[syserror] Add conversions to linuxerr with temporary Equals method.

Add Equals method to compare syserror and unix.Errno errors to linuxerr errors.
This will facilitate removal of syserror definitions in a followup, and
finding needed conversions from unix.Errno to linuxerr.

PiperOrigin-RevId: 380909667

6 files changed, 18 insertions, 12 deletions

diff --git a/pkg/sentry/syscalls/linux/vfs2/BUILD b/pkg/sentry/syscalls/linux/vfs2/BUILD
index 5ce0bc714..a73f096ff 100644
--- a/pkg/sentry/syscalls/linux/vfs2/BUILD
+++ b/pkg/sentry/syscalls/linux/vfs2/BUILD
@@ -41,6 +41,7 @@ go_library(
         "//pkg/abi/linux",
         "//pkg/bits",
         "//pkg/context",
+        "//pkg/errors/linuxerr",
         "//pkg/fspath",
         "//pkg/gohacks",
         "//pkg/hostarch",
diff --git a/pkg/sentry/syscalls/linux/vfs2/epoll.go b/pkg/sentry/syscalls/linux/vfs2/epoll.go
index 047d955b6..7aff01343 100644
--- a/pkg/sentry/syscalls/linux/vfs2/epoll.go
+++ b/pkg/sentry/syscalls/linux/vfs2/epoll.go
@@ -19,6 +19,7 @@ import (
 	"time"
 
 	"gvisor.dev/gvisor/pkg/abi/linux"
+	"gvisor.dev/gvisor/pkg/errors/linuxerr"
 	"gvisor.dev/gvisor/pkg/hostarch"
 	"gvisor.dev/gvisor/pkg/sentry/arch"
 	"gvisor.dev/gvisor/pkg/sentry/kernel"
@@ -174,7 +175,7 @@ func waitEpoll(t *kernel.Task, epfd int32, eventsAddr hostarch.Addr, maxEvents i
 				haveDeadline = true
 			}
 			if err := t.BlockWithDeadline(ch, haveDeadline, deadline); err != nil {
-				if err == syserror.ETIMEDOUT {
+				if linuxerr.Equals(linuxerr.ETIMEDOUT, err) {
 					err = nil
 				}
 				return 0, nil, err
diff --git a/pkg/sentry/syscalls/linux/vfs2/poll.go b/pkg/sentry/syscalls/linux/vfs2/poll.go
index a69c80edd..b16773d65 100644
--- a/pkg/sentry/syscalls/linux/vfs2/poll.go
+++ b/pkg/sentry/syscalls/linux/vfs2/poll.go
@@ -19,6 +19,7 @@ import (
 	"time"
 
 	"gvisor.dev/gvisor/pkg/abi/linux"
+	"gvisor.dev/gvisor/pkg/errors/linuxerr"
 	"gvisor.dev/gvisor/pkg/sentry/arch"
 	"gvisor.dev/gvisor/pkg/sentry/kernel"
 	ktime "gvisor.dev/gvisor/pkg/sentry/kernel/time"
@@ -132,7 +133,7 @@ func pollBlock(t *kernel.Task, pfd []linux.PollFD, timeout time.Duration) (time.
 		// Wait for a notification.
 		timeout, err = t.BlockWithTimeout(ch, haveTimeout, timeout)
 		if err != nil {
-			if err == syserror.ETIMEDOUT {
+			if linuxerr.Equals(linuxerr.ETIMEDOUT, err) {
 				err = nil
 			}
 			return timeout, 0, err
@@ -410,7 +411,7 @@ func (p *pollRestartBlock) Restart(t *kernel.Task) (uintptr, error) {
 func poll(t *kernel.Task, pfdAddr hostarch.Addr, nfds uint, timeout time.Duration) (uintptr, error) {
 	remainingTimeout, n, err := doPoll(t, pfdAddr, nfds, timeout)
 	// On an interrupt poll(2) is restarted with the remaining timeout.
-	if err == syserror.EINTR {
+	if linuxerr.Equals(linuxerr.EINTR, err) {
 		t.SetSyscallRestartBlock(&pollRestartBlock{
 			pfdAddr: pfdAddr,
 			nfds:    nfds,
@@ -462,7 +463,7 @@ func Ppoll(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.Syscall
 	//
 	// Note that this means that if err is nil but copyErr is not, copyErr is
 	// ignored. This is consistent with Linux.
-	if err == syserror.EINTR && copyErr == nil {
+	if linuxerr.Equals(linuxerr.EINTR, err) && copyErr == nil {
 		err = syserror.ERESTARTNOHAND
 	}
 	return n, nil, err
@@ -492,7 +493,7 @@ func Select(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.Syscal
 	n, err := doSelect(t, nfds, readFDs, writeFDs, exceptFDs, timeout)
 	copyErr := copyOutTimevalRemaining(t, startNs, timeout, timevalAddr)
 	// See comment in Ppoll.
-	if err == syserror.EINTR && copyErr == nil {
+	if linuxerr.Equals(linuxerr.EINTR, err) && copyErr == nil {
 		err = syserror.ERESTARTNOHAND
 	}
 	return n, nil, err
@@ -539,7 +540,7 @@ func Pselect(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.Sysca
 	n, err := doSelect(t, nfds, readFDs, writeFDs, exceptFDs, timeout)
 	copyErr := copyOutTimespecRemaining(t, startNs, timeout, timespecAddr)
 	// See comment in Ppoll.
-	if err == syserror.EINTR && copyErr == nil {
+	if linuxerr.Equals(linuxerr.EINTR, err) && copyErr == nil {
 		err = syserror.ERESTARTNOHAND
 	}
 	return n, nil, err
diff --git a/pkg/sentry/syscalls/linux/vfs2/read_write.go b/pkg/sentry/syscalls/linux/vfs2/read_write.go
index b863d7b84..bbfa4c6d7 100644
--- a/pkg/sentry/syscalls/linux/vfs2/read_write.go
+++ b/pkg/sentry/syscalls/linux/vfs2/read_write.go
@@ -18,6 +18,7 @@ import (
 	"time"
 
 	"gvisor.dev/gvisor/pkg/abi/linux"
+	"gvisor.dev/gvisor/pkg/errors/linuxerr"
 	"gvisor.dev/gvisor/pkg/sentry/arch"
 	"gvisor.dev/gvisor/pkg/sentry/kernel"
 	ktime "gvisor.dev/gvisor/pkg/sentry/kernel/time"
@@ -120,7 +121,7 @@ func read(t *kernel.Task, file *vfs.FileDescription, dst usermem.IOSequence, opt
 
 		// Wait for a notification that we should retry.
 		if err = t.BlockWithDeadline(ch, hasDeadline, deadline); err != nil {
-			if err == syserror.ETIMEDOUT {
+			if linuxerr.Equals(linuxerr.ETIMEDOUT, err) {
 				err = syserror.ErrWouldBlock
 			}
 			break
@@ -275,7 +276,7 @@ func pread(t *kernel.Task, file *vfs.FileDescription, dst usermem.IOSequence, of
 
 		// Wait for a notification that we should retry.
 		if err = t.BlockWithDeadline(ch, hasDeadline, deadline); err != nil {
-			if err == syserror.ETIMEDOUT {
+			if linuxerr.Equals(linuxerr.ETIMEDOUT, err) {
 				err = syserror.ErrWouldBlock
 			}
 			break
@@ -371,7 +372,7 @@ func write(t *kernel.Task, file *vfs.FileDescription, src usermem.IOSequence, op
 
 		// Wait for a notification that we should retry.
 		if err = t.BlockWithDeadline(ch, hasDeadline, deadline); err != nil {
-			if err == syserror.ETIMEDOUT {
+			if linuxerr.Equals(linuxerr.ETIMEDOUT, err) {
 				err = syserror.ErrWouldBlock
 			}
 			break
@@ -525,7 +526,7 @@ func pwrite(t *kernel.Task, file *vfs.FileDescription, src usermem.IOSequence, o
 
 		// Wait for a notification that we should retry.
 		if err = t.BlockWithDeadline(ch, hasDeadline, deadline); err != nil {
-			if err == syserror.ETIMEDOUT {
+			if linuxerr.Equals(linuxerr.ETIMEDOUT, err) {
 				err = syserror.ErrWouldBlock
 			}
 			break
diff --git a/pkg/sentry/syscalls/linux/vfs2/socket.go b/pkg/sentry/syscalls/linux/vfs2/socket.go
index 69f69e3af..9a4b5e5fc 100644
--- a/pkg/sentry/syscalls/linux/vfs2/socket.go
+++ b/pkg/sentry/syscalls/linux/vfs2/socket.go
@@ -18,6 +18,7 @@ import (
 	"time"
 
 	"gvisor.dev/gvisor/pkg/abi/linux"
+	"gvisor.dev/gvisor/pkg/errors/linuxerr"
 	"gvisor.dev/gvisor/pkg/marshal"
 	"gvisor.dev/gvisor/pkg/marshal/primitive"
 	"gvisor.dev/gvisor/pkg/sentry/arch"
@@ -309,7 +310,7 @@ func accept(t *kernel.Task, fd int32, addr hostarch.Addr, addrLen hostarch.Addr,
 	if peerRequested {
 		// NOTE(magi): Linux does not give you an error if it can't
 		// write the data back out so neither do we.
-		if err := writeAddress(t, peer, peerLen, addr, addrLen); err == syserror.EINVAL {
+		if err := writeAddress(t, peer, peerLen, addr, addrLen); linuxerr.Equals(linuxerr.EINVAL, err) {
 			return 0, err
 		}
 	}
diff --git a/pkg/sentry/syscalls/linux/vfs2/xattr.go b/pkg/sentry/syscalls/linux/vfs2/xattr.go
index c261050c6..c779c6465 100644
--- a/pkg/sentry/syscalls/linux/vfs2/xattr.go
+++ b/pkg/sentry/syscalls/linux/vfs2/xattr.go
@@ -18,6 +18,7 @@ import (
 	"bytes"
 
 	"gvisor.dev/gvisor/pkg/abi/linux"
+	"gvisor.dev/gvisor/pkg/errors/linuxerr"
 	"gvisor.dev/gvisor/pkg/gohacks"
 	"gvisor.dev/gvisor/pkg/sentry/arch"
 	"gvisor.dev/gvisor/pkg/sentry/kernel"
@@ -295,7 +296,7 @@ func Fremovexattr(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.
 func copyInXattrName(t *kernel.Task, nameAddr hostarch.Addr) (string, error) {
 	name, err := t.CopyInString(nameAddr, linux.XATTR_NAME_MAX+1)
 	if err != nil {
-		if err == syserror.ENAMETOOLONG {
+		if linuxerr.Equals(linuxerr.ENAMETOOLONG, err) {
 			return "", syserror.ERANGE
 		}
 		return "", err