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getgrent.c revision 1.11 
      1 /*	$NetBSD: getgrent.c,v 1.11 2005/09/14 15:31:18 he Exp $	*/
      2 
      3 /*
      4  * Copyright (c) 1989, 1991, 1993
      5  *	The Regents of the University of California.  All rights reserved.
      6  *
      7  * Redistribution and use in source and binary forms, with or without
      8  * modification, are permitted provided that the following conditions
      9  * are met:
     10  * 1. Redistributions of source code must retain the above copyright
     11  *    notice, this list of conditions and the following disclaimer.
     12  * 2. Redistributions in binary form must reproduce the above copyright
     13  *    notice, this list of conditions and the following disclaimer in the
     14  *    documentation and/or other materials provided with the distribution.
     15  * 3. Neither the name of the University nor the names of its contributors
     16  *    may be used to endorse or promote products derived from this software
     17  *    without specific prior written permission.
     18  *
     19  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
     20  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     21  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     22  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
     23  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     24  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     25  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     26  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     27  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     28  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     29  * SUCH DAMAGE.
     30  */
     31 
     32 /*
     33  * Portions Copyright (c) 1994, Jason Downs. All Rights Reserved.
     34  *
     35  * Redistribution and use in source and binary forms, with or without
     36  * modification, are permitted provided that the following conditions
     37  * are met:
     38  * 1. Redistributions of source code must retain the above copyright
     39  *    notice, this list of conditions and the following disclaimer.
     40  * 2. Redistributions in binary form must reproduce the above copyright
     41  *    notice, this list of conditions and the following disclaimer in the
     42  *    documentation and/or other materials provided with the distribution.
     43  *
     44  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR(S) ``AS IS'' AND ANY EXPRESS
     45  * OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
     46  * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
     47  * DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR(S) BE LIABLE FOR ANY DIRECT,
     48  * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
     49  * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
     50  * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
     51  * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     52  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     53  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     54  * SUCH DAMAGE.
     55  */
     56 
     57 /*
     58  * Copied from:  lib/libc/gen/getgrent.c
     59  *     NetBSD: getgrent.c,v 1.46 2003/02/17 00:11:54 simonb Exp
     60  * and then gutted, leaving only /etc/group support.
     61  */
     62 
     63 #include <sys/cdefs.h>
     64 
     65 #ifdef __weak_alias
     66 #define endgrent		_endgrent
     67 #define getgrent		_getgrent
     68 #define getgrgid		_getgrgid
     69 #define getgrnam		_getgrnam
     70 #define getgrnam_r		_getgrnam_r
     71 #define setgrent		_setgrent
     72 #define setgroupent		_setgroupent
     73 #define getgroupmembership	_getgroupmembership
     74 
     75 __weak_alias(endgrent,_endgrent)
     76 __weak_alias(getgrent,_getgrent)
     77 __weak_alias(getgrgid,_getgrgid)
     78 __weak_alias(getgrnam,_getgrnam)
     79 __weak_alias(getgrnam_r,_getgrnam_r)
     80 __weak_alias(setgrent,_setgrent)
     81 __weak_alias(setgroupent,_setgroupent)
     82 __weak_alias(getgroupmembership,_getgroupmembership)
     83 #endif
     84 
     85 #include <sys/param.h>
     86 
     87 #include <grp.h>
     88 #include <limits.h>
     89 #include <stdio.h>
     90 #include <stdlib.h>
     91 #include <string.h>
     92 #include <unistd.h>
     93 #include <errno.h>
     94 
     95 static FILE		*_gr_fp;
     96 static struct group	_gr_group;
     97 static int		_gr_stayopen;
     98 static int		_gr_filesdone;
     99 
    100 static int grscan(int, gid_t, const char *, const char *);
    101 static int grstart(void);
    102 static int grmatchline(int, gid_t, const char *, const char *);
    103 
    104 #define	MAXGRP		200
    105 #define	MAXLINELENGTH	1024
    106 
    107 static __aconst char	*members[MAXGRP];
    108 static char		grline[MAXLINELENGTH];
    109 
    110 struct group *
    111 getgrent(void)
    112 {
    113 
    114 	if ((!_gr_fp && !grstart()) || !grscan(0, 0, NULL, NULL))
    115  		return (NULL);
    116 	return &_gr_group;
    117 }
    118 
    119 int
    120 getgrnam_r(const char *name, struct group *grp, char *buffer,
    121 	size_t buflen, struct group **result)
    122 {
    123 	struct group *gp, *bgp;
    124 
    125 	/*
    126 	 * We blatantly cheat (don't provide reentrancy)
    127 	 * and hope to get away with it
    128 	 */
    129 
    130 	*result = NULL;
    131 	bgp = (struct group*)buffer;
    132 	if (buflen < sizeof(struct group))
    133 		return ENOMEM;
    134 
    135 	gp = getgrnam(name);
    136 	if (gp) {
    137 		*bgp = *gp;
    138 		*result = bgp;
    139 	}
    140 
    141 	return (gp) ? ENOENT : 0;
    142 }
    143 
    144 struct group *
    145 getgrnam(const char *name)
    146 {
    147 	int rval;
    148 
    149 	if (!grstart())
    150 		return NULL;
    151 	rval = grscan(1, 0, name, NULL);
    152 	if (!_gr_stayopen)
    153 		endgrent();
    154 	return (rval) ? &_gr_group : NULL;
    155 }
    156 
    157 struct group *
    158 getgrgid(gid_t gid)
    159 {
    160 	int rval;
    161 
    162 	if (!grstart())
    163 		return NULL;
    164 	rval = grscan(1, gid, NULL, NULL);
    165 	if (!_gr_stayopen)
    166 		endgrent();
    167 	return (rval) ? &_gr_group : NULL;
    168 }
    169 
    170 static int
    171 grstart(void)
    172 {
    173 
    174 	_gr_filesdone = 0;
    175 	if (_gr_fp) {
    176 		rewind(_gr_fp);
    177 		return 1;
    178 	}
    179 	return (_gr_fp = fopen(_PATH_GROUP, "r")) ? 1 : 0;
    180 }
    181 
    182 void
    183 setgrent(void)
    184 {
    185 
    186 	(void) setgroupent(0);
    187 }
    188 
    189 int
    190 setgroupent(int stayopen)
    191 {
    192 
    193 	if (!grstart())
    194 		return 0;
    195 	_gr_stayopen = stayopen;
    196 	return 1;
    197 }
    198 
    199 void
    200 endgrent(void)
    201 {
    202 
    203 	_gr_filesdone = 0;
    204 	if (_gr_fp) {
    205 		(void)fclose(_gr_fp);
    206 		_gr_fp = NULL;
    207 	}
    208 }
    209 
    210 int
    211 getgroupmembership(const char *uname, gid_t agroup,
    212     gid_t *groups, int maxgroups, int *grpcnt)
    213 {
    214 	struct group *grp;
    215 	int i, ngroups, ret;
    216 
    217 	ret = 0;
    218 	ngroups = 0;
    219 
    220 	/*
    221 	 * install primary group
    222 	 */
    223 	if (ngroups < maxgroups)
    224 		groups[ngroups] = agroup;
    225 	else
    226 		ret = -1;
    227 	ngroups++;
    228 
    229 	/*
    230 	 * Scan the group file to find additional groups.
    231 	 */
    232 	setgrent();
    233  nextgroup:
    234 	while ((grp = getgrent()) != NULL) {
    235 		if (grp->gr_gid == agroup)
    236 			continue;
    237 		for (i = 0; grp->gr_mem[i]; i++) {
    238 			if (strcmp(grp->gr_mem[i], uname) != 0)
    239 				continue;
    240 			for (i = 0; i < MIN(ngroups, maxgroups); i++) {
    241 				if (grp->gr_gid == groups[i])
    242 					goto nextgroup;
    243 			}
    244 			if (ngroups < maxgroups)
    245 				groups[ngroups] = grp->gr_gid;
    246 			else
    247 				ret = -1;
    248 			ngroups++;
    249 			break;
    250 		}
    251 	}
    252 	endgrent();
    253 	*grpcnt = ngroups;
    254 	return ret;
    255 }
    256 
    257 static int
    258 grscan(int search, gid_t gid, const char *name, const char *user)
    259 {
    260 
    261 	if (_gr_filesdone)
    262 		return 0;
    263 	for (;;) {
    264 		if (!fgets(grline, sizeof(grline), _gr_fp)) {
    265 			if (!search)
    266 				_gr_filesdone = 1;
    267 			return 0;
    268 		}
    269 		/* skip lines that are too big */
    270 		if (!strchr(grline, '\n')) {
    271 			int ch;
    272 
    273 			while ((ch = getc(_gr_fp)) != '\n' && ch != EOF)
    274 				;
    275 			continue;
    276 		}
    277 		if (grmatchline(search, gid, name, user))
    278 			return 1;
    279 	}
    280 	/* NOTREACHED */
    281 }
    282 
    283 static int
    284 grmatchline(int search, gid_t gid, const char *name, const char *user)
    285 {
    286 	unsigned long	id;
    287 	__aconst char	**m;
    288 	char		*cp, *bp, *ep;
    289 
    290 	/* name may be NULL if search is nonzero */
    291 
    292 	bp = grline;
    293 	_gr_group.gr_name = strsep(&bp, ":\n");
    294 	if (search && name && strcmp(_gr_group.gr_name, name))
    295 		return 0;
    296 	_gr_group.gr_passwd = strsep(&bp, ":\n");
    297 	if (!(cp = strsep(&bp, ":\n")))
    298 		return 0;
    299 	id = strtoul(cp, &ep, 10);
    300 	if (id > GID_MAX || *ep != '\0')
    301 		return 0;
    302 	_gr_group.gr_gid = (gid_t)id;
    303 	if (search && name == NULL && _gr_group.gr_gid != gid)
    304 		return 0;
    305 	cp = NULL;
    306 	if (bp == NULL)
    307 		return 0;
    308 	for (_gr_group.gr_mem = m = members;; bp++) {
    309 		if (m == &members[MAXGRP - 1])
    310 			break;
    311 		if (*bp == ',') {
    312 			if (cp) {
    313 				*bp = '\0';
    314 				*m++ = cp;
    315 				cp = NULL;
    316 			}
    317 		} else if (*bp == '\0' || *bp == '\n' || *bp == ' ') {
    318 			if (cp) {
    319 				*bp = '\0';
    320 				*m++ = cp;
    321 			}
    322 			break;
    323 		} else if (cp == NULL)
    324 			cp = bp;
    325 	}
    326 	*m = NULL;
    327 	if (user) {
    328 		for (m = members; *m; m++)
    329 			if (!strcmp(user, *m))
    330 				return 1;
    331 		return 0;
    332 	}
    333 	return 1;
    334 }
    335