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.Dd $Mdocdate: September 13 2018 $
.Dt USER_FROM_UID 3
.Os
.Sh NAME
.Nm user_from_uid ,
.Nm uid_from_user ,
.Nm group_from_gid ,
.Nm gid_from_group
.Nd cache password and group entries
.Sh SYNOPSIS
.In pwd.h
.Ft int
.Fn uid_from_user "const char *name" "uid_t *uid"
.Ft const char *
.Fn user_from_uid "uid_t uid" "int nouser"
.In grp.h
.Ft int
.Fn gid_from_group "const char *name" "gid_t *gid"
.Ft const char *
.Fn group_from_gid "gid_t gid" "int nogroup"
.Sh DESCRIPTION
The
.Fn user_from_uid
function returns the user name associated with the argument
.Fa uid .
The user name is cached so that multiple calls with the same
.Fa uid
do not require additional calls to
.Xr getpwuid 3 .
If there is no user associated with the
.Fa uid ,
a pointer is returned
to a string representation of the
.Fa uid ,
unless the argument
.Fa nouser
is non-zero, in which case a null pointer is returned.
.Pp
The
.Fn uid_from_user
function returns the user ID associated with the argument
.Fa name .
The user ID is cached so that multiple calls with the same
.Fa name
do not require additional calls to
.Xr getpwnam 3 .
If there is no user ID associated with the
.Fa name ,
the
.Fn uid_from_user
function returns -1;
otherwise it stores the user ID at the location pointed to by
.Fa uid
and returns 0.
.Pp
The
.Fn group_from_gid
function returns the group name associated with the argument
.Fa gid .
The group name is cached so that multiple calls with the same
.Fa gid
do not require additional calls to
.Xr getgrgid 3 .
If there is no group associated with the
.Fa gid ,
a pointer is returned
to a string representation of the
.Fa gid ,
unless the argument
.Fa nogroup
is non-zero, in which case a null pointer is returned.
.Pp
The
.Fn gid_from_group
function returns the group ID associated with the argument
.Fa name .
The group ID is cached so that multiple calls with the same
.Fa name
do not require additional calls to
.Xr getgrnam 3 .
If there is no group ID associated with the
.Fa name ,
the
.Fn gid_from_group
function returns -1;
otherwise it stores the group ID at the location pointed to by
.Fa gid
and returns 0.
.Sh SEE ALSO
.Xr getgrgid 3 ,
.Xr getpwuid 3
.Sh HISTORY
The
.Fn user_from_uid
and
.Fn group_from_gid
functions first appeared in
.Bx 4.4 .
.Pp
The
.Fn uid_from_user
and
.Fn gid_from_group
functions were ported from
.Nx
and first appeared in
.Ox 6.4 .