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
int nfs4_init_name_mapping(char *conffile);
int nfs4_get_default_domain(char *server, char *domain, size_t len);
int nfs4_uid_to_name(uid_t uid, char *domain, char *name, size_t len);
int nfs4_gid_to_name(gid_t gid, char *domain, char *name, size_t len);
int nfs4_name_to_uid(char *name, uid_t *uid);
int nfs4_name_to_gid(char *name, gid_t *gid);
int nfs4_gss_princ_to_ids(char *princ, uid_t *uid, gid_t *gid); int nfs4_get_grouplist(const char *name, gid_t *groups, int *ngroups);
NFSv4 uses names of the form user@domain. To write code that helps the kernel map uids (as rpc.idmapd does) or that processes NFSv4 ACLs, you need to be able to convert between NFSv4 names and local uids and gids.
The nfs4_uid_to_name() and nfs4_gid_to_name() functions, given uid or gid and domain (as a null-terminated string), write the corresponding nfsv4 name into the buffer provided in name, which must be of length at least len.
The nfs4_name_to_uid() and nfs4_name_to_gid() functions, given name (as a null-terminated string), return the corresponding uid or gid in the second parameter.
The 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".
The 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 domain argument to nfs4_get_default_domain() which should be called with server set to NULL. The domain should be a buffer of length len. The constant NFS4_MAX_DOMAIN_LEN may be used to determine a reasonable value for that length.
The function nfs4_get_grouplist(), given a name, fills the provided array groups with up to *ngroups group IDs corresponding to which the user name belongs to, setting *ngroups to the actual number of such groups. If the user belongs to more than *ngroups groups, then an error is returned and the actual number of groups is stored in *ngroups.
Finally, nfs4_gss_princ_to_ids() is used to convert from a gss principal name (as returned by gss_display_name()) to a uid and gid.
All functions return 0 or, in the case of error, -ERRNO.