（gcc）中的封装结构去 [英] Packed Structs in (gcc)go

问题描述

我有一些旧的C代码，使得有点使用压缩结构。我正在研究使用Go作为这个代码的包装，但是很难找到一种方法来传递或者为这些结构写定义。

示例： p>

  importunsafe; 
 
类型AlignTest结构{
 c字节; 
 y int16; 
 z int16; 
 q int32; 
} 
 
 func main（）{
 
 vr：= new（AlignTest）; 
 
 fmt.Println（unsafe.Sizeof（* vr），\\\
）; 
 
 
 
 
 $ b 
返回12而不是1 + 2 + 2 + 4 = 9，我想要一个压缩/未对齐的结构。 
 
 
 
我知道我可以创建一个字节数组并手动执行解析，但这看起来非常脆弱并且容易出错...... 
解决方案
您可能需要重新考虑您的架构 - 尝试将二进制输入传递到C层并使用现有的结构（您不会破坏您的架构，改变）。我假设结构包装看起来像这样： 
 
 
  #ifdef WINDOWS 
 #pragma pack（push）
 #endif 
 #pragma pack（BYTEALIGNMENT）//例如#pragma pack（1）或#pragma pack（8）
 
 // ---一些打包结构
 
 #ifdef WINDOWS 
 #pragma （pop）
 #endif 
 #ifdef POSIX 
 #pragma pack（）
 #endif 
  
所有底层或第三方库都在做一些void *或const char *并对它们进行类型转换。因此，如果可能的话，尝试将数据转发到C层（您可以获取指针），并且根本不公开结构。
 
I have some old C code that makes somewhat heavy use of packed structures. I'm looking into using Go as a wrapper for this code, but am having difficulty finding a way to pass or even write definitions for these structures.

Example: 
import "unsafe";

type AlignTest struct {
    c byte;
    y int16;
    z int16;
    q int32;
}

func main() {

    vr := new(AlignTest);

    fmt.Println(unsafe.Sizeof(*vr),  "\n");

}
Returns 12 rather than the 1+2+2+4 = 9 that I would want with a packed/unaligned struct. 

I know that I could just create a byte array and do the parsing manually, but that seems very brittle and error prone...
解决方案
You may want to rethink your architecture- try passing the binary input down to the C layer and use the existing structures (you won't break what you don't change). I'm assuming the structure packing looks something like this:
#ifdef WINDOWS
#pragma pack(push)
#endif
#pragma pack(BYTEALIGNMENT) // e.g. "#pragma pack(1)" or "#pragma pack(8)"

//--- Some packed structs

#ifdef WINDOWS
#pragma pack(pop)
#endif
#ifdef POSIX
#pragma pack()
#endif
All the underlying or 3rd Party libs are then doing is taking some void* or const char* and typecasting it to these. So if possible, try forwarding that data into a C layer (where you can get pointers) and don't expose the structures at all.

                        
这篇关于（gcc）中的封装结构去的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！