diff options
Diffstat (limited to 'pkg/sentry/fs/ext/utils.go')
| -rw-r--r-- | pkg/sentry/fs/ext/utils.go | 43 |
1 files changed, 8 insertions, 35 deletions
diff --git a/pkg/sentry/fs/ext/utils.go b/pkg/sentry/fs/ext/utils.go index 7c33919e0..3d89d664d 100644 --- a/pkg/sentry/fs/ext/utils.go +++ b/pkg/sentry/fs/ext/utils.go @@ -15,55 +15,30 @@ package ext import ( - "encoding/binary" "io" + "gvisor.dev/gvisor/pkg/binary" "gvisor.dev/gvisor/pkg/sentry/fs/ext/disklayout" "gvisor.dev/gvisor/pkg/syserror" ) // readFromDisk performs a binary read from disk into the given struct from // the absolute offset provided. -// -// All disk reads should use this helper so we avoid reading from stale -// previously used offsets. This function forces the offset parameter. -// -// Precondition: Must hold the mutex of the filesystem containing dev. -func readFromDisk(dev io.ReadSeeker, abOff int64, v interface{}) error { - if _, err := dev.Seek(abOff, io.SeekStart); err != nil { - return syserror.EIO - } - - if err := binary.Read(dev, binary.LittleEndian, v); err != nil { +func readFromDisk(dev io.ReaderAt, abOff int64, v interface{}) error { + n := binary.Size(v) + buf := make([]byte, n) + if read, _ := dev.ReadAt(buf, abOff); read < int(n) { return syserror.EIO } + binary.Unmarshal(buf, binary.LittleEndian, v) return nil } -// readFull is a wrapper around io.ReadFull which enforces the absolute offset -// parameter so that we can ensure that we do not perform incorrect reads from -// stale previously used offsets. -// -// Precondition: Must hold the mutex of the filesystem containing dev. -func readFull(dev io.ReadSeeker, abOff int64, dst []byte) (int, error) { - if _, err := dev.Seek(abOff, io.SeekStart); err != nil { - return 0, syserror.EIO - } - - n, err := io.ReadFull(dev, dst) - if err != nil { - err = syserror.EIO - } - return n, err -} - // readSuperBlock reads the SuperBlock from block group 0 in the underlying // device. There are three versions of the superblock. This function identifies // and returns the correct version. -// -// Precondition: Must hold the mutex of the filesystem containing dev. -func readSuperBlock(dev io.ReadSeeker) (disklayout.SuperBlock, error) { +func readSuperBlock(dev io.ReaderAt) (disklayout.SuperBlock, error) { var sb disklayout.SuperBlock = &disklayout.SuperBlockOld{} if err := readFromDisk(dev, disklayout.SbOffset, sb); err != nil { return nil, err @@ -98,9 +73,7 @@ func blockGroupsCount(sb disklayout.SuperBlock) uint64 { // readBlockGroups reads the block group descriptor table from block group 0 in // the underlying device. -// -// Precondition: Must hold the mutex of the filesystem containing dev. -func readBlockGroups(dev io.ReadSeeker, sb disklayout.SuperBlock) ([]disklayout.BlockGroup, error) { +func readBlockGroups(dev io.ReaderAt, sb disklayout.SuperBlock) ([]disklayout.BlockGroup, error) { bgCount := blockGroupsCount(sb) bgdSize := uint64(sb.BgDescSize()) is64Bit := sb.IncompatibleFeatures().Is64Bit |