[6764] in Athena Bugs
kernel: sys/vfs_vnode.c:vn_rename()
daemon@ATHENA.MIT.EDU (daemon@ATHENA.MIT.EDU)
Tue Jan 1 21:27:15 1991
To: bugs@ATHENA.MIT.EDU
Date: Tue, 01 Jan 91 21:27:03 EST
From: John Carr <jfc@ATHENA.MIT.EDU>
vn_rename() contains this code
error = lookuppn(&fpn, NO_FOLLOW, &fdvp, &fvp);
if (error)
goto out;
/*
* make sure there is an entry
*/
if (fvp == (struct vnode *)0) {
/*
* If parent vnode does not allow search, return
* access error.
*/
if (error = VOP_ACCESS(fdvp, VEXEC, u.u_cred) == 0)
error = ENOENT;
goto out;
}
There are 3 problems with this code.
1. If lookuppn() sets fvp to NULL, then it returns a non-zero
error status, so the test of fvp is redundant.
2. If fvp is 0, ENOENT would be the correct error return always;
there is no need for the VOP_ACCESS call.
3. The test
if (error = VOP_ACCESS(fdvp, VEXEC, u.u_cred) == 0)
is missing a set of parentheses. It parses
if (error = (VOP_ACCESS(fdvp, VEXEC, u.u_cred) == 0))
but what is meant is
if ((error = VOP_ACCESS(fdvp, VEXEC, u.u_cred)) == 0)
I think the entire block of code beginning
if (fvp == (struct vnode *)0) {
should be deleted. probe thinks the VOP_ACCESS call should be deleted
and ENOENT always returned (this is what 4.3 tahoe does). Maybe we
should ask Berkeley if the test for fvp == 0 is really needed.
