Qt for HarmonyOS/platform limitations

This page documents known platform limitations of HarmonyOS that affect Qt behavior. These limitations stem from HarmonyOS security policies, missing system features, or deprecated APIs. Each entry includes its confirmation status and a reference to the corresponding public bug report.

Some items below are still under verification with Huawei and may be refined as more information becomes available.

File System & Permissions

chmod() / QFile::setPermissions() not supported

The HarmonyOS security model does not permit chmod() or fchmod() on existing files. As a result, QFile::setPermissions() is not supported on HarmonyOS for existing files and always returns false.

Note that operations that set permissions on a freshly created file descriptor — for example QFile::copy(), which uses fchmod() internally on the newly created destination — are unaffected.

Huawei's official response:

Due to security concerns, the system review for this interface was cancelled, and there is no alternative interface.

Status: Confirmed by Huawei.
Impact: QFile::setPermissions() is a no-op on HarmonyOS for existing files.
Reference: QTBUG-146619

symlink() not available for third-party applications

::symlink() and its ArkTS equivalent fs.symlink are unavailable to third-party applications on HarmonyOS. QFile::link() and any functionality depending on symbolic links will fail with EACCES (error code 13900012).

Huawei's official response:

fs.symlink is currently not available for third-party applications. The official documentation will be updated accordingly.

Status: Confirmed by Huawei.
Workaround: None available at this time.
Reference: QTBUG-146621

stat() returns EACCES on system paths

stat() returns EACCES (errno 13) when called on system paths such as /bin/sh on HarmonyOS. This causes QFileInfo::isFile() to return false for system executables, while QFileInfo::exists() and QFileInfo::isExecutable() (which use access() internally) return true.

As a consequence, QStandardPaths::findExecutable() cannot locate system executables on HarmonyOS.

Status: Not yet confirmed by Huawei.
Reference: QTBUG-146625

open() with trailing slashes does not fail as expected

On Linux, open("qwe//", O_RDWR|O_CREAT|O_CLOEXEC, 0666) fails with EISDIR because trailing slashes imply a directory path. On HarmonyOS, the trailing slashes are silently stripped and a regular file named qwe is created instead. This behavior differs from POSIX expectations.

Status: Not yet confirmed by Huawei.
Reference: QTBUG-146578

fread() incorrectly sets EOF on a non-blocking pipe

When fread() is called on a non-blocking pipe file descriptor with no data available, the HarmonyOS libc incorrectly sets the EOF flag on the FILE* stream.

Status: Not yet confirmed by Huawei.
Reference: QTBUG-146579

Time and TimeZone

No tzdata available

HarmonyOS doesn’t provide /usr/share/zoneinfo.tab and the whole set files, we can’t use tz backend.

Huawei's analysis:

System musl libc has access to tzdata, but HarmonyOS doesn’t allow other 3rdparty to read tzdata directly.

Status: Acknowledged by Huawei. Fix timeline unknown.
Workaround: Use icu backend for timezone.
Reference: QTBUG-146717 QTBUG-146559

Thread

PTHREAD_CANCEL_DISABLE defined, but no related pthread functions available

PTHREAD_CANCEL_DISABLE defined, but no related pthread functions available

Status: Acknowledged by Huawei. Fix timeline unknown.
Workaround: Undefine PTHREAD_CANCEL_DISABLE.
Reference: QTBUG-146708

Dynamic Linking

MUSL-LDSO cannot load section-header-stripped ELF files

The HarmonyOS MUSL dynamic linker fails to load ELF shared libraries from which the section header table has been stripped. The linker internally depends on e_shnum and e_shoff fields within the LOAD_ORDER_RANDOMIZATION macro and cannot process binaries that omit the section header.

Huawei's analysis:

Whether these dependencies can be eliminated in the future is still under investigation.

Status: Acknowledged by Huawei. Fix timeline unknown.
Reference: QTBUG-146620

MUSL-LDSO namespace policy prevents dlopen() from writable paths

The HarmonyOS MUSL dynamic linker rejects dlopen() for any path under /data/storage/el2/, including temporary directories and all paths returned by QStandardPaths::writableLocation() (AppDataLocation, AppConfigLocation, CacheLocation). All available namespaces (moduleNs_default, default, ndk) reject these paths with errno=22 (EINVAL).

The only paths accessible to dlopen() reside under /data/storage/el1/, which is read-only at runtime.

Status: Not yet confirmed by Huawei.
Reference: QTBUG-146624

Standard Paths

QStandardPaths constraints on HarmonyOS

The HarmonyOS application sandbox imposes several constraints on QStandardPaths:

• standardLocations() and writableLocation() return identical single-path results for all location types, since the sandbox does not expose multiple search locations.

• AppLocalDataLocation maps to HarmonyOS preferencesDir.
• The following location types are unsupported and return an empty path:

 PublicShareLocation, TemplatesLocation,
 StateLocation, GenericStateLocation.

• QStandardPaths::findExecutable() cannot locate system executables due to the stat() restriction described above.

Status: Not yet confirmed by Huawei.
Reference: QTBUG-146625

Application resource directory location

On HarmonyOS, an application's bundled read-only resource directory resides at <bundleCodeDir>/entry/resources/resfile. This is the appropriate location for bundled resources such as .rcc files.

No QStandardPaths::StandardLocation currently maps to this path.

Status: Not yet confirmed by Huawei.
Reference: QTBUG-146626

Font System

No fixed-pitch (monospaced) font provided by default

HarmonyOS does not ship a monospaced (fixed-pitch) system font by default. QFontDatabase::systemFont(QFontDatabase::FixedFont) returns a non-monospaced font as a result.

Huawei confirmed that NotoSansMono must be installed by the user and is not included in the system font set.

Status: Confirmed by Huawei.
Impact: Applications requiring a monospaced font must bundle and register one explicitly via QFontDatabase::addApplicationFont().
Reference: QTBUG-146623

ArkUI / ArkTS API

XComponentType.NODE deprecated in API version 20

XComponentType.NODE, which Qt for HarmonyOS uses as the native rendering surface, has been deprecated since HarmonyOS API version 20. Huawei recommends migrating to the ContentSlot component.

No official porting guide has been provided by Huawei. Relevant documentation:

• NDK access the ArkTS page
• ContentSlot: Enabling Hybrid Development

Status: API deprecated by Huawei.
Impact: XComponentType.NODE remains functional in current API versions. Migration to ContentSlot is required before the deprecated API is removed.
Reference: QTBUG-146622

Clipboard

Pasteboard invokes the record provider prematurely when a record has no directly-added entry

The pasteboard supports paste-on-demand (lazy fetch) by registering a provider callback on a record via OH_UdmfRecord_SetProvider(). The provider is expected to be invoked only when a consumer actually requests data for a specific entry type. However, when a record is built with a registered provider but no directly-added entry, calling OH_Pasteboard_GetData() invokes the provider callback as a side effect — for the record's first registered type — before any consumer has requested that entry. This defeats lazy fetch: the data is materialized immediately when the clipboard is read, rather than on an actual paste.

A record that carries at least one directly-added entry (alongside a provider for the remaining types) does not exhibit this behavior, and lazy fetch works as intended.

Huawei's analysis:

When OH_Pasteboard_GetData is called, the platform clipboard traverses each record and checks the first entry of the record. If the first entry has no actual data (provider path), the platform calls the provider once and then stores the returned data in the platform-side cache.

Status: Confirmed by Huawei. Behavior is undocumented in the public C API.
Impact: For any record served entirely through the provider path (no concrete first entry), paste-on-demand is silently broken — the application's data is fetched eagerly when the clipboard contents are read instead of on paste.
Workaround: Ensure every record carries at least one directly-added ("dummy") entry so that no record is ever provider-only. The injected entry must be kept transparent to the application-visible data model.
Reference: QTBUG-147819

See Also

• Huawei Doc: Native API Symbols Not Exported
• Qt for HarmonyOS
• Building Qt for HarmonyOS
• QTBUG-146618: HarmonyOS platform limitations (all child issues)