Gracefully translate unknown errno.

Neither POSIX.1 nor Linux defines an upperbound for errno.

PiperOrigin-RevId: 332085017

pkg/tcpip/link/rawfile/BUILD

@@ -1,4 +1,4 @@
-load("//tools:defs.bzl", "go_library")
+load("//tools:defs.bzl", "go_library", "go_test")
 
 package(licenses = ["notice"])
 
@@ -18,3 +18,14 @@ go_library(
         "@org_golang_x_sys//unix:go_default_library",
     ],
 )
+
+go_test(
+    name = "rawfile_test",
+    srcs = [
+        "errors_test.go",
+    ],
+    library = "rawfile",
+    deps = [
+        "//pkg/tcpip",
+    ],
+)

pkg/tcpip/link/rawfile/errors.go

@@ -31,10 +31,12 @@ var translations [maxErrno]*tcpip.Error
 // *tcpip.Error.
 //
 // Valid, but unrecognized errnos will be translated to
-// tcpip.ErrInvalidEndpointState (EINVAL). Panics on invalid errnos.
+// tcpip.ErrInvalidEndpointState (EINVAL).
 func TranslateErrno(e syscall.Errno) *tcpip.Error {
-	if err := translations[e]; err != nil {
+	if e > 0 && e < syscall.Errno(len(translations)) {
-		return err
+		if err := translations[e]; err != nil {
+			return err
+		}
 	}
 	return tcpip.ErrInvalidEndpointState
 }

pkg/tcpip/link/rawfile/errors_test.go

@@ -0,0 +1,53 @@
+// Copyright 2020 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.
+
+// +build linux
+
+package rawfile
+
+import (
+	"syscall"
+	"testing"
+
+	"gvisor.dev/gvisor/pkg/tcpip"
+)
+
+func TestTranslateErrno(t *testing.T) {
+	for _, test := range []struct {
+		errno      syscall.Errno
+		translated *tcpip.Error
+	}{
+		{
+			errno:      syscall.Errno(0),
+			translated: tcpip.ErrInvalidEndpointState,
+		},
+		{
+			errno:      syscall.Errno(maxErrno),
+			translated: tcpip.ErrInvalidEndpointState,
+		},
+		{
+			errno:      syscall.Errno(514),
+			translated: tcpip.ErrInvalidEndpointState,
+		},
+		{
+			errno:      syscall.EEXIST,
+			translated: tcpip.ErrDuplicateAddress,
+		},
+	} {
+		got := TranslateErrno(test.errno)
+		if got != test.translated {
+			t.Errorf("TranslateErrno(%q) = %q, want %q", test.errno, got, test.translated)
+		}
+	}
+}