ui-shared.c: fix segfault when repo is empty

PATH_INFO="/$REPONAME/commit/?id=1" QUERY_STRING="id=1" ./cgit.cgi
triggers segfault when the repository is empty and therefore
ctx.qry.head is unset

Signed-off-by: Florian Pritz <bluewind@xssn.at>
Signed-off-by: Lars Hjemli <hjemli@gmail.com>

1 files changed, 2 insertions, 2 deletions

diff --git a/ui-shared.c b/ui-shared.c
index 4049a2b..8a7cc32 100644
--- a/ui-shared.c
+++ b/ui-shared.c
@@ -233,33 +233,33 @@ static char *repolink(char *title, char *class, char *page, char *head,
         }
         if (head && strcmp(head, ctx.repo->defbranch)) {
                 html(delim);
                 html("h=");
                 html_url_arg(head);
                 delim = "&";
         }
         return fmt("%s", delim);
 }
 
 static void reporevlink(char *page, char *name, char *title, char *class,
                         char *head, char *rev, char *path)
 {
         char *delim;
 
         delim = repolink(title, class, page, head, path);
-        if (rev && strcmp(rev, ctx.qry.head)) {
+        if (rev && ctx.qry.head != NULL && strcmp(rev, ctx.qry.head)) {
                 html(delim);
                 html("id=");
                 html_url_arg(rev);
         }
         html("'>");
         html_txt(name);
         html("</a>");
 }
 
 void cgit_summary_link(char *name, char *title, char *class, char *head)
 {
         reporevlink(NULL, name, title, class, head, NULL, NULL);
 }
 
 void cgit_tag_link(char *name, char *title, char *class, char *head,
                    char *rev)
@@ -333,33 +333,33 @@ void cgit_refs_link(char *name, char *title, char *class, char *head,
 {
         reporevlink("refs", name, title, class, head, rev, path);
 }
 
 void cgit_snapshot_link(char *name, char *title, char *class, char *head,
                         char *rev, char *archivename)
 {
         reporevlink("snapshot", name, title, class, head, rev, archivename);
 }
 
 void cgit_diff_link(char *name, char *title, char *class, char *head,
                     char *new_rev, char *old_rev, char *path)
 {
         char *delim;
 
         delim = repolink(title, class, "diff", head, path);
-        if (new_rev && strcmp(new_rev, ctx.qry.head)) {
+        if (new_rev && ctx.qry.head != NULL && strcmp(new_rev, ctx.qry.head)) {
                 html(delim);
                 html("id=");
                 html_url_arg(new_rev);
                 delim = "&amp;";
         }
         if (old_rev) {
                 html(delim);
                 html("id2=");
                 html_url_arg(old_rev);
         }
         html("'>");
         html_txt(name);
         html("</a>");
 }
 
 void cgit_patch_link(char *name, char *title, char *class, char *head,