Messages in this thread | | | Date | Tue, 19 May 1998 23:50:46 -0400 | From | "Theodore Y. Ts'o" <> | Subject | Re: RPMs :o( |
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Date: Tue, 19 May 1998 23:54:40 +0100 (BST) From: Peter Horton <pdh@berserk.demon.co.uk>
RPMs are basically gzipped cpio archives with a header.
If you search the file for the byte 0x1f followed by 0x8b (these bytes mark a gzip file) and remove everything that precedes them, you will be left a gzipped cpio archive, which you can then unzip and unpack.
Since this is so short, I'll take the liberty to repost the following rpm2cpio perl script.
- Ted
#!/usr/local/bin/perl
# why does the world need another rpm2cpio? because the existing one # won't build unless you have half a ton of things that aren't really # required for it, since it uses the same library used to extract RPM's. # in particular, it won't build on the HPsUX box i'm on.
# add a path if desired $gzip = "gzip";
sub printhelp { print "rpm2cpio, perl version by orabidoo <odar\@pobox.com>\n"; print "use: rpm2cpio [file.rpm]\n"; print "dumps the contents to stdout as a GNU cpio archive\n"; exit 0; }
if ($#ARGV == -1) { printhelp if -t STDIN; $f = "STDIN"; } elsif ($#ARGV == 0) { open(F, "< $ARGV[0]") or die "Can't read file $ARGV[0]\n"; $f = 'F'; } else { printhelp; }
printhelp if -t STDOUT;
# gobble the file up undef $/; $|=1; $rpm = <$f>; close ($f);
($magic, $major, $minor, $crap) = unpack("NCC C90", $rpm);
die "Not an RPM\n" if $magic != 0xedabeedb; die "Not a version 3 RPM\n" if $major != 3;
$rpm = substr($rpm, 96);
while ($rpm ne '') { $rpm =~ s/^\c@*//s; ($magic, $crap, $sections, $bytes) = unpack("N4", $rpm); $smagic = unpack("n", $rpm); last if $smagic eq 0x1f8b; die "Error: header not recognized\n" if $magic != 0x8eade801; $rpm = substr($rpm, 16*(1+$sections) + $bytes); }
die "bogus RPM\n" if $rpm eq '';
open(ZCAT, "|gzip -cd") || die "can't pipe to gzip\n"; print STDERR "CPIO archive found!\n";
print ZCAT $rpm; close ZCAT;
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