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SETGID
!!!SETGID
NAME
SYNOPSIS
DESCRIPTION
RETURN VALUE
ERRORS
CONFORMING TO
SEE ALSO
----
!!NAME


setgid - set group identity
!!SYNOPSIS


__#include __
#include __


__int setgid(gid_t__ ''gid''__)__
!!DESCRIPTION


__setgid__ sets the effective group ID of the current
process. If the caller is the superuser, the real and saved
group ID's are also set.


Under Linux, __setgid__ is implemented like the POSIX
version with the _POSIX_SAVED_IDS feature. This allows a
setgid (other than root) program to drop all of its group
privileges, do some un-privileged work, and then re-engage
the original effective group ID in a secure
manner.


If the user is root or the program is setgid root, special
care must be taken. The __setgid__ function checks the
effective gid of the caller and if it is the superuser, all
process related group ID's are set to ''gid''. After this
has occurred, it is impossible for the program to regain
root privileges.


Thus, a setgid-root program wishing to temporarily drop root
privileges, assume the identity of a non-root group, and
then regain root privileges afterwards cannot use
__setgid__. You can accomplish this with the (non-POSIX,
BSD) call __setegid__.
!!RETURN VALUE


On success, zero is returned. On error, -1 is returned, and
''errno'' is set appropriately.
!!ERRORS


__EPERM__


The user is not the super-user, and ''gid'' does not
match the effective group ID or saved set-group-ID of the
calling process.
!!CONFORMING TO


SVr4, SVID.
!!SEE ALSO


getgid(2), setregid(2),
setegid(2)
----

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Last edited on Tuesday, June 4, 2002 12:23:46 am by "perry"

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