aboutsummaryrefslogtreecommitdiff
path: root/libbb/parse_mode.c
blob: 185957bc32d17f1697216a4e5b934862309b8eca (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
/* vi: set sw=4 ts=4: */
/*
 * parse_mode implementation for busybox
 *
 * Copyright (C) 2003  Manuel Novoa III  <mjn3@codepoet.org>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program 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
 * General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
 *
 */

/* http://www.opengroup.org/onlinepubs/007904975/utilities/chmod.html */

#include <stdlib.h>
#include <assert.h>
#include <sys/stat.h>
#include "libbb.h"

#define FILEMODEBITS    (S_ISUID | S_ISGID | S_ISVTX | S_IRWXU | S_IRWXG | S_IRWXO)

extern int bb_parse_mode(const char *s, mode_t *current_mode)
{
	static const mode_t who_mask[] = {
		S_ISUID | S_ISGID | S_ISVTX | S_IRWXU | S_IRWXG | S_IRWXO, /* a */
		S_ISUID | S_IRWXU,		/* u */
		S_ISGID | S_IRWXG,		/* g */
		S_IRWXO					/* o */
	};

	static const mode_t perm_mask[] = {
		S_IRUSR | S_IRGRP | S_IROTH, /* r */
		S_IWUSR | S_IWGRP | S_IWOTH, /* w */
		S_IXUSR | S_IXGRP | S_IXOTH, /* x */
		S_IXUSR | S_IXGRP | S_IXOTH, /* X -- special -- see below */
		S_ISUID | S_ISGID,		/* s */
		S_ISVTX					/* t */
	};

	static const char who_chars[] = "augo";
	static const char perm_chars[] = "rwxXst";

	const char *p;

	mode_t wholist;
	mode_t permlist;
	mode_t mask;
	mode_t new_mode;
	char op;

	assert(s);

	if (((unsigned int)(*s - '0')) < 8) {
		unsigned long tmp;
		char *e;

		tmp = strtol(s, &e, 8);
		if (*e || (tmp > 07777U)) { /* Check range and trailing chars. */
			return 0;
		}
		*current_mode = tmp;
		return 1;
	}

	mask = umask(0);
	umask(mask);

	new_mode = *current_mode;

	/* Note: We allow empty clauses, and hence empty modes.
	 * We treat an empty mode as no change to perms. */

	while (*s) {	/* Process clauses. */

		if (*s == ',') {	/* We allow empty clauses. */
			++s;
			continue;
		}

		/* Get a wholist. */
		wholist = 0;

	WHO_LIST:
		p = who_chars;
		do {
			if (*p == *s) {
				wholist |= who_mask[(int)(p-who_chars)];
				if (!*++s) {
					return 0;
				}
				goto WHO_LIST;
			}
		} while (*++p);

		do {	/* Process action list. */
			if ((*s != '+') && (*s != '-')) {
				if (*s != '=') {
					return 0;
				}
				/* Since op is '=', clear all bits corresponding to the
				 * wholist, of all file bits if wholist is empty. */
				permlist = ~FILEMODEBITS;
				if (wholist) {
					permlist = ~wholist;
				}
				new_mode &= permlist;
			}
			op = *s++;

			/* Check for permcopy. */
			p = who_chars + 1;	/* Skip 'a' entry. */
			do {
				if (*p == *s) {
					int i = 0;
					permlist = who_mask[(int)(p-who_chars)]
							 & (S_IRWXU | S_IRWXG | S_IRWXO)
							 & new_mode;
					do {
						if (permlist & perm_mask[i]) {
							permlist |= perm_mask[i];
						}
					} while (++i < 3);
					++s;
					goto GOT_ACTION;
				}
			} while (*++p);

			/* It was not a permcopy, so get a permlist. */
			permlist = 0;

		PERM_LIST:
			p = perm_chars;
			do {
				if (*p == *s) {
					if ((*p != 'X')
						|| (new_mode & (S_IFDIR | S_IXUSR | S_IXGRP | S_IXOTH))
					) {
						permlist |= perm_mask[(int)(p-perm_chars)];
					}
					if (!*++s) {
						break;
					}
					goto PERM_LIST;
				}
			} while (*++p);

		GOT_ACTION:
			if (permlist) {	/* The permlist was nonempty. */
				mode_t tmp = ~mask;
				if (wholist) {
					tmp = wholist;
				}
				permlist &= tmp;

				if (op == '-') {
					new_mode &= ~permlist;
				} else {
					new_mode |= permlist;
				}
			}
		} while (*s && (*s != ','));
	}

	*current_mode = new_mode;

	return 1;
}