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Diffstat (limited to 'pkg/sentry/fs/file_operations.go')
| -rw-r--r-- | pkg/sentry/fs/file_operations.go | 106 |
1 files changed, 106 insertions, 0 deletions
diff --git a/pkg/sentry/fs/file_operations.go b/pkg/sentry/fs/file_operations.go new file mode 100644 index 000000000..d223bb5c7 --- /dev/null +++ b/pkg/sentry/fs/file_operations.go @@ -0,0 +1,106 @@ +// Copyright 2018 Google Inc. +// +// Licensed under the Apache License, Version 2.0 (the "License"); +// you may not use this file except in compliance with the License. +// You may obtain a copy of the License at +// +// http://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, software +// distributed under the License is distributed on an "AS IS" BASIS, +// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. +// See the License for the specific language governing permissions and +// limitations under the License. + +package fs + +import ( + "gvisor.googlesource.com/gvisor/pkg/sentry/arch" + "gvisor.googlesource.com/gvisor/pkg/sentry/context" + "gvisor.googlesource.com/gvisor/pkg/sentry/memmap" + "gvisor.googlesource.com/gvisor/pkg/sentry/usermem" + "gvisor.googlesource.com/gvisor/pkg/waiter" +) + +// FileOperations are operations on a File that diverge per file system. +// +// Operations that take a *File may use only the following interfaces: +// +// - File.UniqueID: Operations may only read this value. +// - File.Dirent: Operations must not take or drop a reference. +// - File.Offset(): This value is guaranteed to not change for the +// duration of the operation. +// - File.Flags(): This value may change during the operation. +type FileOperations interface { + // Release release resources held by FileOperations. + Release() + + // Waitable defines how this File can be waited on for read and + // write readiness. + waiter.Waitable + + // Seek seeks to offset based on SeekWhence. Returns the new + // offset or no change in the offset and an error. + Seek(ctx context.Context, file *File, whence SeekWhence, offset int64) (int64, error) + + // Readdir reads the directory entries of file and serializes them + // using serializer. + // + // Returns the new directory offset or no change in the offset and + // an error. The offset returned must not be less than file.Offset(). + // + // Serialization of directory entries must not happen asynchronously. + Readdir(ctx context.Context, file *File, serializer DentrySerializer) (int64, error) + + // Read reads from file into dst at offset and returns the number + // of bytes read which must be greater than or equal to 0. File + // systems that do not support reading at an offset, (i.e. pipefs, + // sockfs) may ignore the offset. These file systems are expected + // to construct Files with !FileFlags.Pread. + // + // Read may return a nil error and only partially fill dst (at or + // before EOF). If the file represents a symlink, Read reads the target + // value of the symlink. + // + // Read does not check permissions nor flags. + // + // Read must not be called if !FileFlags.Read. + Read(ctx context.Context, file *File, dst usermem.IOSequence, offset int64) (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) + // may ignore the offset. These file systems are expected to construct + // Files with !FileFlags.Pwrite. + // + // If only part of src could be written, Write must return an error + // indicating why (e.g. syserror.ErrWouldBlock). + // + // Write does not check permissions nor flags. + // + // Write must not be called if !FileFlags.Write. + Write(ctx context.Context, file *File, src usermem.IOSequence, offset int64) (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 + // sized file can be synced. + Fsync(ctx context.Context, file *File, start, end int64, syncType SyncType) error + + // Flush this file's buffers/state (on close(2)). + Flush(ctx context.Context, file *File) error + + // ConfigureMMap mutates opts to implement mmap(2) for the file. Most + // implementations can either embed fsutil.NoMMap (if they don't support + // memory mapping) or call fsutil.GenericConfigureMMap with the appropriate + // memmap.Mappable. + ConfigureMMap(ctx context.Context, file *File, opts *memmap.MMapOpts) error + + // Ioctl implements the ioctl(2) linux syscall. + // + // io provides access to the virtual memory space to which pointers in args + // refer. + // + // Preconditions: The AddressSpace (if any) that io refers to is activated. + Ioctl(ctx context.Context, io usermem.IO, args arch.SyscallArguments) (uintptr, error) +} |