Go/CGo-如何使用作为指针传递的C数组 [英] Go/CGo - how do you use a C array passed as a pointer

问题描述

我将其发布为问题/答案，因为这花了我一段时间才能解决，并且我不介意对我的解决方案提出任何反馈.在Go/CGo中，如何处理作为指针传递的C数组?

I'm posting this as a question/answer, as it took me a while to work out, and I wouldn't mind some feedback on my solution. In Go/CGo, how do you work with a C array passed as a pointer?

例如，使用此C结构:

struct _GNetSnmpVarBind {                     
    guint32     *oid;       /* name of the variable */
    gsize       oid_len;    /* length of the name */
    ... and other fields
};  

我想将oid字段转换为Go字符串，如何使用guint32 *指针?

I want to convert oid field to a Go string, how would I work with the guint32* pointer?

推荐答案

您可以使用未经测试，但希望您能理解！尽管切片直接指向切片，但不要让切片的寿命比C数据长.

Untested but hopefully you get the idea! Don't let the slice live longer than the C data though as it points directly into it.

上次使用此代码时，我查看了反汇编，它生成了非常有效的代码.

Last time I used this I had a look at the disassembly and it generates very efficient code.

func gIntArrayOidString(oid *_Ctype_guint32, oid_len _Ctype_gsize) (result string) {
    var oids []uint32
    sliceHeader := (*reflect.SliceHeader)((unsafe.Pointer(&oids)))
    sliceHeader.Cap = oid_len
    sliceHeader.Len = oid_len
    sliceHeader.Data = uintptr(unsafe.Pointer(oid))

    var result string
    for _, value := range oids {
        result += fmt.Sprintf(".%d", value)
    }
    return result[1:]
}

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