uclibc-ng/libc/pwd_grp/grent.c

/* vi: set sw=4 ts=4: */
/*
 * grent.c - This file is part of the libc-8086/grp package for ELKS,
 * Copyright (C) 1995, 1996 Nat Friedman <ndf@linux.mit.edu>.
 * Copyright (C) 2001-2003 Erik Andersen <andersee@debian.org>
 * 
 *  This library is free software; you can redistribute it and/or
 *  modify it under the terms of the GNU Library General Public
 *  License as published by the Free Software Foundation; either
 *  version 2 of the License, or (at your option) any later version.
 *
 *  This library is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 *  Library General Public License for more details.
 *
 *  You should have received a copy of the GNU Library General Public
 *  License along with this library; if not, write to the Free
 *  Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 *
 */

/*
 * setgrent(), endgrent(), and getgrent() are mutually-dependent functions,
 * so they are all included in the same object file, and thus all linked
 * in together.
 */

#define _GNU_SOURCE
#include <features.h>
#include <unistd.h>
#include <fcntl.h>
#include <paths.h>
#include <errno.h>
#include "config.h"

#ifdef __UCLIBC_HAS_THREADS__
#include <pthread.h>
static pthread_mutex_t mylock = PTHREAD_RECURSIVE_MUTEX_INITIALIZER_NP;
# define LOCK   pthread_mutex_lock(&mylock)
# define UNLOCK pthread_mutex_unlock(&mylock);
#else       
# define LOCK
# define UNLOCK
#endif      

/* file descriptor for the group file currently open */
static int grp_fd = -9;

void setgrent(void)
{
	LOCK;
	if (grp_fd > -1)
		close(grp_fd);
	grp_fd = open(_PATH_GROUP, O_RDONLY);
	UNLOCK;
}

void endgrent(void)
{
	LOCK;
	if (grp_fd > -1)
		close(grp_fd);
	grp_fd = -9;
	UNLOCK;
}

int getgrent_r (struct group *grp, char *buff, 
		size_t buflen, struct group **result)
{
	int ret=EINVAL;
	*result = NULL;

	LOCK;
	/* Open /etc/group if it has never been opened */
	if (grp_fd == -9) {
		setgrent();
	}
	if (grp_fd == -1) {
		UNLOCK;
		return -1;
	}
	ret=__getgrent_r(grp, buff, buflen, grp_fd);
	if (ret == 0) {
		UNLOCK;
		*result = grp;
		return 0;
	}
	UNLOCK;
	__set_errno(ret);
	return ret;
}

struct group *getgrent(void)
{
	int ret;
	struct group *result;
	static struct group grp;
	static char line_buff[PWD_BUFFER_SIZE];

	ret = getgrent_r(&grp, line_buff, sizeof(line_buff),  &result);
	if (ret == 0) {
		return &grp;
	}
	__set_errno(ret);
	return NULL;
}