[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

5 files changed, 10 insertions, 6 deletions

diff --git a/pkg/sentry/fsimpl/host/BUILD b/pkg/sentry/fsimpl/host/BUILD
index b94dfeb7f..f2f83796c 100644
--- a/pkg/sentry/fsimpl/host/BUILD
+++ b/pkg/sentry/fsimpl/host/BUILD
@@ -45,6 +45,7 @@ go_library(
     deps = [
         "//pkg/abi/linux",
         "//pkg/context",
+        "//pkg/errors/linuxerr",
         "//pkg/fdnotifier",
         "//pkg/fspath",
         "//pkg/hostarch",
diff --git a/pkg/sentry/fsimpl/host/host.go b/pkg/sentry/fsimpl/host/host.go
index a81f550b1..2dbfbdecf 100644
--- a/pkg/sentry/fsimpl/host/host.go
+++ b/pkg/sentry/fsimpl/host/host.go
@@ -24,6 +24,7 @@ import (
 	"golang.org/x/sys/unix"
 	"gvisor.dev/gvisor/pkg/abi/linux"
 	"gvisor.dev/gvisor/pkg/context"
+	"gvisor.dev/gvisor/pkg/errors/linuxerr"
 	"gvisor.dev/gvisor/pkg/fdnotifier"
 	"gvisor.dev/gvisor/pkg/fspath"
 	"gvisor.dev/gvisor/pkg/hostarch"
@@ -109,7 +110,7 @@ type inode struct {
 func newInode(ctx context.Context, fs *filesystem, hostFD int, savable bool, fileType linux.FileMode, isTTY bool) (*inode, error) {
 	// Determine if hostFD is seekable.
 	_, err := unix.Seek(hostFD, 0, linux.SEEK_CUR)
-	seekable := err != syserror.ESPIPE
+	seekable := !linuxerr.Equals(linuxerr.ESPIPE, err)
 	// We expect regular files to be seekable, as this is required for them to
 	// be memory-mappable.
 	if !seekable && fileType == unix.S_IFREG {
@@ -301,7 +302,7 @@ func (i *inode) Stat(ctx context.Context, vfsfs *vfs.Filesystem, opts vfs.StatOp
 	mask := opts.Mask & linux.STATX_ALL
 	var s unix.Statx_t
 	err := unix.Statx(i.hostFD, "", int(unix.AT_EMPTY_PATH|opts.Sync), int(mask), &s)
-	if err == syserror.ENOSYS {
+	if linuxerr.Equals(linuxerr.ENOSYS, err) {
 		// Fallback to fstat(2), if statx(2) is not supported on the host.
 		//
 		// TODO(b/151263641): Remove fallback.
diff --git a/pkg/sentry/fsimpl/host/socket.go b/pkg/sentry/fsimpl/host/socket.go
index ca85f5601..8cce36212 100644
--- a/pkg/sentry/fsimpl/host/socket.go
+++ b/pkg/sentry/fsimpl/host/socket.go
@@ -21,6 +21,7 @@ import (
 	"golang.org/x/sys/unix"
 	"gvisor.dev/gvisor/pkg/abi/linux"
 	"gvisor.dev/gvisor/pkg/context"
+	"gvisor.dev/gvisor/pkg/errors/linuxerr"
 	"gvisor.dev/gvisor/pkg/fdnotifier"
 	"gvisor.dev/gvisor/pkg/log"
 	"gvisor.dev/gvisor/pkg/sentry/socket/control"
@@ -160,7 +161,7 @@ func (c *ConnectedEndpoint) Send(ctx context.Context, data [][]byte, controlMess
 		// block (and only for stream sockets).
 		err = syserror.EAGAIN
 	}
-	if n > 0 && err != syserror.EAGAIN {
+	if n > 0 && !linuxerr.Equals(linuxerr.EAGAIN, err) {
 		// The caller may need to block to send more data, but
 		// otherwise there isn't anything that can be done about an
 		// error with a partial write.
diff --git a/pkg/sentry/fsimpl/host/tty.go b/pkg/sentry/fsimpl/host/tty.go
index 0f9e20a84..2cf360065 100644
--- a/pkg/sentry/fsimpl/host/tty.go
+++ b/pkg/sentry/fsimpl/host/tty.go
@@ -17,6 +17,7 @@ package host
 import (
 	"gvisor.dev/gvisor/pkg/abi/linux"
 	"gvisor.dev/gvisor/pkg/context"
+	"gvisor.dev/gvisor/pkg/errors/linuxerr"
 	"gvisor.dev/gvisor/pkg/marshal/primitive"
 	"gvisor.dev/gvisor/pkg/sentry/arch"
 	"gvisor.dev/gvisor/pkg/sentry/kernel"
@@ -211,7 +212,7 @@ func (t *TTYFileDescription) Ioctl(ctx context.Context, io usermem.IO, args arch
 		if err := t.checkChange(ctx, linux.SIGTTOU); err != nil {
 			// drivers/tty/tty_io.c:tiocspgrp() converts -EIO from tty_check_change()
 			// to -ENOTTY.
-			if err == syserror.EIO {
+			if linuxerr.Equals(linuxerr.EIO, err) {
 				return 0, syserror.ENOTTY
 			}
 			return 0, err
diff --git a/pkg/sentry/fsimpl/host/util.go b/pkg/sentry/fsimpl/host/util.go
index 63b465859..95d7ebe2e 100644
--- a/pkg/sentry/fsimpl/host/util.go
+++ b/pkg/sentry/fsimpl/host/util.go
@@ -17,7 +17,7 @@ package host
 import (
 	"golang.org/x/sys/unix"
 	"gvisor.dev/gvisor/pkg/abi/linux"
-	"gvisor.dev/gvisor/pkg/syserror"
+	"gvisor.dev/gvisor/pkg/errors/linuxerr"
 )
 
 func toTimespec(ts linux.StatxTimestamp, omit bool) unix.Timespec {
@@ -44,5 +44,5 @@ func timespecToStatxTimestamp(ts unix.Timespec) linux.StatxTimestamp {
 // isBlockError checks if an error is EAGAIN or EWOULDBLOCK.
 // If so, they can be transformed into syserror.ErrWouldBlock.
 func isBlockError(err error) bool {
-	return err == syserror.EAGAIN || err == syserror.EWOULDBLOCK
+	return linuxerr.Equals(linuxerr.EAGAIN, err) || linuxerr.Equals(linuxerr.EWOULDBLOCK, err)
 }