1 /* modechange.c -- file mode manipulation
2 Copyright (C) 1989, 1990, 1997 Free Software Foundation, Inc.
4 This program is free software; you can redistribute it and/or modify
5 it under the terms of the GNU General Public License as published by
6 the Free Software Foundation; either version 2, or (at your option)
9 This program is distributed in the hope that it will be useful,
10 but WITHOUT ANY WARRANTY; without even the implied warranty of
11 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
12 GNU General Public License for more details.
14 You should have received a copy of the GNU General Public License
15 along with this program; if not, write to the Free Software Foundation,
16 Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. */
18 /* Written by David MacKenzie <djm@ai.mit.edu> */
20 /* The ASCII mode string is compiled into a linked list of `struct
21 modechange', which can then be applied to each file to be changed.
22 We do this instead of re-parsing the ASCII string for each file
23 because the compiled form requires less computation to use; when
24 changing the mode of many files, this probably results in a
31 #include <sys/types.h>
33 #include "modechange.h"
45 #if STAT_MACROS_BROKEN
49 #if !defined(S_ISDIR) && defined(S_IFDIR)
50 # define S_ISDIR(m) (((m) & S_IFMT) == S_IFDIR)
53 /* Return newly allocated memory to hold one element of type TYPE. */
54 #define talloc(type) ((type *) malloc (sizeof (type)))
56 #define isodigit(c) ((c) >= '0' && (c) <= '7')
60 /* Return a linked list of file mode change operations created from
61 MODE_STRING, an ASCII string that contains either an octal number
62 specifying an absolute mode, or symbolic mode change operations with
64 [ugoa...][[+-=][rwxXstugo...]...][,...]
65 MASKED_OPS is a bitmask indicating which symbolic mode operators (=+-)
66 should not affect bits set in the umask when no users are given.
67 Operators not selected in MASKED_OPS ignore the umask.
69 Return MODE_INVALID if `mode_string' does not contain a valid
70 representation of file mode change operations;
71 return MODE_MEMORY_EXHAUSTED if there is insufficient memory. */
74 mode_compile (mode_string, masked_ops)
75 const char *mode_string;
78 struct mode_change *head; /* First element of the linked list. */
79 struct mode_change *change; /* An element of the linked list. */
80 int i; /* General purpose temporary. */
81 int umask_value; /* The umask value (surprise). */
82 unsigned short affected_bits; /* Which bits in the mode are operated on. */
83 unsigned short affected_masked; /* `affected_bits' modified by umask. */
84 unsigned ops_to_mask; /* Operators to actually use umask on. */
86 i = oatoi (mode_string);
91 head = talloc (struct mode_change);
93 return MODE_MEMORY_EXHAUSTED;
98 head->affected = 07777; /* Affect all permissions. */
102 umask_value = umask (0);
103 umask (umask_value); /* Restore the old value. */
111 /* One loop iteration for each "ugoa...=+-rwxXstugo...[=+-rwxXstugo...]". */
116 /* Turn on all the bits in `affected_bits' for each group given. */
117 for (++mode_string;; ++mode_string)
118 switch (*mode_string)
121 affected_bits |= 04700;
124 affected_bits |= 02070;
127 affected_bits |= 01007;
130 affected_bits |= 07777;
133 goto no_more_affected;
137 /* If none specified, affect all bits, except perhaps those
139 if (affected_bits == 0)
141 affected_bits = 07777;
142 ops_to_mask = masked_ops;
145 while (*mode_string == '=' || *mode_string == '+' || *mode_string == '-')
147 /* Add the element to the tail of the list, so the operations
148 are performed in the correct order. */
151 head = talloc (struct mode_change);
153 return MODE_MEMORY_EXHAUSTED;
158 change->next = talloc (struct mode_change);
159 if (change->next == NULL)
162 return MODE_MEMORY_EXHAUSTED;
164 change = change->next;
168 change->op = *mode_string; /* One of "=+-". */
169 affected_masked = affected_bits;
170 if (ops_to_mask & (*mode_string == '=' ? MODE_MASK_EQUALS
171 : *mode_string == '+' ? MODE_MASK_PLUS
173 affected_masked &= ~umask_value;
174 change->affected = affected_masked;
178 /* Set `value' according to the bits set in `affected_masked'. */
179 for (++mode_string;; ++mode_string)
180 switch (*mode_string)
183 change->value |= 00444 & affected_masked;
186 change->value |= 00222 & affected_masked;
189 change->flags |= MODE_X_IF_ANY_X;
192 change->value |= 00111 & affected_masked;
195 /* Set the setuid/gid bits if `u' or `g' is selected. */
196 change->value |= 06000 & affected_masked;
199 /* Set the "save text image" bit if `o' is selected. */
200 change->value |= 01000 & affected_masked;
203 /* Set the affected bits to the value of the `u' bits
207 change->value = 00700;
208 change->flags |= MODE_COPY_EXISTING;
211 /* Set the affected bits to the value of the `g' bits
215 change->value = 00070;
216 change->flags |= MODE_COPY_EXISTING;
219 /* Set the affected bits to the value of the `o' bits
223 change->value = 00007;
224 change->flags |= MODE_COPY_EXISTING;
231 } while (*mode_string == ',');
232 if (*mode_string == 0)
239 /* Return a file mode change operation that sets permissions to match those
240 of REF_FILE. Return MODE_BAD_REFERENCE if REF_FILE can't be accessed. */
243 mode_create_from_ref (ref_file)
244 const char *ref_file;
246 struct mode_change *change; /* the only change element */
247 struct stat ref_stats;
249 if (stat (ref_file, &ref_stats))
250 return MODE_BAD_REFERENCE;
252 change = talloc (struct mode_change);
255 return MODE_MEMORY_EXHAUSTED;
259 change->affected = 07777;
260 change->value = ref_stats.st_mode;
266 /* Return file mode OLDMODE, adjusted as indicated by the list of change
267 operations CHANGES. If OLDMODE is a directory, the type `X'
268 change affects it even if no execute bits were set in OLDMODE.
269 The returned value has the S_IFMT bits cleared. */
272 mode_adjust (oldmode, changes)
274 const struct mode_change *changes;
276 unsigned short newmode; /* The adjusted mode and one operand. */
277 unsigned short value; /* The other operand. */
279 newmode = oldmode & 07777;
281 for (; changes; changes = changes->next)
283 if (changes->flags & MODE_COPY_EXISTING)
285 /* Isolate in `value' the bits in `newmode' to copy, given in
286 the mask `changes->value'. */
287 value = newmode & changes->value;
289 if (changes->value & 00700)
290 /* Copy `u' permissions onto `g' and `o'. */
291 value |= (value >> 3) | (value >> 6);
292 else if (changes->value & 00070)
293 /* Copy `g' permissions onto `u' and `o'. */
294 value |= (value << 3) | (value >> 3);
296 /* Copy `o' permissions onto `u' and `g'. */
297 value |= (value << 3) | (value << 6);
299 /* In order to change only `u', `g', or `o' permissions,
300 or some combination thereof, clear unselected bits.
301 This can not be done in mode_compile because the value
302 to which the `changes->affected' mask is applied depends
303 on the old mode of each file. */
304 value &= changes->affected;
308 value = changes->value;
309 /* If `X', do not affect the execute bits if the file is not a
310 directory and no execute bits are already set. */
311 if ((changes->flags & MODE_X_IF_ANY_X)
312 && !S_ISDIR (oldmode)
313 && (newmode & 00111) == 0)
314 value &= ~00111; /* Clear the execute bits. */
320 /* Preserve the previous values in `newmode' of bits that are
321 not affected by this change operation. */
322 newmode = (newmode & ~changes->affected) | value;
335 /* Free the memory used by the list of file mode change operations
340 register struct mode_change *changes;
342 register struct mode_change *next;
346 next = changes->next;
352 /* Return a positive integer containing the value of the ASCII
353 octal number S. If S is not an octal number, return -1. */
363 for (i = 0; isodigit (*s); ++s)
364 i = i * 8 + *s - '0';