处理Win32 :: API返回的宽字符值 [英] Handling wide char values returned by Win32::API

问题描述

wide char和win32 :: api 中提供的答案适用于传递 utf-16插入Win API.但是，如何通过Win API转换返回的utf16字符串? (我正在尝试使用GetCommandLineW).

The answer provided in wide char and win32::api works for passing utf-16 to the Win API. But how do I convert utf16 strings returned by the Win API? (I am trying to use GetCommandLineW).

我尝试了Unicode::String和Encode::decode都没有成功.我猜想也许数据需要首先打包或解压缩，但是怎么办呢?

I have tried both Unicode::String and Encode::decode without success. I'm guessing that perhaps the data needs to be packed or unpacked first, but how?

此后，下一个问题是如何像CommandLineToArgvW返回的那样处理指向utf16的指针.

After that, the next problem is how to deal with a pointer-to-pointer-to-utf16 like the one returned by CommandLineToArgvW.

感谢您的帮助.

推荐答案

当您指定返回值为字符串时，Win32 :: API假定它以值为0的字节终止，但是在该值中的字节是常见的UTF-16le文字.

When you specify the return value is a string, Win32::API assumes it's a terminated by a byte with value 0, but bytes with that value are common in UTF-16le text.

正如Win32 :: API建议的那样，您应该使用N类型(或在64位版本上为Q)来获取指针作为数字，然后自己读取指向的内存. Win32 :: API提供了ReadMemory来读取内存，但是它需要知道要读取多少内存.这对于NUL终止的字符串和宽NUL终止的字符串没有用.

As Win32::API suggests, you should use the N type (or Q on 64-bit builds) to get the pointer as a number, then read the pointed memory yourself. Win32::API's provides ReadMemory to read memory, but it requires knowing how much memory to read. That's not useful for NUL-terminated strings and wide NUL-terminated strings.

对于NUL终止的宽字符串，Win32 :: API提供了SafeReadWideCString.但是SafeReadWideCString可以是与错误输入无关的字符串，所以我改用自己的decode_LPCWSTR.

For wide NUL-terminated strings, Win32::API provides SafeReadWideCString. But SafeReadWideCString can a string unrelated to the input on error, so I use my own decode_LPCWSTR instead.

use strict;
use warnings;
use feature qw( say state );

use open ':std', ':encoding('.do { require Win32; "cp".Win32::GetConsoleOutputCP() }.')';

use Config     qw( %Config );
use Encode     qw( decode encode );
use Win32::API qw( ReadMemory );

use constant PTR_SIZE => $Config{ptrsize};

use constant PTR_PACK_FORMAT =>
     PTR_SIZE == 8 ? 'Q'
   : PTR_SIZE == 4 ? 'L'
   : die("Unrecognized ptrsize\n");

use constant PTR_WIN32API_TYPE =>
     PTR_SIZE == 8 ? 'Q'
   : PTR_SIZE == 4 ? 'N'
   : die("Unrecognized ptrsize\n");


sub lstrlenW {
   my ($ptr) = @_;

   state $lstrlenW = Win32::API->new('kernel32', 'lstrlenW', PTR_WIN32API_TYPE, 'i')
      or die($^E);

   return $lstrlenW->Call($ptr);
}


sub decode_LPCWSTR {
   my ($ptr) = @_;
   return undef if !$ptr;

   my $num_chars = lstrlenW($ptr)
      or return '';

   return decode('UTF-16le', ReadMemory($ptr, $num_chars * 2));
}


# Returns true on success. Returns false and sets $^E on error.
sub LocalFree {
   my ($ptr) = @_;

   state $LocalFree = Win32::API->new('kernel32', 'LocalFree', PTR_WIN32API_TYPE, PTR_WIN32API_TYPE)
      or die($^E);

   return $LocalFree->Call($ptr) == 0;
}


sub GetCommandLine {
   state $GetCommandLine = Win32::API->new('kernel32', 'GetCommandLineW', '', PTR_WIN32API_TYPE)
      or die($^E);

   return decode_LPCWSTR($GetCommandLine->Call());
}


# Returns a reference to an array on success. Returns undef and sets $^E on error.
sub CommandLineToArgv {
   my ($cmd_line) = @_;

   state $CommandLineToArgv = Win32::API->new('shell32', 'CommandLineToArgvW', 'PP', PTR_WIN32API_TYPE)
      or die($^E);

   my $cmd_line_encoded = encode('UTF-16le', $cmd_line."\0");
   my $num_args_buf = pack('i', 0);  # Allocate space for an "int".

   my $arg_ptrs_ptr = $CommandLineToArgv->Call($cmd_line_encoded, $num_args_buf)
      or return undef;

   my $num_args = unpack('i', $num_args_buf);
   my @args =
      map { decode_LPCWSTR($_) }
         unpack PTR_PACK_FORMAT.'*',
            ReadMemory($arg_ptrs_ptr, PTR_SIZE * $num_args);

   LocalFree($arg_ptrs_ptr);
   return \@args;
}


{
   my $cmd_line = GetCommandLine();

   say $cmd_line;

   my $args = CommandLineToArgv($cmd_line)
      or die("CommandLineToArgv: $^E\n");

   for my $arg (@$args) {
      say "<$arg>";
   }
}

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