/* This test was ripped out of GNU 'id' from coreutils-5.0
 * by Erik Andersen.  
 *
 *
 * id is Copyright (C) 1989-2003 Free Software Foundation, Inc.
 * and licensed under the GPL v2 or later, and was written by 
 * Arnold Robbins, with a major rewrite by David MacKenzie,
 */

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <sys/types.h>
#include <pwd.h>
#include <grp.h>
#include <err.h>

/* The number of errors encountered so far. */
static int problems = 0;

/* Print the name or value of group ID GID. */
static void
print_group (gid_t gid)
{
    struct group *grp = NULL;

    grp = getgrgid (gid);
    if (grp == NULL)
    {
	warn("cannot find name for group ID %u", gid);
	problems++;
    }

    if (grp == NULL)
	printf ("%u", (unsigned) gid);
    else
	printf ("%s", grp->gr_name);
}

static int
xgetgroups (gid_t gid, int *n_groups, gid_t **groups)
{
    int max_n_groups;
    int ng;
    gid_t *g;
    int fail = 0;

    max_n_groups = getgroups (0, NULL);

    /* Add 1 just in case max_n_groups is zero.  */
    g = (gid_t *) malloc (max_n_groups * sizeof (gid_t) + 1);
    if (g==NULL)
	err(EXIT_FAILURE, "out of memory");
    ng = getgroups (max_n_groups, g);

    if (ng < 0)
    {
	warn("cannot get supplemental group list");
	++fail;
	free (groups);
    }
    if (!fail)
    {
	*n_groups = ng;
	*groups = g;
    }
    return fail;
}

/* Print all of the distinct groups the user is in. */
int main (int argc, char **argv)
{
    struct passwd *pwd;

    pwd = getpwuid (getuid());
    if (pwd == NULL)
	problems++;

    print_group (getgid());
    if (getegid() != getgid())
    {
	putchar (' ');
	print_group (getegid());
    }

    {
	int n_groups;
	gid_t *groups;
	register int i;

	if (xgetgroups ((pwd ? pwd->pw_gid : (gid_t) -1),
		    &n_groups, &groups))
	{
	    return ++problems;
	}

	for (i = 0; i < n_groups; i++)
	    if (groups[i] != getgid() && groups[i] != getegid())
	    {
		putchar (' ');
		print_group (groups[i]);
	    }
	free (groups);
    }
    putchar('\n');
    return (problems != 0);
}

