NAME
getgroups —
get group access list
SYNOPSIS
#include
<unistd.h>
int
getgroups(int gidsetsize,
gid_t grouplist[]);
DESCRIPTION
getgroups()
gets the current group access list of the current user process and stores it
in the array grouplist[]. The parameter
gidsetsize indicates the number of entries that may be
placed in grouplist[].
getgroups() returns the actual number of groups
returned in grouplist[]. However, no more than
{NGROUPS_MAX} will be returned. If
gidsetsize is 0, getgroups()
returns the number of groups without modifying the
grouplist[] array.
Calling
initgroups(3) to opt-in for supplementary groups will cause
getgroups()
to return a single entry, the GID that was passed to
initgroups(3).
To provide compatibility with applications that
use
getgroups()
in environments where users may be in more than
{NGROUPS_MAX} groups, a variant of
getgroups(), obtained when compiling with either the
macros _DARWIN_UNLIMITED_GETGROUPS or
_DARWIN_C_SOURCE defined, can be used that is not
limited to {NGROUPS_MAX} groups. However, this
variant only returns the user's default group access list and not the group
list modified by a call to
setgroups(2) (either in the current process or an ancestor process).
Use of setgroups(2) is highly discouraged, and there is no foolproof way to
determine if it has been previously called.
RETURN VALUES
A successful call returns the number of groups in the group set. Otherwise, a value of -1 is returned and the global integer variable errno is set to indicate the error.
ERRORS
The possible errors for getgroups()
are:
- [
EFAULT] - The argument grouplist specifies an invalid address.
- [
EINVAL] - The argument gidsetsize, although non-zero, is smaller than the number of groups in the group set.
LEGACY SYNOPSIS
#include
<sys/param.h> #include
<sys/types.h> #include
<unistd.h>
The include files
<sys/param.h> and
<sys/types.h> are
necessary.
SEE ALSO
HISTORY
The getgroups() function call appeared in
4.2BSD.