coreutils/src/extract-magic

#!/usr/bin/perl -w
# Derive #define directives from specially formatted 'case ...:' statements.

# Copyright (C) 2003-2012 Free Software Foundation, Inc.

# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.

# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.

# You should have received a copy of the GNU General Public License
# along with this program.  If not, see <http://www.gnu.org/licenses/>.

use strict;

use Getopt::Long;

(my $VERSION = '$Revision: 1.5 $ ') =~ tr/[0-9].//cd;
(my $ME = $0) =~ s|.*/||;

END
{
  # Nobody ever checks the status of print()s.  That's okay, because
  # if any do fail, we're guaranteed to get an indicator when we close()
  # the filehandle.
  #
  # Close stdout now, and if there were no errors, return happy status.
  # If stdout has already been closed by the script, though, do nothing.
  defined fileno STDOUT
    or return;
  close STDOUT
    and return;

  # Errors closing stdout.  Indicate that, and hope stderr is OK.
  warn "$ME: closing standard output: $!\n";

  # Don't be so arrogant as to assume that we're the first END handler
  # defined, and thus the last one invoked.  There may be others yet
  # to come.  $? will be passed on to them, and to the final _exit().
  #
  # If it isn't already an error, make it one (and if it _is_ an error,
  # preserve the value: it might be important).
  $? ||= 1;
}

sub usage ($)
{
  my ($exit_code) = @_;
  my $STREAM = ($exit_code == 0 ? *STDOUT : *STDERR);
  if ($exit_code != 0)
    {
      print $STREAM "Try '$ME --help' for more information.\n";
    }
  else
    {
      print $STREAM <<EOF;
Usage: $ME [OPTIONS] FILE

FIXME: describe

OPTIONS:

  There are two modes of operation, the default, which is to emit
  #define directives derived from specially formatted 'case' statements,
  and that with --local, which is to emit a static inline function
  mapping S_MAGIC_* values to 1, 0, -1, corresponding to known-local,
  known-remote/distributed/network and unknown, respectively.

   --local    emit an is_local_fs_type function
   --help     display this help and exit
   --version  output version information and exit

EOF
    }
  exit $exit_code;
}

{
  # The default is to print S_MAGIC_* definitions.
  my $emit_magic = 1;

  GetOptions
    (
     local => sub { $emit_magic = 0 },
     help => sub { usage 0 },
     version => sub { print "$ME version $VERSION\n"; exit },
    ) or usage 1;

  my $fail = 0;

  @ARGV < 1
    and (warn "$ME: missing FILE arguments\n"), $fail = 1;
  1 < @ARGV
    and (warn "$ME: too many arguments\n"), $fail = 1;
  $fail
    and usage 1;

  my $file = $ARGV[0];

  open FH, $file
    or die "$ME: can't open '$file' for reading: $!\n";

  # For each line like this:
  #   case S_MAGIC_ROMFS: /* 0x7275 */
  # emit one like this:
  #   # define S_MAGIC_ROMFS 0x7275
  # Fail if there is a 'case S_MAGIC_.*' line without
  # a properly formed comment.

  my $map_comment = <<EOF;
/* Map each S_MAGIC_* value to 1, 0 or -1.
   1 if it is known to be a remote file system type,
   0 if it is known to be a local file system type, or -1 otherwise.  */
EOF
  my $magic_comment = <<EOF;
/* Define the magic numbers as given by statfs(2).
   Please send additions to bug-coreutils\@gnu.org and meskes\@debian.org.
   This file is generated automatically from $file. */
EOF
  print $emit_magic ? $magic_comment : $map_comment;

  $emit_magic
    and print "\n#if defined __linux__\n";
  $emit_magic
    or print "static inline int\n"
      . "is_local_fs_type (unsigned long int magic)\n"
      . "{\n  switch (magic)\n    {\n";

  while (defined (my $line = <FH>))
    {
      $line =~ /^[ \t]+case S_MAGIC_/
        or next;
      $line =~
        m!^[ \t]+case (S_MAGIC_\w+): /\* (0x[0-9A-Fa-f]+) (local|remote) \*/!
        or (warn "$ME:$file:$.: malformed case S_MAGIC_... line"),
          $fail = 1, next;
      my $name = $1;
      my $magic = $2;
      my $local = $3 eq 'local' ? 1 : 0;
      print $emit_magic
        ? "# define $name $magic\n"
        : "      case $name: return $local;\n";
    }

  $emit_magic
    and print <<\EOF;
#elif defined __GNU__
# include <hurd/hurd_types.h>
#endif
EOF
  $emit_magic
    or printf "      default: return -1;\n    }\n}\n";

  close FH;

  exit $fail;
}