Handle read-only /tmp and missing NUMA/robust-mutex on HarmonyOS

src/coreclr/gc/unix/numasupport.cpp

@@ -12,7 +12,7 @@
 #include <limits.h>
 #include <minipal/utils.h>
 
-#if defined(TARGET_LINUX) && !defined(TARGET_ANDROID)
+#if defined(TARGET_LINUX) && !defined(TARGET_ANDROID) && !defined(TARGET_OPENHARMONY)
 #include <sys/syscall.h>
 #endif
 
@@ -21,7 +21,7 @@ int g_highestNumaNode = 0;
 // Is numa available
 bool g_numaAvailable = false;
 
-#if defined(TARGET_LINUX) && !defined(TARGET_ANDROID)
+#if defined(TARGET_LINUX) && !defined(TARGET_ANDROID) && !defined(TARGET_OPENHARMONY)
 static int GetNodeNum(const char* path, bool firstOnly)
 {
     DIR *dir;
@@ -56,7 +56,7 @@ static int GetNodeNum(const char* path, bool firstOnly)
 
 void NUMASupportInitialize()
 {
-#if defined(TARGET_LINUX) && !defined(TARGET_ANDROID)
+#if defined(TARGET_LINUX) && !defined(TARGET_ANDROID) && !defined(TARGET_OPENHARMONY)
     if (syscall(__NR_get_mempolicy, NULL, NULL, 0, 0, 0) < 0)
         return;
 
@@ -72,7 +72,7 @@ void NUMASupportInitialize()
 
 int GetNumaNodeNumByCpu(int cpu)
 {
-#if defined(TARGET_LINUX) && !defined(TARGET_ANDROID)
+#if defined(TARGET_LINUX) && !defined(TARGET_ANDROID) && !defined(TARGET_OPENHARMONY)
     char path[64];
     if (snprintf(path, sizeof(path), "/sys/devices/system/cpu/cpu%d", cpu) < 0)
         return -1;
@@ -85,7 +85,7 @@ int GetNumaNodeNumByCpu(int cpu)
 
 long BindMemoryPolicy(void* start, unsigned long len, const unsigned long* nodemask, unsigned long maxnode)
 {
-#if defined(TARGET_LINUX) && !defined(TARGET_ANDROID)
+#if defined(TARGET_LINUX) && !defined(TARGET_ANDROID) && !defined(TARGET_OPENHARMONY)
     return syscall(__NR_mbind, (long)start, len, 1, (long)nodemask, maxnode, 0);
 #else
     return -1;

src/libraries/System.Private.CoreLib/src/System.Private.CoreLib.Shared.projitems

@@ -54,6 +54,7 @@
     <DefineConstants Condition="'$(Targetsillumos)' == 'true'">$(DefineConstants);TARGET_ILLUMOS</DefineConstants>
     <DefineConstants Condition="'$(TargetsSolaris)' == 'true'">$(DefineConstants);TARGET_SOLARIS</DefineConstants>
     <DefineConstants Condition="'$(TargetsHaiku)' == 'true'">$(DefineConstants);TARGET_HAIKU</DefineConstants>
+    <DefineConstants Condition="'$(TargetOpenHarmony)' == 'true'">$(DefineConstants);TARGET_OPENHARMONY</DefineConstants>
   </PropertyGroup>
   <PropertyGroup>
     <DefineConstants Condition="'$(FeatureCrossProcessMutex)' == 'true'">$(DefineConstants);FEATURE_CROSS_PROCESS_MUTEX</DefineConstants>

src/libraries/System.Private.CoreLib/src/System/IO/SharedMemoryManager.Unix.cs

@@ -414,7 +414,15 @@ private static string InitalizeSharedFilesPath()
                 }
             }
 
+            // On non-Apple platforms, shared memory files live under the process temp directory.
+#if TARGET_OPENHARMONY
+            // HarmonyOS (OpenHarmony) app sandboxes mount /tmp read-only, so use the process temp
+            // directory (which honors TMPDIR on Unix and falls back to /tmp) for the .NET shared
+            // memory files (named mutexes, etc.).
+            return Path.GetTempPath();
+#else
             return "/tmp/";
+#endif
         }
 
         internal static SafeFileHandle CreateOrOpenFile(string sharedMemoryFilePath, SharedMemoryId id, bool createIfNotExist, out bool createdFile)

src/libraries/System.Private.CoreLib/src/System/OperatingSystem.cs

@@ -220,6 +220,17 @@ internal static bool IsHaiku() =>
             false;
 #endif
 
+        /// <summary>
+        /// Indicates whether the current application is running on HarmonyOS (OpenHarmony).
+        /// </summary>
+        [NonVersionable]
+        internal static bool IsOpenHarmony() =>
+#if TARGET_OPENHARMONY
+            true;
+#else
+            false;
+#endif
+
         /// <summary>
         /// Indicates whether the current application is running on Android.
         /// </summary>

src/libraries/System.Private.CoreLib/src/System/Threading/NamedMutex.Unix.cs

@@ -82,7 +82,7 @@ internal abstract class NamedMutexProcessDataBase(SharedMemoryProcessDataHeader<
         // independently by the processes involved. See https://github.com/dotnet/runtime/issues/10519.
         // On OpenBSD, cross process mutexes are not supported in the pthread implementation. See https://github.com/dotnet/runtime/pull/125089.
         // On Haiku, robust mutexes are WIP. See https://github.com/dotnet/runtime/pull/126701#issuecomment-4334338213.
-        private static bool UsePThreadMutexes => !OperatingSystem.IsApplePlatform() && !OperatingSystem.IsFreeBSD() && !OperatingSystem.IsOpenBSD() && !OperatingSystem.IsHaiku();
+        private static bool UsePThreadMutexes => !OperatingSystem.IsApplePlatform() && !OperatingSystem.IsFreeBSD() && !OperatingSystem.IsOpenBSD() && !OperatingSystem.IsHaiku() && !OperatingSystem.IsOpenHarmony();
 
         private readonly SharedMemoryProcessDataHeader<NamedMutexProcessDataBase> _processDataHeader = header;
         protected nuint _lockCount;

src/libraries/System.Threading/tests/MutexTests.cs

@@ -1039,7 +1039,16 @@ public void NamedMutex_OtherEvent_NotCompatible()
             Assert.Throws<PlatformNotSupportedException>(() => WaitHandle.WaitAny(new WaitHandle[] { m, mre }, 0));
         }
 
-        private const string GlobalSharedMemoryDirectory = $"/tmp/.dotnet/shm/global";
+        // The runtime places global shared memory files under {SharedFilesPath}/.dotnet/shm/global
+        // (see SharedMemoryManager.Unix.cs). SharedFilesPath is /tmp/ on non-Apple platforms except
+        // on HarmonyOS, where it honors TMPDIR. Mirror the runtime's derivation so these tests
+        // always target the same directory the runtime uses.
+        private static string GlobalSharedMemoryDirectory =>
+#if TARGET_OPENHARMONY
+            Path.Combine(Path.GetTempPath(), ".dotnet", "shm", "global");
+#else
+            "/tmp/.dotnet/shm/global";
+#endif
         private const UnixFileMode AllUsersRwx =
             UnixFileMode.UserRead
             | UnixFileMode.UserWrite