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fix: improve conflict detection by tracking previous file hash (fixes #10349) (#10351)

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This adds a new field to the file information we keep, the "previous
blocks hash". This is the hash of the file contents as it was in its
previous incarnation. That is, every scan that updates the blocks hash
will move the current hash to the "previous" field.

This enables an addition to the conflict detection algorithm: if the
file to be synced is in conflict with the current file on disk
(version-counter wise), but it indicates that it was based on the
precise contents we have (new.prevBlocksHash == current.blocksHash),
then it's not really a conflict.

Signed-off-by: Jakob Borg <jakob@kastelo.net>
This commit is contained in:
Jakob Borg
2025-09-13 16:16:28 +02:00
committed by GitHub
parent 1b0eaa093a
commit d037681fd1
8 changed files with 447 additions and 421 deletions
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lib/model/folder_sendrecv.go
+4 -20
View File
@@ -602,7 +602,7 @@ func (f *sendReceiveFolder) handleDir(file protocol.FileInfo, dbUpdateChan chan<
}
// Remove it to replace with the dir.
if !curFile.IsSymlink() && f.inConflict(curFile.Version, file.Version) {
if !curFile.IsSymlink() && file.InConflictWith(curFile) {
// The new file has been changed in conflict with the existing one. We
// should file it away as a conflict instead of just removing or
// archiving.
@@ -800,7 +800,7 @@ func (f *sendReceiveFolder) handleSymlinkCheckExisting(file protocol.FileInfo, s
}
// Remove it to replace with the symlink. This also handles the
// "change symlink type" path.
if !curFile.IsDirectory() && !curFile.IsSymlink() && f.inConflict(curFile.Version, file.Version) {
if !curFile.IsDirectory() && !curFile.IsSymlink() && file.InConflictWith(curFile) {
// The new file has been changed in conflict with the existing one. We
// should file it away as a conflict instead of just removing or
// archiving.
@@ -923,7 +923,7 @@ func (f *sendReceiveFolder) deleteFileWithCurrent(file, cur protocol.FileInfo, h
}
switch {
case f.inConflict(cur.Version, file.Version) && !cur.IsSymlink():
case file.InConflictWith(cur) && !cur.IsSymlink():
// If the delete constitutes winning a conflict, we move the file to
// a conflict copy instead of doing the delete
err = f.inWritableDir(func(name string) error {
@@ -1652,7 +1652,7 @@ func (f *sendReceiveFolder) performFinish(file, curFile protocol.FileInfo, hasCu
return fmt.Errorf("checking existing file: %w", err)
}
if !curFile.IsDirectory() && !curFile.IsSymlink() && f.inConflict(curFile.Version, file.Version) {
if !curFile.IsDirectory() && !curFile.IsSymlink() && file.InConflictWith(curFile) {
// The new file has been changed in conflict with the existing one. We
// should file it away as a conflict instead of just removing or
// archiving.
@@ -1847,22 +1847,6 @@ func (f *sendReceiveFolder) pullScannerRoutine(scanChan <-chan string) {
}
}
func (f *sendReceiveFolder) inConflict(current, replacement protocol.Vector) bool {
if current.Concurrent(replacement) {
// Obvious case
return true
}
if replacement.Counter(f.shortID) > current.Counter(f.shortID) {
// The replacement file contains a higher version for ourselves than
// what we have. This isn't supposed to be possible, since it's only
// we who can increment that counter. We take it as a sign that
// something is wrong (our index may have been corrupted or removed)
// and flag it as a conflict.
return true
}
return false
}
func (f *sendReceiveFolder) moveForConflict(name, lastModBy string, scanChan chan<- string) error {
if isConflict(name) {
f.sl.Info("Conflict on existing conflict copy; not copying again", slogutil.FilePath(name))