On Fri, 1 Nov 2002 12:53:41 -0500 (EST), Andy Dougherty wrote:
>At the moment, the bytecode "fingerprint" is built with Digest::MD5.
>Alas, Digest::MD5 wasn't standard with perl versions prior to 5.8.0.
>What should happen in those cases? Anybody have any good ideas?
The attached patch is a fleshed-out (and lightly tested)
example of my prior post. Invoking 'md5sum' in this way
yields the same fingerprint as Digest::MD5. The fallback
checksum is just the sum of ASCII values of all the ops, so
it does not match the other two, and can be fooled, but it
does give a warning in this case. Since the fingerprint is
only there to help developers shoot themselves in the foot
less often, perhaps this solution is sufficient.
BTW, I ran into this same problem recently while trying to
build Parrot on a minimally-installed Debian box for a demo.
Parrot failed on these missing items:
stdio.h (from pkg libc6-dev)
Digest/MD5.pm (from pkg libdigest-md5-perl)
perldoc (from pkg perl-doc)
I recognized the problems quickly, but only because I have
been knee-deep in the code for a month. Missing C compilers
also sting me frequently, as I am trying to get all the free
Win32 compilers to work out-of-the-box with Parrot, and I
don't have all my patches submitted yet, and sometimes
forget to put the compiler-of-the-day in my PATH, or do a
'perl Configure -cc=bcc32' (note the missing dash).
In Configure.pl and friends, I think that "fail early, fail
loudly" should be a guiding principle, at least for the
things with no workarounds. Unless someone thinks it is a
bad idea, I intend to patch in that direction whenever I see
relevant Configure code.
--
Hope this helps,
Bruce Gray
--- fingerprint_c.pl~ Thu Oct 24 09:14:10 2002
+++ fingerprint_c.pl Fri Nov 1 14:50:43 2002
@@ -2,14 +2,32 @@
use strict;
use lib 'lib';
-use Digest::MD5 qw(md5_hex);
-use Data::Dumper;
use Parrot::OpLib::core;
my $len = 10;
-my $fingerprint = md5_hex join "\n", map {
- join '_', $_->{NAME}, @{$_->{ARGS}}
+
+my $fingerprint = join "\n", map {
+ join '_', $_->{NAME}, @{$_->{ARGS}}
} @$Parrot::OpLib::core::ops;
+if (eval {require Digest::MD5}) {
+ $fingerprint = Digest::MD5::md5_hex $fingerprint;
+}
+elsif (`md5sum </dev/null` and not $? ) {
+ use File::Temp;
+ my ($fh, $filename) = File::Temp::tempfile() or die;
+ print $fh $fingerprint;
+ close $fh or die;
+ $fingerprint = substr(`md5sum $filename`, 0, 32);
+ die "Failed: Can't get valid checksum" unless $fingerprint and not $?;
+ unlink $filename or die;
+}
+else {
+ $fingerprint = unpack('H*', pack 'L', unpack "%128C*", $fingerprint) x 4;
+ warn "$0:warning - MD5 checksum not available - " .
+ "Falling back to a much less secure checksum. " .
+ "We recommend that you install the Digest::MD5 module, or the 'md5sum'
+program.\n";
+}
+
print << "EOF";
/*
