[syserror] Add linuxerr package.

Add linuxerr package to replace syserror and syserr errors. This is done
to improve performance comparing/returning errors to on par with
syscall.Errno.

The below linuxerr_test (formerly syserror_test) shows linuxerr.Error
on par with unix.Error (syscall.Errno) as desired.

BenchmarkAssignErrno
BenchmarkAssignErrno-6                  1000000000               0.6291 ns/op
BenchmarkLinuxerrAssignError
BenchmarkLinuxerrAssignError-6          1000000000               0.5808 ns/op
BenchmarkAssignSyserrorError
BenchmarkAssignSyserrorError-6          1000000000               0.6188 ns/op
BenchmarkCompareErrno
BenchmarkCompareErrno-6                 1000000000               0.5041 ns/op
BenchmarkCompareLinuxerrError
BenchmarkCompareLinuxerrError-6         1000000000               0.4660 ns/op
BenchmarkCompareSyserrorError
BenchmarkCompareSyserrorError-6         309026907                3.386 ns/op
BenchmarkSwitchErrno
BenchmarkSwitchErrno-6                  722253750                1.440 ns/op
BenchmarkSwitchLinuxerrError
BenchmarkSwitchLinuxerrError-6          709108542                1.453 ns/op
BenchmarkSwitchSyserrorError
BenchmarkSwitchSyserrorError-6          106331331               11.21 ns/op

PiperOrigin-RevId: 374507431

1 files changed, 164 insertions, 0 deletions

diff --git a/pkg/linuxerr/linuxerr_test.go b/pkg/linuxerr/linuxerr_test.go
new file mode 100644
index 000000000..d34937e93
--- /dev/null
+++ b/pkg/linuxerr/linuxerr_test.go
@@ -0,0 +1,164 @@
+// Copyright 2018 The gVisor Authors.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package syserror_test
+
+import (
+	"errors"
+	"testing"
+
+	"golang.org/x/sys/unix"
+	"gvisor.dev/gvisor/pkg/linuxerr"
+	"gvisor.dev/gvisor/pkg/syserror"
+)
+
+var globalError error
+
+func BenchmarkAssignErrno(b *testing.B) {
+	for i := b.N; i > 0; i-- {
+		globalError = unix.EINVAL
+	}
+}
+
+func BenchmarkLinuxerrAssignError(b *testing.B) {
+	for i := b.N; i > 0; i-- {
+		globalError = linuxerr.EINVAL
+	}
+}
+
+func BenchmarkAssignSyserrorError(b *testing.B) {
+	for i := b.N; i > 0; i-- {
+		globalError = syserror.EINVAL
+	}
+}
+
+func BenchmarkCompareErrno(b *testing.B) {
+	globalError = unix.EAGAIN
+	j := 0
+	for i := b.N; i > 0; i-- {
+		if globalError == unix.EINVAL {
+			j++
+		}
+	}
+}
+
+func BenchmarkCompareLinuxerrError(b *testing.B) {
+	globalError = linuxerr.E2BIG
+	j := 0
+	for i := b.N; i > 0; i-- {
+		if globalError == linuxerr.EINVAL {
+			j++
+		}
+	}
+}
+
+func BenchmarkCompareSyserrorError(b *testing.B) {
+	globalError = syserror.EAGAIN
+	j := 0
+	for i := b.N; i > 0; i-- {
+		if globalError == syserror.EINVAL {
+			j++
+		}
+	}
+}
+
+func BenchmarkSwitchErrno(b *testing.B) {
+	globalError = unix.EPERM
+	j := 0
+	for i := b.N; i > 0; i-- {
+		switch globalError {
+		case unix.EINVAL:
+			j++
+		case unix.EINTR:
+			j += 2
+		case unix.EAGAIN:
+			j += 3
+		}
+	}
+}
+
+func BenchmarkSwitchLinuxerrError(b *testing.B) {
+	globalError = linuxerr.EPERM
+	j := 0
+	for i := b.N; i > 0; i-- {
+		switch globalError {
+		case linuxerr.EINVAL:
+			j++
+		case linuxerr.EINTR:
+			j += 2
+		case linuxerr.EAGAIN:
+			j += 3
+		}
+	}
+}
+
+func BenchmarkSwitchSyserrorError(b *testing.B) {
+	globalError = syserror.EPERM
+	j := 0
+	for i := b.N; i > 0; i-- {
+		switch globalError {
+		case syserror.EINVAL:
+			j++
+		case syserror.EINTR:
+			j += 2
+		case syserror.EAGAIN:
+			j += 3
+		}
+	}
+}
+
+type translationTestTable struct {
+	fn                  string
+	errIn               error
+	syscallErrorIn      unix.Errno
+	expectedBool        bool
+	expectedTranslation unix.Errno
+}
+
+func TestErrorTranslation(t *testing.T) {
+	myError := errors.New("My test error")
+	myError2 := errors.New("Another test error")
+	testTable := []translationTestTable{
+		{"TranslateError", myError, 0, false, 0},
+		{"TranslateError", myError2, 0, false, 0},
+		{"AddErrorTranslation", myError, unix.EAGAIN, true, 0},
+		{"AddErrorTranslation", myError, unix.EAGAIN, false, 0},
+		{"AddErrorTranslation", myError, unix.EPERM, false, 0},
+		{"TranslateError", myError, 0, true, unix.EAGAIN},
+		{"TranslateError", myError2, 0, false, 0},
+		{"AddErrorTranslation", myError2, unix.EPERM, true, 0},
+		{"AddErrorTranslation", myError2, unix.EPERM, false, 0},
+		{"AddErrorTranslation", myError2, unix.EAGAIN, false, 0},
+		{"TranslateError", myError, 0, true, unix.EAGAIN},
+		{"TranslateError", myError2, 0, true, unix.EPERM},
+	}
+	for _, tt := range testTable {
+		switch tt.fn {
+		case "TranslateError":
+			err, ok := syserror.TranslateError(tt.errIn)
+			if ok != tt.expectedBool {
+				t.Fatalf("%v(%v) => %v expected %v", tt.fn, tt.errIn, ok, tt.expectedBool)
+			} else if err != tt.expectedTranslation {
+				t.Fatalf("%v(%v) (error) => %v expected %v", tt.fn, tt.errIn, err, tt.expectedTranslation)
+			}
+		case "AddErrorTranslation":
+			ok := syserror.AddErrorTranslation(tt.errIn, tt.syscallErrorIn)
+			if ok != tt.expectedBool {
+				t.Fatalf("%v(%v) => %v expected %v", tt.fn, tt.errIn, ok, tt.expectedBool)
+			}
+		default:
+			t.Fatalf("Unknown function %v", tt.fn)
+		}
+	}
+}