usr/src/lib/libc/gen/initgroups.c

/*
 * Copyright (c) 1983 Regents of the University of California.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms are permitted
 * provided that the above copyright notice and this paragraph are
 * duplicated in all such forms and that any documentation,
 * advertising materials, and other materials related to such
 * distribution and use acknowledge that the software was developed
 * by the University of California, Berkeley.  The name of the
 * University may not be used to endorse or promote products derived
 * from this software without specific prior written permission.
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
 * WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE.
 */

#if defined(LIBC_SCCS) && !defined(lint)
static char sccsid[] = "@(#)initgroups.c        5.5 (Berkeley) %G%";
#endif /* LIBC_SCCS and not lint */

/*
 * initgroups
 */
#include <stdio.h>
#include <sys/param.h>
#include <grp.h>

struct group *getgrent();

initgroups(uname, agroup)
        char *uname;
        int agroup;
{
        int groups[NGROUPS], ngroups = 0;
        register struct group *grp;
        register int i;

        /*
         * If installing primary group, duplicate it;
         * the first element of groups is the effective gid
         * and will be overwritten when a setgid file is executed.
         */
        if (agroup >= 0) {
                groups[ngroups++] = agroup;
                groups[ngroups++] = agroup;
        }
        setgrent();
        while (grp = getgrent()) {
                if (grp->gr_gid == agroup)
                        continue;
                for (i = 0; grp->gr_mem[i]; i++)
                        if (!strcmp(grp->gr_mem[i], uname)) {
                                if (ngroups == NGROUPS) {
fprintf(stderr, "initgroups: %s is in too many groups\n", uname);
                                        goto toomany;
                                }
                                groups[ngroups++] = grp->gr_gid;
                        }
        }
toomany:
        endgrent();
        if (setgroups(ngroups, groups) < 0) {
                perror("setgroups");
                return (-1);
        }
        return (0);
}