From 54ada291b199a9f9839dc803cc6ba1c67f9e5708 Mon Sep 17 00:00:00 2001
From: Trung Nguyen <57174311+trungnt2910@users.noreply.github.com>
Date: Sat, 22 Nov 2025 01:33:05 +1100
Subject: [PATCH] Haiku: Initial managed libraries support

This contains the code required to build the first managed runtime
libraries for Haiku, namely `System.Private.CoreLib`.

Co-authored-by: Jessica Hamilton <jessica.l.hamilton@gmail.com>
---
 .../Common/src/Interop/Haiku/Interop.OS.cs    | 28 +++++++++++++
 .../System.Private.CoreLib.Shared.projitems   |  6 +++
 .../src/System/Environment.Haiku.cs           | 28 +++++++++++++
 .../src/System/OperatingSystem.cs             |  2 +
 src/native/libs/Common/pal_config.h.in        |  1 +
 src/native/libs/System.Native/CMakeLists.txt  |  1 +
 src/native/libs/System.Native/entrypoints.c   |  2 +
 src/native/libs/System.Native/pal_getosinfo.c | 42 +++++++++++++++++++
 src/native/libs/System.Native/pal_getosinfo.h | 15 +++++++
 src/native/libs/configure.cmake               |  4 ++
 10 files changed, 129 insertions(+)
 create mode 100644 src/libraries/Common/src/Interop/Haiku/Interop.OS.cs
 create mode 100644 src/libraries/System.Private.CoreLib/src/System/Environment.Haiku.cs
 create mode 100644 src/native/libs/System.Native/pal_getosinfo.c
 create mode 100644 src/native/libs/System.Native/pal_getosinfo.h

diff --git a/src/libraries/Common/src/Interop/Haiku/Interop.OS.cs b/src/libraries/Common/src/Interop/Haiku/Interop.OS.cs
new file mode 100644
index 00000000000000..3246a7c45bd0cd
--- /dev/null
+++ b/src/libraries/Common/src/Interop/Haiku/Interop.OS.cs
@@ -0,0 +1,28 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+
+using System;
+using System.Runtime.InteropServices;
+
+internal static partial class Interop
+{
+    internal static partial class OS
+    {
+        [StructLayout(LayoutKind.Sequential)]
+        internal unsafe struct AreaInfo
+        {
+            public nuint size;
+            public uint ram_size;
+        }
+
+        /// <summary>
+        /// Gets information about areas owned by a team.
+        /// </summary>
+        /// <param name="team">The team ID of the areas to iterate.</param>
+        /// <param name="cookie">A cookie to track the iteration.</param>
+        /// <param name="areaInfo">The <see cref="AreaInfo"/> structure to fill in.</param>
+        /// <returns>Returns 0 on success. Returns an error code on failure or when there are no more areas to iterate.</returns>
+        [LibraryImport(Libraries.SystemNative, EntryPoint = "SystemNative_GetNextAreaInfo")]
+        internal static unsafe partial int GetNextAreaInfo(int team, ref nint cookie, out AreaInfo areaInfo);
+    }
+}
diff --git a/src/libraries/System.Private.CoreLib/src/System.Private.CoreLib.Shared.projitems b/src/libraries/System.Private.CoreLib/src/System.Private.CoreLib.Shared.projitems
index 2db9af120d00cc..fe63de3b15d6f7 100644
--- a/src/libraries/System.Private.CoreLib/src/System.Private.CoreLib.Shared.projitems
+++ b/src/libraries/System.Private.CoreLib/src/System.Private.CoreLib.Shared.projitems
@@ -2720,6 +2720,7 @@
     <Compile Include="$(MSBuildThisFileDirectory)System\Environment.iOS.cs" Condition="'$(IsiOSLike)' == 'true'" />
     <Compile Include="$(MSBuildThisFileDirectory)System\Environment.OSVersion.Unix.cs" Condition="'$(IsApplePlatform)' != 'true'" />
     <Compile Include="$(MSBuildThisFileDirectory)System\Environment.SunOS.cs" Condition="'$(Targetsillumos)' == 'true' or '$(TargetsSolaris)' == 'true'" />
+    <Compile Include="$(MSBuildThisFileDirectory)System\Environment.Haiku.cs" Condition="'$(TargetsHaiku)' == 'true'" />
     <Compile Include="$(MSBuildThisFileDirectory)System\TimeZoneInfo.FullGlobalizationData.Unix.cs" Condition="'$(UseMinimalGlobalizationData)' != 'true'" />
     <Compile Include="$(MSBuildThisFileDirectory)System\IO\DriveInfoInternal.Unix.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)System\IO\PersistedFiles.Unix.cs" />
@@ -2739,6 +2740,11 @@
   <ItemGroup Condition="'$(UseMinimalGlobalizationData)' == 'true'">
     <Compile Include="$(MSBuildThisFileDirectory)System\TimeZoneInfo.MinimalGlobalizationData.cs" />
   </ItemGroup>
+  <ItemGroup Condition="'$(TargetsHaiku)' == 'true'">
+    <Compile Include="$(CommonPath)Interop\Haiku\Interop.OS.cs">
+      <Link>Common\Interop\Haiku\Interop.OS.cs</Link>
+    </Compile>
+  </ItemGroup>
   <ItemGroup Condition="'$(IsApplePlatform)' == 'true'">
     <Compile Include="$(CommonPath)Interop\OSX\Interop.libobjc.cs">
       <Link>Common\Interop\OSX\Interop.libobjc.cs</Link>
diff --git a/src/libraries/System.Private.CoreLib/src/System/Environment.Haiku.cs b/src/libraries/System.Private.CoreLib/src/System/Environment.Haiku.cs
new file mode 100644
index 00000000000000..fba9180e81a204
--- /dev/null
+++ b/src/libraries/System.Private.CoreLib/src/System/Environment.Haiku.cs
@@ -0,0 +1,28 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+
+using System.Runtime.InteropServices;
+
+namespace System
+{
+    public static partial class Environment
+    {
+        public static unsafe long WorkingSet
+        {
+            get
+            {
+                nint cookie = 0;
+                long workingSet = 0;
+
+                Interop.OS.AreaInfo areaInfo;
+
+                while (Interop.OS.GetNextAreaInfo(ProcessId, ref cookie, out areaInfo) == 0)
+                {
+                    workingSet += areaInfo.ram_size;
+                }
+
+                return workingSet;
+            }
+        }
+    }
+}
diff --git a/src/libraries/System.Private.CoreLib/src/System/OperatingSystem.cs b/src/libraries/System.Private.CoreLib/src/System/OperatingSystem.cs
index d8b3c14b103aae..8134e38145590a 100644
--- a/src/libraries/System.Private.CoreLib/src/System/OperatingSystem.cs
+++ b/src/libraries/System.Private.CoreLib/src/System/OperatingSystem.cs
@@ -40,6 +40,8 @@ public sealed class OperatingSystem : ISerializable, ICloneable
         "ILLUMOS"
 #elif TARGET_SOLARIS
         "SOLARIS"
+#elif TARGET_HAIKU
+        "HAIKU"
 #else
 #error Unknown OS, add a corresponding TARGET_* constant to System.Private.CoreLib.Shared.projitems
 #endif
diff --git a/src/native/libs/Common/pal_config.h.in b/src/native/libs/Common/pal_config.h.in
index b546abba1c91c3..b0fe427baeeb50 100644
--- a/src/native/libs/Common/pal_config.h.in
+++ b/src/native/libs/Common/pal_config.h.in
@@ -139,6 +139,7 @@
 #cmakedefine01 HAVE_NET_IF_H
 #cmakedefine01 HAVE_SYS_PROCINFO_H
 #cmakedefine01 HAVE_IOSS_H
+#cmakedefine01 HAVE_OS_H
 #cmakedefine01 HAVE_ALIGNED_ALLOC
 #cmakedefine01 HAVE_MALLOC_SIZE
 #cmakedefine01 HAVE_MALLOC_USABLE_SIZE
diff --git a/src/native/libs/System.Native/CMakeLists.txt b/src/native/libs/System.Native/CMakeLists.txt
index 8fa04ec15a9c9e..0beca0c2bb0ba2 100644
--- a/src/native/libs/System.Native/CMakeLists.txt
+++ b/src/native/libs/System.Native/CMakeLists.txt
@@ -6,6 +6,7 @@ endif ()
 
 set(NATIVE_SOURCES
     pal_errno.c
+    pal_getosinfo.c
     pal_io.c
     pal_maphardwaretype.c
     pal_memory.c
diff --git a/src/native/libs/System.Native/entrypoints.c b/src/native/libs/System.Native/entrypoints.c
index ffff33bfadd6cc..34131dee0312e5 100644
--- a/src/native/libs/System.Native/entrypoints.c
+++ b/src/native/libs/System.Native/entrypoints.c
@@ -10,6 +10,7 @@
 #include "pal_dynamicload.h"
 #include "pal_environment.h"
 #include "pal_errno.h"
+#include "pal_getosinfo.h"
 #include "pal_interfaceaddresses.h"
 #include "pal_io.h"
 #include "pal_iossupportversion.h"
@@ -305,6 +306,7 @@ static const Entry s_sysNative[] =
     DllImportEntry(SystemNative_LowLevelCrossProcessMutex_IsAbandoned)
     DllImportEntry(SystemNative_LowLevelCrossProcessMutex_SetAbandoned)
     DllImportEntry(SystemNative_Select)
+    DllImportEntry(SystemNative_GetNextAreaInfo)
 };
 
 EXTERN_C const void* SystemResolveDllImport(const char* name);
diff --git a/src/native/libs/System.Native/pal_getosinfo.c b/src/native/libs/System.Native/pal_getosinfo.c
new file mode 100644
index 00000000000000..c499e9b9be68cb
--- /dev/null
+++ b/src/native/libs/System.Native/pal_getosinfo.c
@@ -0,0 +1,42 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+
+#include "pal_config.h"
+#include "pal_getosinfo.h"
+#include "pal_utilities.h"
+
+#include <errno.h>
+#include <string.h>
+
+#if HAVE_OS_H
+#include <OS.h>
+#endif
+
+int32_t SystemNative_GetNextAreaInfo(int32_t team, intptr_t* cookie, AreaInfo* areaInfo)
+{
+#if HAVE_OS_H
+    if (cookie == NULL || areaInfo == NULL)
+    {
+        return EINVAL;
+    }
+
+    area_info nativeAreaInfo;
+    memset(&nativeAreaInfo, 0, sizeof(nativeAreaInfo));
+
+    status_t status = get_next_area_info((team_id)team, cookie, &nativeAreaInfo);
+    if (status != B_OK)
+    {
+        return (int32_t)status;
+    }
+
+    areaInfo->size = (uintptr_t)nativeAreaInfo.size;
+    areaInfo->ram_size = (uint32_t)nativeAreaInfo.ram_size;
+
+    return (int32_t)status;
+#else
+    (void)team;
+    (void)cookie;
+    (void)areaInfo;
+    return ENOTSUP;
+#endif
+}
diff --git a/src/native/libs/System.Native/pal_getosinfo.h b/src/native/libs/System.Native/pal_getosinfo.h
new file mode 100644
index 00000000000000..464269e1054347
--- /dev/null
+++ b/src/native/libs/System.Native/pal_getosinfo.h
@@ -0,0 +1,15 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+
+#pragma once
+
+#include "pal_compiler.h"
+#include "pal_types.h"
+
+typedef struct
+{
+    uintptr_t size;
+    uint32_t ram_size;
+} AreaInfo;
+
+PALEXPORT int32_t SystemNative_GetNextAreaInfo(int32_t team, intptr_t* cookie, AreaInfo* areaInfo);
diff --git a/src/native/libs/configure.cmake b/src/native/libs/configure.cmake
index d5fbbc082dd3d4..905801237dfcb3 100644
--- a/src/native/libs/configure.cmake
+++ b/src/native/libs/configure.cmake
@@ -1004,6 +1004,10 @@ check_include_files(
     IOKit/serial/ioss.h
     HAVE_IOSS_H)
 
+check_include_files(
+    OS.h
+    HAVE_OS_H)
+
 check_symbol_exists(
     getpeereid
     "unistd.h;sys/types.h;sys/socket.h"