1 /* modechange.c -- file mode manipulation
2 Copyright (C) 1989, 1990, 1997-2000 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 "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)
54 # define S_ISUID 04000
57 # define S_ISGID 04000
60 # define S_ISVTX 01000
99 /* All the mode bits that can be affected by chmod. */
100 #define CHMOD_MODE_BITS \
101 (S_ISUID | S_ISGID | S_ISVTX | S_IRWXU | S_IRWXG | S_IRWXO)
103 /* Return newly allocated memory to hold one element of type TYPE. */
104 #define talloc(type) ((type *) malloc (sizeof (type)))
106 /* Create a mode_change entry with the specified `=ddd'-style
107 mode change operation, where NEW_MODE is `ddd'. Return the
108 new entry, or NULL upon failure. */
110 static struct mode_change *
111 make_node_op_equals (mode_t new_mode)
113 struct mode_change *p;
114 p = talloc (struct mode_change);
121 p->affected = CHMOD_MODE_BITS; /* Affect all permissions. */
125 /* Append entry E to the end of the link list with the specified
129 mode_append_entry (struct mode_change **head,
130 struct mode_change **tail,
131 struct mode_change *e)
142 /* Return a linked list of file mode change operations created from
143 MODE_STRING, an ASCII string that contains either an octal number
144 specifying an absolute mode, or symbolic mode change operations with
146 [ugoa...][[+-=][rwxXstugo...]...][,...]
147 MASKED_OPS is a bitmask indicating which symbolic mode operators (=+-)
148 should not affect bits set in the umask when no users are given.
149 Operators not selected in MASKED_OPS ignore the umask.
151 Return MODE_INVALID if `mode_string' does not contain a valid
152 representation of file mode change operations;
153 return MODE_MEMORY_EXHAUSTED if there is insufficient memory. */
156 mode_compile (const char *mode_string, unsigned int masked_ops)
158 struct mode_change *head; /* First element of the linked list. */
159 struct mode_change *tail; /* An element of the linked list. */
160 uintmax_t mode_value; /* The mode value, if octal. */
161 char *string_end; /* Pointer to end of parsed value. */
162 mode_t umask_value; /* The umask value (surprise). */
169 if (xstrtoumax (mode_string, &string_end, 8, &mode_value, "") == LONGINT_OK)
171 struct mode_change *p;
172 if (mode_value != (mode_value & CHMOD_MODE_BITS))
174 p = make_node_op_equals ((mode_t) mode_value);
176 return MODE_MEMORY_EXHAUSTED;
177 mode_append_entry (&head, &tail, p);
181 umask_value = umask (0);
182 umask (umask_value); /* Restore the old value. */
185 /* One loop iteration for each "ugoa...=+-rwxXstugo...[=+-rwxXstugo...]". */
188 /* Which bits in the mode are operated on. */
189 mode_t affected_bits = 0;
190 /* `affected_bits' modified by umask. */
191 mode_t affected_masked;
192 /* Operators to actually use umask on. */
193 unsigned ops_to_mask = 0;
199 /* Turn on all the bits in `affected_bits' for each group given. */
200 for (++mode_string;; ++mode_string)
201 switch (*mode_string)
204 affected_bits |= S_ISUID | S_IRWXU;
207 affected_bits |= S_ISGID | S_IRWXG;
210 affected_bits |= S_ISVTX | S_IRWXO;
213 affected_bits |= CHMOD_MODE_BITS;
216 goto no_more_affected;
220 /* If none specified, affect all bits, except perhaps those
227 affected_bits = CHMOD_MODE_BITS;
228 ops_to_mask = masked_ops;
231 while (*mode_string == '=' || *mode_string == '+' || *mode_string == '-')
233 struct mode_change *change = talloc (struct mode_change);
237 return MODE_MEMORY_EXHAUSTED;
241 change->op = *mode_string; /* One of "=+-". */
242 affected_masked = affected_bits;
244 /* Per the Single Unix Spec, if `who' is not specified and the
245 `=' operator is used, then clear all the bits first. */
246 if (!who_specified_p &&
247 ops_to_mask & (*mode_string == '=' ? MODE_MASK_EQUALS : 0))
249 struct mode_change *p = make_node_op_equals (0);
251 return MODE_MEMORY_EXHAUSTED;
252 mode_append_entry (&head, &tail, p);
255 if (ops_to_mask & (*mode_string == '=' ? MODE_MASK_EQUALS
256 : *mode_string == '+' ? MODE_MASK_PLUS
258 affected_masked &= ~umask_value;
259 change->affected = affected_masked;
263 /* Add the element to the tail of the list, so the operations
264 are performed in the correct order. */
265 mode_append_entry (&head, &tail, change);
267 /* Set `value' according to the bits set in `affected_masked'. */
268 for (++mode_string;; ++mode_string)
269 switch (*mode_string)
272 change->value |= ((S_IRUSR | S_IRGRP | S_IROTH)
276 change->value |= ((S_IWUSR | S_IWGRP | S_IWOTH)
280 change->flags |= MODE_X_IF_ANY_X;
283 change->value |= ((S_IXUSR | S_IXGRP | S_IXOTH)
287 /* Set the setuid/gid bits if `u' or `g' is selected. */
288 change->value |= (S_ISUID | S_ISGID) & affected_masked;
291 /* Set the "save text image" bit if `o' is selected. */
292 change->value |= S_ISVTX & affected_masked;
295 /* Set the affected bits to the value of the `u' bits
299 change->value = S_IRWXU;
300 change->flags |= MODE_COPY_EXISTING;
303 /* Set the affected bits to the value of the `g' bits
307 change->value = S_IRWXG;
308 change->flags |= MODE_COPY_EXISTING;
311 /* Set the affected bits to the value of the `o' bits
315 change->value = S_IRWXO;
316 change->flags |= MODE_COPY_EXISTING;
323 } while (*mode_string == ',');
324 if (*mode_string == 0)
331 /* Return a file mode change operation that sets permissions to match those
332 of REF_FILE. Return MODE_BAD_REFERENCE if REF_FILE can't be accessed. */
335 mode_create_from_ref (const char *ref_file)
337 struct mode_change *change; /* the only change element */
338 struct stat ref_stats;
340 if (stat (ref_file, &ref_stats))
341 return MODE_BAD_REFERENCE;
343 change = talloc (struct mode_change);
346 return MODE_MEMORY_EXHAUSTED;
350 change->affected = CHMOD_MODE_BITS;
351 change->value = ref_stats.st_mode;
357 /* Return file mode OLDMODE, adjusted as indicated by the list of change
358 operations CHANGES. If OLDMODE is a directory, the type `X'
359 change affects it even if no execute bits were set in OLDMODE.
360 The returned value has the S_IFMT bits cleared. */
363 mode_adjust (mode_t oldmode, const struct mode_change *changes)
365 mode_t newmode; /* The adjusted mode and one operand. */
366 mode_t value; /* The other operand. */
368 newmode = oldmode & CHMOD_MODE_BITS;
370 for (; changes; changes = changes->next)
372 if (changes->flags & MODE_COPY_EXISTING)
374 /* Isolate in `value' the bits in `newmode' to copy, given in
375 the mask `changes->value'. */
376 value = newmode & changes->value;
378 if (changes->value & S_IRWXU)
379 /* Copy `u' permissions onto `g' and `o'. */
380 value |= ((value & S_IRUSR ? S_IRGRP | S_IROTH : 0)
381 | (value & S_IWUSR ? S_IWGRP | S_IROTH : 0)
382 | (value & S_IXUSR ? S_IXGRP | S_IXOTH : 0));
383 else if (changes->value & S_IRWXG)
384 /* Copy `g' permissions onto `u' and `o'. */
385 value |= ((value & S_IRGRP ? S_IRUSR | S_IROTH : 0)
386 | (value & S_IWGRP ? S_IWUSR | S_IROTH : 0)
387 | (value & S_IXGRP ? S_IXUSR | S_IXOTH : 0));
389 /* Copy `o' permissions onto `u' and `g'. */
390 value |= ((value & S_IROTH ? S_IRUSR | S_IRGRP : 0)
391 | (value & S_IWOTH ? S_IWUSR | S_IRGRP : 0)
392 | (value & S_IXOTH ? S_IXUSR | S_IXGRP : 0));
394 /* In order to change only `u', `g', or `o' permissions,
395 or some combination thereof, clear unselected bits.
396 This can not be done in mode_compile because the value
397 to which the `changes->affected' mask is applied depends
398 on the old mode of each file. */
399 value &= changes->affected;
403 value = changes->value;
404 /* If `X', do not affect the execute bits if the file is not a
405 directory and no execute bits are already set. */
406 if ((changes->flags & MODE_X_IF_ANY_X)
407 && !S_ISDIR (oldmode)
408 && (newmode & (S_IXUSR | S_IXGRP | S_IXOTH)) == 0)
409 /* Clear the execute bits. */
410 value &= ~ (S_IXUSR | S_IXGRP | S_IXOTH);
416 /* Preserve the previous values in `newmode' of bits that are
417 not affected by this change operation. */
418 newmode = (newmode & ~changes->affected) | value;
431 /* Free the memory used by the list of file mode change operations
435 mode_free (register struct mode_change *changes)
437 register struct mode_change *next;
441 next = changes->next;