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Diffstat (limited to 'pkg/sentry/vfs/file_description.go')
| -rw-r--r-- | pkg/sentry/vfs/file_description.go | 216 |
1 files changed, 0 insertions, 216 deletions
diff --git a/pkg/sentry/vfs/file_description.go b/pkg/sentry/vfs/file_description.go deleted file mode 100644 index 7eb2b2821..000000000 --- a/pkg/sentry/vfs/file_description.go +++ /dev/null @@ -1,216 +0,0 @@ -// Copyright 2019 The gVisor Authors. -// -// 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 vfs - -import ( - "sync/atomic" - - "gvisor.dev/gvisor/pkg/abi/linux" - "gvisor.dev/gvisor/pkg/sentry/arch" - "gvisor.dev/gvisor/pkg/sentry/context" - "gvisor.dev/gvisor/pkg/sentry/memmap" - "gvisor.dev/gvisor/pkg/sentry/usermem" - "gvisor.dev/gvisor/pkg/waiter" -) - -// A FileDescription represents an open file description, which is the entity -// referred to by a file descriptor (POSIX.1-2017 3.258 "Open File -// Description"). -// -// FileDescriptions are reference-counted. Unless otherwise specified, all -// FileDescription methods require that a reference is held. -// -// FileDescription is analogous to Linux's struct file. -type FileDescription struct { - // refs is the reference count. refs is accessed using atomic memory - // operations. - refs int64 - - // vd is the filesystem location at which this FileDescription was opened. - // A reference is held on vd. vd is immutable. - vd VirtualDentry - - // impl is the FileDescriptionImpl associated with this Filesystem. impl is - // immutable. This should be the last field in FileDescription. - impl FileDescriptionImpl -} - -// Init must be called before first use of fd. It takes references on mnt and -// d. -func (fd *FileDescription) Init(impl FileDescriptionImpl, mnt *Mount, d *Dentry) { - fd.refs = 1 - fd.vd = VirtualDentry{ - mount: mnt, - dentry: d, - } - fd.vd.IncRef() - fd.impl = impl -} - -// Impl returns the FileDescriptionImpl associated with fd. -func (fd *FileDescription) Impl() FileDescriptionImpl { - return fd.impl -} - -// VirtualDentry returns the location at which fd was opened. It does not take -// a reference on the returned VirtualDentry. -func (fd *FileDescription) VirtualDentry() VirtualDentry { - return fd.vd -} - -// IncRef increments fd's reference count. -func (fd *FileDescription) IncRef() { - atomic.AddInt64(&fd.refs, 1) -} - -// DecRef decrements fd's reference count. -func (fd *FileDescription) DecRef() { - if refs := atomic.AddInt64(&fd.refs, -1); refs == 0 { - fd.impl.Release() - fd.vd.DecRef() - } else if refs < 0 { - panic("FileDescription.DecRef() called without holding a reference") - } -} - -// FileDescriptionImpl contains implementation details for an FileDescription. -// Implementations of FileDescriptionImpl should contain their associated -// FileDescription by value as their first field. -// -// For all functions that return linux.Statx, Statx.Uid and Statx.Gid will -// be interpreted as IDs in the root UserNamespace (i.e. as auth.KUID and -// auth.KGID respectively). -// -// FileDescriptionImpl is analogous to Linux's struct file_operations. -type FileDescriptionImpl interface { - // Release is called when the associated FileDescription reaches zero - // references. - Release() - - // OnClose is called when a file descriptor representing the - // FileDescription is closed. Note that returning a non-nil error does not - // prevent the file descriptor from being closed. - OnClose() error - - // StatusFlags returns file description status flags, as for - // fcntl(F_GETFL). - StatusFlags(ctx context.Context) (uint32, error) - - // SetStatusFlags sets file description status flags, as for - // fcntl(F_SETFL). - SetStatusFlags(ctx context.Context, flags uint32) error - - // Stat returns metadata for the file represented by the FileDescription. - Stat(ctx context.Context, opts StatOptions) (linux.Statx, error) - - // SetStat updates metadata for the file represented by the - // FileDescription. - SetStat(ctx context.Context, opts SetStatOptions) error - - // StatFS returns metadata for the filesystem containing the file - // represented by the FileDescription. - StatFS(ctx context.Context) (linux.Statfs, error) - - // waiter.Waitable methods may be used to poll for I/O events. - waiter.Waitable - - // PRead reads from the file into dst, starting at the given offset, and - // returns the number of bytes read. PRead is permitted to return partial - // reads with a nil error. - PRead(ctx context.Context, dst usermem.IOSequence, offset int64, opts ReadOptions) (int64, error) - - // Read is similar to PRead, but does not specify an offset. - // - // For files with an implicit FileDescription offset (e.g. regular files), - // Read begins at the FileDescription offset, and advances the offset by - // the number of bytes read; note that POSIX 2.9.7 "Thread Interactions - // with Regular File Operations" requires that all operations that may - // mutate the FileDescription offset are serialized. - Read(ctx context.Context, dst usermem.IOSequence, opts ReadOptions) (int64, error) - - // PWrite writes src to the file, starting at the given offset, and returns - // the number of bytes written. PWrite is permitted to return partial - // writes with a nil error. - // - // As in Linux (but not POSIX), if O_APPEND is in effect for the - // FileDescription, PWrite should ignore the offset and append data to the - // end of the file. - PWrite(ctx context.Context, src usermem.IOSequence, offset int64, opts WriteOptions) (int64, error) - - // Write is similar to PWrite, but does not specify an offset, which is - // implied as for Read. - // - // Write is a FileDescriptionImpl method, instead of a wrapper around - // PWrite that uses a FileDescription offset, to make it possible for - // remote filesystems to implement O_APPEND correctly (i.e. atomically with - // respect to writers outside the scope of VFS). - Write(ctx context.Context, src usermem.IOSequence, opts WriteOptions) (int64, error) - - // IterDirents invokes cb on each entry in the directory represented by the - // FileDescription. If IterDirents has been called since the last call to - // Seek, it continues iteration from the end of the last call. - IterDirents(ctx context.Context, cb IterDirentsCallback) error - - // Seek changes the FileDescription offset (assuming one exists) and - // returns its new value. - // - // For directories, if whence == SEEK_SET and offset == 0, the caller is - // rewinddir(), such that Seek "shall also cause the directory stream to - // refer to the current state of the corresponding directory" - - // POSIX.1-2017. - Seek(ctx context.Context, offset int64, whence int32) (int64, error) - - // Sync requests that cached state associated with the file represented by - // the FileDescription is synchronized with persistent storage, and blocks - // until this is complete. - Sync(ctx context.Context) error - - // ConfigureMMap mutates opts to implement mmap(2) for the file. Most - // implementations that support memory mapping can call - // GenericConfigureMMap with the appropriate memmap.Mappable. - ConfigureMMap(ctx context.Context, opts memmap.MMapOpts) error - - // Ioctl implements the ioctl(2) syscall. - Ioctl(ctx context.Context, uio usermem.IO, args arch.SyscallArguments) (uintptr, error) - - // TODO: extended attributes; file locking -} - -// Dirent holds the information contained in struct linux_dirent64. -type Dirent struct { - // Name is the filename. - Name string - - // Type is the file type, a linux.DT_* constant. - Type uint8 - - // Ino is the inode number. - Ino uint64 - - // NextOff is the offset of the *next* Dirent in the directory; that is, - // FileDescription.Seek(NextOff, SEEK_SET) (as called by seekdir(3)) will - // cause the next call to FileDescription.IterDirents() to yield the next - // Dirent. (The offset of the first Dirent in a directory is always 0.) - NextOff int64 -} - -// IterDirentsCallback receives Dirents from FileDescriptionImpl.IterDirents. -type IterDirentsCallback interface { - // Handle handles the given iterated Dirent. It returns true if iteration - // should continue, and false if FileDescriptionImpl.IterDirents should - // terminate now and restart with the same Dirent the next time it is - // called. - Handle(dirent Dirent) bool -} |