Documentation
¶
Overview ¶
Package p9 is a 9P2000.L implementation.
Servers implement Attacher and File interfaces.
Clients can use Client.
Index ¶
- Constants
- Variables
- func CanOpen(mode FileMode) bool
- func HighestVersionString() string
- func StatToAttr(s *internal.Stat_t, req AttrMask) (Attr, AttrMask)
- func VersionSupportsMultiUser(v uint32) bool
- type Attacher
- type Attr
- type AttrMask
- type Client
- type ClientOpt
- type ConnError
- type DefaultWalkGetAttr
- type Dev
- type Dirent
- type Dirents
- type ErrBadResponse
- type ErrInvalidMsgType
- type ErrMessageTooLarge
- type FSStat
- type File
- type FileMode
- func (m FileMode) FileType() FileMode
- func (m FileMode) IsBlockDevice() bool
- func (m FileMode) IsCharacterDevice() bool
- func (m FileMode) IsDir() bool
- func (m FileMode) IsExecutable() bool
- func (m FileMode) IsNamedPipe() bool
- func (m FileMode) IsReadable() bool
- func (m FileMode) IsRegular() bool
- func (m FileMode) IsSocket() bool
- func (m FileMode) IsSymlink() bool
- func (m FileMode) IsWritable() bool
- func (m FileMode) OSMode() os.FileMode
- func (m FileMode) Permissions() FileMode
- func (m FileMode) QIDType() QIDType
- func (m FileMode) Writable() FileMode
- type GID
- type LockFlags
- type LockStatus
- type LockType
- type NLink
- type OpenFlags
- type QID
- type QIDGenerator
- type QIDType
- type Server
- type ServerOpt
- type SetAttr
- type SetAttrMask
- type UID
- type XattrFlags
Constants ¶
const ( // NoUID is a sentinel used to indicate no valid UID. NoUID UID = math.MaxUint32 // NoGID is a sentinel used to indicate no valid GID. NoGID GID = math.MaxUint32 )
const ( // DefaultMessageSize is a sensible default. DefaultMessageSize uint32 = 64 << 10 )
Variables ¶
var AttrMaskAll = AttrMask{ Mode: true, NLink: true, UID: true, GID: true, RDev: true, ATime: true, MTime: true, CTime: true, INo: true, Size: true, Blocks: true, BTime: true, Gen: true, DataVersion: true, }
AttrMaskAll is an AttrMask with all fields masked.
var Debug = func(fmt string, v ...interface{}) {}
Debug can be assigned to log.Printf to print messages received and sent.
var ErrBadVersionString = errors.New("bad version string")
ErrBadVersionString indicates that the version string is malformed or unsupported.
var ErrNoValidMessage = errors.New("buffer contained no valid message")
ErrNoValidMessage indicates no valid message could be decoded.
var ErrOutOfFIDs = errors.New("out of FIDs -- messages lost?")
ErrOutOfFIDs indicates no more FIDs are available.
var ErrOutOfTags = errors.New("out of tags -- messages lost?")
ErrOutOfTags indicates no tags are available.
var ErrUnexpectedTag = errors.New("unexpected tag in response")
ErrUnexpectedTag indicates a response with an unexpected tag was received.
var ErrVersionsExhausted = errors.New("exhausted all versions to negotiate")
ErrVersionsExhausted indicates that all versions to negotiate have been exhausted.
Functions ¶
func CanOpen ¶
CanOpen returns whether this file open can be opened, read and written to.
This includes everything except symlinks and sockets.
func HighestVersionString ¶
func HighestVersionString() string
HighestVersionString returns the highest possible version string that a client may request or a server may support.
func StatToAttr ¶
StatToAttr converts a Linux syscall stat structure to an Attr.
func VersionSupportsMultiUser ¶
VersionSupportsMultiUser returns true if version v supports multi-user fake directory permissions and ID values.
Types ¶
type Attacher ¶
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) }
Attacher is provided by the server.
type Attr ¶
type Attr struct { Mode FileMode UID UID GID GID NLink NLink RDev Dev Size uint64 BlockSize uint64 Blocks uint64 ATimeSeconds uint64 ATimeNanoSeconds uint64 MTimeSeconds uint64 MTimeNanoSeconds uint64 CTimeSeconds uint64 CTimeNanoSeconds uint64 BTimeSeconds uint64 BTimeNanoSeconds uint64 Gen uint64 DataVersion uint64 }
Attr is a set of attributes for getattr.
func (*Attr) Apply ¶
func (a *Attr) Apply(mask SetAttrMask, attr SetAttr)
Apply applies this to the given Attr.
type AttrMask ¶
type AttrMask struct { Mode bool NLink bool UID bool GID bool RDev bool ATime bool MTime bool CTime bool INo bool Size bool Blocks bool BTime bool Gen bool DataVersion bool }
AttrMask is a mask of attributes for getattr.
type Client ¶
type Client struct {
// contains filtered or unexported fields
}
Client is at least a 9P2000.L client.
func NewClient ¶
func NewClient(conn io.ReadWriteCloser, o ...ClientOpt) (*Client, error)
NewClient creates a new client. It performs a Tversion exchange with the server to assert that messageSize is ok to use.
You should not use the same conn for multiple clients.
type ClientOpt ¶
ClientOpt enables optional client configuration.
func WithClientLogger ¶
WithClientLogger overrides the default logger for the client.
func WithMessageSize ¶
WithMessageSize overrides the default message size.
type ConnError ¶
type ConnError struct {
// contains filtered or unexported fields
}
ConnError is returned in cases of a connection issue.
This may be treated differently than other errors.
type DefaultWalkGetAttr ¶
type DefaultWalkGetAttr struct{}
DefaultWalkGetAttr implements File.WalkGetAttr to return ENOSYS for server-side Files.
func (DefaultWalkGetAttr) WalkGetAttr ¶
WalkGetAttr implements File.WalkGetAttr.
type Dev ¶
type Dev uint64
Dev is the device number of an fs object.
While this type has no utilities, it is useful in order to force linux+amd64 only developers to cast to Dev for the Dev field, which will make their code compatible with other GOARCH and GOOS values.
type Dirent ¶
type Dirent struct { // QID is the entry QID. QID QID // Offset is the offset in the directory. // // This will be communicated back the original caller. Offset uint64 // Type is the 9P type. Type QIDType // Name is the name of the entry (i.e. basename). Name string }
Dirent represents a directory entry in File.Readdir.
type ErrBadResponse ¶
type ErrBadResponse struct { Got msgType Want msgType }
ErrBadResponse indicates the response didn't match the request.
func (*ErrBadResponse) Error ¶
func (e *ErrBadResponse) Error() string
Error returns a highly descriptive error.
type ErrInvalidMsgType ¶
type ErrInvalidMsgType struct {
// contains filtered or unexported fields
}
ErrInvalidMsgType is returned when an unsupported message type is found.
func (*ErrInvalidMsgType) Error ¶
func (e *ErrInvalidMsgType) Error() string
Error returns a useful string.
type ErrMessageTooLarge ¶
type ErrMessageTooLarge struct {
// contains filtered or unexported fields
}
ErrMessageTooLarge indicates the size was larger than reasonable.
func (*ErrMessageTooLarge) Error ¶
func (e *ErrMessageTooLarge) Error() string
Error returns a sensible error.
type FSStat ¶
type FSStat struct { // Type is the filesystem type. Type uint32 // BlockSize is the blocksize. BlockSize uint32 // Blocks is the number of blocks. Blocks uint64 // BlocksFree is the number of free blocks. BlocksFree uint64 // BlocksAvailable is the number of blocks *available*. BlocksAvailable uint64 // Files is the number of files available. Files uint64 // FilesFree is the number of free file nodes. FilesFree uint64 // FSID is the filesystem ID. FSID uint64 // NameLength is the maximum name length. NameLength uint32 }
FSStat is used by statfs.
type File ¶
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. // // On the server, Walk has a read concurrency guarantee. Walk(names []string) ([]QID, File, error) // WalkGetAttr walks to the next file and returns its maximal set of // attributes. // // Server-side p9.Files may return linux.ENOSYS to indicate that Walk // and GetAttr should be used separately to satisfy this request. // // On the server, WalkGetAttr has a read concurrency guarantee. WalkGetAttr([]string) ([]QID, File, AttrMask, Attr, error) // StatFS returns information about the file system associated with // this file. // // On the server, StatFS has no concurrency guarantee. StatFS() (FSStat, error) // GetAttr returns attributes of this node. // // On the server, GetAttr has a read concurrency guarantee. GetAttr(req AttrMask) (QID, AttrMask, Attr, error) // SetAttr sets attributes on this node. // // On the server, SetAttr has a write concurrency guarantee. SetAttr(valid SetAttrMask, attr SetAttr) 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. // // On the server, Close has no concurrency guarantee. Close() error // Open must be called prior to using ReadAt, WriteAt, or Readdir. Once // Open is called, some operations, such as Walk, will no longer work. // // On the client, Open should be called only once. The fd return is // optional, and may be nil. // // On the server, Open has a read concurrency guarantee. Open is // guaranteed to be called only once. // // N.B. The server must resolve any lazy paths when open is called. // After this point, read and write may be called on files with no // deletion check, so resolving in the data path is not viable. Open(mode OpenFlags) (QID, uint32, error) // ReadAt reads from this file. Open must be called first. // // This may return io.EOF in addition to linux.Errno values. // // On the server, ReadAt has a read concurrency guarantee. See Open for // additional requirements regarding lazy path resolution. ReadAt(p []byte, offset int64) (int, error) // WriteAt writes to this file. Open must be called first. // // This may return io.EOF in addition to linux.Errno values. // // On the server, WriteAt has a read concurrency guarantee. See Open // for additional requirements regarding lazy path resolution. WriteAt(p []byte, offset int64) (int, error) // SetXattr sets the extended attributes attr=data of the file. // // Flags are implementation-specific, but are // generally Linux setxattr(2) flags. SetXattr(attr string, data []byte, flags XattrFlags) error // GetXattr fetches the extended attribute attr of the file. GetXattr(attr string) ([]byte, error) // ListXattrs lists the extended attribute names of the file. ListXattrs() ([]string, error) // RemoveXattr removes the extended attribute attr from the file. RemoveXattr(attr string) error // FSync syncs this node. Open must be called first. // // On the server, FSync has a read concurrency guarantee. FSync() error // Lock locks the file. The operation as defined in 9P2000.L is fairly // ambitious, being a near-direct mapping to lockf(2)/fcntl(2)-style // locking, but most implementations use flock(2). // // Arguments are defined by the 9P2000.L standard. // // Pid is the PID on the client. Locktype is one of read, write, or // unlock (resp. 0, 1, or 2). Flags are to block (0), meaning wait; or // reclaim (1), which is currently "reserved for future use." Start and // length are the start of the region to use and the size. In many // implementations, they are ignored and flock(2) is used. Client is an // arbitrary string, also frequently unused. The Linux v9fs client // happens to set the client name to the node name. // // The Linux v9fs client implements fcntl(F_SETLK) by calling lock // without any flags set. // // The Linux v9fs client implements the fcntl(F_SETLKW) (blocking) // lock request by calling lock with P9_LOCK_FLAGS_BLOCK set. If the // response is P9_LOCK_BLOCKED, it retries the lock request in an // interruptible loop until status is no longer P9_LOCK_BLOCKED. // // The Linux v9fs client translates BSD advisory locks (flock) to // whole-file POSIX record locks. v9fs does not implement mandatory // locks and will return ENOLCK if use is attempted. // // In the return values, a LockStatus corresponds to an Rlock, while // returning an error corresponds to an Rlerror message. If any non-nil // error is returned, an Rlerror message will be sent. // // The most commonly used return values are success and error (resp. 0 // and 2); blocked (1) and grace (3) are also possible. Lock(pid int, locktype LockType, flags LockFlags, start, length uint64, client string) (LockStatus, error) // Create creates a new regular file and opens it according to the // flags given. This file is already Open. // // N.B. On the client, the returned file is a reference to the current // file, which now represents the created file. This is not the case on // the server. These semantics are very subtle and can easily lead to // bugs, but are a consequence of the 9P create operation. // // On the server, Create has a write concurrency guarantee. Create(name string, flags OpenFlags, permissions FileMode, uid UID, gid GID) (File, QID, uint32, error) // Mkdir creates a subdirectory. // // On the server, Mkdir has a write concurrency guarantee. Mkdir(name string, permissions FileMode, uid UID, gid GID) (QID, error) // Symlink makes a new symbolic link. // // On the server, Symlink has a write concurrency guarantee. Symlink(oldName string, newName string, uid UID, gid GID) (QID, error) // Link makes a new hard link. // // On the server, Link has a write concurrency guarantee. Link(target File, newName string) error // Mknod makes a new device node. // // On the server, Mknod has a write concurrency guarantee. Mknod(name string, mode FileMode, major uint32, minor uint32, uid UID, gid GID) (QID, error) // Rename renames the file. // // Rename will never be called on the server, and RenameAt will always // be used instead. Rename(newDir File, newName string) 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. // // On the server, RenameAt has a global concurrency guarantee. 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. // // On the server, UnlinkAt has a write concurrency guarantee. UnlinkAt(name string, flags uint32) error // Readdir reads directory entries. // // offset is the entry offset, and count the number of entries to // return. // // This may return io.EOF in addition to linux.Errno values. // // On the server, Readdir has a read concurrency guarantee. Readdir(offset uint64, count uint32) (Dirents, error) // Readlink reads the link target. // // On the server, Readlink has a read concurrency guarantee. Readlink() (string, error) // Renamed is called when this node is renamed. // // This may not fail. The file will hold a reference to its parent // within the p9 package, and is therefore safe to use for the lifetime // of this File (until Close is called). // // This method should not be called by clients, who should use the // relevant Rename methods. (Although the method will be a no-op.) // // On the server, Renamed has a global concurrency guarantee. Renamed(newDir File, newName string) }
File is a set of operations corresponding to a single node.
Note that on the server side, the server logic places constraints on concurrent operations to make things easier. This may reduce the need for complex, error-prone locking and logic in the backend. These are documented for each method.
There are three different types of guarantees provided:
none: There is no concurrency guarantee. The method may be invoked concurrently with any other method on any other file.
read: The method is guaranteed to be exclusive of any write or global operation that is mutating the state of the directory tree starting at this node. For example, this means creating new files, symlinks, directories or renaming a directory entry (or renaming in to this target), but the method may be called concurrently with other read methods.
write: The method is guaranteed to be exclusive of any read, write or global operation that is mutating the state of the directory tree starting at this node, as described in read above. There may however, be other write operations executing concurrently on other components in the directory tree.
global: The method is guaranteed to be exclusive of any read, write or global operation.
type FileMode ¶
type FileMode uint32
FileMode are flags corresponding to file modes.
These correspond to bits sent over the wire. These also correspond to mode_t bits.
const ( // FileModeMask is a mask of all the file mode bits of FileMode. FileModeMask FileMode = 0170000 // ModeSocket is an (unused) mode bit for a socket. ModeSocket FileMode = 0140000 // ModeSymlink is a mode bit for a symlink. ModeSymlink FileMode = 0120000 // ModeRegular is a mode bit for regular files. ModeRegular FileMode = 0100000 // ModeBlockDevice is a mode bit for block devices. ModeBlockDevice FileMode = 060000 // ModeDirectory is a mode bit for directories. ModeDirectory FileMode = 040000 // ModeCharacterDevice is a mode bit for a character device. ModeCharacterDevice FileMode = 020000 // ModeNamedPipe is a mode bit for a named pipe. ModeNamedPipe FileMode = 010000 // Read is a mode bit indicating read permission. Read FileMode = 04 // Write is a mode bit indicating write permission. Write FileMode = 02 // Exec is a mode bit indicating exec permission. Exec FileMode = 01 // AllPermissions is a mask with rwx bits set for user, group and others. AllPermissions FileMode = 0777 // Sticky is a mode bit indicating sticky directories. Sticky FileMode = 01000 )
func ModeFromOS ¶
ModeFromOS returns a FileMode from an os.FileMode.
func (FileMode) IsBlockDevice ¶
IsBlockDevice returns true if m represents a character device.
func (FileMode) IsCharacterDevice ¶
IsCharacterDevice returns true if m represents a character device.
func (FileMode) IsExecutable ¶
IsExecutable returns true if m represents a file that can be executed.
func (FileMode) IsNamedPipe ¶
IsNamedPipe returns true if m represents a named pipe.
func (FileMode) IsReadable ¶
IsReadable returns true if m represents a file that can be read.
func (FileMode) IsWritable ¶
IsWritable returns true if m represents a file that can be written to.
func (FileMode) Permissions ¶
Permissions returns just the permission bits of the mode.
type LockFlags ¶ added in v0.3.0
type LockFlags uint32
LockFlags are flags for the lock. Currently, and possibly forever, only one is really used: LockFlagsBlock
type LockStatus ¶ added in v0.3.0
type LockStatus uint8
LockStatus contains lock status result.
const ( LockStatusOK LockStatus = iota LockStatusBlocked LockStatusError LockStatusGrace )
These are the four current return values for Rlock.
func (LockStatus) String ¶ added in v0.3.0
func (s LockStatus) String() string
type LockType ¶ added in v0.3.0
type LockType uint8
LockType is lock type for Tlock
These constants define Lock operations: Read, Write, and Un(lock) They map to Linux values of F_RDLCK, F_WRLCK, F_UNLCK. If that seems a little Linux-centric, recall that the "L" in 9P2000.L means "Linux" :-)
type NLink ¶
type NLink uint64
NLink is the number of links to this fs object.
While this type has no utilities, it is useful in order to force linux+amd64 only developers to cast to NLink for the NLink field, which will make their code compatible with other GOARCH and GOOS values.
type OpenFlags ¶
type OpenFlags uint32
OpenFlags is the mode passed to Open and Create operations.
These correspond to bits sent over the wire.
const ( // ReadOnly is a Topen and Tcreate flag indicating read-only mode. ReadOnly OpenFlags = 0 // WriteOnly is a Topen and Tcreate flag indicating write-only mode. WriteOnly OpenFlags = 1 // ReadWrite is a Topen flag indicates read-write mode. ReadWrite OpenFlags = 2 // OpenFlagsModeMask is a mask of valid OpenFlags mode bits. OpenFlagsModeMask OpenFlags = 3 )
type QID ¶
type QID struct { // Type is the highest order byte of the file mode. Type QIDType // Version is an arbitrary server version number. Version uint32 // Path is a unique server identifier for this path (e.g. inode). Path uint64 }
QID is a unique file identifier.
This may be embedded in other requests and responses.
type QIDGenerator ¶
type QIDGenerator struct {
// contains filtered or unexported fields
}
QIDGenerator is a simple generator for QIDs that atomically increments Path values.
func (*QIDGenerator) Get ¶
func (q *QIDGenerator) Get(t QIDType) QID
Get returns a new 9P unique ID with a unique Path given a QID type.
While the 9P spec allows Version to be incremented every time the file is modified, we currently do not use the Version member for anything. Hence, it is set to 0.
type QIDType ¶
type QIDType uint8
QIDType represents the file type for QIDs.
QIDType corresponds to the high 8 bits of a Plan 9 file mode.
const ( // TypeDir represents a directory type. TypeDir QIDType = 0x80 // TypeAppendOnly represents an append only file. TypeAppendOnly QIDType = 0x40 // TypeExclusive represents an exclusive-use file. TypeExclusive QIDType = 0x20 // TypeMount represents a mounted channel. TypeMount QIDType = 0x10 // TypeAuth represents an authentication file. TypeAuth QIDType = 0x08 // TypeTemporary represents a temporary file. TypeTemporary QIDType = 0x04 // TypeSymlink represents a symlink. TypeSymlink QIDType = 0x02 // TypeLink represents a hard link. TypeLink QIDType = 0x01 // TypeRegular represents a regular file. TypeRegular QIDType = 0x00 )
type Server ¶
type Server struct {
// contains filtered or unexported fields
}
Server is a 9p2000.L server.
func (*Server) Handle ¶
func (s *Server) Handle(t io.ReadCloser, r io.WriteCloser) error
Handle handles a single connection.
func (*Server) Serve ¶
Serve handles requests from the bound socket.
The passed serverSocket _must_ be created in packet mode.
func (*Server) ServeContext ¶ added in v0.3.0
ServeContext handles requests from the bound socket.
The passed serverSocket _must_ be created in packet mode.
When the context is done, the listener is closed and serve returns once every request has been handled.
type ServerOpt ¶
type ServerOpt func(s *Server)
ServerOpt is an optional config for a new server.
func WithServerLogger ¶
WithServerLogger overrides the default logger for the server.
type SetAttr ¶
type SetAttr struct { Permissions FileMode UID UID GID GID Size uint64 ATimeSeconds uint64 ATimeNanoSeconds uint64 MTimeSeconds uint64 MTimeNanoSeconds uint64 }
SetAttr specifies a set of attributes for a setattr.
type SetAttrMask ¶
type SetAttrMask struct { Permissions bool UID bool GID bool Size bool ATime bool MTime bool CTime bool ATimeNotSystemTime bool MTimeNotSystemTime bool }
SetAttrMask specifies a valid mask for setattr.
func (SetAttrMask) Empty ¶
func (s SetAttrMask) Empty() bool
Empty returns true if no fields are masked.
func (SetAttrMask) IsSubsetOf ¶
func (s SetAttrMask) IsSubsetOf(m SetAttrMask) bool
IsSubsetOf returns whether s is a subset of m.
type XattrFlags ¶ added in v0.3.0
type XattrFlags int
XattrFlags are flags set on a setxattr operation.
const ( // XattrCreate set on setxattr requires a pure create, which fails if // the named attribute already exists. XattrCreate XattrFlags = 1 // XattrReplace set on setxattr requires a pure replace, which fails if // the named attribute does not already exist. XattrReplace XattrFlags = 2 )