ui-tag.c: do not segfault when id is missing from query-string

The purpose of the tag page is to print info about a specific tag,
but if no tag was specified on the query-string cgit used to segfault.

With this patch, cgit will fallback to the value of the 'h' parameter
instead (which is never NULL due to prepare_repo_cmd() in cgit.c).

It will now also verify that the specified tagname is in fact a valid
ref in the 'refs/tags/' namespace, i.e. specifying 'id=master' will
trigger a 'Bad tag reference' error.

Noticed-by: Eric Wong <normalperson@yhbt.net>
Signed-off-by: Lars Hjemli <hjemli@gmail.com>

1 files changed, 4 insertions, 1 deletions

diff --git a/ui-tag.c b/ui-tag.c
index 0e056e0..8c263ab 100644
--- a/ui-tag.c
+++ b/ui-tag.c
@@ -1,89 +1,92 @@
 /* ui-tag.c: display a tag
  *
  * Copyright (C) 2007 Lars Hjemli
  *
  * Licensed under GNU General Public License v2
  *   (see COPYING for full license text)
  */
 
 #include "cgit.h"
 #include "html.h"
 #include "ui-shared.h"
 
 static void print_tag_content(char *buf)
 {
         char *p;
 
         if (!buf)
                 return;
 
         html("<div class='commit-subject'>");
         p = strchr(buf, '\n');
         if (p)
                 *p = '\0';
         html_txt(buf);
         html("</div>");
         if (p) {
                 html("<div class='commit-msg'>");
                 html_txt(++p);
                 html("</div>");
         }
 }
 
 void cgit_print_tag(char *revname)
 {
         unsigned char sha1[20];
         struct object *obj;
         struct tag *tag;
         struct taginfo *info;
 
-        if (get_sha1(revname, sha1)) {
+        if (!revname)
+                revname = ctx.qry.head;
+
+        if (get_sha1(fmt("refs/tags/%s", revname), sha1)) {
                 cgit_print_error(fmt("Bad tag reference: %s", revname));
                 return;
         }
         obj = parse_object(sha1);
         if (!obj) {
                 cgit_print_error(fmt("Bad object id: %s", sha1_to_hex(sha1)));
                 return;
         }
         if (obj->type == OBJ_TAG) {
                 tag = lookup_tag(sha1);
                 if (!tag || parse_tag(tag) || !(info = cgit_parse_tag(tag))) {
                         cgit_print_error(fmt("Bad tag object: %s", revname));
                         return;
                 }
                 html("<table class='commit-info'>\n");
                 htmlf("<tr><td>Tag name</td><td>");
                 html_txt(revname);
                 htmlf(" (%s)</td></tr>\n", sha1_to_hex(sha1));
                 if (info->tagger_date > 0) {
                         html("<tr><td>Tag date</td><td>");
                         cgit_print_date(info->tagger_date, FMT_LONGDATE, ctx.cfg.local_time);
                         html("</td></tr>\n");
                 }
                 if (info->tagger) {
                         html("<tr><td>Tagged by</td><td>");
                         html_txt(info->tagger);
                         if (info->tagger_email) {
                                 html(" ");
                                 html_txt(info->tagger_email);
                         }
                         html("</td></tr>\n");
                 }
                 html("<tr><td>Tagged object</td><td>");
                 cgit_object_link(tag->tagged);
                 html("</td></tr>\n");
                 html("</table>\n");
                 print_tag_content(info->msg);
         } else {
                 html("<table class='commit-info'>\n");
                 htmlf("<tr><td>Tag name</td><td>");
                 html_txt(revname);
                 html("</td></tr>\n");
                 html("<tr><td>Tagged object</td><td>");
                 cgit_object_link(obj);
                 html("</td></tr>\n");
                 html("</table>\n");
         }
         return;
 }