diff options
Diffstat (limited to 'pkg/sentry/fs/file_operations.go')
| -rw-r--r-- | pkg/sentry/fs/file_operations.go | 47 |
1 files changed, 47 insertions, 0 deletions
diff --git a/pkg/sentry/fs/file_operations.go b/pkg/sentry/fs/file_operations.go index ab0acb6eb..0f2dfa273 100644 --- a/pkg/sentry/fs/file_operations.go +++ b/pkg/sentry/fs/file_operations.go @@ -22,6 +22,38 @@ import ( "gvisor.googlesource.com/gvisor/pkg/waiter" ) +// SpliceOpts define how a splice works. +type SpliceOpts struct { + // Length is the length of the splice operation. + Length int64 + + // SrcOffset indicates whether the existing source file offset should + // be used. If this is true, then the Start value below is used. + // + // When passed to FileOperations object, this should always be true as + // the offset will be provided by a layer above, unless the object in + // question is a pipe or socket. This value can be relied upon for such + // an indicator. + SrcOffset bool + + // SrcStart is the start of the source file. This is used only if + // SrcOffset is false. + SrcStart int64 + + // Dup indicates that the contents should not be consumed from the + // source (e.g. in the case of a socket or a pipe), but duplicated. + Dup bool + + // DstOffset indicates that the destination file offset should be used. + // + // See SrcOffset for additional information. + DstOffset bool + + // DstStart is the start of the destination file. This is used only if + // DstOffset is false. + DstStart int64 +} + // FileOperations are operations on a File that diverge per file system. // // Operations that take a *File may use only the following interfaces: @@ -67,6 +99,15 @@ type FileOperations interface { // Read must not be called if !FileFlags.Read. Read(ctx context.Context, file *File, dst usermem.IOSequence, offset int64) (int64, error) + // WriteTo is a variant of read that takes another file as a + // destination. For a splice (copy or move from one file to another), + // first a WriteTo on the source is attempted, followed by a ReadFrom + // on the destination, following by a buffered copy with standard Read + // and Write operations. + // + // The same preconditions as Read apply. + WriteTo(ctx context.Context, file *File, dst *File, opts SpliceOpts) (int64, error) + // Write writes src to file at offset and returns the number of bytes // written which must be greater than or equal to 0. Like Read, file // systems that do not support writing at an offset (i.e. pipefs, sockfs) @@ -81,6 +122,12 @@ type FileOperations interface { // Write must not be called if !FileFlags.Write. Write(ctx context.Context, file *File, src usermem.IOSequence, offset int64) (int64, error) + // ReadFrom is a variant of write that takes a another file as a + // source. See WriteTo for details regarding how this is called. + // + // The same preconditions as Write apply; FileFlags.Write must be set. + ReadFrom(ctx context.Context, file *File, src *File, opts SpliceOpts) (int64, error) + // Fsync writes buffered modifications of file and/or flushes in-flight // operations to backing storage based on syncType. The range to sync is // [start, end]. The end is inclusive so that the last byte of a maximally |