Check the good stuff

src/duplicacy_backupmanager.go

@@ -304,7 +304,24 @@ func (manager *BackupManager) Backup(top string, quickMode bool, threads int, ta
 			remoteEntry = nil
 		}
 
-		if compareResult == 0  {
+		if localEntry.IsHardlinkedFrom() {
+			// FIXME: Sanity check?
+			// FIXME: perhaps we can make size = 0 an initial invariant of the link?
+			//
+			// Note that if the initial size was 0 then this original logic doesn't change!
+			localEntry.Size = 0
+			// targetEntry, ok := localEntryList.HardLinkTable[localEntry.Link]
+			// if !ok {
+			// 	LOG_ERROR("BACKUP_CREATE", "Hard link %s not found in entry cache for path %s", localEntry.Link, localEntry.Path)
+			// }
+			// localEntry.Size = targetEntry.Size
+			// localEntry.Hash = targetEntry.Hash
+			// localEntry.StartChunk = targetEntry.StartChunk
+			// localEntry.StartOffset = targetEntry.StartOffset
+			// localEntry.EndChunk = targetEntry.EndChunk
+			// localEntry.EndOffset = targetEntry.EndOffset
+			// LOG_DEBUG("BACKUP_CREATE", "Hard link %s to %s in initial listing", localEntry.Link, targetEntry.Path)
+		} else if compareResult == 0  {
 			// No need to check if it is in hash mode -- in that case remote listing is nil
 			if localEntry.IsSameAs(remoteEntry) && localEntry.IsFile() {
 				if localEntry.Size > 0 {
@@ -709,7 +726,7 @@ func (manager *BackupManager) Restore(top string, revision int, inPlace bool, qu
 	localListingOK := true
 
 	hardLinkTable := make(map[string]hardLinkEntry)
-	hardLinks := make([]*Entry, 0)
+	//hardLinks := make([]*Entry, 0)
 
 	for remoteEntry := range remoteListingChannel {
 
@@ -745,22 +762,28 @@ func (manager *BackupManager) Restore(top string, revision int, inPlace bool, qu
 		}
 
 		if compareResult == 0 {
-			if quickMode && localEntry.IsFile() {
-				checkEntry := remoteEntry
-				if len(remoteEntry.Link) > 0 && remoteEntry.Link != "/" {
-					if e, ok := hardLinkTable[remoteEntry.Link]; !ok {
-						LOG_ERROR("RESTORE_LINK", "Source file %s for hardlink %s missing", remoteEntry.Link, remoteEntry.Path)
-					} else {
-						checkEntry = e.entry
-					}
-				}
-				if localEntry.IsSameAs(checkEntry) {
+			// if quickMode && localEntry.IsFile() {
+				if quickMode && localEntry.IsFile() && localEntry.IsSameAs(remoteEntry) {
 					LOG_TRACE("RESTORE_SKIP", "File %s unchanged (by size and timestamp)", localEntry.Path)
 					skippedFileSize += localEntry.Size
 					skippedFileCount++
 					localEntry = nil
 					continue
-				}
+				// checkEntry := remoteEntry
+				// if len(remoteEntry.Link) > 0 && remoteEntry.Link != "/" {
+				// 	if e, ok := hardLinkTable[remoteEntry.Link]; !ok {
+				// 		LOG_ERROR("RESTORE_LINK", "Source file %s for hardlink %s missing", remoteEntry.Link, remoteEntry.Path)
+				// 	} else {
+				// 		checkEntry = e.entry
+				// 	}
+				// }
+				// if localEntry.IsSameAs(checkEntry) {
+				// 	LOG_TRACE("RESTORE_SKIP", "File %s unchanged (by size and timestamp)", localEntry.Path)
+				// 	skippedFileSize += localEntry.Size
+				// 	skippedFileCount++
+				// 	localEntry = nil
+				// 	continue
+				// }
 			}
 			localEntry = nil
 		}
@@ -807,21 +830,21 @@ func (manager *BackupManager) Restore(top string, revision int, inPlace bool, qu
 			}
 			directoryEntries = append(directoryEntries, remoteEntry)
 		} else {
-			if remoteEntry.Link == "/" {
-				hardLinkTable[remoteEntry.Path] = hardLinkEntry{remoteEntry, true}
-			} else if len(remoteEntry.Link) > 0 {
-				if e, ok := hardLinkTable[remoteEntry.Link]; !ok {
-					LOG_ERROR("RESTORE_LINK", "Source file %s for hardlink %s missing", remoteEntry.Link, remoteEntry.Path)
-				} else if !e.willDownload {
-					origSourcePath := e.entry.Path
-					e.entry.Path = remoteEntry.Path
-					remoteEntry = e.entry
-					hardLinkTable[origSourcePath] = hardLinkEntry{remoteEntry, true}
-				} else {
-					hardLinks = append(hardLinks, remoteEntry)
-					continue
-				}
-			}
+			// if remoteEntry.Link == "/" {
+			// 	hardLinkTable[remoteEntry.Path] = hardLinkEntry{remoteEntry, true}
+			// } else if len(remoteEntry.Link) > 0 {
+			// 	if e, ok := hardLinkTable[remoteEntry.Link]; !ok {
+			// 		LOG_ERROR("RESTORE_LINK", "Source file %s for hardlink %s missing", remoteEntry.Link, remoteEntry.Path)
+			// 	} else if !e.willDownload {
+			// 		origSourcePath := e.entry.Path
+			// 		e.entry.Path = remoteEntry.Path
+			// 		remoteEntry = e.entry
+			// 		hardLinkTable[origSourcePath] = hardLinkEntry{remoteEntry, true}
+			// 	} else {
+			// 		hardLinks = append(hardLinks, remoteEntry)
+			// 		continue
+			// 	}
+			// }
 			// We can't download files here since fileEntries needs to be sorted
 			fileEntries = append(fileEntries, remoteEntry)
 			totalFileSize += remoteEntry.Size
@@ -877,11 +900,11 @@ func (manager *BackupManager) Restore(top string, revision int, inPlace bool, qu
 		stat, _ := os.Stat(fullPath)
 		if stat != nil {
 			if quickMode {
-				cmpFile := file
-				if file.IsFile() && len(file.Link) > 0 && file.Link != "/" {
-					cmpFile = hardLinkTable[file.Link].entry
-				}
-				if cmpFile.IsSameAsFileInfo(stat) {
+				// cmpFile := file
+				// if file.IsFile() && len(file.Link) > 0 && file.Link != "/" {
+				// 	cmpFile = hardLinkTable[file.Link].entry
+				// }
+				if file.IsSameAsFileInfo(stat) {
 					LOG_TRACE("RESTORE_SKIP", "File %s unchanged (by size and timestamp)", file.Path)
 					skippedFileSize += file.Size
 					skippedFileCount++
@@ -944,14 +967,14 @@ func (manager *BackupManager) Restore(top string, revision int, inPlace bool, qu
 		file.RestoreMetadata(fullPath, nil, setOwner)
 	}
 
-	for _, linkEntry := range hardLinks {
-		sourcePath := joinPath(top, hardLinkTable[linkEntry.Link].entry.Path)
-		fullPath := joinPath(top, linkEntry.Path)
-		LOG_INFO("DOWNLOAD_LINK", "Hard linking %s -> %s", fullPath, sourcePath)
-		if err := os.Link(sourcePath, fullPath); err != nil {
-			LOG_ERROR("DOWNLOAD_LINK", "Failed to create hard link %s -> %s", fullPath, sourcePath)
-		}
-	}
+	// for _, linkEntry := range hardLinks {
+	// 	sourcePath := joinPath(top, hardLinkTable[linkEntry.Link].entry.Path)
+	// 	fullPath := joinPath(top, linkEntry.Path)
+	// 	LOG_INFO("DOWNLOAD_LINK", "Hard linking %s -> %s", fullPath, sourcePath)
+	// 	if err := os.Link(sourcePath, fullPath); err != nil {
+	// 		LOG_ERROR("DOWNLOAD_LINK", "Failed to create hard link %s -> %s", fullPath, sourcePath)
+	// 	}
+	// }
 
 	if deleteMode && len(patterns) == 0 {
 		// Reverse the order to make sure directories are empty before being deleted
@@ -1105,6 +1128,9 @@ func (manager *BackupManager) UploadSnapshot(chunkOperator *ChunkOperator, top s
 	lastEndChunk := 0
 
 	uploadEntryInfoFunc := func(entry *Entry) error {
+		if entry.IsHardlinkRoot() {
+			entryList.HardLinkTable[entry.Path] = entry
+		}
 
 		if entry.IsFile() && entry.Size > 0 {
 			delta := entry.StartChunk - len(chunkHashes) + 1
@@ -1127,6 +1153,14 @@ func (manager *BackupManager) UploadSnapshot(chunkOperator *ChunkOperator, top s
 			entry.StartChunk -= lastEndChunk
 			lastEndChunk = entry.EndChunk
 			entry.EndChunk = delta
+		} else if entry.IsHardlinkedFrom() {
+			targetEntry, ok := entryList.HardLinkTable[entry.Link]
+			if !ok {
+				LOG_ERROR("SNAPSHOT_UPLOAD", "Unable to find hardlink target for %s to %s", entry.Path, entry.Link)
+			}
+			// FIXME: We will use a copy, so it is probably sufficient to skip rereading xattrs and such in the initial code
+			entry = entry.LinkTo(targetEntry)
+			LOG_DEBUG("SNAPSHOT_UPLOAD", "Uploading cloned hardlink entry for %s to %s", entry.Path, entry.Link)
 		}
 
 		buffer.Reset()

src/duplicacy_entry.go

@@ -4,6 +4,8 @@
 package duplicacy
 
 import (
+	"bytes"
+	"crypto/sha256"
 	"encoding/base64"
 	"encoding/json"
 	"fmt"
@@ -15,13 +17,10 @@ import (
 	"sort"
 	"strconv"
 	"strings"
-	"time"
-	"bytes"
-	"crypto/sha256"
 	"syscall"
+	"time"
 
 	"github.com/vmihailenco/msgpack"
-
 )
 
 // This is the hidden directory in the repository for storing various files.
@@ -120,6 +119,27 @@ func (entry *Entry) Copy() *Entry {
 	}
 }
 
+func (entry *Entry) LinkTo(target *Entry) *Entry {
+	return &Entry{
+		Path: entry.Path,
+		Size: target.Size,
+		Time: target.Time,
+		Mode: target.Mode,
+		Link: entry.Link,
+		Hash: target.Hash,
+
+		UID: target.UID,
+		GID: target.GID,
+
+		StartChunk:  target.StartChunk,
+		StartOffset: target.StartOffset,
+		EndChunk:    target.EndChunk,
+		EndOffset:   target.EndOffset,
+
+		Attributes: target.Attributes,
+	}
+}
+
 // CreateEntryFromJSON creates an entry from a json description.
 func (entry *Entry) UnmarshalJSON(description []byte) (err error) {
 
@@ -493,6 +513,18 @@ func (entry *Entry) IsComplete() bool {
 	return entry.Size >= 0
 }
 
+func (entry *Entry) IsFileNotHardlink() bool {
+	return entry.IsFile() && (len(entry.Link) == 0 || entry.Link == "/")
+}
+
+func (entry *Entry) IsHardlinkedFrom() bool {
+	return entry.IsFile() && len(entry.Link) > 0 && entry.Link != "/"
+}
+
+func (entry *Entry) IsHardlinkRoot() bool {
+	return entry.IsFile() && entry.Link == "/"
+}
+
 func (entry *Entry) GetPermissions() os.FileMode {
 	return os.FileMode(entry.Mode) & fileModeMask
 }
@@ -806,9 +838,8 @@ func ListEntries(top string, path string, patterns []string, nobackupFile string
 			if ok && stat != nil && stat.Nlink > 1 {
 				k := listEntryLinkKey{dev: uint64(stat.Dev), ino: uint64(stat.Ino)}
 				if path, ok := listingState.linkTable[k]; ok {
-					LOG_WARN("LIST_LINK", "Linking %s to %s", entry.Path, path)
+					LOG_DEBUG("LIST_HARDLINK", "Detected hardlink %s to %s", entry.Path, path)
 					entry.Link = path
-					entry.Size = 0
 				} else {
 					entry.Link = "/"
 					listingState.linkTable[k] = entry.Path

src/duplicacy_entrylist.go

@@ -62,6 +62,7 @@ type EntryList struct {
 	uploadedChunkIndex int                  // counter for upload chunks
 	uploadedChunkOffset int                 // the start offset for the current modified entry
 
+	HardLinkTable map[string]*Entry
 }
 
 // Create a new entry list
@@ -78,6 +79,7 @@ func CreateEntryList(snapshotID string, cachePath string, maximumInMemoryEntries
 		maximumInMemoryEntries: maximumInMemoryEntries,
 		cachePath: cachePath,
 		Token: string(token),
+		HardLinkTable: make(map[string]*Entry),
 	}
 
 	return entryList, nil
@@ -118,7 +120,7 @@ func (entryList *EntryList)AddEntry(entry *Entry) error {
 	if !entry.IsComplete() {
 		if entry.IsDir() || entry.IsLink() {
 			entry.Size = 0
-		} else {
+		} else if !entry.IsHardlinkedFrom() {
 			modifiedEntry := ModifiedEntry {
 				Path: entry.Path,
 				Size: -1,

src/duplicacy_snapshot.go

@@ -51,7 +51,7 @@ type Snapshot struct {
 // CreateEmptySnapshot creates an empty snapshot.
 func CreateEmptySnapshot(id string) (snapshto *Snapshot) {
 	return &Snapshot{
-		Version:   0x6a6c01,
+		Version:   1,
 		ID:        id,
 		Revision:  0,
 		StartTime: time.Now().Unix(),
@@ -161,7 +161,7 @@ func (snapshot *Snapshot)ListRemoteFiles(config *Config, chunkOperator *ChunkOpe
 				return
 			}
 		}
-	} else if snapshot.Version == 1 || snapshot.Version == 0x6a6c01 {
+	} else if snapshot.Version == 1 {
 		decoder := msgpack.NewDecoder(reader)
 
 		lastEndChunk := 0