netstack: fix Mac build error

- Stub out sighandling functions with panics on Darwin
- Put Linux-specific errors into their own syserr file

Not sure how best to get automated tests running, so I'll leave that for a later
change.

Fixes #6839.
Related to #1270.

PiperOrigin-RevId: 409516969

pkg/sighandling/BUILD

@@ -6,7 +6,8 @@ go_library(
     name = "sighandling",
     srcs = [
         "sighandling.go",
-        "sighandling_unsafe.go",
+        "sighandling_darwin.go",
+        "sighandling_linux_unsafe.go",
     ],
     visibility = ["//:sandbox"],
     deps = [

pkg/sighandling/sighandling_darwin.go

@@ -0,0 +1,40 @@
+// Copyright 2021 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.
+
+//go:build darwin
+// +build darwin
+
+package sighandling
+
+import (
+	"errors"
+
+	"golang.org/x/sys/unix"
+)
+
+// IgnoreChildStop sets the SA_NOCLDSTOP flag, causing child processes to not
+// generate SIGCHLD when they stop.
+func IgnoreChildStop() error {
+	return errors.New("IgnoreChildStop not supported on Darwin")
+}
+
+// ReplaceSignalHandler replaces the existing signal handler for the provided
+// signal with the function pointer at `handler`. This bypasses the Go runtime
+// signal handlers, and should only be used for low-level signal handlers where
+// use of signal.Notify is not appropriate.
+//
+// It stores the value of the previously set handler in previous.
+func ReplaceSignalHandler(sig unix.Signal, handler uintptr, previous *uintptr) error {
+	return errors.New("ReplaceSignalHandler not supported on Darwin")
+}

pkg/sighandling/sighandling_linux_unsafe.go

@@ -12,6 +12,9 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
+//go:build linux
+// +build linux
+
 package sighandling
 
 import (

pkg/syserr/BUILD

@@ -5,6 +5,7 @@ package(licenses = ["notice"])
 go_library(
     name = "syserr",
     srcs = [
+        "host_darwin.go",
         "host_linux.go",
         "syserr.go",
     ],

pkg/syserr/host_darwin.go

@@ -0,0 +1,50 @@
+// Copyright 2021 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.
+
+//go:build darwin
+// +build darwin
+
+package syserr
+
+import (
+	"fmt"
+
+	"golang.org/x/sys/unix"
+)
+
+const maxErrno = 107
+
+type darwinHostTranslation struct {
+	err *Error
+	ok  bool
+}
+
+var darwinHostTranslations [maxErrno]darwinHostTranslation
+
+// FromHost translates a unix.Errno to a corresponding Error value.
+func FromHost(err unix.Errno) *Error {
+	if int(err) >= len(darwinHostTranslations) || !darwinHostTranslations[err].ok {
+		panic(fmt.Sprintf("unknown host errno %q (%d)", err.Error(), err))
+	}
+	return darwinHostTranslations[err].err
+}
+
+// TODO(gvisor.dev/issue/1270): We currently only add translations for errors
+// that exist both on Darwin and Linux.
+func addHostTranslation(host unix.Errno, trans *Error) {
+	if darwinHostTranslations[host].ok {
+		panic(fmt.Sprintf("duplicate translation for host errno %q (%d)", host.Error(), host))
+	}
+	darwinHostTranslations[host] = darwinHostTranslation{err: trans, ok: true}
+}

pkg/syserr/host_linux.go

@@ -21,6 +21,7 @@ import (
 	"fmt"
 
 	"golang.org/x/sys/unix"
+	"gvisor.dev/gvisor/pkg/abi/linux/errno"
 )
 
 const maxErrno = 134
@@ -40,9 +41,57 @@ func FromHost(err unix.Errno) *Error {
 	return linuxHostTranslations[err].err
 }
 
-func addLinuxHostTranslation(host unix.Errno, trans *Error) {
+func addHostTranslation(host unix.Errno, trans *Error) {
 	if linuxHostTranslations[host].ok {
 		panic(fmt.Sprintf("duplicate translation for host errno %q (%d)", host.Error(), host))
 	}
 	linuxHostTranslations[host] = linuxHostTranslation{err: trans, ok: true}
 }
+
+// TODO(b/34162363): Remove or replace most of these errors.
+//
+// Some of the errors should be replaced with package specific errors and
+// others should be removed entirely.
+var (
+	ErrDeadlock                  = newWithHost("resource deadlock would occur", errno.EDEADLOCK, unix.EDEADLOCK)
+	ErrChannelOutOfRange         = newWithHost("channel number out of range", errno.ECHRNG, unix.ECHRNG)
+	ErrLevelTwoNotSynced         = newWithHost("level 2 not synchronized", errno.EL2NSYNC, unix.EL2NSYNC)
+	ErrLevelThreeHalted          = newWithHost("level 3 halted", errno.EL3HLT, unix.EL3HLT)
+	ErrLevelThreeReset           = newWithHost("level 3 reset", errno.EL3RST, unix.EL3RST)
+	ErrLinkNumberOutOfRange      = newWithHost("link number out of range", errno.ELNRNG, unix.ELNRNG)
+	ErrProtocolDriverNotAttached = newWithHost("protocol driver not attached", errno.EUNATCH, unix.EUNATCH)
+	ErrNoCSIAvailable            = newWithHost("no CSI structure available", errno.ENOCSI, unix.ENOCSI)
+	ErrLevelTwoHalted            = newWithHost("level 2 halted", errno.EL2HLT, unix.EL2HLT)
+	ErrInvalidExchange           = newWithHost("invalid exchange", errno.EBADE, unix.EBADE)
+	ErrInvalidRequestDescriptor  = newWithHost("invalid request descriptor", errno.EBADR, unix.EBADR)
+	ErrExchangeFull              = newWithHost("exchange full", errno.EXFULL, unix.EXFULL)
+	ErrNoAnode                   = newWithHost("no anode", errno.ENOANO, unix.ENOANO)
+	ErrInvalidRequestCode        = newWithHost("invalid request code", errno.EBADRQC, unix.EBADRQC)
+	ErrInvalidSlot               = newWithHost("invalid slot", errno.EBADSLT, unix.EBADSLT)
+	ErrBadFontFile               = newWithHost("bad font file format", errno.EBFONT, unix.EBFONT)
+	ErrMachineNotOnNetwork       = newWithHost("machine is not on the network", errno.ENONET, unix.ENONET)
+	ErrPackageNotInstalled       = newWithHost("package not installed", errno.ENOPKG, unix.ENOPKG)
+	ErrAdvertise                 = newWithHost("advertise error", errno.EADV, unix.EADV)
+	ErrSRMount                   = newWithHost("srmount error", errno.ESRMNT, unix.ESRMNT)
+	ErrSendCommunication         = newWithHost("communication error on send", errno.ECOMM, unix.ECOMM)
+	ErrRFS                       = newWithHost("RFS specific error", errno.EDOTDOT, unix.EDOTDOT)
+	ErrNetworkNameNotUnique      = newWithHost("name not unique on network", errno.ENOTUNIQ, unix.ENOTUNIQ)
+	ErrFDInBadState              = newWithHost("file descriptor in bad state", errno.EBADFD, unix.EBADFD)
+	ErrRemoteAddressChanged      = newWithHost("remote address changed", errno.EREMCHG, unix.EREMCHG)
+	ErrSharedLibraryInaccessible = newWithHost("can not access a needed shared library", errno.ELIBACC, unix.ELIBACC)
+	ErrCorruptedSharedLibrary    = newWithHost("accessing a corrupted shared library", errno.ELIBBAD, unix.ELIBBAD)
+	ErrLibSectionCorrupted       = newWithHost(".lib section in a.out corrupted", errno.ELIBSCN, unix.ELIBSCN)
+	ErrTooManySharedLibraries    = newWithHost("attempting to link in too many shared libraries", errno.ELIBMAX, unix.ELIBMAX)
+	ErrSharedLibraryExeced       = newWithHost("cannot exec a shared library directly", errno.ELIBEXEC, unix.ELIBEXEC)
+	ErrShouldRestart             = newWithHost("interrupted system call should be restarted", errno.ERESTART, unix.ERESTART)
+	ErrStreamPipe                = newWithHost("streams pipe error", errno.ESTRPIPE, unix.ESTRPIPE)
+	ErrStructureNeedsCleaning    = newWithHost("structure needs cleaning", errno.EUCLEAN, unix.EUCLEAN)
+	ErrIsNamedFile               = newWithHost("is a named type file", errno.ENOTNAM, unix.ENOTNAM)
+	ErrRemoteIO                  = newWithHost("remote I/O error", errno.EREMOTEIO, unix.EREMOTEIO)
+	ErrNoMedium                  = newWithHost("no medium found", errno.ENOMEDIUM, unix.ENOMEDIUM)
+	ErrWrongMediumType           = newWithHost("wrong medium type", errno.EMEDIUMTYPE, unix.EMEDIUMTYPE)
+	ErrNoKey                     = newWithHost("required key not available", errno.ENOKEY, unix.ENOKEY)
+	ErrKeyExpired                = newWithHost("key has expired", errno.EKEYEXPIRED, unix.EKEYEXPIRED)
+	ErrKeyRevoked                = newWithHost("key has been revoked", errno.EKEYREVOKED, unix.EKEYREVOKED)
+	ErrKeyRejected               = newWithHost("key was rejected by service", errno.EKEYREJECTED, unix.EKEYREJECTED)
+)

pkg/syserr/syserr.go

@@ -76,7 +76,7 @@ func NewDynamic(message string, linuxTranslation errno.Errno) *Error {
 
 func newWithHost(message string, linuxTranslation errno.Errno, hostErrno unix.Errno) *Error {
 	e := New(message, linuxTranslation)
-	addLinuxHostTranslation(hostErrno, e)
+	addHostTranslation(hostErrno, e)
 	return e
 }
 
@@ -129,6 +129,8 @@ func (e *Error) ToLinux() errno.Errno {
 //
 // Some of the errors should be replaced with package specific errors and
 // others should be removed entirely.
+//
+// Note that some errors are declared in platform-specific files.
 var (
 	ErrNotPermitted               = newWithHost("operation not permitted", errno.EPERM, unix.EPERM)
 	ErrNoFileOrDir                = newWithHost("no such file or directory", errno.ENOENT, unix.ENOENT)
@@ -164,7 +166,6 @@ var (
 	ErrBrokenPipe                 = newWithHost("broken pipe", errno.EPIPE, unix.EPIPE)
 	ErrDomain                     = newWithHost("math argument out of domain of func", errno.EDOM, unix.EDOM)
 	ErrRange                      = newWithHost("math result not representable", errno.ERANGE, unix.ERANGE)
-	ErrDeadlock                   = newWithHost("resource deadlock would occur", errno.EDEADLOCK, unix.EDEADLOCK)
 	ErrNameTooLong                = newWithHost("file name too long", errno.ENAMETOOLONG, unix.ENAMETOOLONG)
 	ErrNoLocksAvailable           = newWithHost("no record locks available", errno.ENOLCK, unix.ENOLCK)
 	ErrInvalidSyscall             = newWithHost("invalid system call number", errno.ENOSYS, unix.ENOSYS)
@@ -172,48 +173,17 @@ var (
 	ErrLinkLoop                   = newWithHost("too many symbolic links encountered", errno.ELOOP, unix.ELOOP)
 	ErrNoMessage                  = newWithHost("no message of desired type", errno.ENOMSG, unix.ENOMSG)
 	ErrIdentifierRemoved          = newWithHost("identifier removed", errno.EIDRM, unix.EIDRM)
-	ErrChannelOutOfRange          = newWithHost("channel number out of range", errno.ECHRNG, unix.ECHRNG)
-	ErrLevelTwoNotSynced          = newWithHost("level 2 not synchronized", errno.EL2NSYNC, unix.EL2NSYNC)
-	ErrLevelThreeHalted           = newWithHost("level 3 halted", errno.EL3HLT, unix.EL3HLT)
-	ErrLevelThreeReset            = newWithHost("level 3 reset", errno.EL3RST, unix.EL3RST)
-	ErrLinkNumberOutOfRange       = newWithHost("link number out of range", errno.ELNRNG, unix.ELNRNG)
-	ErrProtocolDriverNotAttached  = newWithHost("protocol driver not attached", errno.EUNATCH, unix.EUNATCH)
-	ErrNoCSIAvailable             = newWithHost("no CSI structure available", errno.ENOCSI, unix.ENOCSI)
-	ErrLevelTwoHalted             = newWithHost("level 2 halted", errno.EL2HLT, unix.EL2HLT)
-	ErrInvalidExchange            = newWithHost("invalid exchange", errno.EBADE, unix.EBADE)
-	ErrInvalidRequestDescriptor   = newWithHost("invalid request descriptor", errno.EBADR, unix.EBADR)
-	ErrExchangeFull               = newWithHost("exchange full", errno.EXFULL, unix.EXFULL)
-	ErrNoAnode                    = newWithHost("no anode", errno.ENOANO, unix.ENOANO)
-	ErrInvalidRequestCode         = newWithHost("invalid request code", errno.EBADRQC, unix.EBADRQC)
-	ErrInvalidSlot                = newWithHost("invalid slot", errno.EBADSLT, unix.EBADSLT)
-	ErrBadFontFile                = newWithHost("bad font file format", errno.EBFONT, unix.EBFONT)
 	ErrNotStream                  = newWithHost("device not a stream", errno.ENOSTR, unix.ENOSTR)
 	ErrNoDataAvailable            = newWithHost("no data available", errno.ENODATA, unix.ENODATA)
 	ErrTimerExpired               = newWithHost("timer expired", errno.ETIME, unix.ETIME)
 	ErrStreamsResourceDepleted    = newWithHost("out of streams resources", errno.ENOSR, unix.ENOSR)
-	ErrMachineNotOnNetwork        = newWithHost("machine is not on the network", errno.ENONET, unix.ENONET)
-	ErrPackageNotInstalled        = newWithHost("package not installed", errno.ENOPKG, unix.ENOPKG)
 	ErrIsRemote                   = newWithHost("object is remote", errno.EREMOTE, unix.EREMOTE)
 	ErrNoLink                     = newWithHost("link has been severed", errno.ENOLINK, unix.ENOLINK)
-	ErrAdvertise                  = newWithHost("advertise error", errno.EADV, unix.EADV)
-	ErrSRMount                    = newWithHost("srmount error", errno.ESRMNT, unix.ESRMNT)
-	ErrSendCommunication          = newWithHost("communication error on send", errno.ECOMM, unix.ECOMM)
 	ErrProtocol                   = newWithHost("protocol error", errno.EPROTO, unix.EPROTO)
 	ErrMultihopAttempted          = newWithHost("multihop attempted", errno.EMULTIHOP, unix.EMULTIHOP)
-	ErrRFS                        = newWithHost("RFS specific error", errno.EDOTDOT, unix.EDOTDOT)
 	ErrInvalidDataMessage         = newWithHost("not a data message", errno.EBADMSG, unix.EBADMSG)
 	ErrOverflow                   = newWithHost("value too large for defined data type", errno.EOVERFLOW, unix.EOVERFLOW)
-	ErrNetworkNameNotUnique       = newWithHost("name not unique on network", errno.ENOTUNIQ, unix.ENOTUNIQ)
-	ErrFDInBadState               = newWithHost("file descriptor in bad state", errno.EBADFD, unix.EBADFD)
-	ErrRemoteAddressChanged       = newWithHost("remote address changed", errno.EREMCHG, unix.EREMCHG)
-	ErrSharedLibraryInaccessible  = newWithHost("can not access a needed shared library", errno.ELIBACC, unix.ELIBACC)
-	ErrCorruptedSharedLibrary     = newWithHost("accessing a corrupted shared library", errno.ELIBBAD, unix.ELIBBAD)
-	ErrLibSectionCorrupted        = newWithHost(".lib section in a.out corrupted", errno.ELIBSCN, unix.ELIBSCN)
-	ErrTooManySharedLibraries     = newWithHost("attempting to link in too many shared libraries", errno.ELIBMAX, unix.ELIBMAX)
-	ErrSharedLibraryExeced        = newWithHost("cannot exec a shared library directly", errno.ELIBEXEC, unix.ELIBEXEC)
 	ErrIllegalByteSequence        = newWithHost("illegal byte sequence", errno.EILSEQ, unix.EILSEQ)
-	ErrShouldRestart              = newWithHost("interrupted system call should be restarted", errno.ERESTART, unix.ERESTART)
-	ErrStreamPipe                 = newWithHost("streams pipe error", errno.ESTRPIPE, unix.ESTRPIPE)
 	ErrTooManyUsers               = newWithHost("too many users", errno.EUSERS, unix.EUSERS)
 	ErrNotASocket                 = newWithHost("socket operation on non-socket", errno.ENOTSOCK, unix.ENOTSOCK)
 	ErrDestinationAddressRequired = newWithHost("destination address required", errno.EDESTADDRREQ, unix.EDESTADDRREQ)
@@ -244,17 +214,8 @@ var (
 	ErrAlreadyInProgress          = newWithHost("operation already in progress", errno.EALREADY, unix.EALREADY)
 	ErrInProgress                 = newWithHost("operation now in progress", errno.EINPROGRESS, unix.EINPROGRESS)
 	ErrStaleFileHandle            = newWithHost("stale file handle", errno.ESTALE, unix.ESTALE)
-	ErrStructureNeedsCleaning     = newWithHost("structure needs cleaning", errno.EUCLEAN, unix.EUCLEAN)
-	ErrIsNamedFile                = newWithHost("is a named type file", errno.ENOTNAM, unix.ENOTNAM)
-	ErrRemoteIO                   = newWithHost("remote I/O error", errno.EREMOTEIO, unix.EREMOTEIO)
 	ErrQuotaExceeded              = newWithHost("quota exceeded", errno.EDQUOT, unix.EDQUOT)
-	ErrNoMedium                   = newWithHost("no medium found", errno.ENOMEDIUM, unix.ENOMEDIUM)
-	ErrWrongMediumType            = newWithHost("wrong medium type", errno.EMEDIUMTYPE, unix.EMEDIUMTYPE)
 	ErrCanceled                   = newWithHost("operation canceled", errno.ECANCELED, unix.ECANCELED)
-	ErrNoKey                      = newWithHost("required key not available", errno.ENOKEY, unix.ENOKEY)
-	ErrKeyExpired                 = newWithHost("key has expired", errno.EKEYEXPIRED, unix.EKEYEXPIRED)
-	ErrKeyRevoked                 = newWithHost("key has been revoked", errno.EKEYREVOKED, unix.EKEYREVOKED)
-	ErrKeyRejected                = newWithHost("key was rejected by service", errno.EKEYREJECTED, unix.EKEYREJECTED)
 	ErrOwnerDied                  = newWithHost("owner died", errno.EOWNERDEAD, unix.EOWNERDEAD)
 	ErrNotRecoverable             = newWithHost("state not recoverable", errno.ENOTRECOVERABLE, unix.ENOTRECOVERABLE)