all: Support syncing ownership (fixes #1329) (#8434)

This adds support for syncing ownership on Unixes and on Windows. The
scanner always picks up ownership information, but it is not applied
unless the new folder option "Sync Ownership" is set.

Ownership data is stored in a new FileInfo field called "platform data". This
is intended to hold further platform-specific data in the future
(specifically, extended attributes), which is why the whole design is a
bit overkill for just ownership.

proto/lib/config/folderconfiguration.proto

@@ -54,6 +54,7 @@ message FolderConfiguration {
     fs.CopyRangeMethod                 copy_range_method          = 32 [(ext.default) = "standard"];
     bool                               case_sensitive_fs          = 33 [(ext.goname) = "CaseSensitiveFS", (ext.xml) = "caseSensitiveFS", (ext.json) = "caseSensitiveFS"];
     bool                               follow_junctions           = 34 [(ext.goname) = "JunctionsAsDirs", (ext.xml) = "junctionsAsDirs", (ext.json) = "junctionsAsDirs"];
+    bool                               sync_ownership             = 35;
 
     // Legacy deprecated
     bool   read_only         = 9000 [deprecated=true, (ext.xml) = "ro,attr,omitempty"];

proto/lib/db/structs.proto

@@ -36,6 +36,7 @@ message FileInfoTruncated {
     uint32                permissions    = 4;
     int32                 modified_ns    = 11;
     int32                 block_size     = 13 [(ext.goname) = "RawBlockSize"];
+    protocol.PlatformData platform       = 14;
 
     // see bep.proto
     uint32 local_flags  = 1000;

proto/lib/protocol/bep.proto

@@ -107,6 +107,7 @@ message FileInfo {
     uint32             permissions    = 4;
     int32              modified_ns    = 11;
     int32              block_size     = 13 [(ext.goname) = "RawBlockSize"];
+    PlatformData       platform       = 14;
 
     // The local_flags fields stores flags that are relevant to the local
     // host only. It is not part of the protocol, doesn't get sent or
@@ -147,6 +148,29 @@ message Counter {
     uint64 value = 2;
 }
 
+message PlatformData {
+    UnixData    unix    = 1 [(gogoproto.nullable) = true];
+    WindowsData windows = 2 [(gogoproto.nullable) = true];
+}
+
+message UnixData {
+    // The owner name and group name are set when known (i.e., could be
+    // resolved on the source device), while the UID and GID are always set
+    // as they come directly from the stat() call.
+    string owner_name = 1;
+    string group_name = 2;
+    int32  uid        = 3 [(ext.goname) = "UID"];
+    int32  gid        = 4 [(ext.goname) = "GID"];
+}
+
+message WindowsData {
+    // Windows file objects have a single owner, which may be a user or a
+    // group. We keep the name of that account, and a flag to indicate what
+    // type it is.
+    string owner_name     = 1;
+    bool   owner_is_group = 2;
+}
+
 // Request
 
 message Request {