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.\" Copyright (C) 2001 Chad David <davidc@acns.ab.ca>. All rights reserved.
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.\" $FreeBSD$
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.Dd July 9, 2001
.Dt UCRED 9
.Os
.Sh NAME
.Nm ucred ,
.Nm crget ,
.Nm crhold ,
.Nm crfree ,
.Nm crcopy ,
.Nm crdup
.Nd "functions related to user credentials"
.Sh SYNOPSIS
.In sys/param.h
.In sys/ucred.h
.Ft "struct ucred *"
.Fn crget void
.Ft void
.Fn crhold "struct ucred *cr"
.Ft void
.Fn crfree "struct ucred *cr"
.Ft "struct ucred *"
.Fn crcopy "struct ucred *cr"
.Ft "struct ucred *"
.Fn crdup "struct ucred *cr"
.Sh DESCRIPTION
The
.Nm
family of functions is used to manage user credential structures
.Pq Vt "struct ucred"
within the kernel.
.Pp
The
.Fn crget
function allocates memory
for a new structure, sets its reference count to 1, and
initializes its lock.
.Pp
The
.Fn crhold
function increases the reference count on the credential.
.Pp
The
.Fn crfree
function decreases the reference count on the credential.
If the count drops to 0, the storage for the structure is freed.
.Pp
The
.Fn crcopy
function calls
.Fn crdup
to create a new structure, and copies the old credentials,
if the reference count is greater than 1;
otherwise, the original is returned.
.Pp
The
.Fn crdup
function allocates memory for a new structure,
copies the contents of the original structure
into it, references the
.Va cr_uidinfo
and
.Va cr_ruidinfo
fields, sets the reference count
to 1, and then returns the new structure.
.Sh RETURN VALUES
The functions that return values all return a pointer to a
.Vt ucred
structure.
In the case of
.Fn crcopy ,
the return value may be the same structure you passed to it.
.Sh SEE ALSO
.Xr uihold 9
.Sh AUTHORS
This man page was written by
.An Chad David Aq davidc@acns.ab.ca .