builtins/umask.def

   1 This file is umask.def, from which is created umask.c.
   2 It implements the builtin "umask" in Bash.
   3
   4 Copyright (C) 1987, 1989, 1991 Free Software Foundation, Inc.
   5
   6 This file is part of GNU Bash, the Bourne Again SHell.
   7
   8 Bash is free software; you can redistribute it and/or modify it under
   9 the terms of the GNU General Public License as published by the Free
  10 Software Foundation; either version 2, or (at your option) any later
  11 version.
  12
  13 Bash is distributed in the hope that it will be useful, but WITHOUT ANY
  14 WARRANTY; without even the implied warranty of MERCHANTABILITY or
  15 FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  16 for more details.
  17
  18 You should have received a copy of the GNU General Public License along
  19 with Bash; see the file COPYING.  If not, write to the Free Software
  20 Foundation, 59 Temple Place, Suite 330, Boston, MA 02111 USA.
  21
  22 $PRODUCES umask.c
  23
  24 $BUILTIN umask
  25 $FUNCTION umask_builtin
  26 $SHORT_DOC umask [-p] [-S] [mode]
  27 The user file-creation mask is set to MODE.  If MODE is omitted, or if
  28 `-S' is supplied, the current value of the mask is printed.  The `-S'
  29 option makes the output symbolic; otherwise an octal number is output.
  30 If `-p' is supplied, and MODE is omitted, the output is in a form
  31 that may be used as input.  If MODE begins with a digit, it is
  32 interpreted as an octal number, otherwise it is a symbolic mode string
  33 like that accepted by chmod(1).
  34 $END
  35
  36 #include <config.h>
  37
  38 #include "../bashtypes.h"
  39 #include "filecntl.h"
  40 #ifndef _MINIX
  41 #  include <sys/file.h>
  42 #endif
  43
  44 #if defined (HAVE_UNISTD_H)
  45 #include <unistd.h>
  46 #endif
  47
  48 #include <stdio.h>
  49
  50 #include "../shell.h"
  51 #include "posixstat.h"
  52 #include "common.h"
  53 #include "bashgetopt.h"
  54
  55 /* **************************************************************** */
  56 /*                                                                  */
  57 /*                     UMASK Builtin and Helpers                    */
  58 /*                                                                  */
  59 /* **************************************************************** */
  60
  61 static void print_symbolic_umask ();
  62 static int symbolic_umask ();
  63
  64 /* Set or display the mask used by the system when creating files.  Flag
  65    of -S means display the umask in a symbolic mode. */
  66 int
  67 umask_builtin (list)
  68      WORD_LIST *list;
  69 {
  70   int print_symbolically, opt, umask_value, pflag;
  71   mode_t umask_arg;
  72
  73   print_symbolically = pflag = 0;
  74   reset_internal_getopt ();
  75   while ((opt = internal_getopt (list, "Sp")) != -1)
  76     {
  77       switch (opt)
  78         {
  79         case 'S':
  80           print_symbolically++;
  81           break;
  82         case 'p':
  83           pflag++;
  84           break;
  85         default:
  86           builtin_usage ();
  87           return (EX_USAGE);
  88         }
  89     }
  90
  91   list = loptend;
  92
  93   if (list)
  94     {
  95       if (digit (*list->word->word))
  96         {
  97           umask_value = read_octal (list->word->word);
  98
  99           /* Note that other shells just let you set the umask to zero
 100              by specifying a number out of range.  This is a problem
 101              with those shells.  We don't change the umask if the input
 102              is lousy. */
 103           if (umask_value == -1)
 104             {
 105               builtin_error ("`%s' is not an octal number from 000 to 777",
 106                                 list->word->word);
 107               return (EXECUTION_FAILURE);
 108             }
 109         }
 110       else
 111         {
 112           umask_value = symbolic_umask (list);
 113           if (umask_value == -1)
 114             return (EXECUTION_FAILURE);
 115         }
 116       umask_arg = (mode_t)umask_value;
 117       umask (umask_arg);
 118       if (print_symbolically)
 119         print_symbolic_umask (umask_arg);
 120     }
 121   else                          /* Display the UMASK for this user. */
 122     {
 123       umask_arg = umask (022);
 124       umask (umask_arg);
 125
 126       if (pflag)
 127         printf ("umask%s ", (print_symbolically ? " -S" : ""));
 128       if (print_symbolically)
 129         print_symbolic_umask (umask_arg);
 130       else
 131         printf ("%03o\n", umask_arg);
 132     }
 133
 134   fflush (stdout);
 135   return (EXECUTION_SUCCESS);
 136 }
 137
 138 /* Print the umask in a symbolic form.  In the output, a letter is
 139    printed if the corresponding bit is clear in the umask. */
 140 static void
 141 print_symbolic_umask (um)
 142      mode_t um;
 143 {
 144   char ubits[4], gbits[4], obits[4];            /* u=rwx,g=rwx,o=rwx */
 145   int i;
 146
 147   i = 0;
 148   if ((um & S_IRUSR) == 0)
 149     ubits[i++] = 'r';
 150   if ((um & S_IWUSR) == 0)
 151     ubits[i++] = 'w';
 152   if ((um & S_IXUSR) == 0)
 153     ubits[i++] = 'x';
 154   ubits[i] = '\0';
 155
 156   i = 0;
 157   if ((um & S_IRGRP) == 0)
 158     gbits[i++] = 'r';
 159   if ((um & S_IWGRP) == 0)
 160     gbits[i++] = 'w';
 161   if ((um & S_IXGRP) == 0)
 162     gbits[i++] = 'x';
 163   gbits[i] = '\0';
 164
 165   i = 0;
 166   if ((um & S_IROTH) == 0)
 167     obits[i++] = 'r';
 168   if ((um & S_IWOTH) == 0)
 169     obits[i++] = 'w';
 170   if ((um & S_IXOTH) == 0)
 171     obits[i++] = 'x';
 172   obits[i] = '\0';
 173
 174   printf ("u=%s,g=%s,o=%s\n", ubits, gbits, obits);
 175 }
 176
 177 int
 178 parse_symbolic_mode (mode, initial_bits)
 179      char *mode;
 180      int initial_bits;
 181 {
 182   int who, op, perm, mask, bits, c;
 183   char *s;
 184
 185   for (s = mode, bits = initial_bits;;)
 186     {
 187       who = op = perm = mask = 0;
 188
 189       /* Parse the `who' portion of the symbolic mode clause. */
 190       while (member (*s, "agou"))
 191         {
 192           switch (c = *s++)
 193             {
 194             case 'u':
 195               who |= S_IRWXU;
 196               continue;
 197             case 'g':
 198               who |= S_IRWXG;
 199               continue;
 200             case 'o':
 201               who |= S_IRWXO;
 202               continue;
 203             case 'a':
 204               who |= S_IRWXU | S_IRWXG | S_IRWXO;
 205               continue;
 206             default:
 207               break;
 208             }
 209         }
 210
 211       /* The operation is now sitting in *s. */
 212       op = *s++;
 213       switch (op)
 214         {
 215         case '+':
 216         case '-':
 217         case '=':
 218           break;
 219         default:
 220           builtin_error ("bad symbolic mode operator: %c", op);
 221           return (-1);
 222         }
 223
 224       /* Parse out the `perm' section of the symbolic mode clause. */
 225       while (member (*s, "rwx"))
 226         {
 227           c = *s++;
 228
 229           switch (c)
 230             {
 231             case 'r':
 232               perm |= S_IRUGO;
 233               break;
 234             case 'w':
 235               perm |= S_IWUGO;
 236               break;
 237             case 'x':
 238               perm |= S_IXUGO;
 239               break;
 240             }
 241         }
 242
 243       /* Now perform the operation or return an error for a
 244          bad permission string. */
 245       if (!*s || *s == ',')
 246         {
 247           if (who)
 248             perm &= who;
 249
 250           switch (op)
 251             {
 252             case '+':
 253               bits |= perm;
 254               break;
 255             case '-':
 256               bits &= ~perm;
 257               break;
 258             case '=':
 259               bits &= ~who;
 260               bits |= perm;
 261               break;
 262
 263             /* No other values are possible. */
 264             }
 265
 266           if (*s == '\0')
 267             break;
 268           else
 269             s++;        /* skip past ',' */
 270         }
 271       else
 272         {
 273           builtin_error ("bad character in symbolic mode: %c", *s);
 274           return (-1);
 275         }
 276     }
 277
 278   return (bits);
 279 }
 280
 281 /* Set the umask from a symbolic mode string similar to that accepted
 282    by chmod.  If the -S argument is given, then print the umask in a
 283    symbolic form. */
 284 static int
 285 symbolic_umask (list)
 286      WORD_LIST *list;
 287 {
 288   int um, bits;
 289
 290   /* Get the initial umask.  Don't change it yet. */
 291   um = umask (022);
 292   umask (um);
 293
 294   /* All work is done with the complement of the umask -- it's
 295      more intuitive and easier to deal with.  It is complemented
 296      again before being returned. */
 297   bits = parse_symbolic_mode (list->word->word, ~um);
 298   if (bits == -1)
 299     return (-1);
 300
 301   um = ~bits & 0777;
 302   return (um);
 303 }