libbb/parse_mode.c

   1 /* vi: set sw=4 ts=4: */
   2 /*
   3  * Utility routines.
   4  *
   5  * Copyright (C) many different people.  If you wrote this, please
   6  * acknowledge your work.
   7  *
   8  * This program is free software; you can redistribute it and/or modify
   9  * it under the terms of the GNU General Public License as published by
  10  * the Free Software Foundation; either version 2 of the License, or
  11  * (at your option) any later version.
  12  *
  13  * This program is distributed in the hope that it will be useful, but
  14  * WITHOUT ANY WARRANTY; without even the implied warranty of
  15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  16  * General Public License for more details.
  17  *
  18  * You should have received a copy of the GNU General Public License
  19  * along with this program; if not, write to the Free Software
  20  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307
  21  * USA
  22  */
  23
  24 #include <stdio.h>
  25 #include <stdlib.h>
  26 #include "libbb.h"
  27
  28 /* This function parses the sort of string you might pass
  29  * to chmod (i.e., [ugoa]{+|-|=}[rwxst] ) and returns the
  30  * correct mode described by the string. */
  31 extern int parse_mode(const char *s, mode_t * theMode)
  32 {
  33         static const mode_t group_set[] = {
  34                 S_ISUID | S_IRWXU,      /* u */
  35                 S_ISGID | S_IRWXG,      /* g */
  36                 S_IRWXO,        /* o */
  37                 S_ISUID | S_ISGID | S_ISVTX | S_IRWXU | S_IRWXG | S_IRWXO       /* a */
  38         };
  39
  40         static const mode_t mode_set[] = {
  41                 S_IRUSR | S_IRGRP | S_IROTH,    /* r */
  42                 S_IWUSR | S_IWGRP | S_IWOTH,    /* w */
  43                 S_IXUSR | S_IXGRP | S_IXOTH,    /* x */
  44                 S_ISUID | S_ISGID,      /* s */
  45                 S_ISVTX         /* t */
  46         };
  47
  48         static const char group_chars[] = "ugoa";
  49         static const char mode_chars[] = "rwxst";
  50
  51         const char *p;
  52
  53         mode_t andMode =
  54             S_ISVTX | S_ISUID | S_ISGID | S_IRWXU | S_IRWXG | S_IRWXO;
  55         mode_t orMode = 0;
  56         mode_t mode;
  57         mode_t groups;
  58         char type;
  59         char c;
  60
  61         if (s == NULL) {
  62                 return (FALSE);
  63         }
  64
  65         do {
  66                 mode = 0;
  67                 groups = 0;
  68 NEXT_GROUP:
  69                 if ((c = *s++) == '\0') {
  70                         return -1;
  71                 }
  72                 for (p = group_chars; *p; p++) {
  73                         if (*p == c) {
  74                                 groups |= group_set[(int)(p - group_chars)];
  75                                 goto NEXT_GROUP;
  76                         }
  77                 }
  78                 switch (c) {
  79                 case '=':
  80                 case '+':
  81                 case '-':
  82                         type = c;
  83                         if (groups == 0) {      /* The default is "all" */
  84                                 groups |= S_ISUID | S_ISGID | S_ISVTX
  85                                     | S_IRWXU | S_IRWXG | S_IRWXO;
  86                         }
  87                         break;
  88                 default:
  89                         if ((c < '0') || (c > '7') || (mode | groups)) {
  90                                 return (FALSE);
  91                         } else {
  92                                 *theMode = strtol(--s, NULL, 8);
  93                                 return (TRUE);
  94                         }
  95                 }
  96
  97 NEXT_MODE:
  98                 if (((c = *s++) != '\0') && (c != ',')) {
  99                         for (p = mode_chars; *p; p++) {
 100                                 if (*p == c) {
 101                                         mode |= mode_set[(int)(p - mode_chars)];
 102                                         goto NEXT_MODE;
 103                                 }
 104                         }
 105                         break;  /* We're done so break out of loop. */
 106                 }
 107                 switch (type) {
 108                 case '=':
 109                         andMode &= ~(groups);   /* Now fall through. */
 110                 case '+':
 111                         orMode |= mode & groups;
 112                         break;
 113                 case '-':
 114                         andMode &= ~(mode & groups);
 115                         orMode &= ~(mode & groups);
 116                         break;
 117                 }
 118         } while (c == ',');
 119
 120         *theMode &= andMode;
 121         *theMode |= orMode;
 122
 123         return TRUE;
 124 }
 125
 126 /* END CODE */
 127 /*
 128 Local Variables:
 129 c-file-style: "linux"
 130 c-basic-offset: 4
 131 tab-width: 4
 132 End:
 133 */