当将指针从 Struct 传递到 C 方法时，“cgo 参数具有指向 Go 指针的 Go 指针”

Question

I am using cgo to calling C method which accept struct pointer as below:

package main

/*
typedef struct Client{
    struct real_client c;
} Client;

int doSomething(struct real_client *c ) {
    ....
}

*/
import "C"
import "fmt"

type Client struct {
    client C.Client
}

func main() {
    cl := Client{}
    C.doSomething(&cl.client.c);   
 
    // no compile error

}

However, I get an error: cgo argument has Go pointer to Go pointer.

I am using go version go1.16.13.

Is that any way to do make it work?

Answer 1

Is that any way to do make it work?

You can set the environment variable GODEBUG to cgocheck=0 .

See https://pkg.go.dev/cmd/cgo#hdr-Passing_pointers .

Keep in mind the mechanism exists to prevent C code accessing managed memory not pinned for the duration of the C function call. This can become relevant in the future when changes to Go's garbage collector pertaining memory relocation may be made.