unix: extend support for z/OS

This change syncs the IBM internal version of sys/unix with the public
repository.

There are a variety of new syscalls and const definitions that have been
accumulated over the past few years to support developers using Go on
the platform. Old simulations of calls like 'epoll' and 'fstatfs' have
been replaced with their real counterparts. The zos/s390x syscalls also
have extensive trampolining to handle zos systems that might not have
support for some of these new system calls.

Closes golang/go#67071

Change-Id: I973d9e0abca2b05365308cf2b890438e50ae5957
Reviewed-on: https://go-review.googlesource.com/c/sys/+/582035
Reviewed-by: David Chase <drchase@google.com>
Reviewed-by: Bill O'Farrell <billotosyr@gmail.com>
Reviewed-by: Ian Lance Taylor <iant@google.com>
Auto-Submit: Ian Lance Taylor <iant@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>

unix/xattr_zos_test.go

@@ -0,0 +1,238 @@
+// Copyright 2024 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+//go:build zos
+
+package unix_test
+
+import (
+	"os"
+	"testing"
+
+	"golang.org/x/sys/unix"
+)
+
+func TestXattr(t *testing.T) {
+	defer chtmpdir(t)()
+
+	f := "xattr1"
+	touch(t, f)
+
+	xattrName := "system.filetag"
+	xattrDataSet := make([]byte, 4)
+	xattrDataSet[0] = 0xFF
+	xattrDataSet[1] = 0xFF
+	xattrDataSet[2] = 0
+	xattrDataSet[3] = 0
+
+	err := unix.Setxattr(f, xattrName, xattrDataSet, 0)
+	if err != nil {
+		t.Fatalf("Setxattr: %v", err)
+	}
+
+	// find size
+	size, err := unix.Listxattr(f, nil)
+	if err != nil {
+		t.Fatalf("Listxattr: %v", err)
+	}
+
+	if size <= 0 {
+		t.Fatalf("Listxattr returned an empty list of attributes")
+	}
+
+	buf := make([]byte, size)
+	read, err := unix.Listxattr(f, buf)
+	if err != nil {
+		t.Fatalf("Listxattr: %v", err)
+	}
+
+	xattrs := stringsFromByteSlice(buf[:read])
+
+	xattrWant := xattrName
+	found := false
+	for _, name := range xattrs {
+		if name == xattrWant {
+			found = true
+			break
+		}
+	}
+
+	if !found {
+		t.Errorf("Listxattr did not return previously set attribute '%s'", xattrName)
+	}
+
+	// find size
+	size, err = unix.Getxattr(f, xattrName, nil)
+	if err != nil {
+		t.Fatalf("Getxattr: %v", err)
+	}
+
+	if size <= 0 {
+		t.Fatalf("Getxattr returned an empty attribute")
+	}
+
+	xattrDataGet := make([]byte, size)
+	_, err = unix.Getxattr(f, xattrName, xattrDataGet)
+	if err != nil {
+		t.Fatalf("Getxattr: %v", err)
+	}
+	got := string([]byte(xattrDataGet))
+	if got != string(xattrDataSet) {
+		t.Errorf("Getxattr: expected attribute value %s, got %s", xattrDataSet, got)
+	}
+
+	err = unix.Removexattr(f, xattrName)
+	if err != nil {
+		t.Fatalf("Removexattr: %v", err)
+	}
+
+	//confirm xattr removed
+	// find size
+	size, err = unix.Listxattr(f, nil)
+	if err != nil {
+		t.Fatalf("Listxattr: %v", err)
+	}
+	if size != 0 {
+		buf := make([]byte, size)
+		read, err = unix.Listxattr(f, buf)
+		if err != nil {
+			t.Fatalf("Listxattr: %v", err)
+		}
+
+		xattrs = stringsFromByteSlice(buf[:read])
+
+		found = false
+		for _, name := range xattrs {
+			if name == xattrWant {
+				found = true
+				break
+			}
+			if found {
+				t.Errorf("Removexattr failed to remove attribute '%s'", xattrName)
+			}
+		}
+	}
+	n := "nonexistent"
+	err = unix.Lsetxattr(n, xattrName, xattrDataSet, 0)
+	if err != unix.ENOENT {
+		t.Errorf("Lsetxattr: expected %v on non-existent file, got %v", unix.ENODATA, err)
+	}
+
+	_, err = unix.Lgetxattr(f, n, nil)
+	if err != unix.ENODATA {
+		t.Errorf("Lgetxattr: %v", err)
+	}
+
+	_, err = unix.Lgetxattr(n, xattrName, nil)
+	if err != unix.ENOENT {
+		t.Errorf("Lgetxattr: %v", err)
+	}
+}
+
+func TestFdXattr(t *testing.T) {
+	file, err := os.CreateTemp("", "TestFdXattr")
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer os.Remove(file.Name())
+	defer file.Close()
+
+	fd := int(file.Fd())
+	xattrName := "system.filetag"
+	xattrDataSet := make([]byte, 4)
+	xattrDataSet[0] = 0xFF
+	xattrDataSet[1] = 0xFF
+	xattrDataSet[2] = 0
+	xattrDataSet[3] = 0
+
+	err = unix.Fsetxattr(fd, xattrName, xattrDataSet, 0)
+	if err == unix.ENOTSUP || err == unix.EOPNOTSUPP {
+		t.Skip("filesystem does not support extended attributes, skipping test")
+	} else if err != nil {
+		t.Fatalf("Fsetxattr: %v", err)
+	}
+
+	// find size
+	size, err := unix.Flistxattr(fd, nil)
+	if err != nil {
+		t.Fatalf("Flistxattr: %v", err)
+	}
+	if size <= 0 {
+		t.Fatalf("Flistxattr returned an empty list of attributes")
+	}
+
+	buf := make([]byte, size)
+	read, err := unix.Flistxattr(fd, buf)
+	if err != nil {
+		t.Fatalf("Flistxattr: %v", err)
+	}
+
+	xattrs := stringsFromByteSlice(buf[:read])
+
+	xattrWant := xattrName
+	found := false
+	for _, name := range xattrs {
+		if name == xattrWant {
+			found = true
+			break
+		}
+	}
+
+	if !found {
+		t.Errorf("Flistxattr did not return previously set attribute '%s'", xattrName)
+	}
+
+	// find size
+	size, err = unix.Fgetxattr(fd, xattrName, nil)
+	if err != nil {
+		t.Fatalf("Fgetxattr: %v", err)
+	}
+
+	if size <= 0 {
+		t.Fatalf("Fgetxattr returned an empty attribute")
+	}
+
+	xattrDataGet := make([]byte, size)
+	_, err = unix.Fgetxattr(fd, xattrName, xattrDataGet)
+	if err != nil {
+		t.Fatalf("Fgetxattr: %v", err)
+	}
+
+	got := string([]byte(xattrDataGet))
+	if got != string(xattrDataSet) {
+		t.Errorf("Getxattr: expected attribute value %s, got %s", xattrDataSet, got)
+	}
+
+	err = unix.Fremovexattr(fd, xattrName)
+	if err != nil {
+		t.Fatalf("Fremovexattr: %v", err)
+	}
+
+	//confirm xattr removed
+	// find size
+	size, err = unix.Flistxattr(fd, nil)
+	if err != nil {
+		t.Fatalf("Flistxattr: %v", err)
+	}
+	if size != 0 {
+		buf := make([]byte, size)
+		read, err = unix.Flistxattr(fd, buf)
+		if err != nil {
+			t.Fatalf("Flistxattr: %v", err)
+		}
+
+		xattrs = stringsFromByteSlice(buf[:read])
+
+		found = false
+		for _, name := range xattrs {
+			if name == xattrWant {
+				found = true
+				break
+			}
+			if found {
+				t.Errorf("Fremovexattr failed to remove attribute '%s'", xattrName)
+			}
+		}
+	}
+}