src/extract-magic

   1 #!/usr/bin/perl -w
   2 # Derive #define directives from specially formatted 'case ...:' statements.
   3
   4 # Copyright (C) 2003-2023 Free Software Foundation, Inc.
   5
   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 3 of the License, or
   9 # (at your option) any later version.
  10
  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.
  15
  16 # You should have received a copy of the GNU General Public License
  17 # along with this program.  If not, see <https://www.gnu.org/licenses/>.
  18
  19 use strict;
  20
  21 use Getopt::Long;
  22
  23 (my $VERSION = '$Revision: 1.5 $ ') =~ tr/[0-9].//cd;
  24 (my $ME = $0) =~ s|.*/||;
  25
  26 END
  27 {
  28   # Nobody ever checks the status of print()s.  That's okay, because
  29   # if any do fail, we're guaranteed to get an indicator when we close()
  30   # the filehandle.
  31   #
  32   # Close stdout now, and if there were no errors, return happy status.
  33   # If stdout has already been closed by the script, though, do nothing.
  34   defined fileno STDOUT
  35     or return;
  36   close STDOUT
  37     and return;
  38
  39   # Errors closing stdout.  Indicate that, and hope stderr is OK.
  40   warn "$ME: closing standard output: $!\n";
  41
  42   # Don't be so arrogant as to assume that we're the first END handler
  43   # defined, and thus the last one invoked.  There may be others yet
  44   # to come.  $? will be passed on to them, and to the final _exit().
  45   #
  46   # If it isn't already an error, make it one (and if it _is_ an error,
  47   # preserve the value: it might be important).
  48   $? ||= 1;
  49 }
  50
  51 sub usage ($)
  52 {
  53   my ($exit_code) = @_;
  54   my $STREAM = ($exit_code == 0 ? *STDOUT : *STDERR);
  55   if ($exit_code != 0)
  56     {
  57       print $STREAM "Try '$ME --help' for more information.\n";
  58     }
  59   else
  60     {
  61       print $STREAM <<EOF;
  62 Usage: $ME [OPTIONS] FILE
  63
  64 FIXME: describe
  65
  66 OPTIONS:
  67
  68   There are two modes of operation, the default, which is to emit
  69   #define directives derived from specially formatted 'case' statements,
  70   and that with --local, which is to emit a static inline function
  71   mapping S_MAGIC_* values to 1, 0, -1, corresponding to known-local,
  72   known-remote/distributed/network and unknown, respectively.
  73
  74    --local    emit an is_local_fs_type function
  75    --help     display this help and exit
  76    --version  output version information and exit
  77
  78 EOF
  79     }
  80   exit $exit_code;
  81 }
  82
  83 {
  84   # The default is to print S_MAGIC_* definitions.
  85   my $emit_magic = 1;
  86
  87   GetOptions
  88     (
  89      local => sub { $emit_magic = 0 },
  90      help => sub { usage 0 },
  91      version => sub { print "$ME version $VERSION\n"; exit },
  92     ) or usage 1;
  93
  94   my $fail = 0;
  95
  96   @ARGV < 1
  97     and (warn "$ME: missing FILE arguments\n"), $fail = 1;
  98   1 < @ARGV
  99     and (warn "$ME: too many arguments\n"), $fail = 1;
 100   $fail
 101     and usage 1;
 102
 103   my $file = $ARGV[0];
 104
 105   open FH, $file
 106     or die "$ME: can't open '$file' for reading: $!\n";
 107
 108   # For each line like this:
 109   #   case S_MAGIC_ROMFS: /* 0x7275 */
 110   # emit one like this:
 111   #   # define S_MAGIC_ROMFS 0x7275
 112   # Fail if there is a 'case S_MAGIC_.*' line without
 113   # a properly formed comment.
 114
 115   my $map_comment = <<EOF;
 116 /* Map each S_MAGIC_* value to 1, 0 or -1.
 117    1 if it is known to be a remote file system type,
 118    0 if it is known to be a local file system type, or -1 otherwise.  */
 119 EOF
 120   my $magic_comment = <<EOF;
 121 /* Define the magic numbers as given by statfs(2).
 122    Please send additions to bug-coreutils\@gnu.org and meskes\@debian.org.
 123    This file is generated automatically from $file. */
 124 EOF
 125   print $emit_magic ? $magic_comment : $map_comment;
 126
 127   $emit_magic
 128     and print "\n#if defined __linux__ || defined __ANDROID__\n";
 129   $emit_magic
 130     or print "static inline int\n"
 131       . "is_local_fs_type (unsigned long int magic)\n"
 132       . "{\n  switch (magic)\n    {\n";
 133
 134   while (defined (my $line = <FH>))
 135     {
 136       $line =~ /^[ \t]+case S_MAGIC_/
 137         or next;
 138       $line =~
 139         m!^[ \t]+case (S_MAGIC_\w+): /\* (0x[0-9A-Fa-f]+) (local|remote) \*/!
 140         or (warn "$ME:$file:$.: malformed case S_MAGIC_... line"),
 141           $fail = 1, next;
 142       my $name = $1;
 143       my $magic = $2;
 144       my $local = $3 eq 'local' ? 1 : 0;
 145       print $emit_magic
 146         ? "# define $name $magic\n"
 147         : "      case $name: return $local;\n";
 148     }
 149
 150   $emit_magic
 151     and print <<\EOF;
 152 #elif defined __GNU__
 153 # include <hurd/hurd_types.h>
 154 #endif
 155 EOF
 156   $emit_magic
 157     or printf "      default: return -1;\n    }\n}\n";
 158
 159   close FH;
 160
 161   exit $fail;
 162 }