#!/usr/bin/perl
#
# $Id: showhdr,v 1.1 1998/01/30 20:42:20 vogelke Exp $
#
# NAME:
#	showhdr
#
# SYNOPSIS:
#	showhdr [-v] files
#
# DESCRIPTION:
#	"showhdr" is a program to display the first 8 bytes from each file;
#	we can use to figure out the filetype.
#
# OPTIONS:
#	"-v" prints the current version and exits.
#
# EXAMPLE:
#	% showhdr *.doc
#	chklst.doc:	0xd0cf11e0	d0cf 11e0 a1b1 1ae1
#	datetest.doc:	0xd0cf11e0	d0cf 11e0 a1b1 1ae1
#	netver21.doc:	0xd0cf11e0	d0cf 11e0 a1b1 1ae1
#	nyconfsm.doc:	0xdba52d00	dba5 2d00 0000 0904
#	phases.doc:	0xd0cf11e0	d0cf 11e0 a1b1 1ae1
#	readines.doc:	0xd0cf11e0	d0cf 11e0 a1b1 1ae1
#	vendrev.doc:	0xd0cf11e0	d0cf 11e0 a1b1 1ae1
#	y2ktools.doc:	0x31be0000	31be 0000 00ab 0000
#
# AUTHOR:
#	Karl Vogel <vogelke@c17.com>
#	Sumaria Systems, Inc.

eval 'exec perl -S $0 ${1+"$@"}'    # If the shell can't handle "#!",
  if 0;                             # fire up perl directly.

require "getopts.pl";               # command line args.

$ENV{"PATH"} = "/bin:/usr/sbin:/usr/local/bin";
$tmp = "/tmp/showhdr.$$";
($myname) = split(/\//, reverse($0));
$myname = reverse($myname);         # script basename.

#
# Trap most common signals.  Handle command line arguments (if any).
#

$SIG{'HUP'}  = 'sigcatcher';
$SIG{'INT'}  = 'sigcatcher';
$SIG{'QUIT'} = 'sigcatcher';
$SIG{'TERM'} = 'sigcatcher';

&usage unless &Getopts('v');
&version if $opt_v;

while ($file = shift(@ARGV)) {
    open(IN, "$file") || die "$file: $!\n";
    read(IN, $buf, 8);
    close(IN);

    @s     = unpack("H4" x 4, $buf);
    $first = unpack("H8",     $buf);
    print "$file:\t0x$first\t@s\n";
}

&exit(0);

#---------------------------------------------------------------------
#	Print a short usage message from the comment header and exit.
#

sub usage {
    if (open(PROG, "$myname")) {
        while (<PROG>) {
            last if /^# NAME:/;
        }

        print STDERR " NAME:\n";

        while (<PROG>) {
            last if /^\s*$/;
            last if /^# AUTHOR:/;
            s/^#//;
            print STDERR;
        }

        close(PROG);
    }
    else {
        print STDERR "No usage information available.\n";
    }

    &exit(1);
}

#---------------------------------------------------------------------
#	Do something if we get a signal.
#

sub sigcatcher {
    local ($sig) = @_;
    &exit(2, "caught signal SIG$sig -- shutting down.\n");
}

#---------------------------------------------------------------------
#	Print the current version and exit.
#

sub version {
    $_ = '$RCSfile: showhdr,v $ $Revision: 1.1 $ '
      . '$Date: 1998/01/30 20:42:20 $';

    s/RCSfile: //;
    s/.Date: //;
    s/,v . .Revision: /  v/;
    s/\$//g;

    print "$_\n";
    exit(0);
}

#---------------------------------------------------------------------
#	Clean up.
#

sub exit {
    local ($code, $msg) = @_;
    unlink($tmp);

    warn "$myname: $msg\n" if $msg;
    exit($code);
}