#!/usr/bin/perl
#
# Usage: minimized-SDL-crash-fix.pl nvidia_drv.so
#
# Patches nvidia_drv.so from the NVIDIA Linux/X11 driver distribution,
# version 169.12, to avoid a bug that causes crashes when switching to
# another virtual console while an SDL program is minimized.  Renames
# the original file to nvidia_drv.so~ before creating the patched file.

use strict;
use Digest::MD5 qw(md5_hex);

if (@ARGV < 1) {
    die "Usage: $0 nvidia_drv.so\n";
}
my $filename = $ARGV[0];

open F, "<$filename" or die "$filename: $!\n";
binmode F;
seek F, 0, 2 or die "seek($filename,0,SEEK_END): $!\n";
my $filesize = tell(F);
seek F, 0, 0 or die "seek($filename,0,SEEK_SET): $!\n";
my $data;
read(F, $data, $filesize) == $filesize or die "$filename: Short read\n";
close F;

die "$filename: Invalid checksum\n"
    if md5_hex($data) ne "55780dd627bcc5b1549f3d64d4b98dc9";

my $newdata = $data;
die "$filename: Invalid data 1\n" if substr($newdata, 0x1CC84, 4) ne
    "\xC4\xA5\x0C\x00";
$newdata = substr($newdata, 0, 0x1CC84) . "\xC2" . substr($newdata, 0x1CC85);
die "$filename: Invalid data 2\n" if substr($newdata, 0xCA570, 0xA0) ne
    "\x55\x89\xE5\x83\xEC\x2C\x57\x56\x53\x8B\x55\x0C\x8B\x02\x8B\x15" .
    "\xD0\x2F\x16\x00\x8B\x80\x68\x01\x00\x00\x8B\x7D\x08\x8B\x75\x24" .
    "\x8B\x14\x90\x89\x55\xE4\x80\x3F\x01\x74\x16\x8B\x47\x10\x83\xC4" .
    "\xF4\x57\x8B\x80\x74\x01\x00\x00\xFF\xD0\x83\xC4\x10\x89\xC3\xEB" .
    "\x02\x89\xFB\x8D\x45\xFC\x50\x8D\x45\xF8\x50\x53\x57\xE8\xD6\xB5" .
    "\xFF\xFF\x8B\x15\xC8\x2F\x16\x00\x8B\x43\x24\x8B\x04\x90\x8B\x40" .
    "\x28\x8B\x00\x8B\x4D\x0C\x89\x45\xEC\x0F\xB6\x40\x15\x8B\x55\x0C" .
    "\x8B\x49\x14\x8B\x04\x85\xDC\x2F\x16\x00\xF7\xD0\x09\xC8\x89\x45" .
    "\xE8\x8B\x42\x54\x83\xC4\x10\x8B\x40\x08\x85\xC0\x74\x0A\x83\x78" .
    "\x04\x00\x0F\x84\x4F\x02\x00\x00\x0F\xB7\x4D\x14\x0F\xB7\x55\x1C";
my $newdata = substr($newdata, 0, 0xCA59A)
            . "\x14"
            . substr($newdata, 0xCA59B, 7)
            . "\xFF\x90"
            . substr($newdata, 0xCA5A4, 4)
            . substr($newdata, 0xCA5AA, 0x27)
            . "\x85\xC0\x74\x2F\x90\x8B\x00"
            . substr($newdata, 0xCA5D6, 11)
            . "\x4A"
            . substr($newdata, 0xCA5E2);

die "$filename: Invalid checksum after patching\n"
    if md5_hex($newdata) ne "b21120ba0cd1b02b97f9f9f729115dcf";

rename $filename, "$filename~" or die "rename($filename, $filename~): $!\n";
open F, ">$filename" or die "open $filename for writing: $!\n";
binmode F;
print F $newdata or die "write to $filename: $!\n";
close F;

exit 0;