unix: enable Sysv shared memory support on darwin/arm64

Keep it disabled on ios though.

For golang/go#45696
For golang/go#46084

Change-Id: I3d551227a4ebc0eebabdd16b175aa6a75ea9de19
Reviewed-on: https://go-review.googlesource.com/c/sys/+/353509
Trust: Tobias Klauser <tobias.klauser@gmail.com>
Run-TryBot: Tobias Klauser <tobias.klauser@gmail.com>
Reviewed-by: Ian Lance Taylor <iant@golang.org>

unix/example_sysvshm_test.go

@@ -2,8 +2,8 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-//go:build (darwin && amd64) || (linux && !android)
+//go:build (darwin && !ios) || (linux && !android)
-// +build darwin,amd64 linux,!android
+// +build darwin,!ios linux,!android
 
 package unix_test
 
@@ -14,7 +14,6 @@ import (
 )
 
 func ExampleSysvShmGet() {
-
 	// create shared memory region of 1024 bytes
 	id, err := unix.SysvShmGet(unix.IPC_PRIVATE, 1024, unix.IPC_CREAT|unix.IPC_EXCL|0o600)
 	if err != nil {

unix/sysvshm_unix.go

@@ -2,8 +2,8 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-//go:build (darwin && amd64) || linux
+//go:build (darwin && !ios) || linux
-// +build darwin,amd64 linux
+// +build darwin,!ios linux
 
 package unix
 

unix/sysvshm_unix_other.go

@@ -2,8 +2,8 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-//go:build (darwin && amd64)
+//go:build darwin && !ios
-// +build darwin,amd64
+// +build darwin,!ios
 
 package unix
 

unix/zsyscall_darwin_arm64.go

@@ -734,6 +734,65 @@ var libc_sendfile_trampoline_addr uintptr
 
 // THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
 
+func shmat(id int, addr uintptr, flag int) (ret uintptr, err error) {
+	r0, _, e1 := syscall_syscall(libc_shmat_trampoline_addr, uintptr(id), uintptr(addr), uintptr(flag))
+	ret = uintptr(r0)
+	if e1 != 0 {
+		err = errnoErr(e1)
+	}
+	return
+}
+
+var libc_shmat_trampoline_addr uintptr
+
+//go:cgo_import_dynamic libc_shmat shmat "/usr/lib/libSystem.B.dylib"
+
+// THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
+
+func shmctl(id int, cmd int, buf *SysvShmDesc) (result int, err error) {
+	r0, _, e1 := syscall_syscall(libc_shmctl_trampoline_addr, uintptr(id), uintptr(cmd), uintptr(unsafe.Pointer(buf)))
+	result = int(r0)
+	if e1 != 0 {
+		err = errnoErr(e1)
+	}
+	return
+}
+
+var libc_shmctl_trampoline_addr uintptr
+
+//go:cgo_import_dynamic libc_shmctl shmctl "/usr/lib/libSystem.B.dylib"
+
+// THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
+
+func shmdt(addr uintptr) (err error) {
+	_, _, e1 := syscall_syscall(libc_shmdt_trampoline_addr, uintptr(addr), 0, 0)
+	if e1 != 0 {
+		err = errnoErr(e1)
+	}
+	return
+}
+
+var libc_shmdt_trampoline_addr uintptr
+
+//go:cgo_import_dynamic libc_shmdt shmdt "/usr/lib/libSystem.B.dylib"
+
+// THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
+
+func shmget(key int, size int, flag int) (id int, err error) {
+	r0, _, e1 := syscall_syscall(libc_shmget_trampoline_addr, uintptr(key), uintptr(size), uintptr(flag))
+	id = int(r0)
+	if e1 != 0 {
+		err = errnoErr(e1)
+	}
+	return
+}
+
+var libc_shmget_trampoline_addr uintptr
+
+//go:cgo_import_dynamic libc_shmget shmget "/usr/lib/libSystem.B.dylib"
+
+// THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
+
 func Access(path string, mode uint32) (err error) {
 	var _p0 *byte
 	_p0, err = BytePtrFromString(path)

unix/ztypes_darwin_arm64.go

@@ -639,3 +639,39 @@ type Ucred struct {
 	Ngroups int16
 	Groups  [16]uint32
 }
+
+type SysvIpcPerm struct {
+	Uid  uint32
+	Gid  uint32
+	Cuid uint32
+	Cgid uint32
+	Mode uint16
+	_    uint16
+	_    int32
+}
+type SysvShmDesc struct {
+	Perm   SysvIpcPerm
+	Segsz  uint64
+	Lpid   int32
+	Cpid   int32
+	Nattch uint16
+	_      [34]byte
+}
+
+const (
+	IPC_CREAT   = 0x200
+	IPC_EXCL    = 0x400
+	IPC_NOWAIT  = 0x800
+	IPC_PRIVATE = 0x0
+)
+
+const (
+	IPC_RMID = 0x0
+	IPC_SET  = 0x1
+	IPC_STAT = 0x2
+)
+
+const (
+	SHM_RDONLY = 0x1000
+	SHM_RND    = 0x2000
+)