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

use Getopt::Long;

(my $VERSION = '$Revision: 1.3 $ ') =~ 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:

  Derive #define directives from specially formatted `case ...:' statements.

   --help             display this help and exit
   --version          output version information and exit

EOF
    }
  exit $exit_code;
}

{
  GetOptions
    (
     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.

  print <<EOF;
/* Define the magic numbers as given by statfs(2).
   Please send additions to meskes\@debian.org.
   This file is generated automatically from $file. */

#if defined __linux__
EOF

  while (defined (my $line = <FH>))
    {
      $line =~ /^[ \t]+case S_MAGIC_/
	or next;
      $line =~ m!^[ \t]+case (S_MAGIC_\w+): /\* (0x[0-9A-Fa-f]+) \*/$!
	or (warn "$ME:$file:$.: malformed case S_MAGIC_... line"),
	  $fail = 1, next;
      my $name = $1;
      my $value = $2;
      print "# define $name $value\n";
    }

  print <<\EOF;
#elif defined __GNU__
# include <hurd/hurd_types.h>
#endif
EOF
  close FH;

  exit $fail;
}