# nfs4_uid_to_name - ID mapping routines used for NFSv4 - man(3) - [phpMan]

[_nfs4_uid_to_name_(3)](https://www.chedong.com/phpMan.php/man/nfs4uidtoname/3/markdown)                   Library Functions Manual                   [_nfs4_uid_to_name_(3)](https://www.chedong.com/phpMan.php/man/nfs4uidtoname/3/markdown)

## NAME
       nfs4_uid_to_name,  nfs4_gid_to_name,  nfs4_name_to_uid, nfs4_name_to_gid, nfs4_init_name_map‐
       ping,    nfs4_get_default_domain,     nfs4_gss_princ_to_ids,     nfs4_gss_princ_to_grouplist,
       nfs4_gss_princ_to_ids_ex,  nfs4_gss_princ_to_grouplist_ex,  nfs4_set_debug  - ID mapping rou‐
       tines used for NFSv4

## SYNOPSIS
### #include <nfs4_idmap.h>

       **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_uid_to_owner(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_gid_to_owner(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_owner_to_uid(char *name, uid_t *uid);**

       **int nfs4_owner_to_gid(char *name, gid_t *gid);**

       **int nfs4_gss_princ_to_ids(char *secname, char *princ, uid_t *uid, gid_t *gid);**

       **int nfs4_gss_princ_to_grouplist(char *secname, char *princ, gid_t *groups, int *ngroups);**

       **int nfs4_gss_princ_to_ids_ex(char *secname, char *princ, uid_t *uid, gid_t  *gid,  extra_map‐**
       **ping_params **ex);**

       **int  nfs4_gss_princ_to_grouplist_ex(char  *secname, char *princ, gid_t *groups, int *ngroups,**
       **extra_mapping_params **ex);**

       **void nfs4_set_debug(int dbg_level, void (*logger)(const char *, ...));**


## DESCRIPTION
       NFSv4 uses names of the form _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.

       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_uid_to_owner() **and **nfs4_gid_to_group_owner() **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_.  If there is no valid mapping from _uid_ or _gid_  to
       _name_, then the numerical string representing uid or gid is returned instead.

       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_owner_to_uid() **and **nfs4_group_owner_to_gid() **functions, given _name_ (as a null-termi‐
       nated string), return the corresponding uid or gid in the second parameter.  If there  is  no
       valid  mapping  from  _name_ to _uid_ or _gid_ the value for the user or group "nobody" will be re‐
       turned instead.

       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 er‐
       ror is returned and the actual number of groups is stored in *ngroups.

       Functions **nfs4_gss_princ_to_ids()**, **nfs4_gss_princ_to_grouplist()**, **nfs4_gss_princ_to_ids_ex()**,
       and **nfs4_gss_princ_to_grouplist_ex() **are used to convert from a gss principal  name  (as  re‐
       turned by **gss_display_name()**) to a uid and gid, or list of gids.

       Finally,  **nfs4_set_debug()  **allows  the application to set a debugging level to produce extra
       debugging information from within the library.  The optional _logger_ function specifies an al‐
       ternative logging function to call for the debug messages rather than  the  default  internal
       function within the library.

## RETURN VALUE
       All functions return 0 or, in the case of error, -ERRNO.

                                             2004-08-05                          [_nfs4_uid_to_name_(3)](https://www.chedong.com/phpMan.php/man/nfs4uidtoname/3/markdown)