1 /* modechange.c -- file mode manipulation
3 Copyright (C) 1989, 1990, 1997, 1998, 1999, 2001, 2003, 2004, 2005,
4 2006 Free Software Foundation, Inc.
6 This program is free software; you can redistribute it and/or modify
7 it under the terms of the GNU General Public License as published by
8 the Free Software Foundation; either version 2, or (at your option)
11 This program is distributed in the hope that it will be useful,
12 but WITHOUT ANY WARRANTY; without even the implied warranty of
13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 GNU General Public License for more details.
16 You should have received a copy of the GNU General Public License
17 along with this program; if not, write to the Free Software Foundation,
18 Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA. */
20 /* Written by David MacKenzie <djm@ai.mit.edu> */
22 /* The ASCII mode string is compiled into an array of `struct
23 modechange', which can then be applied to each file to be changed.
24 We do this instead of re-parsing the ASCII string for each file
25 because the compiled form requires less computation to use; when
26 changing the mode of many files, this probably results in a
33 #include "modechange.h"
35 #include "stat-macros.h"
39 /* The traditional octal values corresponding to each mode bit. */
52 #define ALLM 07777 /* all octal mode bits */
54 /* Convert OCTAL, which uses one of the traditional octal values, to
55 an internal mode_t value. */
57 octal_to_mode (unsigned int octal)
59 /* Help the compiler optimize the usual case where mode_t uses
60 the traditional octal representation. */
61 return ((S_ISUID == SUID && S_ISGID == SGID && S_ISVTX == SVTX
62 && S_IRUSR == RUSR && S_IWUSR == WUSR && S_IXUSR == XUSR
63 && S_IRGRP == RGRP && S_IWGRP == WGRP && S_IXGRP == XGRP
64 && S_IROTH == ROTH && S_IWOTH == WOTH && S_IXOTH == XOTH)
66 : (mode_t) ((octal & SUID ? S_ISUID : 0)
67 | (octal & SGID ? S_ISGID : 0)
68 | (octal & SVTX ? S_ISVTX : 0)
69 | (octal & RUSR ? S_IRUSR : 0)
70 | (octal & WUSR ? S_IWUSR : 0)
71 | (octal & XUSR ? S_IXUSR : 0)
72 | (octal & RGRP ? S_IRGRP : 0)
73 | (octal & WGRP ? S_IWGRP : 0)
74 | (octal & XGRP ? S_IXGRP : 0)
75 | (octal & ROTH ? S_IROTH : 0)
76 | (octal & WOTH ? S_IWOTH : 0)
77 | (octal & XOTH ? S_IXOTH : 0)));
80 /* Special operations flags. */
83 /* For the sentinel at the end of the mode changes array. */
86 /* The typical case. */
89 /* In addition to the typical case, affect the execute bits if at
90 least one execute bit is set already, or if the file is a
94 /* Instead of the typical case, copy some existing permissions for
95 u, g, or o onto the other two. Which of u, g, or o is copied
96 is determined by which bits are set in the `value' field. */
100 /* Description of a mode change. */
103 char op; /* One of "=+-". */
104 char flag; /* Special operations flag. */
105 mode_t affected; /* Set for u, g, o, or a. */
106 mode_t value; /* Bits to add/remove. */
107 mode_t mentioned; /* Bits explicitly mentioned. */
110 /* Return a mode_change array with the specified `=ddd'-style
111 mode change operation, where NEW_MODE is `ddd' and MENTIONED
112 contains the bits explicitly mentioned in the mode are MENTIONED. */
114 static struct mode_change *
115 make_node_op_equals (mode_t new_mode, mode_t mentioned)
117 struct mode_change *p = xmalloc (2 * sizeof *p);
119 p->flag = MODE_ORDINARY_CHANGE;
120 p->affected = CHMOD_MODE_BITS;
122 p->mentioned = mentioned;
123 p[1].flag = MODE_DONE;
127 /* Return a pointer to an array of file mode change operations created from
128 MODE_STRING, an ASCII string that contains either an octal number
129 specifying an absolute mode, or symbolic mode change operations with
131 [ugoa...][[+-=][rwxXstugo...]...][,...]
133 Return NULL if `mode_string' does not contain a valid
134 representation of file mode change operations. */
137 mode_compile (char const *mode_string)
139 /* The array of mode-change directives to be returned. */
140 struct mode_change *mc;
143 if ('0' <= *mode_string && *mode_string < '8')
145 unsigned int octal_mode = 0;
146 unsigned int octal_mentioned = 0;
150 octal_mode = 8 * octal_mode + *mode_string++ - '0';
151 octal_mentioned = 8 * octal_mentioned + 7;
152 if (ALLM < octal_mode)
155 while ('0' <= *mode_string && *mode_string < '8');
160 return make_node_op_equals (octal_to_mode (octal_mode),
161 octal_to_mode (octal_mentioned & ALLM));
164 /* Allocate enough space to hold the result. */
168 for (p = mode_string; *p; p++)
169 needed += (*p == '=' || *p == '+' || *p == '-');
170 mc = xnmalloc (needed, sizeof *mc);
173 /* One loop iteration for each `[ugoa]*([-+=]([rwxXst]*|[ugo]))+'. */
174 for (;; mode_string++)
176 /* Which bits in the mode are operated on. */
179 /* Turn on all the bits in `affected' for each group given. */
180 for (;; mode_string++)
181 switch (*mode_string)
186 affected |= S_ISUID | S_IRWXU;
189 affected |= S_ISGID | S_IRWXG;
192 affected |= S_ISVTX | S_IRWXO;
195 affected |= CHMOD_MODE_BITS;
197 case '=': case '+': case '-':
198 goto no_more_affected;
204 char op = *mode_string++;
206 char flag = MODE_COPY_EXISTING;
207 struct mode_change *change;
209 switch (*mode_string++)
212 /* Set the affected bits to the value of the `u' bits
217 /* Set the affected bits to the value of the `g' bits
222 /* Set the affected bits to the value of the `o' bits
229 flag = MODE_ORDINARY_CHANGE;
231 for (mode_string--;; mode_string++)
232 switch (*mode_string)
235 value |= S_IRUSR | S_IRGRP | S_IROTH;
238 value |= S_IWUSR | S_IWGRP | S_IWOTH;
241 value |= S_IXUSR | S_IXGRP | S_IXOTH;
244 flag = MODE_X_IF_ANY_X;
247 /* Set the setuid/gid bits if `u' or `g' is selected. */
248 value |= S_ISUID | S_ISGID;
251 /* Set the "save text image" bit if `o' is selected. */
260 change = &mc[used++];
263 change->affected = affected;
264 change->value = value;
265 change->mentioned = (affected ? affected & value : value);
267 while (*mode_string == '=' || *mode_string == '+'
268 || *mode_string == '-');
270 if (*mode_string != ',')
274 if (*mode_string == 0)
276 mc[used].flag = MODE_DONE;
285 /* Return a file mode change operation that sets permissions to match those
286 of REF_FILE. Return NULL (setting errno) if REF_FILE can't be accessed. */
289 mode_create_from_ref (const char *ref_file)
291 struct stat ref_stats;
293 if (stat (ref_file, &ref_stats) != 0)
295 return make_node_op_equals (ref_stats.st_mode, CHMOD_MODE_BITS);
298 /* Return the file mode bits of OLDMODE (which is the mode of a
299 directory if DIR), assuming the umask is UMASK_VALUE, adjusted as
300 indicated by the list of change operations CHANGES. If DIR, the
301 type 'X' change affects the returned value even if no execute bits
302 were set in OLDMODE. If PMODE_BITS is not null, store into
303 *PMODE_BITS a mask denoting file mode bits that are affected by
306 The returned value and *PMODE_BITS contain only file mode bits.
307 For example, they have the S_IFMT bits cleared on a standard
311 mode_adjust (mode_t oldmode, bool dir, mode_t umask_value,
312 struct mode_change const *changes, mode_t *pmode_bits)
314 /* The adjusted mode. */
315 mode_t newmode = oldmode & CHMOD_MODE_BITS;
317 /* File mode bits that CHANGES cares about. */
318 mode_t mode_bits = 0;
320 for (; changes->flag != MODE_DONE; changes++)
322 mode_t affected = changes->affected;
324 (dir ? S_ISUID | S_ISGID : 0) & ~ changes->mentioned;
325 mode_t value = changes->value;
327 switch (changes->flag)
329 case MODE_ORDINARY_CHANGE:
332 case MODE_COPY_EXISTING:
333 /* Isolate in `value' the bits in `newmode' to copy. */
336 /* Copy the isolated bits to the other two parts. */
337 value |= ((value & (S_IRUSR | S_IRGRP | S_IROTH)
338 ? S_IRUSR | S_IRGRP | S_IROTH : 0)
339 | (value & (S_IWUSR | S_IWGRP | S_IWOTH)
340 ? S_IWUSR | S_IWGRP | S_IWOTH : 0)
341 | (value & (S_IXUSR | S_IXGRP | S_IXOTH)
342 ? S_IXUSR | S_IXGRP | S_IXOTH : 0));
345 case MODE_X_IF_ANY_X:
346 /* Affect the execute bits if execute bits are already set
347 or if the file is a directory. */
348 if ((newmode & (S_IXUSR | S_IXGRP | S_IXOTH)) | dir)
349 value |= S_IXUSR | S_IXGRP | S_IXOTH;
353 /* If WHO was specified, limit the change to the affected bits.
354 Otherwise, apply the umask. Either way, omit changes as
356 value &= (affected ? affected : ~umask_value) & ~ omit_change;
361 /* If WHO was specified, preserve the previous values of
362 bits that are not affected by this change operation.
363 Otherwise, clear all the bits. */
365 mode_t preserved = (affected ? ~affected : 0) | omit_change;
366 mode_bits |= CHMOD_MODE_BITS & ~preserved;
367 newmode = (newmode & preserved) | value;
384 *pmode_bits = mode_bits;