getgrouplist - calculate group access list
Standard C Library (libc, -lc)
getgrouplist(const char *name, gid_t basegid, gid_t *groups,
The getgrouplist() function reads through the group database and calculates
the group access list for the user specified in name. The basegid
is automatically included in the groups list. Typically this value is
given as the group number from the password database.
The resulting group list is returned in the integer array pointed to by
groups. The caller specifies the size of the groups array in the integer
pointed to by ngroups; the actual number of groups found is returned in
Duplicate group ids will be suppressed from the result.
The getgrouplist() function returns -1 if the size of the group list is
too small to hold all the user's groups. Here, the group array will be
filled with as many groups as will fit.
/etc/group group membership list
The getgrouplist() function first appeared in 4.4BSD.
The getgrouplist() function uses the routines based on getgrent(3). If
the invoking program uses any of these routines, the group structure will
be overwritten in the call to getgrouplist().
In the case where the group array is too small and duplicate gids have
been suppressed, the returned ngroups will be too large by a factor of
the difference between the given size and the number of matches. This is
not considered to be a major problem, since it's still going to be a
smaller figure than when duplicates were not suppressed.
BSD April 25, 1999 BSD
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