如何在 Perl6 NativeCall 结构中定义固定长度的字符串? [英] How to define fixed-length strings in a Perl6 NativeCall struct?

问题描述

我有一个第三方 C 库，它定义了一个类似于以下内容的结构:

I have a third-party C library that defines a struct similar to:

struct myStruct {
  int a;
  int b;
  char str1[32];
  char str2[32];
};

还有一个函数，它接受一个指向这个结构体的指针并填充它.我需要我的 Perl6 本机调用来提供该结构，然后读取结果.

And a function that takes a pointer to this struct and populates it. I need my Perl6 native call to provide that struct, and then read the results.

到目前为止，我已经在 Perl6 中定义了结构体:

So far I've got the struct defined in Perl6 as:

class myStruct is repr('CStruct') {
  has int32 $.a;
  has int32 $.b;
  has Str $.str1; # Option A: This won't work as Perl won't know what length to allocate
  has CArray[uint8] $.str2; # Option B: This makes more sense, but again how to define length?  
                     # Also, would this allocate the array in place, or 
                     #    reference an array that is separately allocated (and therefore not valid)?
}

还有一个原生调用，例如:

And a native call like:

sub fillStruct(myStruct) is native('test_lib') { ... }
my $struct = myStruct.new();
fillStruct($struct); # Gives a seg fault with any variation I've tried so far

我怎样才能做到这一点?

How can I make this work?

推荐答案

正如其他人所说，目前似乎没有任何方法可以实现这一点.

As others have said, there does not appear to be any way to achieve this at present.

我求助于定义一个新的 C 函数作为解决方法.该函数有效地充当访问器方法，仅返回我需要的作为离散 NativeCall 友好指针的字段.

I've resorted to defining a new C function(s) as a workaround. The function effectively acts as an accessor method returning just the fields that I need as discrete NativeCall-friendly pointers.

希望社区在某个时候能够为此案例提供适当的支持.

Hopefully the community will get to implementing proper support for this case at some point.

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