shadow/lib/sgetgrent.c

/*
 * Copyright (c) 1990 - 1994, Julianne Frances Haugh
 * Copyright (c) 1996 - 1998, Marek Michałkiewicz
 * Copyright (c) 2005       , Tomasz Kłoczko
 * Copyright (c) 2008       , Nicolas François
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. The name of the copyright holders or contributors may not be used to
 *    endorse or promote products derived from this software without
 *    specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
 * PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE COPYRIGHT
 * HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

#include <config.h>

#ident "$Id$"

#include <stdio.h>
#include <grp.h>
#include "defines.h"
#include "prototypes.h"

#define	NFIELDS	4

/*
 * list - turn a comma-separated string into an array of (char *)'s
 *
 *	list() converts the comma-separated list of member names into
 *	an array of character pointers.
 *
 *	WARNING: I profiled this once with and without strchr() calls
 *	and found that using a register variable and an explicit loop
 *	works best.  For large /etc/group files, this is a major win.
 *
 * FINALLY added dynamic allocation.  Still need to fix sgetsgent().
 *  --marekm
 */
static char **list (char *s)
{
	static char **members = 0;
	static int size = 0;	/* max members + 1 */
	int i;
	char **rbuf;

	i = 0;
	for (;;) {
		/* check if there is room for another pointer (to a group
		   member name, or terminating NULL).  */
		if (i >= size) {
			size = i + 100;	/* at least: i + 1 */
			if (members) {
				rbuf =
				    realloc (members, size * sizeof (char *));
			} else {
				/* for old (before ANSI C) implementations of
				   realloc() that don't handle NULL properly */
				rbuf = malloc (size * sizeof (char *));
			}
			if (!rbuf) {
				if (members)
					free (members);
				members = 0;
				size = 0;
				return (char **) 0;
			}
			members = rbuf;
		}
		if (!s || s[0] == '\0')
			break;
		members[i++] = s;
		while (('\0' != *s) && (',' != *s)) {
			s++;
		}
		if ('\0' != *s) {
			*s++ = '\0';
		}
	}
	members[i] = (char *) 0;
	return members;
}


struct group *sgetgrent (const char *buf)
{
	static char *grpbuf = 0;
	static size_t size = 0;
	static char *grpfields[NFIELDS];
	static struct group grent;
	int i;
	char *cp;

	if (strlen (buf) + 1 > size) {
		/* no need to use realloc() here - just free it and
		   allocate a larger block */
		if (grpbuf)
			free (grpbuf);
		size = strlen (buf) + 1000;	/* at least: strlen(buf) + 1 */
		grpbuf = malloc (size);
		if (!grpbuf) {
			size = 0;
			return 0;
		}
	}
	strcpy (grpbuf, buf);

	cp = strrchr (grpbuf, '\n');
	if (NULL != cp) {
		*cp = '\0';
	}

	for (cp = grpbuf, i = 0; (i < NFIELDS) && (NULL != cp); i++) {
		grpfields[i] = cp;
		cp = strchr (cp, ':');
		if (NULL != cp) {
			*cp = '\0';
			cp++;
		}
	}
	if (i < (NFIELDS - 1) || *grpfields[2] == '\0') {
		return (struct group *) 0;
	}
	grent.gr_name = grpfields[0];
	grent.gr_passwd = grpfields[1];
	grent.gr_gid = atoi (grpfields[2]);
	grent.gr_mem = list (grpfields[3]);
	if (NULL == grent.gr_mem) {
		return (struct group *) 0;	/* out of memory */
	}

	return &grent;
}