feat: add -x flag to strip xattr keys on non-client setxattr

src/openvfsfuse/main.cpp

@@ -6,6 +6,7 @@
 #include <getopt.h>
 #include <iostream>
 #include <optional>
+#include <sstream>
 #include <vector>
 
 #include <nlohmann/json.hpp>
@@ -42,7 +43,7 @@ namespace {
 void usage(char *name)
 {
     std::cerr << "Usage:" << std::endl //
-              << name << " [-h] | [-f] [-p] [-d] -i config-file -o ownerId /directory-mountpoint" << std::endl //
+              << name << " [-h] | [-f] [-p] [-d] [-x key1,key2,...] -i config-file -o ownerId /directory-mountpoint" << std::endl //
               << "Type 'man openvfsfuse' for more details" << std::endl;
 }
 
@@ -57,7 +58,7 @@ std::optional<openVFSfuse_Args> processArgs(int argc, char *argv[])
 
     bool got_p = false;
 
-    while ((res = getopt(argc, argv, "hpfdi:o:")) != -1) {
+    while ((res = getopt(argc, argv, "hpfdi:o:x:")) != -1) {
         switch (res) {
         case 'h':
             usage(argv[0]);
@@ -90,6 +91,19 @@ std::optional<openVFSfuse_Args> processArgs(int argc, char *argv[])
         case 'o':
             out.owner = optarg;
             break;
+        case 'x': {
+            // Parse comma-separated list of msgpack keys to strip on non-client setxattr
+            std::string keys(optarg);
+            std::istringstream ss(keys);
+            std::string key;
+            while (std::getline(ss, key, ',')) {
+                if (!key.empty()) {
+                    out.stripXattrKeys.push_back(key);
+                }
+            }
+            std::cout << "openVFSfuse stripping xattr keys: " << keys << std::endl;
+            break;
+        }
         default:
             assert(false);
             break;

src/openvfsfuse/openvfsfuse.cpp

@@ -55,6 +55,7 @@ class VFSFuseContext
         , _rootHandle(open(_mountPoint.c_str(), 0))
         , _appsNoHydrateFull(args.appsNoHydrateFull)
         , _appsNoHydrateEndsWith(args.appsNoHydrateEndsWith)
+        , _stripXattrKeys(args.stripXattrKeys)
     {
         assert(!_instance);
         _instance = this;
@@ -99,13 +100,16 @@ class VFSFuseContext
             || std::ranges::find_if(_appsNoHydrateEndsWith, [app](const auto &a) { return app.ends_with(a); }) != _appsNoHydrateEndsWith.cend();
     }
 
+    const auto &stripXattrKeys() const { return _stripXattrKeys; }
+
 private:
     static VFSFuseContext *_instance;
     std::filesystem::path _mountPoint;
     std::string _owner;
     int _rootHandle;
     std::vector<std::string> _appsNoHydrateFull;
     std::vector<std::string> _appsNoHydrateEndsWith;
+    std::vector<std::string> _stripXattrKeys;
 };
 
 VFSFuseContext *VFSFuseContext::_instance = nullptr;
@@ -671,6 +675,39 @@ static int openVFSfuse_fsync(const char *orig_path, int isdatasync, struct fuse_
 /* xattr operations are optional and can safely be left unimplemented */
 static int openVFSfuse_setxattr(const char *orig_path, const char *name, const char *value, size_t size, int flags)
 {
+    // When a non-client process writes user.openvfs.data, strip keys listed
+    // in stripXattrKeys (configured via -x flag). This prevents file managers
+    // from copying per-file identity fields (fileid, immutable, syncerror)
+    // on copy+paste, while preserving user-set metadata (comments, tags, etag).
+    //
+    // We selectively remove keys rather than stripping all openvfs xattrs
+    // because some fields (etag, pinstate, size) are harmless or even useful
+    // to keep, and future user-defined metadata should survive copies.
+    if (std::string_view(name) == OpenVFS::Constants::XAttributeNames::Data
+        && !VFSFuseContext::instance().stripXattrKeys().empty()) {
+        auto *context = fuse_get_context();
+        if (context && context->pid != _jobs.desktopClientPid()) {
+            try {
+                auto j = nlohmann::json::from_msgpack(std::vector<uint8_t>(value, value + size));
+                bool modified = false;
+                for (const auto &key : VFSFuseContext::instance().stripXattrKeys()) {
+                    if (j.contains(key)) {
+                        j.erase(key);
+                        modified = true;
+                    }
+                }
+                if (modified) {
+                    auto cleaned = nlohmann::json::to_msgpack(j);
+                    const auto path = getInternalPath(orig_path);
+                    openvfsfuse_log(path, "setxattr", 0, "stripped keys from copy by pid %d", context->pid);
+                    return Xattr::setxattr(path, name, reinterpret_cast<const char *>(cleaned.data()), cleaned.size(), flags);
+                }
+            } catch (...) {
+                // If msgpack parsing fails, pass through unchanged
+            }
+        }
+    }
+
     const auto path = getInternalPath(orig_path);
     return Xattr::setxattr(path, name, value, size, flags);
 }

src/openvfsfuse/openvfsfuse.h

@@ -23,6 +23,7 @@ struct openVFSfuse_Args
     std::vector<std::string> fuseArgv;
     std::vector<std::string> appsNoHydrateFull; // these apps are not permitted to cause a dehydration
     std::vector<std::string> appsNoHydrateEndsWith;
+    std::vector<std::string> stripXattrKeys; // msgpack keys stripped from user.openvfs.data on non-client writes
 };
 
 int initializeOpenVFSFuse(openVFSfuse_Args &openVFSArgs);