Mini Shell
#!/usr/bin/perl
## shasum: filter for computing SHA digests (ref. sha1sum/md5sum)
##
## Copyright (C) 2003-2018 Mark Shelor, All Rights Reserved
##
## Version: 6.02
## Fri Apr 20 16:25:30 MST 2018
## shasum SYNOPSIS adapted from GNU Coreutils sha1sum. Add
## "-a" option for algorithm selection,
## "-U" option for Universal Newlines support, and
## "-0" option for reading bit strings.
BEGIN { pop @INC if $INC[-1] eq '.' }
use strict;
use warnings;
use Fcntl;
use Getopt::Long;
use Digest::SHA qw($errmsg);
my $POD = <<'END_OF_POD';
=head1 NAME
shasum - Print or Check SHA Checksums
=head1 SYNOPSIS
Usage: shasum [OPTION]... [FILE]...
Print or check SHA checksums.
With no FILE, or when FILE is -, read standard input.
-a, --algorithm 1 (default), 224, 256, 384, 512, 512224, 512256
-b, --binary read in binary mode
-c, --check read SHA sums from the FILEs and check them
--tag create a BSD-style checksum
-t, --text read in text mode (default)
-U, --UNIVERSAL read in Universal Newlines mode
produces same digest on Windows/Unix/Mac
-0, --01 read in BITS mode
ASCII '0' interpreted as 0-bit,
ASCII '1' interpreted as 1-bit,
all other characters ignored
The following five options are useful only when verifying checksums:
--ignore-missing don't fail or report status for missing files
-q, --quiet don't print OK for each successfully verified file
-s, --status don't output anything, status code shows success
--strict exit non-zero for improperly formatted checksum lines
-w, --warn warn about improperly formatted checksum lines
-h, --help display this help and exit
-v, --version output version information and exit
When verifying SHA-512/224 or SHA-512/256 checksums, indicate the
algorithm explicitly using the -a option, e.g.
shasum -a 512224 -c checksumfile
The sums are computed as described in FIPS PUB 180-4. When checking,
the input should be a former output of this program. The default
mode is to print a line with checksum, a character indicating type
(`*' for binary, ` ' for text, `U' for UNIVERSAL, `^' for BITS),
and name for each FILE. The line starts with a `\' character if the
FILE name contains either newlines or backslashes, which are then
replaced by the two-character sequences `\n' and `\\' respectively.
Report shasum bugs to mshelor@cpan.org
=head1 DESCRIPTION
Running I<shasum> is often the quickest way to compute SHA message
digests. The user simply feeds data to the script through files or
standard input, and then collects the results from standard output.
The following command shows how to compute digests for typical inputs
such as the NIST test vector "abc":
perl -e "print qq(abc)" | shasum
Or, if you want to use SHA-256 instead of the default SHA-1, simply say:
perl -e "print qq(abc)" | shasum -a 256
Since I<shasum> mimics the behavior of the combined GNU I<sha1sum>,
I<sha224sum>, I<sha256sum>, I<sha384sum>, and I<sha512sum> programs,
you can install this script as a convenient drop-in replacement.
Unlike the GNU programs, I<shasum> encompasses the full SHA standard by
allowing partial-byte inputs. This is accomplished through the BITS
option (I<-0>). The following example computes the SHA-224 digest of
the 7-bit message I<0001100>:
perl -e "print qq(0001100)" | shasum -0 -a 224
=head1 AUTHOR
Copyright (C) 2003-2018 Mark Shelor <mshelor@cpan.org>.
=head1 SEE ALSO
I<shasum> is implemented using the Perl module L<Digest::SHA>.
=cut
END_OF_POD
my $VERSION = "6.02";
sub usage {
my($err, $msg) = @_;
$msg = "" unless defined $msg;
if ($err) {
warn($msg . "Type shasum -h for help\n");
exit($err);
}
my($USAGE) = $POD =~ /SYNOPSIS(.+?)^=/sm;
$USAGE =~ s/^\s*//;
$USAGE =~ s/\s*$//;
$USAGE =~ s/^ //gm;
print $USAGE, "\n";
exit($err);
}
## Sync stdout and stderr by forcing a flush after every write
select((select(STDOUT), $| = 1)[0]);
select((select(STDERR), $| = 1)[0]);
## Collect options from command line
my ($alg, $binary, $check, $text, $status, $quiet, $warn, $help);
my ($version, $BITS, $UNIVERSAL, $tag, $strict, $ignore_missing);
eval { Getopt::Long::Configure ("bundling") };
GetOptions(
'b|binary' => \$binary, 'c|check' => \$check,
't|text' => \$text, 'a|algorithm=i' => \$alg,
's|status' => \$status, 'w|warn' => \$warn,
'q|quiet' => \$quiet,
'h|help' => \$help, 'v|version' => \$version,
'0|01' => \$BITS,
'U|UNIVERSAL' => \$UNIVERSAL,
'tag' => \$tag,
'strict' => \$strict,
'ignore-missing' => \$ignore_missing,
) or usage(1, "");
## Deal with help requests and incorrect uses
usage(0)
if $help;
usage(1, "shasum: Ambiguous file mode\n")
if scalar(grep {defined $_}
($binary, $text, $BITS, $UNIVERSAL)) > 1;
usage(1, "shasum: --warn option used only when verifying checksums\n")
if $warn && !$check;
usage(1, "shasum: --status option used only when verifying checksums\n")
if $status && !$check;
usage(1, "shasum: --quiet option used only when verifying checksums\n")
if $quiet && !$check;
usage(1, "shasum: --ignore-missing option used only when verifying checksums\n")
if $ignore_missing && !$check;
usage(1, "shasum: --strict option used only when verifying checksums\n")
if $strict && !$check;
usage(1, "shasum: --tag does not support --text mode\n")
if $tag && $text;
usage(1, "shasum: --tag does not support Universal Newlines mode\n")
if $tag && $UNIVERSAL;
usage(1, "shasum: --tag does not support BITS mode\n")
if $tag && $BITS;
## Default to SHA-1 unless overridden by command line option
my %isAlg = map { $_ => 1 } (1, 224, 256, 384, 512, 512224, 512256);
$alg = 1 unless defined $alg;
usage(1, "shasum: Unrecognized algorithm\n") unless $isAlg{$alg};
my %Tag = map { $_ => "SHA$_" } (1, 224, 256, 384, 512);
$Tag{512224} = "SHA512/224";
$Tag{512256} = "SHA512/256";
## Display version information if requested
if ($version) {
print "$VERSION\n";
exit(0);
}
## Try to figure out if the OS is DOS-like. If it is,
## default to binary mode when reading files, unless
## explicitly overridden by command line "--text" or
## "--UNIVERSAL" options.
my $isDOSish = ($^O =~ /^(MSWin\d\d|os2|dos|mint|cygwin)$/);
if ($isDOSish) { $binary = 1 unless $text || $UNIVERSAL }
my $modesym = $binary ? '*' : ($UNIVERSAL ? 'U' : ($BITS ? '^' : ' '));
## Read from STDIN (-) if no files listed on command line
@ARGV = ("-") unless @ARGV;
## sumfile($file): computes SHA digest of $file
sub sumfile {
my $file = shift;
my $mode = $binary ? 'b' : ($UNIVERSAL ? 'U' : ($BITS ? '0' : ''));
my $digest = eval { Digest::SHA->new($alg)->addfile($file, $mode) };
if ($@) { warn "shasum: $file: $errmsg\n"; return }
$digest->hexdigest;
}
## %len2alg: maps hex digest length to SHA algorithm
my %len2alg = (40 => 1, 56 => 224, 64 => 256, 96 => 384, 128 => 512);
$len2alg{56} = 512224 if $alg == 512224;
$len2alg{64} = 512256 if $alg == 512256;
## unescape: convert backslashed filename to plain filename
sub unescape {
$_ = shift;
s/\\\\/\0/g;
s/\\n/\n/g;
s/\0/\\/g;
return $_;
}
## verify: confirm the digest values in a checksum file
sub verify {
my $checkfile = shift;
my ($err, $fmt_errs, $read_errs, $match_errs) = (0, 0, 0, 0);
my ($num_fmt_OK, $num_OK) = (0, 0);
my ($bslash, $sum, $fname, $rsp, $digest, $isOK);
local *FH;
$checkfile eq '-' and open(FH, '< -')
and $checkfile = 'standard input'
or sysopen(FH, $checkfile, O_RDONLY)
or die "shasum: $checkfile: $!\n";
while (<FH>) {
next if /^#/;
if (/^[ \t]*\\?SHA/) {
$modesym = '*';
($bslash, $alg, $fname, $sum) =
/^[ \t]*(\\?)SHA(\S+) \((.+)\) = ([\da-fA-F]+)/;
$alg =~ tr{/}{}d if defined $alg;
}
else {
($bslash, $sum, $modesym, $fname) =
/^[ \t]*(\\?)([\da-fA-F]+)[ \t]([ *^U])(.+)/;
$alg = defined $sum ? $len2alg{length($sum)} : undef;
}
if (grep { ! defined $_ } ($alg, $sum, $modesym, $fname) or
! $isAlg{$alg}) {
warn("shasum: $checkfile: $.: improperly " .
"formatted SHA checksum line\n") if $warn;
$fmt_errs++;
$err = 1 if $strict;
next;
}
$num_fmt_OK++;
$fname = unescape($fname) if $bslash;
next if $ignore_missing && ! -e $fname;
$rsp = "$fname: ";
($binary, $text, $UNIVERSAL, $BITS) =
map { $_ eq $modesym } ('*', ' ', 'U', '^');
$isOK = 0;
unless ($digest = sumfile($fname)) {
$rsp .= "FAILED open or read\n";
$err = 1; $read_errs++;
}
elsif (lc($sum) eq $digest) {
$rsp .= "OK\n";
$isOK = 1;
$num_OK++;
}
else { $rsp .= "FAILED\n"; $err = 1; $match_errs++ }
print $rsp unless ($status || ($quiet && $isOK));
}
close(FH);
if (! $num_fmt_OK) {
warn("shasum: $checkfile: no properly formatted " .
"SHA checksum lines found\n");
$err = 1;
}
elsif (! $status) {
warn("shasum: WARNING: $fmt_errs line" . ($fmt_errs>1?
's are':' is') . " improperly formatted\n") if $fmt_errs;
warn("shasum: WARNING: $read_errs listed file" .
($read_errs>1?'s':'') . " could not be read\n") if $read_errs;
warn("shasum: WARNING: $match_errs computed checksum" .
($match_errs>1?'s':'') . " did NOT match\n") if $match_errs;
}
if ($ignore_missing && ! $num_OK && $num_fmt_OK) {
warn("shasum: $checkfile: no file was verified\n")
unless $status;
$err = 1;
}
return($err == 0);
}
## Verify or compute SHA checksums of requested files
my($file, $digest);
my $STATUS = 0;
for $file (@ARGV) {
if ($check) { $STATUS = 1 unless verify($file) }
elsif ($digest = sumfile($file)) {
if ($file =~ /[\n\\]/) {
$file =~ s/\\/\\\\/g; $file =~ s/\n/\\n/g;
print "\\";
}
unless ($tag) { print "$digest $modesym$file\n" }
else { print "$Tag{$alg} ($file) = $digest\n" }
}
else { $STATUS = 1 }
}
exit($STATUS);
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