USBOOT.PAK文件格式研究
我打算制作linux和dos双启动U盘，但很多dos启动U盘用USBOOT安装，它们的文件都存放在一个叫做USBOOT.PAK中。这个文件好像不是开放文件格式，要想提取出来必须使用USBOOT还得用到U盘,把U盘根目录搞的乱乱的，还可能把引导区给覆盖了，十分不方便。于是拿起十六进制编辑工具，研究了一下USBOOT.PAK的文件格式，写了一个perl脚本从中提取文件。(进入查看更多)USBOOT.PAK的文件格式
#开头4个字节
########
55 53 42 54 USBT
#接下来是文件,这里只写一个文件,每个文件格式是相同的,好像没有记录文件个数的字节
#一个文件开始的标志(1个字节)
########
cf
#文件名的长度(1个字节)
########
xx
#4个字节(不知道作用,但对提取文件无影响)
########
xx xx xx xx
#文件的大小(4个字节little endian)
########
xx xx xx xx
#6个字节(不知道作用,但对提取文件无影响)
########
xx xx xx xx xx xx
#文件名
#文件内容
###其他文件,格式相同###
下面是提取的代码.提取到当前目录.
unpak.pl
#!/usr/bin/perl
use strict;
use warnings;
use Carp;
my $PAK;
my $buf;
my $OUT;
open $PAK,"<","USBOOT.PAK";
binmode($PAK);
# TODO: Error Handle
read $PAK,$buf,4;
croak "This is not a USBOOT.PAK file. " unless $buf eq "USBT";
while (!eof($PAK)){
read $PAK,$buf,1; # 0xCF
croak "This file may be broken at the position " . tell($PAK) ."." unless $buf eq pack("H2","cf");
read $PAK,$buf,1; # read the lenth of file name
my $nlen=unpack("C",$buf);
seek $PAK,4,1; # jump over 4 bytes
read $PAK,$buf,4; # read the lenth of file
my $flen=unpack("V",$buf);
seek $PAK,6,1; # jump 6 bytes
read $PAK,$buf,$nlen; # read the file name
my $name=unpack("a$nlen",$buf);
open $OUT,">",$name;
binmode $OUT;
read $PAK,$buf,$flen; # read the file
print $OUT $buf;
close $OUT;
#print "hello:",$name,"\n";
}
use strict;
use warnings;
use Carp;
my $PAK;
my $buf;
my $OUT;
open $PAK,"<","USBOOT.PAK";
binmode($PAK);
# TODO: Error Handle
read $PAK,$buf,4;
croak "This is not a USBOOT.PAK file. " unless $buf eq "USBT";
while (!eof($PAK)){
read $PAK,$buf,1; # 0xCF
croak "This file may be broken at the position " . tell($PAK) ."." unless $buf eq pack("H2","cf");
read $PAK,$buf,1; # read the lenth of file name
my $nlen=unpack("C",$buf);
seek $PAK,4,1; # jump over 4 bytes
read $PAK,$buf,4; # read the lenth of file
my $flen=unpack("V",$buf);
seek $PAK,6,1; # jump 6 bytes
read $PAK,$buf,$nlen; # read the file name
my $name=unpack("a$nlen",$buf);
open $OUT,">",$name;
binmode $OUT;
read $PAK,$buf,$flen; # read the file
print $OUT $buf;
close $OUT;
#print "hello:",$name,"\n";
}
2022年8月07日 12:44
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2022年8月18日 14:36
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