, title, class, head, rev, archivename);
 }
 
 void cgit_diff_link(char *name, char *title, char *class, char *head,
-                    char *new_rev, char *old_rev, char *path)
+                    char *new_rev, char *old_rev, char *path,
+                    int toggle_ssdiff)
 {
         char *delim;
 
         delim = repolink(title, class, "diff", head, path);
         if (new_rev && strcmp(new_rev, ctx.qry.head)) {
                 html(delim);
                 html("id=");
                 html_url_arg(new_rev);
                 delim = "&amp;";
         }
         if (old_rev) {
                 html(delim);
                 html("id2=");
                 html_url_arg(old_rev);
+                delim = "&amp;";
+        }
+        if ((ctx.qry.ssdiff && !toggle_ssdiff) || (!ctx.qry.ssdiff && toggle_ssdiff)) {
+                html(delim);
+                html("ss=1");
         }
         html("'>");
         html_txt(name);
         html("</a>");
 }
 
 void cgit_patch_link(char *name, char *title, char *class, char *head,
                      char *rev)
 {
         reporevlink("patch", name, title, class, head, rev, NULL);
 }
 
 void cgit_stats_link(char *name, char *title, char *class, char *head,
                      char *path)
 {
         reporevlink("stats", name, title, class, head, NULL, path);
 }
 
 void cgit_object_link(struct object *obj)
 {
         char *page, *shortrev, *fullrev, *name;
 
         fullrev = sha1_to_hex(obj->sha1);
         shortrev = xstrdup(fullrev);
         shortrev[10] = '\0';
         if (obj->type == OBJ_COMMIT) {
                 cgit_commit_link(fmt("commit %s...", shortrev), NULL, NULL,
-                                 ctx.qry.head, fullrev);
+                                 ctx.qry.head, fullrev, 0);
                 return;
         } else if (obj->type == OBJ_TREE)
                 page = "tree";
         else if (obj->type == OBJ_TAG)
                 page = "tag";
         else
                 page = "blob";
         name = fmt("%s %s...", typename(obj->type), shortrev);
         reporevlink(page, name, NULL, NULL, ctx.qry.head, fullrev, NULL);
 }
 
 void cgit_print_date(time_t secs, char *format, int local_time)
 {
         char buf[64];
         struct tm *time;
 
         if (!secs)
                 return;
         if(local_time)
                 time = localtime(&secs);
         else
                 time = gmtime(&secs);
         strftime(buf, sizeof(buf)-1, format, time);
         html_txt(buf);
 }
 
 void cgit_print_age(time_t t, time_t max_relative, char *format)
 {
         time_t now, secs;
 
         if (!t)
                 return;
@@ -666,67 +688,67 @@ static void print_header(struct cgit_context *ctx)
                 html_txt(ctx->repo->owner);
         } else {
                 if (ctx->cfg.root_desc)
                         html_txt(ctx->cfg.root_desc);
                 else if (ctx->cfg.index_info)
                         html_include(ctx->cfg.index_info);
         }
         html("</td></tr></table>\n");
 }
 
 void cgit_print_pageheader(struct cgit_context *ctx)
 {
         struct cgit_cmd *cmd = cgit_get_cmd(ctx);
 
         if (!cmd && ctx->repo)
                 fallback_cmd = "summary";
 
         html("<div id='cgit'>");
         if (!ctx->cfg.noheader)
                 print_header(ctx);
 
         html("<table class='tabs'><tr><td>\n");
         if (ctx->repo) {
                 cgit_summary_link("summary", NULL, hc(cmd, "summary"),
                                   ctx->qry.head);
                 cgit_refs_link("refs", NULL, hc(cmd, "refs"), ctx->qry.head,
                                ctx->qry.sha1, NULL);
                 cgit_log_link("log", NULL, hc(cmd, "log"), ctx->qry.head,
                               NULL, NULL, 0, NULL, NULL, ctx->qry.showmsg);
                 cgit_tree_link("tree", NULL, hc(cmd, "tree"), ctx->qry.head,
                                ctx->qry.sha1, NULL);
                 cgit_commit_link("commit", NULL, hc(cmd, "commit"),
-                                 ctx->qry.head, ctx->qry.sha1);
+                                 ctx->qry.head, ctx->qry.sha1, 0);
                 cgit_diff_link("diff", NULL, hc(cmd, "diff"), ctx->qry.head,
-                               ctx->qry.sha1, ctx->qry.sha2, NULL);
+                               ctx->qry.sha1, ctx->qry.sha2, NULL, 0);
                 if (ctx->repo->max_stats)
                         cgit_stats_link("stats", NULL, hc(cmd, "stats"),
                                         ctx->qry.head, NULL);
                 if (ctx->repo->readme)
                         reporevlink("about", "about", NULL,
                                     hc(cmd, "about"), ctx->qry.head, NULL,
                                     NULL);
                 html("</td><td class='form'>");
                 html("<form class='right' method='get' action='");
                 if (ctx->cfg.virtual_root)
                         html_url_path(cgit_fileurl(ctx->qry.repo, "log",
                                                    ctx->qry.path, NULL));
                 html("'>\n");
                 cgit_add_hidden_formfields(1, 0, "log");
                 html("<select name='qt'>\n");
                 html_option("grep", "log msg", ctx->qry.grep);
                 html_option("author", "author", ctx->qry.grep);
                 html_option("committer", "committer", ctx->qry.grep);
                 html("</select>\n");
                 html("<input class='txt' type='text' size='10' name='q' value='");
                 html_attr(ctx->qry.search);
                 html("'/>\n");
                 html("<input type='submit' value='search'/>\n");
                 html("</form>\n");
         } else {
                 site_link(NULL, "index", NULL, hc(cmd, "repolist"), NULL, 0);
                 if (ctx->cfg.root_readme)
                         site_link("about", "about", NULL, hc(cmd, "about"),
                                   NULL, 0);
                 html("</td><td class='form'>");
                 html("<form method='get' action='");
                 html_attr(cgit_rooturl());
diff --git a/ui-shared.h b/ui-shared.h
index bff4826..166246d 100644
--- a/ui-shared.h
+++ b/ui-shared.h
@@ -1,50 +1,51 @@
 #ifndef UI_SHARED_H
 #define UI_SHARED_H
 
 extern char *cgit_httpscheme();
 extern char *cgit_hosturl();
 extern char *cgit_repourl(const char *reponame);
 extern char *cgit_fileurl(const char *reponame, const char *pagename,
                           const char *filename, const char *query);
 extern char *cgit_pageurl(const char *reponame, const char *pagename,
                           const char *query);
 
 extern void cgit_index_link(char *name, char *title, char *class,
                             char *pattern, int ofs);
 extern void cgit_summary_link(char *name, char *title, char *class, char *head);
 extern void cgit_tag_link(char *name, char *title, char *class, char *head,
                           char *rev);
 extern void cgit_tree_link(char *name, char *title, char *class, char *head,
                            char *rev, char *path);
 extern void cgit_plain_link(char *name, char *title, char *class, char *head,
                             char *rev, char *path);
 extern void cgit_log_link(char *name, char *title, char *class, char *head,
                           char *rev, char *path, int ofs, char *grep,
                           char *pattern, int showmsg);
 extern void cgit_commit_link(char *name, char *title, char *class, char *head,
-                             char *rev);
+                             char *rev, int toggle_ssdiff);
 extern void cgit_patch_link(char *name, char *title, char *class, char *head,
                             char *rev);
 extern void cgit_refs_link(char *name, char *title, char *class, char *head,
                            char *rev, char *path);
 extern void cgit_snapshot_link(char *name, char *title, char *class,
                                char *head, char *rev, char *archivename);
 extern void cgit_diff_link(char *name, char *title, char *class, char *head,
-                           char *new_rev, char *old_rev, char *path);
+                           char *new_rev, char *old_rev, char *path,
+                           int toggle_ssdiff);
 extern void cgit_stats_link(char *name, char *title, char *class, char *head,
                             char *path);
 extern void cgit_object_link(struct object *obj);
 
 extern void cgit_print_error(char *msg);
 extern void cgit_print_date(time_t secs, char *format, int local_time);
 extern void cgit_print_age(time_t t, time_t max_relative, char *format);
 extern void cgit_print_http_headers(struct cgit_context *ctx);
 extern void cgit_print_docstart(struct cgit_context *ctx);
 extern void cgit_print_docend();
 extern void cgit_print_pageheader(struct cgit_context *ctx);
 extern void cgit_print_filemode(unsigned short mode);
 extern void cgit_print_snapshot_links(const char *repo, const char *head,
                                       const char *hex, int snapshots);
 extern void cgit_add_hidden_formfields(int incl_head, int incl_search,
                                        char *page);
 #endif /* UI_SHARED_H */