setmode.c revision 1574 
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
41#include <sys/types.h>
42#include <sys/stat.h>
43
44#include <ctype.h>
45#include <errno.h>
46#include <signal.h>
47#include <stddef.h>
48#include <stdlib.h>
49
50#ifdef SETMODE_DEBUG
51#include <stdio.h>
52#endif
53
54#define	SET_LEN	6		/* initial # of bitcmd struct to malloc */
55#define	SET_LEN_INCR 4		/* # of bitcmd structs to add as needed */
56
57typedef struct bitcmd {
58	char	cmd;
59	char	cmd2;
60	mode_t	bits;
61} BITCMD;
62
63#define	CMD2_CLR	0x01
64#define	CMD2_SET	0x02
65#define	CMD2_GBITS	0x04
66#define	CMD2_OBITS	0x08
67#define	CMD2_UBITS	0x10
68
69static BITCMD	*addcmd __P((BITCMD *, int, int, int, u_int));
70static int	 compress_mode __P((BITCMD *));
71#ifdef SETMODE_DEBUG
72static void	 dumpmode __P((BITCMD *));
73#endif
74
75/*
76 * Given the old mode and an array of bitcmd structures, apply the operations
77 * described in the bitcmd structures to the old mode, and return the new mode.
78 * Note that there is no '=' command; a strict assignment is just a '-' (clear
79 * bits) followed by a '+' (set bits).
80 */
81mode_t
82getmode(bbox, omode)
83	void *bbox;
84	mode_t omode;
85{
86	register BITCMD *set;
87	register mode_t clrval, newmode, value;
88
89	set = (BITCMD *)bbox;
90	newmode = omode;
91	for (value = 0;; set++)
92		switch(set->cmd) {
93		/*
94		 * When copying the user, group or other bits around, we "know"
95		 * where the bits are in the mode so that we can do shifts to
96		 * copy them around.  If we don't use shifts, it gets real
97		 * grundgy with lots of single bit checks and bit sets.
98		 */
99		case 'u':
100			value = (newmode & S_IRWXU) >> 6;
101			goto common;
102
103		case 'g':
104			value = (newmode & S_IRWXG) >> 3;
105			goto common;
106
107		case 'o':
108			value = newmode & S_IRWXO;
109common:			if (set->cmd2 & CMD2_CLR) {
110				clrval =
111				    (set->cmd2 & CMD2_SET) ?  S_IRWXO : value;
112				if (set->cmd2 & CMD2_UBITS)
113					newmode &= ~((clrval<<6) & set->bits);
114				if (set->cmd2 & CMD2_GBITS)
115					newmode &= ~((clrval<<3) & set->bits);
116				if (set->cmd2 & CMD2_OBITS)
117					newmode &= ~(clrval & set->bits);
118			}
119			if (set->cmd2 & CMD2_SET) {
120				if (set->cmd2 & CMD2_UBITS)
121					newmode |= (value<<6) & set->bits;
122				if (set->cmd2 & CMD2_GBITS)
123					newmode |= (value<<3) & set->bits;
124				if (set->cmd2 & CMD2_OBITS)
125					newmode |= value & set->bits;
126			}
127			break;
128
129		case '+':
130			newmode |= set->bits;
131			break;
132
133		case '-':
134			newmode &= ~set->bits;
135			break;
136
137		case 'X':
138			if (omode & (S_IFDIR|S_IXUSR|S_IXGRP|S_IXOTH))
139				newmode |= set->bits;
140			break;
141
142		case '\0':
143		default:
144#ifdef SETMODE_DEBUG
145			(void)printf("getmode:%04o -> %04o\n", omode, newmode);
146#endif
147			return (newmode);
148		}
149}
150
151#define	ADDCMD(a, b, c, d)						\
152	if (set >= endset) {						\
153		register BITCMD *newset;				\
154		setlen += SET_LEN_INCR;					\
155		newset = realloc(saveset, sizeof(BITCMD) * setlen);	\
156		if (!saveset)						\
157			return (NULL);					\
158		set = newset + (set - saveset);				\
159		saveset = newset;					\
160		endset = newset + (setlen - 2);				\
161	}								\
162	set = addcmd(set, (a), (b), (c), (d))
163
164#define	STANDARD_BITS	(S_ISUID|S_ISGID|S_IRWXU|S_IRWXG|S_IRWXO)
165
166void *
167setmode(p)
168	register char *p;
169{
170	register int perm, who;
171	register char op;
172	BITCMD *set, *saveset, *endset;
173	sigset_t sigset, sigoset;
174	mode_t mask;
175	int equalopdone, permXbits, setlen;
176
177	if (!*p)
178		return (NULL);
179
180	/*
181	 * Get a copy of the mask for the permissions that are mask relative.
182	 * Flip the bits, we want what's not set.  Since it's possible that
183	 * the caller is opening files inside a signal handler, protect them
184	 * as best we can.
185	 */
186	sigfillset(&sigset);
187        (void)sigprocmask(SIG_BLOCK, &sigset, &sigoset);
188	(void)umask(mask = umask(0));
189	mask = ~mask;
190        (void)sigprocmask(SIG_SETMASK, &sigoset, NULL);
191
192	setlen = SET_LEN + 2;
193
194	if ((set = malloc((u_int)(sizeof(BITCMD) * setlen))) == NULL)
195		return (NULL);
196	saveset = set;
197	endset = set + (setlen - 2);
198
199	/*
200	 * If an absolute number, get it and return; disallow non-octal digits
201	 * or illegal bits.
202	 */
203	if (isdigit(*p)) {
204		perm = (mode_t)strtol(p, NULL, 8);
205		if (perm & ~(STANDARD_BITS|S_ISTXT)) {
206			free(saveset);
207			return (NULL);
208		}
209		while (*++p)
210			if (*p < '0' || *p > '7') {
211				free(saveset);
212				return (NULL);
213			}
214		ADDCMD('=', (STANDARD_BITS|S_ISTXT), perm, mask);
215		return (saveset);
216	}
217
218	/*
219	 * Build list of structures to set/clear/copy bits as described by
220	 * each clause of the symbolic mode.
221	 */
222	for (;;) {
223		/* First, find out which bits might be modified. */
224		for (who = 0;; ++p) {
225			switch (*p) {
226			case 'a':
227				who |= STANDARD_BITS;
228				break;
229			case 'u':
230				who |= S_ISUID|S_IRWXU;
231				break;
232			case 'g':
233				who |= S_ISGID|S_IRWXG;
234				break;
235			case 'o':
236				who |= S_IRWXO;
237				break;
238			default:
239				goto getop;
240			}
241		}
242
243getop:		if ((op = *p++) != '+' && op != '-' && op != '=') {
244			free(saveset);
245			return (NULL);
246		}
247		if (op == '=')
248			equalopdone = 0;
249
250		who &= ~S_ISTXT;
251		for (perm = 0, permXbits = 0;; ++p) {
252			switch (*p) {
253			case 'r':
254				perm |= S_IRUSR|S_IRGRP|S_IROTH;
255				break;
256			case 's':
257				/* If only "other" bits ignore set-id. */
258				if (who & ~S_IRWXO)
259					perm |= S_ISUID|S_ISGID;
260				break;
261			case 't':
262				/* If only "other" bits ignore sticky. */
263				if (who & ~S_IRWXO) {
264					who |= S_ISTXT;
265					perm |= S_ISTXT;
266				}
267				break;
268			case 'w':
269				perm |= S_IWUSR|S_IWGRP|S_IWOTH;
270				break;
271			case 'X':
272				permXbits = S_IXUSR|S_IXGRP|S_IXOTH;
273				break;
274			case 'x':
275				perm |= S_IXUSR|S_IXGRP|S_IXOTH;
276				break;
277			case 'u':
278			case 'g':
279			case 'o':
280				/*
281				 * When ever we hit 'u', 'g', or 'o', we have
282				 * to flush out any partial mode that we have,
283				 * and then do the copying of the mode bits.
284				 */
285				if (perm) {
286					ADDCMD(op, who, perm, mask);
287					perm = 0;
288				}
289				if (op == '=')
290					equalopdone = 1;
291				if (op == '+' && permXbits) {
292					ADDCMD('X', who, permXbits, mask);
293					permXbits = 0;
294				}
295				ADDCMD(*p, who, op, mask);
296				break;
297
298			default:
299				/*
300				 * Add any permissions that we haven't already
301				 * done.
302				 */
303				if (perm || (op == '=' && !equalopdone)) {
304					if (op == '=')
305						equalopdone = 1;
306					ADDCMD(op, who, perm, mask);
307					perm = 0;
308				}
309				if (permXbits) {
310					ADDCMD('X', who, permXbits, mask);
311					permXbits = 0;
312				}
313				goto apply;
314			}
315		}
316
317apply:		if (!*p)
318			break;
319		if (*p != ',')
320			goto getop;
321		++p;
322	}
323	set->cmd = 0;
324#ifdef SETMODE_DEBUG
325	(void)printf("Before compress_mode()\n");
326	dumpmode(saveset);
327#endif
328	compress_mode(saveset);
329#ifdef SETMODE_DEBUG
330	(void)printf("After compress_mode()\n");
331	dumpmode(saveset);
332#endif
333	return (saveset);
334}
335
336static BITCMD *
337addcmd(set, op, who, oparg, mask)
338	BITCMD *set;
339	register int oparg, who;
340	register int op;
341	u_int mask;
342{
343	switch (op) {
344	case '=':
345		set->cmd = '-';
346		set->bits = who ? who : STANDARD_BITS;
347		set++;
348
349		op = '+';
350		/* FALLTHROUGH */
351	case '+':
352	case '-':
353	case 'X':
354		set->cmd = op;
355		set->bits = (who ? who : mask) & oparg;
356		break;
357
358	case 'u':
359	case 'g':
360	case 'o':
361		set->cmd = op;
362		if (who) {
363			set->cmd2 = ((who & S_IRUSR) ? CMD2_UBITS : 0) |
364				    ((who & S_IRGRP) ? CMD2_GBITS : 0) |
365				    ((who & S_IROTH) ? CMD2_OBITS : 0);
366			set->bits = ~0;
367		} else {
368			set->cmd2 = CMD2_UBITS | CMD2_GBITS | CMD2_OBITS;
369			set->bits = mask;
370		}
371
372		if (oparg == '+')
373			set->cmd2 |= CMD2_SET;
374		else if (oparg == '-')
375			set->cmd2 |= CMD2_CLR;
376		else if (oparg == '=')
377			set->cmd2 |= CMD2_SET|CMD2_CLR;
378		break;
379	}
380	return (set + 1);
381}
382
383#ifdef SETMODE_DEBUG
384static void
385dumpmode(set)
386	register BITCMD *set;
387{
388	for (; set->cmd; ++set)
389		(void)printf("cmd: '%c' bits %04o%s%s%s%s%s%s\n",
390		    set->cmd, set->bits, set->cmd2 ? " cmd2:" : "",
391		    set->cmd2 & CMD2_CLR ? " CLR" : "",
392		    set->cmd2 & CMD2_SET ? " SET" : "",
393		    set->cmd2 & CMD2_UBITS ? " UBITS" : "",
394		    set->cmd2 & CMD2_GBITS ? " GBITS" : "",
395		    set->cmd2 & CMD2_OBITS ? " OBITS" : "");
396}
397#endif
398
399/*
400 * Given an array of bitcmd structures, compress by compacting consecutive
401 * '+', '-' and 'X' commands into at most 3 commands, one of each.  The 'u',
402 * 'g' and 'o' commands continue to be separate.  They could probably be
403 * compacted, but it's not worth the effort.
404 */
405static int
406compress_mode(set)
407	register BITCMD *set;
408{
409	register BITCMD *nset;
410	register int setbits, clrbits, Xbits, op;
411
412	for (nset = set;;) {
413		/* Copy over any 'u', 'g' and 'o' commands. */
414		while ((op = nset->cmd) != '+' && op != '-' && op != 'X') {
415			*set++ = *nset++;
416			if (!op)
417				return;
418		}
419
420		for (setbits = clrbits = Xbits = 0;; nset++) {
421			if ((op = nset->cmd) == '-') {
422				clrbits |= nset->bits;
423				setbits &= ~nset->bits;
424				Xbits &= ~nset->bits;
425			} else if (op == '+') {
426				setbits |= nset->bits;
427				clrbits &= ~nset->bits;
428				Xbits &= ~nset->bits;
429			} else if (op == 'X')
430				Xbits |= nset->bits & ~setbits;
431			else
432				break;
433		}
434		if (clrbits) {
435			set->cmd = '-';
436			set->cmd2 = 0;
437			set->bits = clrbits;
438			set++;
439		}
440		if (setbits) {
441			set->cmd = '+';
442			set->cmd2 = 0;
443			set->bits = setbits;
444			set++;
445		}
446		if (Xbits) {
447			set->cmd = 'X';
448			set->cmd2 = 0;
449			set->bits = Xbits;
450			set++;
451		}
452	}
453}
454