Qt for HarmonyOS/platform limitations: Difference between revisions
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As a consequence, <tt>QStandardPaths::findExecutable()</tt> cannot locate system executables on HarmonyOS. | As a consequence, <tt>QStandardPaths::findExecutable()</tt> cannot locate system executables on HarmonyOS. | ||
'''Status:''' | '''Status:''' Not yet confirmed by Huawei.<br>'''Reference:''' [https://bugreports.qt.io/browse/QTBUG-146625 QTBUG-146625] | ||
=== open() with trailing slashes does not fail as expected === | === open() with trailing slashes does not fail as expected === | ||
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<tt>StateLocation</tt>, <tt>GenericStateLocation</tt>. | <tt>StateLocation</tt>, <tt>GenericStateLocation</tt>. | ||
* <tt>QStandardPaths::findExecutable()</tt> cannot locate system executables due to the <tt>stat()</tt> restriction described above. | * <tt>QStandardPaths::findExecutable()</tt> cannot locate system executables due to the <tt>stat()</tt> restriction described above. | ||
'''Status:''' | '''Status:''' Not yet confirmed by Huawei.<br>'''Reference:''' [https://bugreports.qt.io/browse/QTBUG-146625 QTBUG-146625] | ||
=== Application resource directory location === | === Application resource directory location === | ||
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No <tt>QStandardPaths::StandardLocation</tt> currently maps to this path. | No <tt>QStandardPaths::StandardLocation</tt> currently maps to this path. | ||
'''Status:''' | '''Status:''' Not yet confirmed by Huawei.<br>'''Reference:''' [https://bugreports.qt.io/browse/QTBUG-146626 QTBUG-146626] | ||
== Font System == | == Font System == | ||
Revision as of 08:26, 7 May 2026
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
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:
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