Re: How to concatenate binary files

[Tanktalus]

Here's my sub on creating self-extracting EXE's which may come in useful. Note that this works on both Windows and Unix/Linux, even though it's always creating a Windows-based self-extracting EXE. (I know - I developed it on Linux, and just ran tests on Windows to make sure it still worked.)

use File::Copy;
use IO::File;

sub _create_sfx
{
    my $self = shift;
    my $zip = shift;
    my $exe = shift;

    my $fh = IO::File->new($exe, "w");
    binmode($fh); # stupid Windows
    copy(File::Spec->catfile(LocationOfUnzipsfxExe(),
                             'unzipsfx.exe'),
         $fh);
    copy($zip, $fh);
    unlink($zip);
    $fh->close();
    system(qw(zip -A), $exe);
}

As you can see, I open my output filehandle, set it to binary mode, and use File::Copy::copy to copy each filename (the unzipsfx.exe file and the zip file) into my still-open file handle. Once closed, then I tell zip to fix the sfx executable (offsets and stuff), and we're done. Funny thing is that "zip -A" run on Linux ... works to create the Windows self-extractor. :-)

[tlm]

I've never done this kind of thing, so this is a completely ignorant question: why don't you do the whole thing with a single call to zip -A, like this:

my $sfx = File::Spec->catfile(LocationOfUnzipsfxExe(), 'unzipsfx.exe')
+;
system( qw( zip -A ), $exe, $sfx, $zip ) and die "$?";
unlink $zip;

[Tanktalus]

That's a very good and interesting question. I suppose the reason why I did it the way above is because it's a perl interpretation of the unzipsfx docs (check the man page on unzipsfx - the EXAMPLES section near the bottom).

A quick test shows:

$ zip -A mysfx /usr/bin/unzipsfx x
  adding: usr/bin/unzipsfx (deflated 52%)
  adding: x (deflated 12%)
$ file mysfx
mysfx: Zip archive data, at least v2.0 to extract

which is far from what we want. The output is still a zip file. But, if we do the shell version of the perl code above, we get:

$ cat /usr/bin/unzipsfx mysfx > mysfx_exe
$ zip -A mysfx_exe
mysfx_exe: adjusting offsets for a preamble of 47552 bytes
$ file mysfx_exe
mysfx_exe: ELF 32-bit LSB executable, Intel 80386, version 1 (SYSV), f
+or GNU/Linux 2.2.5, dynamically linked (uses shared libs), stripped

I hope that helps.