Hi Gophers,
I'm trying to use cgo for a C library, specifically a function which takes
a void pointer to a buffer, and I'm trying to pass a Go-Slice as this
buffer.
```
func Write(buf []byte) (int, error) {
// var pin rumtime.Pinner
// pin.Pin(&buf[0])
// defer pin.Unpin()
// is this necessary? Is it even safe?
...
ret := C.lib_read(unsafe.Pointer(&buf[0]), C.int(len(buf))) // function
which reads from this buffer
...
}
```
Does this require explicit pinning of buf? And if so, is the commented part
a valid pinning of a slice? The documentation states that pointers passed
to C functions are implicitly pinned (on the top-level that is), but does
this also apply to slices, i.e. if I pass a (unsafe) pointer to the first
element, is the slice's entire backing array implicitly pinned?
I know that there are some runtime checks for this, but I am worried that
any use of unsafe.Pointer might perhaps override these checks completely.
Thanks a lot.
Julio
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