mirror of
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110 lines
2.9 KiB
Go
110 lines
2.9 KiB
Go
// Package sqlite3vfs wraps the C SQLite VFS API.
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package sqlite3vfs
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import "sync"
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// A VFS defines the interface between the SQLite core and the underlying operating system.
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//
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// Use sqlite3.ErrorCode or sqlite3.ExtendedErrorCode to return specific error codes to SQLite.
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//
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// https://www.sqlite.org/c3ref/vfs.html
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type VFS interface {
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Open(name string, flags OpenFlag) (File, OpenFlag, error)
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Delete(name string, syncDir bool) error
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Access(name string, flags AccessFlag) (bool, error)
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FullPathname(name string) (string, error)
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}
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// A File represents an open file in the OS interface layer.
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//
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// Use sqlite3.ErrorCode or sqlite3.ExtendedErrorCode to return specific error codes to SQLite.
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// In particular, sqlite3.BUSY is necessary to correctly implement lock methods.
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//
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// https://www.sqlite.org/c3ref/io_methods.html
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type File interface {
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Close() error
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ReadAt(p []byte, off int64) (n int, err error)
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WriteAt(p []byte, off int64) (n int, err error)
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Truncate(size int64) error
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Sync(flags SyncFlag) error
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FileSize() (int64, error)
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Lock(lock LockLevel) error
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Unlock(lock LockLevel) error
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CheckReservedLock() (bool, error)
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SectorSize() int
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DeviceCharacteristics() DeviceCharacteristic
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}
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// FileLockState extends [File] to implement the
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// SQLITE_FCNTL_LOCKSTATE file control opcode.
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//
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// https://www.sqlite.org/c3ref/c_fcntl_begin_atomic_write.html
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type FileLockState interface {
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File
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LockState() LockLevel
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}
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// FileSizeHint extends [File] to implement the
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// SQLITE_FCNTL_SIZE_HINT file control opcode.
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//
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// https://www.sqlite.org/c3ref/c_fcntl_begin_atomic_write.html
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type FileSizeHint interface {
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File
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SizeHint(size int64) error
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}
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// FileHasMoved extends [File] to implement the
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// SQLITE_FCNTL_HAS_MOVED file control opcode.
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//
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// https://www.sqlite.org/c3ref/c_fcntl_begin_atomic_write.html
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type FileHasMoved interface {
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File
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HasMoved() (bool, error)
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}
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// FilePowersafeOverwrite extends [File] to implement the
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// SQLITE_FCNTL_POWERSAFE_OVERWRITE file control opcode.
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//
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// https://www.sqlite.org/c3ref/c_fcntl_begin_atomic_write.html
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type FilePowersafeOverwrite interface {
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File
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PowersafeOverwrite() bool
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SetPowersafeOverwrite(bool)
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}
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var (
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vfsRegistry map[string]VFS
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vfsRegistryMtx sync.Mutex
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)
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// Find returns a VFS given its name.
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// If there is no match, nil is returned.
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//
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// https://www.sqlite.org/c3ref/vfs_find.html
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func Find(name string) VFS {
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vfsRegistryMtx.Lock()
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defer vfsRegistryMtx.Unlock()
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return vfsRegistry[name]
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}
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// Register registers a VFS.
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//
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// https://www.sqlite.org/c3ref/vfs_find.html
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func Register(name string, vfs VFS) {
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vfsRegistryMtx.Lock()
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defer vfsRegistryMtx.Unlock()
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if vfsRegistry == nil {
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vfsRegistry = map[string]VFS{}
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}
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vfsRegistry[name] = vfs
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}
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// Unregister unregisters a VFS.
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//
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// https://www.sqlite.org/c3ref/vfs_find.html
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func Unregister(name string) {
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vfsRegistryMtx.Lock()
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defer vfsRegistryMtx.Unlock()
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delete(vfsRegistry, name)
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}
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