unix: add Major, Minor and Mkdev functions on OpenBSD
Add Major, Minor and Mkdev functions for converting devices numbers to
their major/minor components and vice versa.
The functions follow the behavior of the macros defined in OpenBSD's
sys/types.h header. However, the parameter and return types are changed
to match the existing implementations of these functions.
Test the conversion macros with some well-known device numbers.
Updates golang/go#8106
Change-Id: Ia50b7ccab18ff7c7e9dd77ddc7e4aa6cf5c79963
Reviewed-on: https://go-review.googlesource.com/63070
Reviewed-by: Ian Lance Taylor <iant@golang.org>
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
diff --git a/unix/dev_openbsd.go b/unix/dev_openbsd.go
new file mode 100644
index 0000000..f3430c4
--- /dev/null
+++ b/unix/dev_openbsd.go
@@ -0,0 +1,29 @@
+// Copyright 2017 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.
+
+// Functions to access/create device major and minor numbers matching the
+// encoding used in OpenBSD's sys/types.h header.
+
+package unix
+
+// Major returns the major component of an OpenBSD device number.
+func Major(dev uint64) uint32 {
+ return uint32((dev & 0x0000ff00) >> 8)
+}
+
+// Minor returns the minor component of an OpenBSD device number.
+func Minor(dev uint64) uint32 {
+ minor := uint32((dev & 0x000000ff) >> 0)
+ minor |= uint32((dev & 0xffff0000) >> 8)
+ return minor
+}
+
+// Mkdev returns an OpenBSD device number generated from the given major and minor
+// components.
+func Mkdev(major, minor uint32) uint64 {
+ dev := (uint64(major) << 8) & 0x0000ff00
+ dev |= (uint64(minor) << 8) & 0xffff0000
+ dev |= (uint64(minor) << 0) & 0x000000ff
+ return dev
+}
diff --git a/unix/dev_openbsd_test.go b/unix/dev_openbsd_test.go
new file mode 100644
index 0000000..5635d27
--- /dev/null
+++ b/unix/dev_openbsd_test.go
@@ -0,0 +1,52 @@
+// Copyright 2017 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 unix_test
+
+import (
+ "fmt"
+ "testing"
+
+ "golang.org/x/sys/unix"
+)
+
+func TestDevices(t *testing.T) {
+ testCases := []struct {
+ path string
+ major uint32
+ minor uint32
+ }{
+ // well known major/minor numbers according to /dev/MAKEDEV on
+ // OpenBSD 6.0
+ {"/dev/null", 2, 2},
+ {"/dev/zero", 2, 12},
+ {"/dev/ttyp0", 5, 0},
+ {"/dev/ttyp1", 5, 1},
+ {"/dev/random", 45, 0},
+ {"/dev/srandom", 45, 1},
+ {"/dev/urandom", 45, 2},
+ {"/dev/arandom", 45, 3},
+ }
+ for _, tc := range testCases {
+ t.Run(fmt.Sprintf("%s %v:%v", tc.path, tc.major, tc.minor), func(t *testing.T) {
+ var stat unix.Stat_t
+ err := unix.Stat(tc.path, &stat)
+ if err != nil {
+ t.Errorf("failed to stat device: %v", err)
+ return
+ }
+
+ dev := uint64(stat.Rdev)
+ if unix.Major(dev) != tc.major {
+ t.Errorf("for %s Major(%#x) == %d, want %d", tc.path, dev, unix.Major(dev), tc.major)
+ }
+ if unix.Minor(dev) != tc.minor {
+ t.Errorf("for %s Minor(%#x) == %d, want %d", tc.path, dev, unix.Minor(dev), tc.minor)
+ }
+ if unix.Mkdev(tc.major, tc.minor) != dev {
+ t.Errorf("for %s Mkdev(%d, %d) == %#x, want %#x", tc.path, tc.major, tc.minor, unix.Mkdev(tc.major, tc.minor), dev)
+ }
+ })
+ }
+}
