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.TH nfs4_uid_to_name 3 2004-08-05
.SH NAME
nfs4_uid_to_name, nfs4_gid_to_name, nfs4_name_to_uid, nfs4_name_to_gid, nfs4_init_name_mapping, nfs4_get_default_domain, nfs4_gss_princ_to_ids: idmapping for nfsv4
.SH SYNOPSIS
.B #include <nfs4_idmap.h>
.sp
.BI "int nfs4_init_name_mapping(char *conffile);"
.sp
.BI "int nfs4_get_default_domain(char *server, char *domain, size_t len);"
.sp
.BI "int nfs4_uid_to_name(uid_t uid, char *domain, char *name, size_t len);"
.sp
.BI "int nfs4_gid_to_name(gid_t gid, char *domain, char *name, size_t len);"
.sp
.BI "int nfs4_name_to_uid(char *name, uid_t *uid);"
.sp
.BI "int nfs4_name_to_gid(char *name, gid_t *gid);"
.sp
.BI "int nfs4_gss_princ_to_ids(char *princ, uid_t *uid, gid_t *gid);"
.fi
.BI "int nfs4_get_grouplist(const char *name, gid_t *groups, int *ngroups);"
.fi
.SH DESCRIPTION
NFSv4 uses names of the form
.IR user@domain .
To write code that helps the kernel map uid's (as
rpc.idmapd
does) or that processes NFSv4 ACLs, you need to be able to convert between
NFSv4 names and local uids and gids.
.PP
The
.B nfs4_uid_to_name()
and
.B nfs4_gid_to_name()
functions, given
.I uid
or
.I gid
and
.I domain
(as a null-terminated string),
write the corresponding nfsv4 name into the buffer provided in
.IR name ,
which must be of length at least
.IR len .
.PP
The
.B nfs4_name_to_uid()
and
.B nfs4_name_to_gid()
functions, given
.I name
(as a null-terminated string), return the corresponding uid or gid in
the second parameter.
. PP
The
.B nfs4_init_name_mapping()
function must be called before using any of these functions. It reads
defaults from the configuration file at the provided path, usually
"etc/idmapd.conf".
.PP
The
.I domain
argument to the id-to-name functions is there to provide a hint to the name
mapper in the case where an id might be mapped to names in multiple domains.
In most cases, this argument should just be the name returned in the
.I domain
argument to
.B nfs4_get_default_domain()
which should be called with
.I server
set to NULL. The
.I domain
should be a buffer of length
.IR len .
The constant NFS4_MAX_DOMAIN_LEN may be used to determine a reasonable
value for that length.
.PP
The function
.BR nfs4_get_grouplist() ,
given a
.IR name ,
fills the provided array
.I groups
with up to
.I *ngroups
group IDs corresponding to which the user
.I name
belongs to, setting
.I *ngroups
to the actual number of such groups. If the user belongs to more than
.I *ngroups
groups, then an error is returned and the actual number of groups is stored in
*ngroups.
.PP
Finally,
.B nfs4_gss_princ_to_ids()
is used to convert from a gss principal name (as returned by
.BR gss_display_name() )
to a uid and gid.
.SH RETURN VALUE
All functions return 0 or, in the case of error, -ERRNO.
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