1 files changed, 17 insertions, 6 deletions

diff --git a/contrib/cvs/src/diff.c b/contrib/cvs/src/diff.c
index 66d155eba5c3..ff1c4ed504d6 100644
--- a/contrib/cvs/src/diff.c
+++ b/contrib/cvs/src/diff.c
@@ -434,16 +434,23 @@ diff_fileproc (callerdat, finfo)
 		exists = 0;
 		/* special handling for TAG_HEAD */
 		if (diff_rev1 && strcmp (diff_rev1, TAG_HEAD) == 0)
-		    exists = (vers->vn_rcs != NULL &&	/* XXX ? */
-			    !RCS_isdead (vers->srcfile, vers->vn_rcs)); /*XXX*/
+		{
+		    char *head =
+			(vers->vn_rcs == NULL
+			 ? NULL
+			 : RCS_branch_head (vers->srcfile, vers->vn_rcs));
+		    exists = head != NULL;
+		    if (head != NULL)
+			free (head);
+		}
 		else
 		{
 		    Vers_TS *xvers;
 
 		    xvers = Version_TS (finfo, NULL, diff_rev1, diff_date1,
 					1, 0);
-		    exists = (vers->vn_rcs != NULL &&
-			    !RCS_isdead (vers->srcfile, vers->vn_rcs)); /*XXX*/
+		    exists = (xvers->vn_rcs != NULL &&
+			!RCS_isdead (xvers->srcfile, xvers->vn_rcs)); /*XXX*/
 		    freevers_ts (&xvers);
 		}
 		if (exists)
@@ -816,7 +823,9 @@ diff_file_nodiff (finfo, vers, empty_file)
     {
 	/* special handling for TAG_HEAD */
 	if (diff_rev1 && strcmp (diff_rev1, TAG_HEAD) == 0)
-	    use_rev1 = xstrdup (vers->vn_rcs);
+	    use_rev1 = ((vers->vn_rcs == NULL || vers->srcfile == NULL)
+			? NULL
+			: RCS_branch_head (vers->srcfile, vers->vn_rcs));
 	else
 	{
 	    xvers = Version_TS (finfo, NULL, diff_rev1, diff_date1, 1, 0);
@@ -829,7 +838,9 @@ diff_file_nodiff (finfo, vers, empty_file)
     {
 	/* special handling for TAG_HEAD */
 	if (diff_rev2 && strcmp (diff_rev2, TAG_HEAD) == 0)
-	    use_rev2 = xstrdup (vers->vn_rcs);
+	    use_rev2 = ((vers->vn_rcs == NULL || vers->srcfile == NULL)
+			? NULL
+			: RCS_branch_head (vers->srcfile, vers->vn_rcs));
 	else
 	{
 	    xvers = Version_TS (finfo, NULL, diff_rev2, diff_date2, 1, 0);