debian man page for capng_change_id

CAPNG_CHANGE_ID(3)						   Libcap-ng API						CAPNG_CHANGE_ID(3)

NAME
       capng_change_id - change the credentials retaining capabilities

SYNOPSIS
       #include <cap-ng.h>

       int capng_change_id(int uid, int gid, capng_flags_t flag);

DESCRIPTION
       This  function  will  change uid and gid to the ones given while retaining the capabilities previously specified in capng_update. It is not
       necessary and perhaps better if capng_apply has not been called prior to this function so that all necessary privileges are  still  intact.
       The caller is required to have CAP_SETPCAP capability still active before calling this function.

       This  function  also takes a flag parameter that helps to tailor the exact actions performed by the function to secure the environment. The
       option may be or'ed together. The legal values are:

	      CAPNG_NO_FLAG
		     Simply change uid and retain specified capabilities and that's all.

	      CAPNG_DROP_SUPP_GRP
		     After changing id, remove and supplement groups that may come with the account.

	      CAPNG_CLEAR_BOUNDING
		     After changing the uid and gid, clear the bounding set regardless to the internal representation already setup.

RETURN VALUE
       This returns 0 on success and a negative number on failure. -1 means capng has not been initted properly, -2 means a failure requesting	to
       keep  capabilities  across  the	uid  change, -3 means that applying the intermediate capabilities failed, -4 means changing gid failed, -5
       means dropping supplemental groups failed, -6 means changing the uid failed, -7 means dropping the ability to  retain  caps  across  a  uid
       change failed, -8 means clearing the bounding set failed, -9 means dropping CAP_SETPCAP failed.

       Note: the only safe action to do upon failure of this function is to probably exit. This is because you are likely in a situation with par-
       tial permissions and not what you intended.

SEE ALSO
       capng_update(3), capng_apply(3), prctl(2), capabilities(7)

AUTHOR
       Steve Grubb

Red Hat 							     June 2009							CAPNG_CHANGE_ID(3)