diff options
Diffstat (limited to 'pkg/sentry/fs/ext/utils.go')
| -rw-r--r-- | pkg/sentry/fs/ext/utils.go | 17 |
1 files changed, 17 insertions, 0 deletions
diff --git a/pkg/sentry/fs/ext/utils.go b/pkg/sentry/fs/ext/utils.go index 8790c7778..7c33919e0 100644 --- a/pkg/sentry/fs/ext/utils.go +++ b/pkg/sentry/fs/ext/utils.go @@ -41,6 +41,23 @@ func readFromDisk(dev io.ReadSeeker, abOff int64, v interface{}) error { 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. |