lib/api: Expose `blocksHash` in file info (#8810)

This adds the BlocksHash field from the FileInfo to our API output. It
can be useful for debugging, or for external tools. I'm intentionally
leaving it as an opaque base64 string because no meaning should be
derived from it: it's just a string.

lib/api/api.go

@@ -1828,6 +1828,7 @@ func fileIntfJSONMap(f protocol.FileIntf) map[string]interface{} {
 		"localFlags":    f.FileLocalFlags(),
 		"platform":      f.PlatformData(),
 		"inodeChange":   f.InodeChangeTime(),
+		"blocksHash":    f.FileBlocksHash(),
 	}
 	if f.HasPermissionBits() {
 		out["permissions"] = fmt.Sprintf("%#o", f.FilePermissions())

lib/db/structs.go

@@ -133,6 +133,10 @@ func (f FileInfoTruncated) InodeChangeTime() time.Time {
 	return time.Unix(0, f.InodeChangeNs)
 }
 
+func (f FileInfoTruncated) FileBlocksHash() []byte {
+	return f.BlocksHash
+}
+
 func (f FileInfoTruncated) ConvertToIgnoredFileInfo() protocol.FileInfo {
 	file := f.copyToFileInfo()
 	file.SetIgnored()

lib/protocol/bep_extensions.go

@@ -46,6 +46,7 @@ type FileIntf interface {
 	ModTime() time.Time
 	PlatformData() PlatformData
 	InodeChangeTime() time.Time
+	FileBlocksHash() []byte
 }
 
 func (Hello) Magic() uint32 {
@@ -170,6 +171,10 @@ func (f FileInfo) InodeChangeTime() time.Time {
 	return time.Unix(0, f.InodeChangeNs)
 }
 
+func (f FileInfo) FileBlocksHash() []byte {
+	return f.BlocksHash
+}
+
 // WinsConflict returns true if "f" is the one to choose when it is in
 // conflict with "other".
 func WinsConflict(f, other FileIntf) bool {