5 files changed, 103 insertions, 28 deletions

diff --git a/pkg/sentry/fs/attr.go b/pkg/sentry/fs/attr.go
index 9fc6a5bc2..4f3d6410e 100644
--- a/pkg/sentry/fs/attr.go
+++ b/pkg/sentry/fs/attr.go
@@ -111,6 +111,50 @@ func (n InodeType) LinuxType() uint32 {
 	}
 }
 
+// ToDirentType converts an InodeType to a linux dirent type field.
+func ToDirentType(nodeType InodeType) uint8 {
+	switch nodeType {
+	case RegularFile, SpecialFile:
+		return linux.DT_REG
+	case Symlink:
+		return linux.DT_LNK
+	case Directory, SpecialDirectory:
+		return linux.DT_DIR
+	case Pipe:
+		return linux.DT_FIFO
+	case CharacterDevice:
+		return linux.DT_CHR
+	case BlockDevice:
+		return linux.DT_BLK
+	case Socket:
+		return linux.DT_SOCK
+	default:
+		return linux.DT_UNKNOWN
+	}
+}
+
+// ToInodeType coverts a linux file type to InodeType.
+func ToInodeType(linuxFileType linux.FileMode) InodeType {
+	switch linuxFileType {
+	case linux.ModeRegular:
+		return RegularFile
+	case linux.ModeDirectory:
+		return Directory
+	case linux.ModeSymlink:
+		return Symlink
+	case linux.ModeNamedPipe:
+		return Pipe
+	case linux.ModeCharacterDevice:
+		return CharacterDevice
+	case linux.ModeBlockDevice:
+		return BlockDevice
+	case linux.ModeSocket:
+		return Socket
+	default:
+		panic(fmt.Sprintf("unknown file mode: %d", linuxFileType))
+	}
+}
+
 // StableAttr contains Inode attributes that will be stable throughout the
 // lifetime of the Inode.
 //
diff --git a/pkg/sentry/kernel/seqatomic_taskgoroutineschedinfo_unsafe.go b/pkg/sentry/kernel/seqatomic_taskgoroutineschedinfo_unsafe.go
index 24528b66a..25ad17a4e 100755
--- a/pkg/sentry/kernel/seqatomic_taskgoroutineschedinfo_unsafe.go
+++ b/pkg/sentry/kernel/seqatomic_taskgoroutineschedinfo_unsafe.go
@@ -1,12 +1,12 @@
 package kernel
 
 import (
+	"fmt"
+	"reflect"
 	"strings"
 	"unsafe"
 
-	"fmt"
 	"gvisor.dev/gvisor/third_party/gvsync"
-	"reflect"
 )
 
 // SeqAtomicLoad returns a copy of *ptr, ensuring that the read does not race
diff --git a/pkg/sentry/safemem/io.go b/pkg/sentry/safemem/io.go
index 5c3d73eb7..f039a5c34 100644
--- a/pkg/sentry/safemem/io.go
+++ b/pkg/sentry/safemem/io.go
@@ -157,7 +157,8 @@ func (w ToIOWriter) Write(src []byte) (int, error) {
 }
 
 // FromIOReader implements Reader for an io.Reader by repeatedly invoking
-// io.Reader.Read until it returns an error or partial read.
+// io.Reader.Read until it returns an error or partial read. This is not
+// thread-safe.
 //
 // FromIOReader will return a successful partial read iff Reader.Read does so.
 type FromIOReader struct {
@@ -206,6 +207,58 @@ func (r FromIOReader) readToBlock(dst Block, buf []byte) (int, []byte, error) {
 	return wbn, buf, rerr
 }
 
+// FromIOReaderAt implements Reader for an io.ReaderAt. Does not repeatedly
+// invoke io.ReaderAt.ReadAt because ReadAt is more strict than Read. A partial
+// read indicates an error. This is not thread-safe.
+type FromIOReaderAt struct {
+	ReaderAt io.ReaderAt
+	Offset   int64
+}
+
+// ReadToBlocks implements Reader.ReadToBlocks.
+func (r FromIOReaderAt) ReadToBlocks(dsts BlockSeq) (uint64, error) {
+	var buf []byte
+	var done uint64
+	for !dsts.IsEmpty() {
+		dst := dsts.Head()
+		var n int
+		var err error
+		n, buf, err = r.readToBlock(dst, buf)
+		done += uint64(n)
+		if n != dst.Len() {
+			return done, err
+		}
+		dsts = dsts.Tail()
+		if err != nil {
+			if dsts.IsEmpty() && err == io.EOF {
+				return done, nil
+			}
+			return done, err
+		}
+	}
+	return done, nil
+}
+
+func (r FromIOReaderAt) readToBlock(dst Block, buf []byte) (int, []byte, error) {
+	// io.Reader isn't safecopy-aware, so we have to buffer Blocks that require
+	// safecopy.
+	if !dst.NeedSafecopy() {
+		n, err := r.ReaderAt.ReadAt(dst.ToSlice(), r.Offset)
+		r.Offset += int64(n)
+		return n, buf, err
+	}
+	if len(buf) < dst.Len() {
+		buf = make([]byte, dst.Len())
+	}
+	rn, rerr := r.ReaderAt.ReadAt(buf[:dst.Len()], r.Offset)
+	r.Offset += int64(rn)
+	wbn, wberr := Copy(dst, BlockFromSafeSlice(buf[:rn]))
+	if wberr != nil {
+		return wbn, buf, wberr
+	}
+	return wbn, buf, rerr
+}
+
 // FromIOWriter implements Writer for an io.Writer by repeatedly invoking
 // io.Writer.Write until it returns an error or partial write.
 //
diff --git a/pkg/sentry/syscalls/linux/sys_getdents.go b/pkg/sentry/syscalls/linux/sys_getdents.go
index 63e2c5a5d..912cbe4ff 100644
--- a/pkg/sentry/syscalls/linux/sys_getdents.go
+++ b/pkg/sentry/syscalls/linux/sys_getdents.go
@@ -120,7 +120,7 @@ func newDirent(width uint, name string, attr fs.DentAttr, offset uint64) *dirent
 				Ino: attr.InodeID,
 				Off: offset,
 			},
-			Typ: toType(attr.Type),
+			Typ: fs.ToDirentType(attr.Type),
 		},
 		Name: []byte(name),
 	}
@@ -142,28 +142,6 @@ func smallestDirent64(a arch.Context) uint {
 	return uint(binary.Size(d.Hdr)) + a.Width()
 }
 
-// toType converts an fs.InodeOperationsInfo to a linux dirent typ field.
-func toType(nodeType fs.InodeType) uint8 {
-	switch nodeType {
-	case fs.RegularFile, fs.SpecialFile:
-		return linux.DT_REG
-	case fs.Symlink:
-		return linux.DT_LNK
-	case fs.Directory, fs.SpecialDirectory:
-		return linux.DT_DIR
-	case fs.Pipe:
-		return linux.DT_FIFO
-	case fs.CharacterDevice:
-		return linux.DT_CHR
-	case fs.BlockDevice:
-		return linux.DT_BLK
-	case fs.Socket:
-		return linux.DT_SOCK
-	default:
-		return linux.DT_UNKNOWN
-	}
-}
-
 // padRec pads the name field until the rec length is a multiple of the width,
 // which must be a power of 2. It returns the padded rec length.
 func (d *dirent) padRec(width int) uint16 {
diff --git a/pkg/sentry/time/seqatomic_parameters_unsafe.go b/pkg/sentry/time/seqatomic_parameters_unsafe.go
index fb30a22c6..89792c56d 100755
--- a/pkg/sentry/time/seqatomic_parameters_unsafe.go
+++ b/pkg/sentry/time/seqatomic_parameters_unsafe.go
@@ -1,12 +1,12 @@
 package time
 
 import (
+	"fmt"
+	"reflect"
 	"strings"
 	"unsafe"
 
-	"fmt"
 	"gvisor.dev/gvisor/third_party/gvsync"
-	"reflect"
 )
 
 // SeqAtomicLoad returns a copy of *ptr, ensuring that the read does not race