Portable service shared-memory ACL file target is a reparse

Error message

Portable service shared-memory ACL file target is a reparse point and is rejected: '{}'

What it means

Raised by set_path_permission_for_portable_service_shmem_impl (file variant) when the file target carries the reparse-point attribute. Symlinked or placeholder file targets are rejected because applying a protected DACL would hit the reparse target or the link inconsistently, which is a security hazard for shared memory.

Source

Thrown at src/platform/windows/acl.rs:389

fn set_path_permission_for_portable_service_shmem_impl(
    path: &Path,
    expect_dir: bool,
) -> ResultType<()> {
    if expect_dir {
        validate_portable_service_shmem_dir_target(path)?;
    } else {
        let metadata_result = fs::symlink_metadata(path);
        match metadata_result {
            Ok(metadata) => {
                if metadata.file_type().is_dir() {
                    bail!(
                        "Portable service shared-memory ACL target is a directory, expected file-like path: '{}'",
                        path.display()
                    );
                }
                if is_reparse_point(&metadata) {
                    bail!(
                        "Portable service shared-memory ACL file target is a reparse point and is rejected: '{}'",
                        path.display()
                    );
                }
            }
            Err(e)
                if e.kind() == io::ErrorKind::NotFound
                    || e.kind() == io::ErrorKind::PermissionDenied =>
            {
                // Keep going and let Win32 ACL APIs return the final OS error.
                // `Path::exists()/is_file()` and metadata can collapse ACL-denied paths into
                // a false "not found" signal under restricted directory ACLs.
            }
            Err(e) => {
                bail!(
                    "Failed to inspect portable service shared-memory ACL target '{}': {}",
                    path.display(),
                    e

View on GitHub (pinned to 91c9fccbb0)

Solutions

Use the real (non-link) file path; resolve the symlink before applying the ACL.
Move the file out of the synced/placeholder location into a plain NTFS directory.
If a test needs a reparse target, update the test to use a real file, matching the function's contract.

Example fix

// before
set_path_permission_for_portable_service_shmem_file(&link_path)?;
// after
let real = fs::read_link(&link_path)?;
set_path_permission_for_portable_service_shmem_file(&real)?;

Defensive patterns

Strategy: validation

Validate before calling

let m = std::fs::symlink_metadata(&file_path)?;
if m.is_dir() || m.is_symlink() {
    return Err(anyhow!("reparse/dir target rejected: {}", file_path.display()));
}

Type guard

fn is_plain_file(p: &Path) -> bool {
    matches!(std::fs::symlink_metadata(p), Ok(m) if !m.is_dir() && !m.is_symlink())
}

Try / catch

if let Err(e) = set_path_permission_for_portable_service_shmem_file(&p) {
    if e.to_string().contains("reparse point") {
        let real = std::fs::read_link(&p).unwrap_or(p.to_path_buf());
        set_path_permission_for_portable_service_shmem_file(&real)?;
    } else { return Err(e); }
}

Prevention

Do not symlink shmem files in production deployments
Keep shmem files out of cloud-synced/placeholder directories
Resolve links with fs::read_link before ACL operations

When it happens

Trigger: Calling set_path_permission_for_portable_service_shmem_file(path) where symlink_metadata shows path is a symlink, or where the file is a OneDrive/Dev Drive placeholder with FILE_ATTRIBUTE_REPARSE_POINT.

Common situations: The shmem file path is a symlink created for testing (fs::symlink_file); the file lives in a cloud-synced folder that placeholders its contents; a junctioned directory redirects to the file.

Understand the failure class

Background: UnsupportedOperationException and "is not supported" errors: when a library deliberately refuses a call — this error's family across 30 libraries.

Related errors

AI-assisted analysis of rustdesk/rustdesk@91c9fccbb0 (2026-09-10). Data as JSON: /api/errors/102b2352f1682bd8. Report an issue: GitHub.