duplicacy/src/duplicacy_snapshot.go

// Copyright (c) Acrosync LLC. All rights reserved.
// Free for personal use and commercial trial
// Commercial use requires per-user licenses available from https://duplicacy.com

package duplicacy

import (
	"encoding/hex"
	"encoding/json"
	"fmt"
	"io/ioutil"
	"os"
	"path"
	"strconv"
	"strings"
	"time"
)

// Snapshot represents a backup of the repository.
type Snapshot struct {
	ID            string // the snapshot id; must be different for different repositories
	Revision      int    // the revision number
	Options       string // options used to create this snapshot (some not included)
	Tag           string // user-assigned tag
	StartTime     int64  // at what time the snapshot was created
	EndTime       int64  // at what time the snapshot was done
	FileSize      int64  // total file size
	NumberOfFiles int64  // number of files

	// A sequence of chunks whose aggregated content is the json representation of 'Files'.
	FileSequence []string

	// A sequence of chunks whose aggregated content is the json representation of 'ChunkHashes'.
	ChunkSequence []string

	// A sequence of chunks whose aggregated content is the json representation of 'ChunkLengths'.
	LengthSequence []string

	Files []*Entry // list of files and subdirectories

	ChunkHashes  []string // a sequence of chunks representing the file content
	ChunkLengths []int    // the length of each chunk

	Flag bool // used to mark certain snapshots for deletion or copy

	discardAttributes bool
}

// CreateEmptySnapshot creates an empty snapshot.
func CreateEmptySnapshot(id string) (snapshto *Snapshot) {
	return &Snapshot{
		ID:        id,
		Revision:  0,
		StartTime: time.Now().Unix(),
	}
}

// CreateSnapshotFromDirectory creates a snapshot from the local directory 'top'.  Only 'Files'
// will be constructed, while 'ChunkHashes' and 'ChunkLengths' can only be populated after uploading.
func CreateSnapshotFromDirectory(id string, top string, nobackupFile string) (snapshot *Snapshot, skippedDirectories []string,
	skippedFiles []string, err error) {

	snapshot = &Snapshot{
		ID:        id,
		Revision:  0,
		StartTime: time.Now().Unix(),
	}

	var patterns []string

	patternFile, err := ioutil.ReadFile(path.Join(GetDuplicacyPreferencePath(), "filters"))
	if err == nil {
		for _, pattern := range strings.Split(string(patternFile), "\n") {
			pattern = strings.TrimSpace(pattern)
			if len(pattern) == 0 {
				continue
			}

			if pattern[0] == '#' {
				continue
			}

			if IsUnspecifiedFilter(pattern) {
				pattern = "+" + pattern
			}

			if IsEmptyFilter(pattern) {
				continue
			}

			if strings.HasPrefix(pattern, "i:") || strings.HasPrefix(pattern, "e:") {
				valid, err := IsValidRegex(pattern[2:])
				if !valid || err != nil {
					LOG_ERROR("SNAPSHOT_FILTER", "Invalid regular expression encountered for filter: \"%s\", error: %v", pattern, err)
				}
			}

			patterns = append(patterns, pattern)
		}

		LOG_DEBUG("REGEX_DEBUG", "There are %d compiled regular expressions stored", len(RegexMap))

		LOG_INFO("SNAPSHOT_FILTER", "Loaded %d include/exclude pattern(s)", len(patterns))

		if IsTracing() {
			for _, pattern := range patterns {
				LOG_TRACE("SNAPSHOT_PATTERN", "Pattern: %s", pattern)
			}
		}

	}

	directories := make([]*Entry, 0, 256)
	directories = append(directories, CreateEntry("", 0, 0, 0))

	snapshot.Files = make([]*Entry, 0, 256)

	attributeThreshold := 1024 * 1024
	if attributeThresholdValue, found := os.LookupEnv("DUPLICACY_ATTRIBUTE_THRESHOLD"); found && attributeThresholdValue != "" {
		attributeThreshold, _ = strconv.Atoi(attributeThresholdValue)
	}

	for len(directories) > 0 {

		directory := directories[len(directories)-1]
		directories = directories[:len(directories)-1]
		snapshot.Files = append(snapshot.Files, directory)
		subdirectories, skipped, err := ListEntries(top, directory.Path, &snapshot.Files, patterns, nobackupFile, snapshot.discardAttributes)
		if err != nil {
			LOG_WARN("LIST_FAILURE", "Failed to list subdirectory: %v", err)
			skippedDirectories = append(skippedDirectories, directory.Path)
			continue
		}

		directories = append(directories, subdirectories...)
		skippedFiles = append(skippedFiles, skipped...)

		if !snapshot.discardAttributes && len(snapshot.Files) > attributeThreshold {
			LOG_INFO("LIST_ATTRIBUTES", "Discarding file attributes")
			snapshot.discardAttributes = true
			for _, file := range snapshot.Files {
				file.Attributes = nil
			}
		}
	}

	// Remove the root entry
	snapshot.Files = snapshot.Files[1:]

	return snapshot, skippedDirectories, skippedFiles, nil
}

// This is the struct used to save/load incomplete snapshots
type IncompleteSnapshot struct {
	Files        []*Entry
	ChunkHashes  []string
	ChunkLengths []int
}

// LoadIncompleteSnapshot loads the incomplete snapshot if it exists
func LoadIncompleteSnapshot() (snapshot *Snapshot) {
	snapshotFile := path.Join(GetDuplicacyPreferencePath(), "incomplete")
	description, err := ioutil.ReadFile(snapshotFile)
	if err != nil {
		LOG_DEBUG("INCOMPLETE_LOCATE", "Failed to locate incomplete snapshot: %v", err)
		return nil
	}

	var incompleteSnapshot IncompleteSnapshot

	err = json.Unmarshal(description, &incompleteSnapshot)
	if err != nil {
		LOG_DEBUG("INCOMPLETE_PARSE", "Failed to parse incomplete snapshot: %v", err)
		return nil
	}

	var chunkHashes []string
	for _, chunkHash := range incompleteSnapshot.ChunkHashes {
		hash, err := hex.DecodeString(chunkHash)
		if err != nil {
			LOG_DEBUG("INCOMPLETE_DECODE", "Failed to decode incomplete snapshot: %v", err)
			return nil
		}
		chunkHashes = append(chunkHashes, string(hash))
	}

	snapshot = &Snapshot{
		Files:        incompleteSnapshot.Files,
		ChunkHashes:  chunkHashes,
		ChunkLengths: incompleteSnapshot.ChunkLengths,
	}
	LOG_INFO("INCOMPLETE_LOAD", "Incomplete snapshot loaded from %s", snapshotFile)
	return snapshot
}

// SaveIncompleteSnapshot saves the incomplete snapshot under the preference directory
func SaveIncompleteSnapshot(snapshot *Snapshot) {
	var files []*Entry
	for _, file := range snapshot.Files {
		// All unprocessed files will have a size of -1
		if file.Size >= 0 {
			file.Attributes = nil
			files = append(files, file)
		} else {
			break
		}
	}
	var chunkHashes []string
	for _, chunkHash := range snapshot.ChunkHashes {
		chunkHashes = append(chunkHashes, hex.EncodeToString([]byte(chunkHash)))
	}

	incompleteSnapshot := IncompleteSnapshot{
		Files:        files,
		ChunkHashes:  chunkHashes,
		ChunkLengths: snapshot.ChunkLengths,
	}

	description, err := json.MarshalIndent(incompleteSnapshot, "", "  ")
	if err != nil {
		LOG_WARN("INCOMPLETE_ENCODE", "Failed to encode the incomplete snapshot: %v", err)
		return
	}

	snapshotFile := path.Join(GetDuplicacyPreferencePath(), "incomplete")
	err = ioutil.WriteFile(snapshotFile, description, 0644)
	if err != nil {
		LOG_WARN("INCOMPLETE_WRITE", "Failed to save the incomplete snapshot: %v", err)
		return
	}

	LOG_INFO("INCOMPLETE_SAVE", "Incomplete snapshot saved to %s", snapshotFile)
}

func RemoveIncompleteSnapshot() {
	snapshotFile := path.Join(GetDuplicacyPreferencePath(), "incomplete")
	if stat, err := os.Stat(snapshotFile); err == nil && !stat.IsDir() {
		err = os.Remove(snapshotFile)
		if err != nil {
			LOG_INFO("INCOMPLETE_SAVE", "Failed to remove ncomplete snapshot: %v", err)
		} else {
			LOG_INFO("INCOMPLETE_SAVE", "Removed incomplete snapshot %s", snapshotFile)
		}
	}
}

// CreateSnapshotFromDescription creates a snapshot from json decription.
func CreateSnapshotFromDescription(description []byte) (snapshot *Snapshot, err error) {

	var root map[string]interface{}

	err = json.Unmarshal(description, &root)
	if err != nil {
		return nil, err
	}

	snapshot = &Snapshot{}

	if value, ok := root["id"]; !ok {
		return nil, fmt.Errorf("No id is specified in the snapshot")
	} else if snapshot.ID, ok = value.(string); !ok {
		return nil, fmt.Errorf("Invalid id is specified in the snapshot")
	}

	if value, ok := root["revision"]; !ok {
		return nil, fmt.Errorf("No revision is specified in the snapshot")
	} else if _, ok = value.(float64); !ok {
		return nil, fmt.Errorf("Invalid revision is specified in the snapshot")
	} else {
		snapshot.Revision = int(value.(float64))
	}

	if value, ok := root["tag"]; !ok {
	} else if snapshot.Tag, ok = value.(string); !ok {
		return nil, fmt.Errorf("Invalid tag is specified in the snapshot")
	}

	if value, ok := root["options"]; !ok {
	} else if snapshot.Options, ok = value.(string); !ok {
		return nil, fmt.Errorf("Invalid options is specified in the snapshot")
	}

	if value, ok := root["start_time"]; !ok {
		return nil, fmt.Errorf("No creation time is specified in the snapshot")
	} else if _, ok = value.(float64); !ok {
		return nil, fmt.Errorf("Invalid creation time is specified in the snapshot")
	} else {
		snapshot.StartTime = int64(value.(float64))
	}

	if value, ok := root["end_time"]; !ok {
		return nil, fmt.Errorf("No creation time is specified in the snapshot")
	} else if _, ok = value.(float64); !ok {
		return nil, fmt.Errorf("Invalid creation time is specified in the snapshot")
	} else {
		snapshot.EndTime = int64(value.(float64))
	}

	if value, ok := root["file_size"]; ok {
		if _, ok = value.(float64); ok {
			snapshot.FileSize = int64(value.(float64))
		}
	}

	if value, ok := root["number_of_files"]; ok {
		if _, ok = value.(float64); ok {
			snapshot.NumberOfFiles = int64(value.(float64))
		}
	}

	for _, sequenceType := range []string{"files", "chunks", "lengths"} {
		if value, ok := root[sequenceType]; !ok {
			return nil, fmt.Errorf("No %s are specified in the snapshot", sequenceType)
		} else if _, ok = value.([]interface{}); !ok {
			return nil, fmt.Errorf("Invalid %s are specified in the snapshot", sequenceType)
		} else {
			array := value.([]interface{})
			sequence := make([]string, len(array))
			for i := 0; i < len(array); i++ {
				if hashInHex, ok := array[i].(string); !ok {
					return nil, fmt.Errorf("Invalid file sequence is specified in the snapshot")
				} else if hash, err := hex.DecodeString(hashInHex); err != nil {
					return nil, fmt.Errorf("Hash %s is not a valid hex string in the snapshot", hashInHex)
				} else {
					sequence[i] = string(hash)
				}
			}

			snapshot.SetSequence(sequenceType, sequence)
		}
	}

	return snapshot, nil
}

// LoadChunks construct 'ChunkHashes' from the json description.
func (snapshot *Snapshot) LoadChunks(description []byte) (err error) {

	var root []interface{}
	err = json.Unmarshal(description, &root)
	if err != nil {
		return err
	}

	snapshot.ChunkHashes = make([]string, len(root))

	for i, object := range root {
		if hashInHex, ok := object.(string); !ok {
			return fmt.Errorf("Invalid chunk hash is specified in the snapshot")
		} else if hash, err := hex.DecodeString(hashInHex); err != nil {
			return fmt.Errorf("The chunk hash %s is not a valid hex string", hashInHex)
		} else {
			snapshot.ChunkHashes[i] = string(hash)
		}
	}

	return err
}

// ClearChunks removes loaded chunks from memory
func (snapshot *Snapshot) ClearChunks() {
	snapshot.ChunkHashes = nil
}

// LoadLengths construct 'ChunkLengths' from the json description.
func (snapshot *Snapshot) LoadLengths(description []byte) (err error) {
	return json.Unmarshal(description, &snapshot.ChunkLengths)
}

// MarshalJSON creates a json representation of the snapshot.
func (snapshot *Snapshot) MarshalJSON() ([]byte, error) {

	object := make(map[string]interface{})

	object["id"] = snapshot.ID
	object["revision"] = snapshot.Revision
	object["options"] = snapshot.Options
	object["tag"] = snapshot.Tag
	object["start_time"] = snapshot.StartTime
	object["end_time"] = snapshot.EndTime

	if snapshot.FileSize != 0 && snapshot.NumberOfFiles != 0 {
		object["file_size"] = snapshot.FileSize
		object["number_of_files"] = snapshot.NumberOfFiles
	}
	object["files"] = encodeSequence(snapshot.FileSequence)
	object["chunks"] = encodeSequence(snapshot.ChunkSequence)
	object["lengths"] = encodeSequence(snapshot.LengthSequence)

	return json.Marshal(object)
}

// MarshalSequence creates a json represetion for the specified chunk sequence.
func (snapshot *Snapshot) MarshalSequence(sequenceType string) ([]byte, error) {

	if sequenceType == "files" {
		return json.Marshal(snapshot.Files)
	} else if sequenceType == "chunks" {
		return json.Marshal(encodeSequence(snapshot.ChunkHashes))
	} else {
		return json.Marshal(snapshot.ChunkLengths)
	}
}

// SetSequence assign a chunk sequence to the specified field.
func (snapshot *Snapshot) SetSequence(sequenceType string, sequence []string) {
	if sequenceType == "files" {
		snapshot.FileSequence = sequence
	} else if sequenceType == "chunks" {
		snapshot.ChunkSequence = sequence
	} else {
		snapshot.LengthSequence = sequence
	}
}

// encodeSequence turns a sequence of binary hashes into a sequence of hex hashes.
func encodeSequence(sequence []string) []string {

	sequenceInHex := make([]string, len(sequence))

	for i, hash := range sequence {
		sequenceInHex[i] = hex.EncodeToString([]byte(hash))
	}

	return sequenceInHex
}