add os.Link

Signed-off-by: leongross <leon.gross@9elements.com>

src/os/os_hardlink_test.go

@@ -0,0 +1,53 @@
+//go:build !windows && !baremetal && !js && !wasi && !wasip1 && !wasm_unknown
+
+// 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.
+
+package os_test
+
+import (
+	. "os"
+	"syscall"
+	"testing"
+)
+
+func TestHardlink(t *testing.T) {
+	defer chtmpdir(t)()
+	from, to := "hardlinktestfrom", "hardlinktestto"
+
+	file, err := Create(to)
+	if err != nil {
+		t.Fatalf("Create(%q) failed: %v", to, err)
+	}
+	if err = file.Close(); err != nil {
+		t.Errorf("Close(%q) failed: %v", to, err)
+	}
+	err = Link(to, from)
+	if err != nil {
+		t.Fatalf("Link(%q, %q) failed: %v", to, from, err)
+	}
+
+	tostat, err := Lstat(to)
+	if err != nil {
+		t.Fatalf("Lstat(%q) failed: %v", to, err)
+	}
+	fromstat, err := Stat(from)
+	if err != nil {
+		t.Fatalf("Stat(%q) failed: %v", from, err)
+	}
+	if !SameFile(tostat, fromstat) {
+		t.Errorf("Symlink(%q, %q) did not create symlink", to, from)
+	}
+
+	fromstat, err = Lstat(from)
+	if err != nil {
+		t.Fatalf("Lstat(%q) failed: %v", from, err)
+	}
+	// if they have the same inode, they are hard links
+	if fromstat.Sys().(*syscall.Stat_t).Ino != tostat.Sys().(*syscall.Stat_t).Ino {
+		t.Fatalf("Lstat(%q).Sys().Ino = %v, Lstat(%q).Sys().Ino = %v, want the same", to, tostat.Sys().(*syscall.Stat_t).Ino, from, fromstat.Sys().(*syscall.Stat_t).Ino)
+	}
+
+	file.Close()
+}