diff options
Diffstat (limited to 'pkg/sentry')
| -rw-r--r-- | pkg/sentry/fs/flags.go | 7 | ||||
| -rw-r--r-- | pkg/sentry/fs/gofer/file_state.go | 8 | ||||
| -rw-r--r-- | pkg/sentry/fs/gofer/handles.go | 5 | ||||
| -rw-r--r-- | pkg/sentry/fs/gofer/inode.go | 18 | ||||
| -rw-r--r-- | pkg/sentry/syscalls/linux/flags.go | 1 |
5 files changed, 31 insertions, 8 deletions
diff --git a/pkg/sentry/fs/flags.go b/pkg/sentry/fs/flags.go index 0fab876a9..4338ae1fa 100644 --- a/pkg/sentry/fs/flags.go +++ b/pkg/sentry/fs/flags.go @@ -64,6 +64,10 @@ type FileFlags struct { // NonSeekable indicates that file.offset isn't used. NonSeekable bool + + // Truncate indicates that the file should be truncated before opened. + // This is only applicable if the file is regular. + Truncate bool } // SettableFileFlags is a subset of FileFlags above that can be changed @@ -118,6 +122,9 @@ func (f FileFlags) ToLinux() (mask uint) { if f.LargeFile { mask |= linux.O_LARGEFILE } + if f.Truncate { + mask |= linux.O_TRUNC + } switch { case f.Read && f.Write: diff --git a/pkg/sentry/fs/gofer/file_state.go b/pkg/sentry/fs/gofer/file_state.go index c2fbb4be9..bb8312849 100644 --- a/pkg/sentry/fs/gofer/file_state.go +++ b/pkg/sentry/fs/gofer/file_state.go @@ -28,8 +28,14 @@ func (f *fileOperations) afterLoad() { // Manually load the open handles. var err error + + // The file may have been opened with Truncate, but we don't + // want to re-open it with Truncate or we will lose data. + flags := f.flags + flags.Truncate = false + // TODO(b/38173783): Context is not plumbed to save/restore. - f.handles, err = f.inodeOperations.fileState.getHandles(context.Background(), f.flags, f.inodeOperations.cachingInodeOps) + f.handles, err = f.inodeOperations.fileState.getHandles(context.Background(), flags, f.inodeOperations.cachingInodeOps) if err != nil { return fmt.Errorf("failed to re-open handle: %v", err) } diff --git a/pkg/sentry/fs/gofer/handles.go b/pkg/sentry/fs/gofer/handles.go index 39c8ec33d..b86c49b39 100644 --- a/pkg/sentry/fs/gofer/handles.go +++ b/pkg/sentry/fs/gofer/handles.go @@ -64,7 +64,7 @@ func (h *handles) DecRef() { }) } -func newHandles(ctx context.Context, file contextFile, flags fs.FileFlags) (*handles, error) { +func newHandles(ctx context.Context, client *p9.Client, file contextFile, flags fs.FileFlags) (*handles, error) { _, newFile, err := file.walk(ctx, nil) if err != nil { return nil, err @@ -81,6 +81,9 @@ func newHandles(ctx context.Context, file contextFile, flags fs.FileFlags) (*han default: panic("impossible fs.FileFlags") } + if flags.Truncate && p9.VersionSupportsOpenTruncateFlag(client.Version()) { + p9flags |= p9.OpenTruncate + } hostFile, _, _, err := newFile.open(ctx, p9flags) if err != nil { diff --git a/pkg/sentry/fs/gofer/inode.go b/pkg/sentry/fs/gofer/inode.go index 99910388f..4237bf353 100644 --- a/pkg/sentry/fs/gofer/inode.go +++ b/pkg/sentry/fs/gofer/inode.go @@ -180,7 +180,7 @@ func (i *inodeFileState) setSharedHandlesLocked(flags fs.FileFlags, h *handles) // given flags. func (i *inodeFileState) getHandles(ctx context.Context, flags fs.FileFlags, cache *fsutil.CachingInodeOperations) (*handles, error) { if !i.canShareHandles() { - return newHandles(ctx, i.file, flags) + return newHandles(ctx, i.s.client, i.file, flags) } i.handlesMu.Lock() @@ -201,19 +201,25 @@ func (i *inodeFileState) getHandles(ctx context.Context, flags fs.FileFlags, cac // whether previously open read handle was recreated. Host mappings must be // invalidated if so. func (i *inodeFileState) getHandlesLocked(ctx context.Context, flags fs.FileFlags) (*handles, bool, error) { - // Do we already have usable shared handles? - if flags.Write { + // Check if we are able to use cached handles. + if flags.Truncate && p9.VersionSupportsOpenTruncateFlag(i.s.client.Version()) { + // If we are truncating (and the gofer supports it), then we + // always need a new handle. Don't return one from the cache. + } else if flags.Write { if i.writeHandles != nil && (i.writeHandlesRW || !flags.Read) { + // File is opened for writing, and we have cached write + // handles that we can use. i.writeHandles.IncRef() return i.writeHandles, false, nil } } else if i.readHandles != nil { + // File is opened for reading and we have cached handles. i.readHandles.IncRef() return i.readHandles, false, nil } - // No; get new handles and cache them for future sharing. - h, err := newHandles(ctx, i.file, flags) + // Get new handles and cache them for future sharing. + h, err := newHandles(ctx, i.s.client, i.file, flags) if err != nil { return nil, false, err } @@ -239,7 +245,7 @@ func (i *inodeFileState) recreateReadHandles(ctx context.Context, writer *handle if !flags.Read { // Writer can't be used for read, must create a new handle. var err error - h, err = newHandles(ctx, i.file, fs.FileFlags{Read: true}) + h, err = newHandles(ctx, i.s.client, i.file, fs.FileFlags{Read: true}) if err != nil { return err } diff --git a/pkg/sentry/syscalls/linux/flags.go b/pkg/sentry/syscalls/linux/flags.go index 444f2b004..07961dad9 100644 --- a/pkg/sentry/syscalls/linux/flags.go +++ b/pkg/sentry/syscalls/linux/flags.go @@ -50,5 +50,6 @@ func linuxToFlags(mask uint) fs.FileFlags { Directory: mask&linux.O_DIRECTORY != 0, Async: mask&linux.O_ASYNC != 0, LargeFile: mask&linux.O_LARGEFILE != 0, + Truncate: mask&linux.O_TRUNC != 0, } } |