ui-snapshot: avoid segfault when no filename is specified

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

1 files changed, 17 insertions, 6 deletions

diff --git a/ui-snapshot.c b/ui-snapshot.c
index f25613e..5372f5d 100644
--- a/ui-snapshot.c
+++ b/ui-snapshot.c
@@ -111,84 +111,95 @@ static int make_snapshot(const struct cgit_snapshot_format *format,
 	ctx.page.filename = xstrdup(filename);
 	cgit_print_http_headers(&ctx);
 	format->write_func(&args);
 	return 0;
 }
 
 /* Try to guess the requested revision from the requested snapshot name.
  * First the format extension is stripped, e.g. "cgit-0.7.2.tar.gz" become
  * "cgit-0.7.2". If this is a valid commit object name we've got a winner.
  * Otherwise, if the snapshot name has a prefix matching the result from
  * repo_basename(), we strip the basename and any following '-' and '_'
  * characters ("cgit-0.7.2" -> "0.7.2") and check the resulting name once
  * more. If this still isn't a valid commit object name, we check if pre-
  * pending a 'v' to the remaining snapshot name ("0.7.2" -> "v0.7.2") gives
  * us something valid.
  */
 static const char *get_ref_from_filename(const char *url, const char *filename,
 					 const struct cgit_snapshot_format *format)
 {
 	const char *reponame;
 	unsigned char sha1[20];
 	char *snapshot;
 
 	snapshot = xstrdup(filename);
 	snapshot[strlen(snapshot) - strlen(format->suffix)] = '\0';
 	fprintf(stderr, "snapshot=%s\n", snapshot);
 
 	if (get_sha1(snapshot, sha1) == 0)
 		return snapshot;
 
 	reponame = cgit_repobasename(url);
 	fprintf(stderr, "reponame=%s\n", reponame);
 	if (prefixcmp(snapshot, reponame) == 0) {
 		snapshot += strlen(reponame);
 		while (snapshot && (*snapshot == '-' || *snapshot == '_'))
 			snapshot++;
 	}
 
 	if (get_sha1(snapshot, sha1) == 0)
 		return snapshot;
 
 	snapshot = fmt("v%s", snapshot);
 	if (get_sha1(snapshot, sha1) == 0)
 		return snapshot;
 
 	return NULL;
 }
 
+void show_error(char *msg)
+{
+	ctx.page.mimetype = "text/html";
+	cgit_print_http_headers(&ctx);
+	cgit_print_docstart(&ctx);
+	cgit_print_pageheader(&ctx);
+	cgit_print_error(msg);
+	cgit_print_docend();
+}
+
 void cgit_print_snapshot(const char *head, const char *hex,
 			 const char *filename, int snapshots, int dwim)
 {
 	const struct cgit_snapshot_format* f;
 	char *prefix = NULL;
 
+	if (!filename) {
+		show_error("No snapshot name specified");
+		return;
+	}
+
 	f = get_format(filename);
 	if (!f) {
-		ctx.page.mimetype = "text/html";
-		cgit_print_http_headers(&ctx);
-		cgit_print_docstart(&ctx);
-		cgit_print_pageheader(&ctx);
-		cgit_print_error(fmt("Unsupported snapshot format: %s", filename));
-		cgit_print_docend();
+		show_error(xstrdup(fmt("Unsupported snapshot format: %s",
+				       filename)));
 		return;
 	}
 
 	if (!hex && dwim) {
 		hex = get_ref_from_filename(ctx.repo->url, filename, f);
 		if (hex == NULL) {
 			html_status(404, "Not found", 0);
 			return;
 		}
 		prefix = xstrdup(filename);
 		prefix[strlen(filename) - strlen(f->suffix)] = '\0';
 	}
 
 	if (!hex)
 		hex = head;
 
 	if (!prefix)
 		prefix = xstrdup(cgit_repobasename(ctx.repo->url));
 
 	make_snapshot(f, hex, prefix, filename);
 	free(prefix);
 }