13 files changed, 586 insertions, 25 deletions

diff --git a/Makefile b/Makefile
index 4e101d3..f8a4d47 100644
--- a/Makefile
+++ b/Makefile
@@ -93,6 +93,7 @@ OBJECTS += ui-refs.o
 OBJECTS += ui-repolist.o
 OBJECTS += ui-shared.o
 OBJECTS += ui-snapshot.o
+OBJECTS += ui-ssdiff.o
 OBJECTS += ui-stats.o
 OBJECTS += ui-summary.o
 OBJECTS += ui-tag.o
diff --git a/cgit.c b/cgit.c
index 08cb5d2..4f68a4b 100644
--- a/cgit.c
+++ b/cgit.c
@@ -184,6 +184,8 @@ void config_cb(const char *name, const char *value)
                 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"))
@@ -242,6 +244,8 @@ static void querystring_cb(const char *name, const char *value)
                 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);
         }
 }
 
@@ -284,6 +288,7 @@ static void prepare_context(struct cgit_context *ctx)
         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"));
diff --git a/cgit.css b/cgit.css
index ef7d3c1..0cb894a 100644
--- a/cgit.css
+++ b/cgit.css
@@ -606,3 +606,102 @@ table.hgraph div.bar {
         background-color: #eee;
         height: 1em;
 }
+
+table.ssdiff {
+        width: 100%;
+}
+
+table.ssdiff td {
+        font-size: 75%;
+        font-family: monospace;
+        white-space: pre;
+        padding: 1px 4px 1px 4px;
+        border-left: solid 1px #aaa;
+        border-right: solid 1px #aaa;
+}
+
+table.ssdiff td.add {
+        color: black;
+        background: #cfc;
+        min-width: 50%;
+}
+
+table.ssdiff td.add_dark {
+        color: black;
+        background: #aca;
+        min-width: 50%;
+}
+
+table.ssdiff span.add {
+        background: #cfc;
+        font-weight: bold;
+}
+
+table.ssdiff td.del {
+        color: black;
+        background: #fcc;
+        min-width: 50%;
+}
+
+table.ssdiff td.del_dark {
+        color: black;
+        background: #caa;
+        min-width: 50%;
+}
+
+table.ssdiff span.del {
+        background: #fcc;
+        font-weight: bold;
+}
+
+table.ssdiff td.changed {
+        color: black;
+        background: #ffc;
+        min-width: 50%;
+}
+
+table.ssdiff td.changed_dark {
+        color: black;
+        background: #cca;
+        min-width: 50%;
+}
+
+table.ssdiff td.lineno {
+        color: black;
+        background: #eee;
+        text-align: right;
+        width: 3em;
+        min-width: 3em;
+}
+
+table.ssdiff td.hunk {
+        color: #black;
+        background: #ccf;
+        border-top: solid 1px #aaa;
+        border-bottom: solid 1px #aaa;
+}
+
+table.ssdiff td.head {
+        border-top: solid 1px #aaa;
+        border-bottom: solid 1px #aaa;
+}
+
+table.ssdiff td.head div.head {
+        font-weight: bold;
+        color: black;
+}
+
+table.ssdiff td.foot {
+        border-top: solid 1px #aaa;
+        border-left: none;
+        border-right: none;
+        border-bottom: none;
+}
+
+table.ssdiff td.space {
+        border: none;
+}
+
+table.ssdiff td.space div {
+        min-height: 3em;
+}
\ No newline at end of file
diff --git a/cgit.h b/cgit.h
index 39853df..5941ec0 100644
--- a/cgit.h
+++ b/cgit.h
@@ -143,6 +143,7 @@ struct cgit_query {
         int nohead;
         char *sort;
         int showmsg;
+        int ssdiff;
 };
 
 struct cgit_config {
@@ -195,6 +196,7 @@ struct cgit_config {
         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;
diff --git a/cgitrc.5.txt b/cgitrc.5.txt
index e69140b..70e4c78 100644
--- a/cgitrc.5.txt
+++ b/cgitrc.5.txt
@@ -245,6 +245,10 @@ section::
         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
diff --git a/ui-commit.c b/ui-commit.c
index f5b0ae5..b5e3c01 100644
--- a/ui-commit.c
+++ b/ui-commit.c
@@ -58,9 +58,14 @@ void cgit_print_commit(char *hex)
         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);
@@ -78,10 +83,10 @@ void cgit_print_commit(char *hex)
                 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++;
         }
diff --git a/ui-diff.c b/ui-diff.c
index 2196745..a92a768 100644
--- a/ui-diff.c
+++ b/ui-diff.c
@@ -9,6 +9,7 @@
 #include "cgit.h"
 #include "html.h"
 #include "ui-shared.h"
+#include "ui-ssdiff.h"
 
 unsigned char old_rev_sha1[20];
 unsigned char new_rev_sha1[20];
@@ -32,6 +33,7 @@ static struct fileinfo {
         int binary:1;
 } *items;
 
+static int use_ssdiff = 0;
 
 static void print_fileinfo(struct fileinfo *info)
 {
@@ -83,7 +85,7 @@ static void print_fileinfo(struct fileinfo *info)
         }
         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",
@@ -158,7 +160,7 @@ void cgit_print_diffstat(const unsigned char *old_sha1,
 
         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;
@@ -246,26 +248,54 @@ static void header(unsigned char *sha1, char *path1, int mode1,
         html("</div>");
 }
 
+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, ctx.qry.path, 1);
+                else
+                        cgit_diff_link("Side-by-side diff", NULL, NULL,
+                                       ctx.qry.head, ctx.qry.sha1,
+                                       ctx.qry.sha2, ctx.qry.path, 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;
 
+        if (use_ssdiff) {
+                cgit_ssdiff_header_begin();
+                print_line_fn = cgit_ssdiff_line_cb;
+        }
         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_end();
         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);
+                        print_line_fn(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);
+                        print_line_fn(fmt("+Subproject %s", sha1_to_hex(pair->two->sha1)), 52);
+                if (use_ssdiff)
+                        cgit_ssdiff_footer();
                 return;
         }
-        if (cgit_diff_files(pair->one->sha1, pair->two->sha1, &old_size, 
-                            &new_size, &binary, print_line))
+        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)
+        if (binary) {