Documentation
¶
Overview ¶
Package backupfile reads and writes the folder a backup is kept in:
manifest.json what the backup holds, written last <kind>.jsonl the records of one kind, a JSON line each content/aa/bb/<sha> file content, by its checksum
A record file begins with a header line. With a key the records follow in encrypted blocks of about a thousand lines, so a backup of any size is read and written a block at a time. Content is stored as it is, once however many files share it, so repeating a backup into the same folder copies only what is new.
Index ¶
- Constants
- Variables
- func ClearUnfinished(dir string) error
- func ContentPath(dir, sha string) string
- func DownloadContent(dir, sha string, fetch Fetch) (int64, error)
- func HasContent(dir, sha string) bool
- func HasContentOfSize(dir, sha string, size int64) bool
- func IsBackupDir(dir string) bool
- func MarkUnfinished(dir string) error
- func OpenContent(dir, sha string) (*os.File, error)
- func PartialPath(dir, sha string) string
- func Prune(dir string, keep func(sha string) bool) (removed int, freed int64, err error)
- func RecordPath(dir, kind string) string
- func WriteContent(dir, sha string, r io.Reader) (int64, error)
- func WriteManifest(dir string, m *Manifest) error
- type Fetch
- type Manifest
- type Reader
- type Writer
Constants ¶
const (
// Version is the folder format.
Version = 1
)
Variables ¶
var ErrWrongKey = errors.New("cannot decrypt the backup: wrong key, or the file is damaged")
ErrWrongKey is returned when a block does not decrypt.
Functions ¶
func ClearUnfinished ¶
ClearUnfinished removes the mark once the backup is complete.
func ContentPath ¶
ContentPath is where the content with a checksum is kept.
func DownloadContent ¶
DownloadContent copies the content with a checksum into the backup, carrying on from a partial copy if there is one, and checking the whole against the checksum before keeping it. A failure leaves the partial copy for the next attempt; content that fails its checksum is discarded. It returns the bytes copied in this call.
func HasContent ¶
HasContent reports whether the backup holds the content with a checksum.
func HasContentOfSize ¶
HasContentOfSize is HasContent that also checks the size, so content a crash left empty or cut short is copied again rather than trusted. Content is not synced file by file, which would make a backup of many small files crawl.
func IsBackupDir ¶
IsBackupDir reports whether dir holds a backup, finished or not.
func MarkUnfinished ¶
MarkUnfinished records that a backup into dir has begun.
func OpenContent ¶
OpenContent opens the content with a checksum.
func PartialPath ¶
PartialPath is where content with a checksum is kept while it is being copied. A copy that fails leaves it, so the next attempt, in this run or the next, carries on from there.
func Prune ¶
Prune removes content that no file refers to: keep reports whether a checksum is still wanted. It also clears partial copies. It returns how many files it removed and the bytes they held.
func RecordPath ¶
RecordPath is the file the records of a kind are kept in.
func WriteContent ¶
WriteContent stores content read from r under its checksum, refusing content that does not match it. It returns the bytes written.
func WriteManifest ¶
WriteManifest writes the manifest into dir.
Types ¶
type Fetch ¶
type Fetch func(offset int64) (rc io.ReadCloser, resumed bool, err error)
Fetch opens content from byte offset. It returns the stream and whether the stream starts at offset: false means it starts at the beginning, because the server sent everything again.
type Manifest ¶
type Manifest struct {
Version int `json:"version" msgpack:"version"`
Created time.Time `json:"created" msgpack:"created"`
Server string `json:"server" msgpack:"server"` // the knot version that made it
Encrypted bool `json:"encrypted" msgpack:"encrypted"`
Counts map[string]int `json:"counts" msgpack:"counts"`
Content bool `json:"content" msgpack:"content"` // file content was copied
}
Manifest says what a backup holds. It is written when the backup is complete, so a folder without one is unfinished.
func ReadManifest ¶
ReadManifest reads the manifest of the backup in dir.
type Reader ¶
type Reader struct {
// contains filtered or unexported fields
}
Reader reads the records of one kind.
Source Files