On Sat, May 9, 2020 at 12:56 PM Gert <gert.cuyk...@gmail.com> wrote: > > This is the closest I get, I am out of ideas. Don't know why it runs but > doesn't update the string.
I don't know what you are really trying to do, but I want to be clear that this code is not supported. The supported way to call from Go to C is to use cgo. See https://golang.org/cmd/cgo and https://blog.golang.org/cgo. One big problem I see in your code is that you are assuming that Go and C use the same ABI. That is, that the arguments passed to the Go function will be seen as the arguments passed to the C function. That is not the case. When using the gc compiler, Go and C pass arguments in different locations. Ian > go run . > test [116 101 115 116 0 0 0 0 0 0] 4 0 0 > > #include <stdio.h> > #include <string.h> > > int hello(char *s) { > char c[80]; > strcpy (c, s); > sprintf(s, "hello %s", c); > printf("------\n"); > return 0; > } > > #include "textflag.h" > > TEXT ·hello_trampoline(SB),NOSPLIT,$0-0 > JMP hello_c(SB) > > package main > > import ( > "fmt" > "unsafe" > > "golang.org/x/sys/unix" > ) > > //go:linkname hello_t hello_c > //go:cgo_import_dynamic hello_c hello "./c/hello.dylib" > > //go:nosplit > func hello_t(s unsafe.Pointer) (uintptr, uintptr, unix.Errno) { > return unix.Syscall(funcPC(hello_trampoline), uintptr(s), 0, 0) > } > > func hello_trampoline() > > //go:nosplit > func funcPC(f func()) uintptr { > return **(**uintptr)(unsafe.Pointer(&f)) > } > > func main() { > b := make([]byte, 10, 10) > copy(b, []byte("test")) > r1, r2, err := hello_t(unsafe.Pointer(&b[0])) > fmt.Printf("%s %v %d %d %d\n", b, b, r1, r2, err) > } > > -- > You received this message because you are subscribed to the Google Groups > "golang-nuts" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to golang-nuts+unsubscr...@googlegroups.com. > To view this discussion on the web visit > https://groups.google.com/d/msgid/golang-nuts/68003925-1a44-4b7c-8cec-21849784bee5%40googlegroups.com. -- You received this message because you are subscribed to the Google Groups "golang-nuts" group. To unsubscribe from this group and stop receiving emails from it, send an email to golang-nuts+unsubscr...@googlegroups.com. To view this discussion on the web visit https://groups.google.com/d/msgid/golang-nuts/CAOyqgcU3zDA30YrFvh0GrNtqEie2hi0RBVfbHEB_4BpS%2BOvQFg%40mail.gmail.com.
