#!/usr/bin/perl -w
#
# Retrieve modules required for an initrd image
# $Id$

unless ( @ARGV ) {
  die "Syntax: $0 [ -d target_directory ] module_1 module_2 module_3\n"
}

# Parse command line arguments
my @requested_modules = ();
my $target_dir = "";
my $kernel_ver;
my $quiet;
chomp ( my $current_kernel_ver = `uname -r` );
while ( $_ = shift ) {
  if    ( /-d/ ) { $target_dir = shift }
  elsif ( /-k/ ) { $kernel_ver = shift }
  elsif ( /-q/ ) { $quiet = 1 }
  else           { push @requested_modules, $_ };
}

# Create target directory if required
if ( $target_dir ) {
  print STDERR "Target directory is $target_dir\n" unless $quiet;
  system ( "mkdir -p $target_dir" );
  chdir $target_dir;
}

# Use modprobe -nav to retrieve locations of modules and their dependencies
print STDERR "Requested modules ". join (' ', @requested_modules)."\n" unless $quiet;
my @modules_dups;
foreach my $module ( @requested_modules ) {
  my @module_list = map { /^\S+\s+(.*)$/ ; $1 } `/sbin/modprobe -nva $module`;
  die "Cannot find any modules matching $module\n" unless @module_list;
  push @modules_dups, @module_list;
}

# Remove duplicates from list
my %module_basenames = ();
my @modules = ();
foreach my $module ( @modules_dups ) {
  # Ugly hack : assume that dependencies are independent of kernel version
  # This seems to be necessary because we can't run modprobe and specify
  # an alternate modules.dep file; it refuses to understand lines of the 
  # form "depfile=XXX" as documented in modules.conf(5)
  $module =~ s/$current_kernel_ver/$kernel_ver/ if $kernel_ver;
  push @modules, $module unless $module_basenames{$module};
  ( my $basename ) = ( $module =~ /([^\/]+)\.o/ ); 
  $module_basenames{$module} = $basename;
}

# Process module list
print "#!/bin/sh\n";
foreach my $module ( @modules ) {
  my $basename = $module_basenames{$module};
  # Report via stdout
  print STDERR "Using module $basename from $module\n" unless $quiet;
  # Copy uncompressed module to current directory
  system ("gunzip -c $module > $basename.o");
  # Print insmod line to stdout
  print "insmod $basename\n";
}