ack/lang/cem/libcc.ansi/misc/getgrent.c

/*
 * getgrent - get entry form group file
 *
 * Author: Patrick van Kleef
 */
/* $Id$ */

#include <stdlib.h>
#include <string.h>
#include <grp.h>

#define O_RDONLY 0

int open(const char* path, int flags);

#if defined(__BSD4_2)
typedef int off_t; /* see lseek(2) */
#else
typedef long off_t;
#endif

off_t _lseek(int d, off_t offset, int whence);
int _read(int d, char* buf, int nbytes);
int _close(int d);

#define RBUFSIZE 1024
static char _gr_file[] = "/etc/group";
static char _grbuf[256];
static char _buffer[RBUFSIZE];
static char* _pnt;
static char* _buf;
static int _gfd = -1;
static int _bufcnt;
static struct group grp;

int setgrent(void)
{
	if (_gfd >= 0)
		_lseek(_gfd, 0L, 0);
	else
		_gfd = open(_gr_file, O_RDONLY);

	_bufcnt = 0;
	return _gfd;
}

void endgrent(void)
{
	if (_gfd >= 0)
		_close(_gfd);

	_gfd = -1;
	_bufcnt = 0;
}

static int
getline(void)
{
	if (_gfd < 0 && setgrent() < 0)
		return 0;

	_buf = _grbuf;
	do
	{
		if (--_bufcnt <= 0)
		{
			if ((_bufcnt = _read(_gfd, _buffer, RBUFSIZE)) <= 0)
				return 0;
			else
				_pnt = _buffer;
		}
		*_buf++ = *_pnt++;
	} while (*_pnt != '\n');
	_pnt++;
	_bufcnt--;
	*_buf = 0;
	_buf = _grbuf;
	return 1;
}

static void
skip_period(void)
{
	while (*_buf && *_buf != ':')
		_buf++;
	*_buf++ = '\0';
}

struct group*
getgrent(void)
{
	if (getline() == 0)
		return 0;

	grp.gr_name = _buf;
	skip_period();
	grp.gr_passwd = _buf;
	skip_period();
	grp.gr_gid = atoi(_buf);
	skip_period();
	return &grp;
}

struct group*
getgrnam(const char* name)
{
	struct group* g;

	setgrent();
	while ((g = getgrent()) != 0)
		if (!strcmp(g->gr_name, name))
			break;
	endgrent();
	if (g != 0)
		return g;
	else
		return 0;
}

struct group*
getgrgid(int gid)
{
	struct group* g;

	setgrent();
	while ((g = getgrent()) != 0)
		if (g->gr_gid == gid)
			break;
	endgrent();
	if (g != 0)
		return g;
	else
		return 0;
}