Enable automated marshalling for struct stat.

This requires fixing a few build issues for non-am64 platforms.

PiperOrigin-RevId: 295196922

4 files changed, 24 insertions, 156 deletions

diff --git a/pkg/sentry/syscalls/linux/BUILD b/pkg/sentry/syscalls/linux/BUILD
index 0d24fd3c4..c7883e68e 100644
--- a/pkg/sentry/syscalls/linux/BUILD
+++ b/pkg/sentry/syscalls/linux/BUILD
@@ -42,8 +42,6 @@ go_library(
         "sys_socket.go",
         "sys_splice.go",
         "sys_stat.go",
-        "sys_stat_amd64.go",
-        "sys_stat_arm64.go",
         "sys_sync.go",
         "sys_sysinfo.go",
         "sys_syslog.go",
diff --git a/pkg/sentry/syscalls/linux/sys_stat.go b/pkg/sentry/syscalls/linux/sys_stat.go
index c841abccb..8b66a9006 100644
--- a/pkg/sentry/syscalls/linux/sys_stat.go
+++ b/pkg/sentry/syscalls/linux/sys_stat.go
@@ -23,6 +23,24 @@ import (
 	"gvisor.dev/gvisor/pkg/usermem"
 )
 
+func statFromAttrs(t *kernel.Task, sattr fs.StableAttr, uattr fs.UnstableAttr) linux.Stat {
+	return linux.Stat{
+		Dev:     sattr.DeviceID,
+		Ino:     sattr.InodeID,
+		Nlink:   uattr.Links,
+		Mode:    sattr.Type.LinuxType() | uint32(uattr.Perms.LinuxMode()),
+		UID:     uint32(uattr.Owner.UID.In(t.UserNamespace()).OrOverflow()),
+		GID:     uint32(uattr.Owner.GID.In(t.UserNamespace()).OrOverflow()),
+		Rdev:    uint64(linux.MakeDeviceID(sattr.DeviceFileMajor, sattr.DeviceFileMinor)),
+		Size:    uattr.Size,
+		Blksize: sattr.BlockSize,
+		Blocks:  uattr.Usage / 512,
+		ATime:   uattr.AccessTime.Timespec(),
+		MTime:   uattr.ModificationTime.Timespec(),
+		CTime:   uattr.StatusChangeTime.Timespec(),
+	}
+}
+
 // Stat implements linux syscall stat(2).
 func Stat(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.SyscallControl, error) {
 	addr := args[0].Pointer()
@@ -112,7 +130,9 @@ func stat(t *kernel.Task, d *fs.Dirent, dirPath bool, statAddr usermem.Addr) err
 	if err != nil {
 		return err
 	}
-	return copyOutStat(t, statAddr, d.Inode.StableAttr, uattr)
+	s := statFromAttrs(t, d.Inode.StableAttr, uattr)
+	_, err = s.CopyOut(t, statAddr)
+	return err
 }
 
 // fstat implements fstat for the given *fs.File.
@@ -121,7 +141,9 @@ func fstat(t *kernel.Task, f *fs.File, statAddr usermem.Addr) error {
 	if err != nil {
 		return err
 	}
-	return copyOutStat(t, statAddr, f.Dirent.Inode.StableAttr, uattr)
+	s := statFromAttrs(t, f.Dirent.Inode.StableAttr, uattr)
+	_, err = s.CopyOut(t, statAddr)
+	return err
 }
 
 // Statx implements linux syscall statx(2).
diff --git a/pkg/sentry/syscalls/linux/sys_stat_amd64.go b/pkg/sentry/syscalls/linux/sys_stat_amd64.go
deleted file mode 100644
index 75a567bd4..000000000
--- a/pkg/sentry/syscalls/linux/sys_stat_amd64.go
+++ /dev/null
@@ -1,75 +0,0 @@
-// 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 amd64
-
-package linux
-
-import (
-	"gvisor.dev/gvisor/pkg/abi/linux"
-	"gvisor.dev/gvisor/pkg/binary"
-	"gvisor.dev/gvisor/pkg/sentry/fs"
-	"gvisor.dev/gvisor/pkg/sentry/kernel"
-	"gvisor.dev/gvisor/pkg/usermem"
-)
-
-// copyOutStat copies the attributes (sattr, uattr) to the struct stat at
-// address dst in t's address space. It encodes the stat struct to bytes
-// manually, as stat() is a very common syscall for many applications, and
-// t.CopyObjectOut has noticeable performance impact due to its many slice
-// allocations and use of reflection.
-func copyOutStat(t *kernel.Task, dst usermem.Addr, sattr fs.StableAttr, uattr fs.UnstableAttr) error {
-	b := t.CopyScratchBuffer(int(linux.SizeOfStat))[:0]
-
-	// Dev (uint64)
-	b = binary.AppendUint64(b, usermem.ByteOrder, uint64(sattr.DeviceID))
-	// Ino (uint64)
-	b = binary.AppendUint64(b, usermem.ByteOrder, uint64(sattr.InodeID))
-	// Nlink (uint64)
-	b = binary.AppendUint64(b, usermem.ByteOrder, uattr.Links)
-	// Mode (uint32)
-	b = binary.AppendUint32(b, usermem.ByteOrder, sattr.Type.LinuxType()|uint32(uattr.Perms.LinuxMode()))
-	// UID (uint32)
-	b = binary.AppendUint32(b, usermem.ByteOrder, uint32(uattr.Owner.UID.In(t.UserNamespace()).OrOverflow()))
-	// GID (uint32)
-	b = binary.AppendUint32(b, usermem.ByteOrder, uint32(uattr.Owner.GID.In(t.UserNamespace()).OrOverflow()))
-	// Padding (uint32)
-	b = binary.AppendUint32(b, usermem.ByteOrder, 0)
-	// Rdev (uint64)
-	b = binary.AppendUint64(b, usermem.ByteOrder, uint64(linux.MakeDeviceID(sattr.DeviceFileMajor, sattr.DeviceFileMinor)))
-	// Size (uint64)
-	b = binary.AppendUint64(b, usermem.ByteOrder, uint64(uattr.Size))
-	// Blksize (uint64)
-	b = binary.AppendUint64(b, usermem.ByteOrder, uint64(sattr.BlockSize))
-	// Blocks (uint64)
-	b = binary.AppendUint64(b, usermem.ByteOrder, uint64(uattr.Usage/512))
-
-	// ATime
-	atime := uattr.AccessTime.Timespec()
-	b = binary.AppendUint64(b, usermem.ByteOrder, uint64(atime.Sec))
-	b = binary.AppendUint64(b, usermem.ByteOrder, uint64(atime.Nsec))
-
-	// MTime
-	mtime := uattr.ModificationTime.Timespec()
-	b = binary.AppendUint64(b, usermem.ByteOrder, uint64(mtime.Sec))
-	b = binary.AppendUint64(b, usermem.ByteOrder, uint64(mtime.Nsec))
-
-	// CTime
-	ctime := uattr.StatusChangeTime.Timespec()
-	b = binary.AppendUint64(b, usermem.ByteOrder, uint64(ctime.Sec))
-	b = binary.AppendUint64(b, usermem.ByteOrder, uint64(ctime.Nsec))
-
-	_, err := t.CopyOutBytes(dst, b)
-	return err
-}
diff --git a/pkg/sentry/syscalls/linux/sys_stat_arm64.go b/pkg/sentry/syscalls/linux/sys_stat_arm64.go
deleted file mode 100644
index 80c98d05c..000000000
--- a/pkg/sentry/syscalls/linux/sys_stat_arm64.go
+++ /dev/null
@@ -1,77 +0,0 @@
-// 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 arm64
-
-package linux
-
-import (
-	"gvisor.dev/gvisor/pkg/abi/linux"
-	"gvisor.dev/gvisor/pkg/binary"
-	"gvisor.dev/gvisor/pkg/sentry/fs"
-	"gvisor.dev/gvisor/pkg/sentry/kernel"
-	"gvisor.dev/gvisor/pkg/usermem"
-)
-
-// copyOutStat copies the attributes (sattr, uattr) to the struct stat at
-// address dst in t's address space. It encodes the stat struct to bytes
-// manually, as stat() is a very common syscall for many applications, and
-// t.CopyObjectOut has noticeable performance impact due to its many slice
-// allocations and use of reflection.
-func copyOutStat(t *kernel.Task, dst usermem.Addr, sattr fs.StableAttr, uattr fs.UnstableAttr) error {
-	b := t.CopyScratchBuffer(int(linux.SizeOfStat))[:0]
-
-	// Dev (uint64)
-	b = binary.AppendUint64(b, usermem.ByteOrder, uint64(sattr.DeviceID))
-	// Ino (uint64)
-	b = binary.AppendUint64(b, usermem.ByteOrder, uint64(sattr.InodeID))
-	// Mode (uint32)
-	b = binary.AppendUint32(b, usermem.ByteOrder, sattr.Type.LinuxType()|uint32(uattr.Perms.LinuxMode()))
-	// Nlink (uint32)
-	b = binary.AppendUint32(b, usermem.ByteOrder, uint32(uattr.Links))
-	// UID (uint32)
-	b = binary.AppendUint32(b, usermem.ByteOrder, uint32(uattr.Owner.UID.In(t.UserNamespace()).OrOverflow()))
-	// GID (uint32)
-	b = binary.AppendUint32(b, usermem.ByteOrder, uint32(uattr.Owner.GID.In(t.UserNamespace()).OrOverflow()))
-	// Rdev (uint64)
-	b = binary.AppendUint64(b, usermem.ByteOrder, uint64(linux.MakeDeviceID(sattr.DeviceFileMajor, sattr.DeviceFileMinor)))
-	// Padding (uint64)
-	b = binary.AppendUint64(b, usermem.ByteOrder, 0)
-	// Size (uint64)
-	b = binary.AppendUint64(b, usermem.ByteOrder, uint64(uattr.Size))
-	// Blksize (uint32)
-	b = binary.AppendUint32(b, usermem.ByteOrder, uint32(sattr.BlockSize))
-	// Padding (uint32)
-	b = binary.AppendUint32(b, usermem.ByteOrder, 0)
-	// Blocks (uint64)
-	b = binary.AppendUint64(b, usermem.ByteOrder, uint64(uattr.Usage/512))
-
-	// ATime
-	atime := uattr.AccessTime.Timespec()
-	b = binary.AppendUint64(b, usermem.ByteOrder, uint64(atime.Sec))
-	b = binary.AppendUint64(b, usermem.ByteOrder, uint64(atime.Nsec))
-
-	// MTime
-	mtime := uattr.ModificationTime.Timespec()
-	b = binary.AppendUint64(b, usermem.ByteOrder, uint64(mtime.Sec))
-	b = binary.AppendUint64(b, usermem.ByteOrder, uint64(mtime.Nsec))
-
-	// CTime
-	ctime := uattr.StatusChangeTime.Timespec()
-	b = binary.AppendUint64(b, usermem.ByteOrder, uint64(ctime.Sec))
-	b = binary.AppendUint64(b, usermem.ByteOrder, uint64(ctime.Nsec))
-
-	_, err := t.CopyOutBytes(dst, b)
-	return err
-}