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// Copyright 2018 Google LLC
//
// 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 p9
import (
"syscall"
"gvisor.googlesource.com/gvisor/pkg/fd"
)
// Attacher is provided by the server.
type Attacher interface {
// Attach returns a new File.
//
// The client-side attach will be translate to a series of walks from
// the file returned by this Attach call.
Attach() (File, error)
}
// File is a set of operations corresponding to a single node.
//
// Functions below MUST return syscall.Errno values.
// TODO: Enforce that with the type.
//
// These must be implemented in all circumstances.
type File interface {
// Walk walks to the path components given in names.
//
// Walk returns QIDs in the same order that the names were passed in.
//
// An empty list of arguments should return a copy of the current file.
Walk(names []string) ([]QID, File, error)
// StatFS returns information about the file system associated with
// this file.
StatFS() (FSStat, error)
// GetAttr returns attributes of this node.
GetAttr(req AttrMask) (QID, AttrMask, Attr, error)
// SetAttr sets attributes on this node.
SetAttr(valid SetAttrMask, attr SetAttr) error
// Remove removes the file.
//
// This is deprecated in favor of UnlinkAt below.
Remove() error
// Rename renames the file.
Rename(directory File, name string) error
// Close is called when all references are dropped on the server side,
// and Close should be called by the client to drop all references.
//
// For server-side implementations of Close, the error is ignored.
//
// Close must be called even when Open has not been called.
Close() error
// Open is called prior to using read/write.
//
// The *fd.FD may be nil. If an *fd.FD is provided, ownership now
// belongs to the caller and the FD must be non-blocking.
//
// If Open returns a non-nil *fd.FD, it should do so for all possible
// OpenFlags. If Open returns a nil *fd.FD, it should similarly return
// a nil *fd.FD for all possible OpenFlags.
//
// This can be assumed to be one-shot only.
Open(mode OpenFlags) (*fd.FD, QID, uint32, error)
// Read reads from this file.
//
// This may return io.EOF in addition to syscall.Errno values.
//
// Preconditions: Open has been called and returned success.
ReadAt(p []byte, offset uint64) (int, error)
// Write writes to this file.
//
// This may return io.EOF in addition to syscall.Errno values.
//
// Preconditions: Open has been called and returned success.
WriteAt(p []byte, offset uint64) (int, error)
// FSync syncs this node.
//
// Preconditions: Open has been called and returned success.
FSync() error
// Create creates a new regular file and opens it according to the
// flags given.
//
// See p9.File.Open for a description of *fd.FD.
Create(name string, flags OpenFlags, permissions FileMode, uid UID, gid GID) (*fd.FD, File, QID, uint32, error)
// Mkdir creates a subdirectory.
Mkdir(name string, permissions FileMode, uid UID, gid GID) (QID, error)
// Symlink makes a new symbolic link.
Symlink(oldname string, newname string, uid UID, gid GID) (QID, error)
// Link makes a new hard link.
Link(target File, newname string) error
// Mknod makes a new device node.
Mknod(name string, permissions FileMode, major uint32, minor uint32, uid UID, gid GID) (QID, error)
// RenameAt renames a given file to a new name in a potentially new
// directory.
//
// oldname must be a name relative to this file, which must be a
// directory. newname is a name relative to newdir.
//
// This is deprecated in favor of Rename.
RenameAt(oldname string, newdir File, newname string) error
// UnlinkAt the given named file.
//
// name must be a file relative to this directory.
//
// Flags are implementation-specific (e.g. O_DIRECTORY), but are
// generally Linux unlinkat(2) flags.
UnlinkAt(name string, flags uint32) error
// Readdir reads directory entries.
//
// This may return io.EOF in addition to syscall.Errno values.
//
// Preconditions: Open has been called and returned success.
Readdir(offset uint64, count uint32) ([]Dirent, error)
// Readlink reads the link target.
Readlink() (string, error)
// Flush is called prior to Close.
//
// Whereas Close drops all references to the file, Flush cleans up the
// file state. Behavior is implementation-specific.
//
// Flush is not related to flush(9p). Flush is an extension to 9P2000.L,
// see version.go.
Flush() error
// WalkGetAttr walks to the next file and returns its maximal set of
// attributes.
//
// Server-side p9.Files may return syscall.ENOSYS to indicate that Walk
// and GetAttr should be used separately to satisfy this request.
WalkGetAttr([]string) ([]QID, File, AttrMask, Attr, error)
// Connect establishes a new host-socket backed connection with a
// socket. A File does not need to be opened before it can be connected
// and it can be connected to multiple times resulting in a unique
// *fd.FD each time. In addition, the lifetime of the *fd.FD is
// independent from the lifetime of the p9.File and must be managed by
// the caller.
//
// The returned FD must be non-blocking.
//
// flags indicates the requested type of socket.
Connect(flags ConnectFlags) (*fd.FD, error)
}
// DefaultWalkGetAttr implements File.WalkGetAttr to return ENOSYS for server-side Files.
type DefaultWalkGetAttr struct{}
// WalkGetAttr implements File.WalkGetAttr.
func (DefaultWalkGetAttr) WalkGetAttr([]string) ([]QID, File, AttrMask, Attr, error) {
return nil, nil, AttrMask{}, Attr{}, syscall.ENOSYS
}
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