ssdiff: point line links at exact blob by prepending "id="

Previously, the id_str (i.e. the current or diffed-against commit's
SHA1 ID) was simply concatenated to the URL. Now, prepend an "id="
string so that the links actually point to the right blobs and thus
the exact lines.

Signed-off-by: Julius Plenz <plenz@cis.fu-berlin.de>
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>

ui-ssdiff.c

@@ -230,7 +230,7 @@ static void print_ssdiff_line(char *class,
 	if (old_line_no > 0) {
 		struct diff_filespec *old_file = cgit_get_current_old_file();
 		char *lineno_str = fmt("n%d", old_line_no);
-		char *id_str = fmt("%s#%s", is_null_sha1(old_file->sha1)?"HEAD":sha1_to_hex(old_rev_sha1), lineno_str);
+		char *id_str = fmt("id=%s#%s", is_null_sha1(old_file->sha1)?"HEAD":sha1_to_hex(old_rev_sha1), lineno_str);
 		html("<td class='lineno'><a class='no' href='");
 		html(cgit_fileurl(ctx.repo->url, "tree", old_file->path, id_str));
 		htmlf("' id='%s' name='%s'>%s</a>", lineno_str, lineno_str, lineno_str + 1);
@@ -251,7 +251,7 @@ static void print_ssdiff_line(char *class,
 	if (new_line_no > 0) {
 		struct diff_filespec *new_file = cgit_get_current_new_file();
 		char *lineno_str = fmt("n%d", new_line_no);
-		char *id_str = fmt("%s#%s", is_null_sha1(new_file->sha1)?"HEAD":sha1_to_hex(new_rev_sha1), lineno_str);
+		char *id_str = fmt("id=%s#%s", is_null_sha1(new_file->sha1)?"HEAD":sha1_to_hex(new_rev_sha1), lineno_str);
 		html("<td class='lineno'><a class='no' href='");
 		html(cgit_fileurl(ctx.repo->url, "tree", new_file->path, id_str));
 		htmlf("' id='%s' name='%s'>%s</a>", lineno_str, lineno_str, lineno_str + 1);