如何将 Go 的 []byte 转换为 C 的 *uint8_t

Question

I want to set a uint8_t* in a C struct using Go. The data in Go comes from and ELF and is a byte slice. This is the error I currently get:

cannot use &buf[0] (type *byte) as type *_Ctype_uchar in assignment

using this code:

args.vm_snapshot_data = &buf[0]

How do I do it?

When I use the proper cast:
args.vm_snapshot_data = (*C.uint8_t)(&buf[0])
I get this error:
panic: runtime error: cgo argument has Go pointer to Go pointer

Answer 1

Golang count types rather than compatibility of them. And there's only one method to cast over the place it's using unsafe.Pointer as original value.

args.vm_snapshot_data = (*C.uint8_t)(unsafe.Pointer(&buf[0]))

If you're not sure if buf slice will be alive on the Go side (garbage collector might dispose it) at the time when C side using it, then you have to use copy and dispose it manually.

args.vm_snapshot_data = (*C.uint8_t)(C.CBytes(buf))

...

C.free(unsafe.Pointer(args.vm_snapshot_data))