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getgroups(2) [opensolaris man page]

getgroups(2)							   System Calls 						      getgroups(2)

NAME
getgroups, setgroups - get or set supplementary group access list IDs SYNOPSIS
#include <unistd.h> int getgroups(int gidsetsize, gid_t *grouplist); int setgroups(int ngroups, const gid_t *grouplist); DESCRIPTION
The getgroups() function gets the current supplemental group access list of the calling process and stores the result in the array of group IDs specified by grouplist. This array has gidsetsize entries and must be large enough to contain the entire list. This list cannot be larger than NGROUPS_UMAX. If gidsetsize equals 0, getgroups() will return the number of groups to which the calling process belongs without modifying the array pointed to by grouplist. The setgroups() function sets the supplementary group access list of the calling process from the array of group IDs specified by grou- plist. The number of entries is specified by ngroups and can not be greater than NGROUPS_MAX. RETURN VALUES
Upon successful completion, getgroups() returns the number of supplementary group IDs set for the calling process and setgroups() returns 0. Otherwise, -1 is returned and errno is set to indicate the error. ERRORS
The getgroups() and setgroups() functions will fail if: EFAULT A referenced part of the array pointed to by grouplist is an illegal address. The getgroups() function will fail if: EINVAL The value of gidsetsize is non-zero and less than the number of supplementary group IDs set for the calling process. The setgroups() function will fail if: EINVAL The value of ngroups is greater than {NGROUPS_MAX}. EPERM The {PRIV_PROC_SETID} privilege is not asserted in the effective set of the calling process. USAGE
Use of the setgroups() function requires the {PRIV_PROC_SETID} privilege. ATTRIBUTES
See attributes(5) for descriptions of the following attributes: +-----------------------------+-----------------------------+ | ATTRIBUTE TYPE | ATTRIBUTE VALUE | +-----------------------------+-----------------------------+ |Interface Stability |getgroups() is Standard. | +-----------------------------+-----------------------------+ |MT-Level |Async-Signal-Safe | +-----------------------------+-----------------------------+ SEE ALSO
groups(1), chown(2), getuid(2), setuid(2), getgrnam(3C), initgroups(3C), attributes(5), privileges(5), standards(5) SunOS 5.11 8 Sep 2006 getgroups(2)

Check Out this Related Man Page

GETGROUPS(2)						      BSD System Calls Manual						      GETGROUPS(2)

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 vari- ant 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 modi- fied 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
setgroups(2), initgroups(3), compat(5) HISTORY
The getgroups() function call appeared in 4.2BSD. 4.2 Berkeley Distribution October 28, 2011 4.2 Berkeley Distribution
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