setmode.c revision 111274 
1/*
2 * Copyright (c) 1989, 1993, 1994
3 *	The Regents of the University of California.  All rights reserved.
4 *
5 * This code is derived from software contributed to Berkeley by
6 * Dave Borman at Cray Research, Inc.
7 *
8 * Redistribution and use in source and binary forms, with or without
9 * modification, are permitted provided that the following conditions
10 * are met:
11 * 1. Redistributions of source code must retain the above copyright
12 *    notice, this list of conditions and the following disclaimer.
13 * 2. Redistributions in binary form must reproduce the above copyright
14 *    notice, this list of conditions and the following disclaimer in the
15 *    documentation and/or other materials provided with the distribution.
16 * 3. All advertising materials mentioning features or use of this software
17 *    must display the following acknowledgement:
18 *	This product includes software developed by the University of
19 *	California, Berkeley and its contributors.
20 * 4. Neither the name of the University nor the names of its contributors
21 *    may be used to endorse or promote products derived from this software
22 *    without specific prior written permission.
23 *
24 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
25 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
26 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
27 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
28 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
29 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
30 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
31 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
32 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
33 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
34 * SUCH DAMAGE.
35 */
36
37#if defined(LIBC_SCCS) && !defined(lint)
38static char sccsid[] = "@(#)setmode.c	8.2 (Berkeley) 3/25/94";
39#endif /* LIBC_SCCS and not lint */
40#include <sys/cdefs.h>
41__FBSDID("$FreeBSD: head/lib/libc/gen/setmode.c 111274 2003-02-23 00:24:03Z mikeh $");
42
43#include "namespace.h"
44#include <sys/types.h>
45#include <sys/stat.h>
46
47#include <ctype.h>
48#include <signal.h>
49#include <stddef.h>
50#include <stdlib.h>
51#include <unistd.h>
52
53#ifdef SETMODE_DEBUG
54#include <stdio.h>
55#endif
56#include "un-namespace.h"
57
58#define	SET_LEN	6		/* initial # of bitcmd struct to malloc */
59#define	SET_LEN_INCR 4		/* # of bitcmd structs to add as needed */
60
61typedef struct bitcmd {
62	char	cmd;
63	char	cmd2;
64	mode_t	bits;
65} BITCMD;
66
67#define	CMD2_CLR	0x01
68#define	CMD2_SET	0x02
69#define	CMD2_GBITS	0x04
70#define	CMD2_OBITS	0x08
71#define	CMD2_UBITS	0x10
72
73static BITCMD	*addcmd(BITCMD *, int, int, int, u_int);
74static void	 compress_mode(BITCMD *);
75#ifdef SETMODE_DEBUG
76static void	 dumpmode(BITCMD *);
77#endif
78
79/*
80 * Given the old mode and an array of bitcmd structures, apply the operations
81 * described in the bitcmd structures to the old mode, and return the new mode.
82 * Note that there is no '=' command; a strict assignment is just a '-' (clear
83 * bits) followed by a '+' (set bits).
84 */
85mode_t
86getmode(bbox, omode)
87	const void *bbox;
88	mode_t omode;
89{
90	const BITCMD *set;
91	mode_t clrval, newmode, value;
92
93	set = (const BITCMD *)bbox;
94	newmode = omode;
95	for (value = 0;; set++)
96		switch(set->cmd) {
97		/*
98		 * When copying the user, group or other bits around, we "know"
99		 * where the bits are in the mode so that we can do shifts to
100		 * copy them around.  If we don't use shifts, it gets real
101		 * grundgy with lots of single bit checks and bit sets.
102		 */
103		case 'u':
104			value = (newmode & S_IRWXU) >> 6;
105			goto common;
106
107		case 'g':
108			value = (newmode & S_IRWXG) >> 3;
109			goto common;
110
111		case 'o':
112			value = newmode & S_IRWXO;
113common:			if (set->cmd2 & CMD2_CLR) {
114				clrval =
115				    (set->cmd2 & CMD2_SET) ?  S_IRWXO : value;
116				if (set->cmd2 & CMD2_UBITS)
117					newmode &= ~((clrval<<6) & set->bits);
118				if (set->cmd2 & CMD2_GBITS)
119					newmode &= ~((clrval<<3) & set->bits);
120				if (set->cmd2 & CMD2_OBITS)
121					newmode &= ~(clrval & set->bits);
122			}
123			if (set->cmd2 & CMD2_SET) {
124				if (set->cmd2 & CMD2_UBITS)
125					newmode |= (value<<6) & set->bits;
126				if (set->cmd2 & CMD2_GBITS)
127					newmode |= (value<<3) & set->bits;
128				if (set->cmd2 & CMD2_OBITS)
129					newmode |= value & set->bits;
130			}
131			break;
132
133		case '+':
134			newmode |= set->bits;
135			break;
136
137		case '-':
138			newmode &= ~set->bits;
139			break;
140
141		case 'X':
142			if (omode & (S_IFDIR|S_IXUSR|S_IXGRP|S_IXOTH))
143				newmode |= set->bits;
144			break;
145
146		case '\0':
147		default:
148#ifdef SETMODE_DEBUG
149			(void)printf("getmode:%04o -> %04o\n", omode, newmode);
150#endif
151			return (newmode);
152		}
153}
154
155#define	ADDCMD(a, b, c, d)						\
156	if (set >= endset) {						\
157		BITCMD *newset;						\
158		setlen += SET_LEN_INCR;					\
159		newset = realloc(saveset, sizeof(BITCMD) * setlen);	\
160		if (!newset) {						\
161			if (saveset)					\
162				free(saveset);				\
163			saveset = NULL;					\
164			return (NULL);					\
165		}							\
166		set = newset + (set - saveset);				\
167		saveset = newset;					\
168		endset = newset + (setlen - 2);				\
169	}								\
170	set = addcmd(set, (a), (b), (c), (d))
171
172#define	STANDARD_BITS	(S_ISUID|S_ISGID|S_IRWXU|S_IRWXG|S_IRWXO)
173
174void *
175setmode(p)
176	const char *p;
177{
178	int perm, who;
179	char op, *ep;
180	BITCMD *set, *saveset, *endset;
181	sigset_t sigset, sigoset;
182	mode_t mask;
183	int equalopdone=0, permXbits, setlen;
184	long perml;
185
186	if (!*p)
187		return (NULL);
188
189	/*
190	 * Get a copy of the mask for the permissions that are mask relative.
191	 * Flip the bits, we want what's not set.  Since it's possible that
192	 * the caller is opening files inside a signal handler, protect them
193	 * as best we can.
194	 */
195	sigfillset(&sigset);
196        (void)_sigprocmask(SIG_BLOCK, &sigset, &sigoset);
197	(void)umask(mask = umask(0));
198	mask = ~mask;
199        (void)_sigprocmask(SIG_SETMASK, &sigoset, NULL);
200
201	setlen = SET_LEN + 2;
202
203	if ((set = malloc((u_int)(sizeof(BITCMD) * setlen))) == NULL)
204		return (NULL);
205	saveset = set;
206	endset = set + (setlen - 2);
207
208	/*
209	 * If an absolute number, get it and return; disallow non-octal digits
210	 * or illegal bits.
211	 */
212	if (isdigit((unsigned char)*p)) {
213		perml = strtol(p, &ep, 8);
214		if (*ep || perml < 0 || perml & ~(STANDARD_BITS|S_ISTXT)) {
215			free(saveset);
216			return (NULL);
217		}
218		perm = (mode_t)perml;
219		ADDCMD('=', (STANDARD_BITS|S_ISTXT), perm, mask);
220		set->cmd = 0;
221		return (saveset);
222	}
223
224	/*
225	 * Build list of structures to set/clear/copy bits as described by
226	 * each clause of the symbolic mode.
227	 */
228	for (;;) {
229		/* First, find out which bits might be modified. */
230		for (who = 0;; ++p) {
231			switch (*p) {
232			case 'a':
233				who |= STANDARD_BITS;
234				break;
235			case 'u':
236				who |= S_ISUID|S_IRWXU;
237				break;
238			case 'g':
239				who |= S_ISGID|S_IRWXG;
240				break;
241			case 'o':
242				who |= S_IRWXO;
243				break;
244			default:
245				goto getop;
246			}
247		}
248
249getop:		if ((op = *p++) != '+' && op != '-' && op != '=') {
250			free(saveset);
251			return (NULL);
252		}
253		if (op == '=')
254			equalopdone = 0;
255
256		who &= ~S_ISTXT;
257		for (perm = 0, permXbits = 0;; ++p) {
258			switch (*p) {
259			case 'r':
260				perm |= S_IRUSR|S_IRGRP|S_IROTH;
261				break;
262			case 's':
263				/* If only "other" bits ignore set-id. */
264				if (!who || who & ~S_IRWXO)
265					perm |= S_ISUID|S_ISGID;
266				break;
267			case 't':
268				/* If only "other" bits ignore sticky. */
269				if (!who || who & ~S_IRWXO) {
270					who |= S_ISTXT;
271					perm |= S_ISTXT;
272				}
273				break;
274			case 'w':
275				perm |= S_IWUSR|S_IWGRP|S_IWOTH;
276				break;
277			case 'X':
278				permXbits = S_IXUSR|S_IXGRP|S_IXOTH;
279				break;
280			case 'x':
281				perm |= S_IXUSR|S_IXGRP|S_IXOTH;
282				break;
283			case 'u':
284			case 'g':
285			case 'o':
286				/*
287				 * When ever we hit 'u', 'g', or 'o', we have
288				 * to flush out any partial mode that we have,
289				 * and then do the copying of the mode bits.
290				 */
291				if (perm) {
292					ADDCMD(op, who, perm, mask);
293					perm = 0;
294				}
295				if (op == '=')
296					equalopdone = 1;
297				if (op == '+' && permXbits) {
298					ADDCMD('X', who, permXbits, mask);
299					permXbits = 0;
300				}
301				ADDCMD(*p, who, op, mask);
302				break;
303
304			default:
305				/*
306				 * Add any permissions that we haven't already
307				 * done.
308				 */
309				if (perm || (op == '=' && !equalopdone)) {
310					if (op == '=')
311						equalopdone = 1;
312					ADDCMD(op, who, perm, mask);
313					perm = 0;
314				}
315				if (permXbits) {
316					ADDCMD('X', who, permXbits, mask);
317					permXbits = 0;
318				}
319				goto apply;
320			}
321		}
322
323apply:		if (!*p)
324			break;
325		if (*p != ',')
326			goto getop;
327		++p;
328	}
329	set->cmd = 0;
330#ifdef SETMODE_DEBUG
331	(void)printf("Before compress_mode()\n");
332	dumpmode(saveset);
333#endif
334	compress_mode(saveset);
335#ifdef SETMODE_DEBUG
336	(void)printf("After compress_mode()\n");
337	dumpmode(saveset);
338#endif
339	return (saveset);
340}
341
342static BITCMD *
343addcmd(set, op, who, oparg, mask)
344	BITCMD *set;
345	int oparg, who;
346	int op;
347	u_int mask;
348{
349	switch (op) {
350	case '=':
351		set->cmd = '-';
352		set->bits = who ? who : STANDARD_BITS;
353		set++;
354
355		op = '+';
356		/* FALLTHROUGH */
357	case '+':
358	case '-':
359	case 'X':
360		set->cmd = op;
361		set->bits = (who ? who : mask) & oparg;
362		break;
363
364	case 'u':
365	case 'g':
366	case 'o':
367		set->cmd = op;
368		if (who) {
369			set->cmd2 = ((who & S_IRUSR) ? CMD2_UBITS : 0) |
370				    ((who & S_IRGRP) ? CMD2_GBITS : 0) |
371				    ((who & S_IROTH) ? CMD2_OBITS : 0);
372			set->bits = (mode_t)~0;
373		} else {
374			set->cmd2 = CMD2_UBITS | CMD2_GBITS | CMD2_OBITS;
375			set->bits = mask;
376		}
377
378		if (oparg == '+')
379			set->cmd2 |= CMD2_SET;
380		else if (oparg == '-')
381			set->cmd2 |= CMD2_CLR;
382		else if (oparg == '=')
383			set->cmd2 |= CMD2_SET|CMD2_CLR;
384		break;
385	}
386	return (set + 1);
387}
388
389#ifdef SETMODE_DEBUG
390static void
391dumpmode(set)
392	BITCMD *set;
393{
394	for (; set->cmd; ++set)
395		(void)printf("cmd: '%c' bits %04o%s%s%s%s%s%s\n",
396		    set->cmd, set->bits, set->cmd2 ? " cmd2:" : "",
397		    set->cmd2 & CMD2_CLR ? " CLR" : "",
398		    set->cmd2 & CMD2_SET ? " SET" : "",
399		    set->cmd2 & CMD2_UBITS ? " UBITS" : "",
400		    set->cmd2 & CMD2_GBITS ? " GBITS" : "",
401		    set->cmd2 & CMD2_OBITS ? " OBITS" : "");
402}
403#endif
404
405/*
406 * Given an array of bitcmd structures, compress by compacting consecutive
407 * '+', '-' and 'X' commands into at most 3 commands, one of each.  The 'u',
408 * 'g' and 'o' commands continue to be separate.  They could probably be
409 * compacted, but it's not worth the effort.
410 */
411static void
412compress_mode(set)
413	BITCMD *set;
414{
415	BITCMD *nset;
416	int setbits, clrbits, Xbits, op;
417
418	for (nset = set;;) {
419		/* Copy over any 'u', 'g' and 'o' commands. */
420		while ((op = nset->cmd) != '+' && op != '-' && op != 'X') {
421			*set++ = *nset++;
422			if (!op)
423				return;
424		}
425
426		for (setbits = clrbits = Xbits = 0;; nset++) {
427			if ((op = nset->cmd) == '-') {
428				clrbits |= nset->bits;
429				setbits &= ~nset->bits;
430				Xbits &= ~nset->bits;
431			} else if (op == '+') {
432				setbits |= nset->bits;
433				clrbits &= ~nset->bits;
434				Xbits &= ~nset->bits;
435			} else if (op == 'X')
436				Xbits |= nset->bits & ~setbits;
437			else
438				break;
439		}
440		if (clrbits) {
441			set->cmd = '-';
442			set->cmd2 = 0;
443			set->bits = clrbits;
444			set++;
445		}
446		if (setbits) {
447			set->cmd = '+';
448			set->cmd2 = 0;
449			set->bits = setbits;
450			set++;
451		}
452		if (Xbits) {
453			set->cmd = 'X';
454			set->cmd2 = 0;
455			set->bits = Xbits;
456			set++;
457		}
458	}
459}
460