Add prefix parameter to cgit_print_diff()

This allows a diff to be restricted to the path prefix specified in the url.

Signed-off-by: Lars Hjemli <hjemli@gmail.com>

cgit.c

@@ -107,7 +107,7 @@ static void cgit_print_repo_page(struct cacheitem *item)
 		cgit_print_tag(cgit_query_sha1);
 		break;
 	case CMD_DIFF:
-		cgit_print_diff(cgit_query_sha1, cgit_query_sha2);
+		cgit_print_diff(cgit_query_sha1, cgit_query_sha2, cgit_query_path);
 		break;
 	default:
 		cgit_print_error("Invalid request");

cgit.h

@@ -238,7 +238,7 @@ extern void cgit_print_blob(struct cacheitem *item, const char *hex, char *path)
 extern void cgit_print_tree(const char *rev, char *path);
 extern void cgit_print_commit(char *hex);
 extern void cgit_print_tag(char *revname);
-extern void cgit_print_diff(const char *new_hex, const char *old_hex);
+extern void cgit_print_diff(const char *new_hex, const char *old_hex, const char *prefix);
 extern void cgit_print_snapshot(struct cacheitem *item, const char *head,
 				const char *hex, const char *prefix,
 				const char *filename, int snapshot);

ui-diff.c

@@ -89,7 +89,7 @@ static void filepair_cb(struct diff_filepair *pair)
 		cgit_print_error("Error running diff");
 }
 
-void cgit_print_diff(const char *new_rev, const char *old_rev)
+void cgit_print_diff(const char *new_rev, const char *old_rev, const char *prefix)
 {
 	unsigned char sha1[20], sha2[20];
 	enum object_type type;
@@ -133,7 +133,7 @@ void cgit_print_diff(const char *new_rev, const char *old_rev)
 	}
 	html("<table class='diff'>");
 	html("<tr><td>");
-	cgit_diff_tree(sha2, sha1, filepair_cb, NULL);
+	cgit_diff_tree(sha2, sha1, filepair_cb, prefix);
 	html("</td></tr>");
 	html("</table>");
 }