logo: include svg variant for both favicon and logov1.3.1+11

The reasoning behind using svg as primary defaults is simple – at
close-up it is much neater, plus svg favicon is supported since 2015 in
Firefox, 2020 in Chromium, 2025 in Safari. For old browsers ico is still
kept as a fallback.

The svg was auto-generated using a Python script and then simplified to
a path, but kept close to an original.

1 files changed, 74 insertions, 5 deletions

diff --git a/ui-shared.c b/ui-shared.c
index 97d1839..686fde0 100644
--- a/ui-shared.c
+++ b/ui-shared.c
@@ -7,6 +7,8 @@
  *   Implement ci link tab
  *   Check repo existence
  *   Replace memrchr() for macOS compatibility
+ *   Allow multiple favicons of different mime types to be used
+ *   Include favicon.svg as default
  *
  * Licensed under GNU General Public License v2
  *   (see COPYING for full license text)
@@ -774,6 +776,51 @@ void cgit_redirect(const char *url, bool permanent)
 	html("\n\n");
 }
 
+static const struct {
+	const char *ext;
+	const char *mimetype;
+} favicon_mimetypes[] = {
+	{ "ico",  "image/x-icon" },
+	{ "png",  "image/png" },
+	{ "svg",  "image/svg+xml" },
+	{ "gif",  "image/gif" },
+	{ "jpg",  "image/jpeg" },
+	{ "jpeg", "image/jpeg" },
+	{ "webp", "image/webp" },
+	{ "avif", "image/avif" },
+};
+
+/* Deduce the mimetype of a favicon from the extension of its url, ignoring
+ * any query string or fragment. Returns NULL for unknown extensions.
+ */
+static const char *favicon_mimetype(const char *url)
+{
+	const char *p, *end, *ext = NULL;
+	size_t len;
+	int i;
+
+	end = strpbrk(url, "?#");
+	if (!end)
+		end = url + strlen(url);
+
+	for (p = url; p < end; p++) {
+		if (*p == '/')
+			ext = NULL;
+		else if (*p == '.')
+			ext = p + 1;
+	}
+	if (!ext)
+		return NULL;
+	len = end - ext;
+
+	for (i = 0; i < ARRAY_SIZE(favicon_mimetypes); i++) {
+		if (strlen(favicon_mimetypes[i].ext) == len &&
+		    !strncasecmp(favicon_mimetypes[i].ext, ext, len))
+			return favicon_mimetypes[i].mimetype;
+	}
+	return NULL;
+}
+
 static void print_rel_vcs_link(const char *url)
 {
 	html("<link rel='vcs-git' href='");
@@ -815,6 +862,27 @@ static int emit_js_link(struct string_list_item *s, void *arg)
 	return 0;
 }
 
+static int emit_favicon_link(struct string_list_item *s, void *arg)
+{
+	const char *url = s ? s->string : (const char *)arg;
+	const char *mimetype;
+
+	/* Do not emit anything if favicon= is specified. */
+	if (!*url)
+		return 0;
+
+	html("<link rel='shortcut icon' href='");
+	html_attr(url);
+	mimetype = favicon_mimetype(url);
+	if (mimetype) {
+		html("' type='");
+		html_attr(mimetype);
+	}
+	html("'/>\n");
+
+	return 0;
+}
+
 void cgit_print_docstart(void)
 {
 	char *host = cgit_hosturl();
@@ -845,11 +913,12 @@ void cgit_print_docstart(void)
 	else
 		emit_js_link(NULL, "/cgit.js");
 
-	if (ctx.cfg.favicon && *ctx.cfg.favicon) {
-		html("<link rel='shortcut icon' href='");
-		html_attr(ctx.cfg.favicon);
-		html("'/>\n");
-	}
+	if (ctx.cfg.favicon.items)
+		for_each_string_list(&ctx.cfg.favicon, emit_favicon_link, NULL);
+	else
+	    emit_favicon_link(NULL, "/favicon.svg");
+		emit_favicon_link(NULL, "/favicon.ico");
+
 	if (host && ctx.repo && ctx.qry.head) {
 		char *fileurl;
 		struct strbuf sb = STRBUF_INIT;