Switch to using a struct xucred instead of a struct xucred when not

actually in the kernel.  This structure is a different size than
what is currently in -CURRENT, but should hopefully be the last time
any application breakage is caused there.  As soon as any major
inconveniences are removed, the definition of the in-kernel struct
ucred should be conditionalized upon defined(_KERNEL).

This also changes struct export_args to remove dependency on the
constantly-changing struct ucred, as well as limiting the bounds
of the size fields to the correct size.  This means: a) mountd and
friends won't break all the time, b) mountd and friends won't crash
the kernel all the time if they don't know what they're doing wrt
actual struct export_args layout.

Reviewed by:	bde

1 files changed, 13 insertions, 0 deletions

diff --git a/sys/sys/ucred.h b/sys/sys/ucred.h
index 5fb8d6d..63adce8 100644
--- a/sys/sys/ucred.h
+++ b/sys/sys/ucred.h
@@ -57,6 +57,19 @@ struct ucred {
 #define NOCRED ((struct ucred *)0)	/* no credential available */
 #define FSCRED ((struct ucred *)-1)	/* filesystem credential */
 
+/*
+ * This is the external representation of struct ucred, based upon the
+ * size of a 4.2-RELEASE struct ucred.  There will probably never be
+ * any need to change the size of this or layout of its used fields.
+ */
+struct xucred {
+	u_short	_cr_unused0;		/* compatibility with old ucred */
+	uid_t	cr_uid;			/* effective user id */
+	short	cr_ngroups;		/* number of groups */
+	gid_t	cr_groups[NGROUPS];	/* groups */
+	void	*_cr_unused1;		/* compatibility with old ucred */
+};
+
 #ifdef _KERNEL
 
 struct proc;