Keep an overlong path out of the tab title

`fmt()` aborts the request rather than truncate, so a very long path
fed into a context-sensitive tab title took down page rendering.

1 file changed, 15 insertions, 4 deletions

diff --git a/source/ui-shared.c b/source/ui-shared.c
index 4084748..7cb8607 100644
--- a/source/ui-shared.c
+++ b/source/ui-shared.c
@@ -993,6 +993,17 @@ static const char *hc(const char *page)
 	return strcmp(ctx.qry.page, page) ? NULL : "active";
 }
 
+/* Build a context-sensitive tab title such as "Commit history of <path>".
+ * fmt() aborts the request rather than truncate, so fall back to the plain
+ * label when the path is long enough to risk overflowing its buffer. */
+static const char *tab_title(const char *format, const char *generic,
+			     const char *vpath)
+{
+	if (!vpath || !*vpath || strlen(vpath) > 256)
+		return generic;
+	return fmt(format, vpath);
+}
+
 static void cgit_print_path_crumbs(char *path)
 {
 	char *old_path = ctx.qry.path;
@@ -1114,19 +1125,19 @@ void cgit_print_pageheader(void)
 			       ctx.qry.oid, NULL);
 		html("</li>\n<li>");
 		cgit_log_link("log",
-			      vp && *vp ? fmt("Commit history of %s", vp) : "Commit history",
+			      tab_title("Commit history of %s", "Commit history", vp),
 			      hc("log"), ctx.qry.head,
 			      NULL, ctx.qry.vpath, 0, NULL, NULL,
 			      ctx.qry.showmsg, ctx.qry.follow);
 		html("</li>\n<li>");
 		if (ctx.qry.page && !strcmp(ctx.qry.page, "blame"))
 			cgit_blame_link("blame",
-					vp && *vp ? fmt("Line-by-line blame of %s", vp) : "Blame",
+					tab_title("Line-by-line blame of %s", "Blame", vp),
 					hc("blame"), ctx.qry.head,
 				        ctx.qry.oid, ctx.qry.vpath);
 		else
 			cgit_tree_link("tree",
-				       vp && *vp ? fmt("Browse the tree at %s", vp) : "Browse the file tree",
+				       tab_title("Browse the tree at %s", "Browse the file tree", vp),
 				       hc("tree"), ctx.qry.head,
 				       ctx.qry.oid, ctx.qry.vpath);
 		html("</li>\n<li>");
@@ -1134,7 +1145,7 @@ void cgit_print_pageheader(void)
 				 ctx.qry.head, ctx.qry.oid, ctx.qry.vpath);
 		html("</li>\n<li>");
 		cgit_diff_link("diff",
-			       vp && *vp ? fmt("Changes to %s", vp) : "Changes in the current commit",
+			       tab_title("Changes to %s", "Changes in the current commit", vp),
 			       hc("diff"), ctx.qry.head,
 			       ctx.qry.oid, ctx.qry.oid2, ctx.qry.vpath);
 		html("</li>\n");