Update to .NET 7 paths and add error reporting (#5627)

kant2002 · web-flow · commit 3e634d0b7c4e · 2025-04-03T12:54:03.000-07:00
diff --git a/core/nativeaot/NativeLibrary/Class1.cs b/core/nativeaot/NativeLibrary/Class1.cs
diff --git a/core/nativeaot/NativeLibrary/LibraryFunctions.cs b/core/nativeaot/NativeLibrary/LibraryFunctions.cs
@@ -0,0 +1,54 @@
+// 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;
+
+namespace NativeLibrary;
+
+public class LibraryFunctions
+{
+    [UnmanagedCallersOnly(EntryPoint = "add")]
+    public static int Add(int a, int b)
+    {
+        return a + b;
+    }
+
+    [UnmanagedCallersOnly(EntryPoint = "write_line")]
+    public static int WriteLine(IntPtr pString)
+    {
+        // The marshalling code is typically auto-generated by a custom tool in larger projects.
+        try
+        {
+            // UnmanagedCallersOnly methods only accept primitive arguments. The primitive arguments
+            // have to be marshalled manually if necessary.
+            string str = Marshal.PtrToStringAnsi(pString);
+
+            Console.WriteLine(str);
+        }
+        catch
+        {
+            // Exceptions escaping out of UnmanagedCallersOnly methods are treated as unhandled exceptions.
+            // The errors have to be marshalled manually if necessary.
+            return -1;
+        }
+        return 0;
+    }
+
+    [UnmanagedCallersOnly(EntryPoint = "sumstring")]
+    public static IntPtr sumstring(IntPtr first, IntPtr second)
+    {
+        // Parse strings from the passed pointers 
+        string my1String = Marshal.PtrToStringAnsi(first);
+        string my2String = Marshal.PtrToStringAnsi(second);
+
+        // Concatenate strings 
+        string sum = my1String + my2String;
+
+        // Assign pointer of the concatenated string to sumPointer
+        IntPtr sumPointer = Marshal.StringToHGlobalAnsi(sum);
+
+        // Return pointer
+        return sumPointer;
+    }
+}
diff --git a/core/nativeaot/NativeLibrary/LoadLibrary.c b/core/nativeaot/NativeLibrary/LoadLibrary.c
@@ -33,6 +33,8 @@
 int callSumFunc(char *path, char *funcName, int a, int b);
 char *callSumStringFunc(char *path, char *funcName, char *a, char *b);
 
+void* loadSymbol(char *path, char *funcName);
+
 int main()
 {
     // Check if the library file exists
@@ -54,43 +56,53 @@ int main()
     CoTaskMemFree(sumstring);
 }
 
-int callSumFunc(char *path, char *funcName, int firstInt, int secondInt)
+void *loadSymbol(char *path, char *funcName)
 {
-    // Call sum function defined in C# shared library
+    // Library loading
     #ifdef _WIN32
         HINSTANCE handle = LoadLibraryA(path);
     #else
         void *handle = dlopen(path, RTLD_LAZY);
     #endif
+    if (!handle)
+    {
+#ifdef _WIN32
+        int errorCode = GetLastError();
+        printf("Failed to load library at specified path. Error code: %d\n", errorCode);
+#else
+        puts("Failed to load library at specified path");
+#endif
+        return NULL;
+    }
+
+    // Declare a typedef
+    typedef char *(*myFunc)(char*,char*);
+
+    // Import Symbol named funcName
+
+    // NativeAOT libraries do not support unloading
+    // See https://github.com/dotnet/corert/issues/7887
+    return symLoad(handle, funcName);
+}
 
+int callSumFunc(char *path, char *funcName, int firstInt, int secondInt)
+{
     typedef int(*myFunc)(int,int);
-    myFunc MyImport = (myFunc)symLoad(handle, funcName);
+    myFunc MyImport = (myFunc)loadSymbol(path, funcName);
 
     int result = MyImport(firstInt, secondInt);
-
-    // NOTE: Native AOT libraries do not support unloading
     return result;
 }
 
 char *callSumStringFunc(char *path, char *funcName, char *firstString, char *secondString)
 {
-    // Library loading
-    #ifdef _WIN32
-        HINSTANCE handle = LoadLibraryA(path);
-    #else
-        void *handle = dlopen(path, RTLD_LAZY);
-    #endif
-
     // Declare a typedef
     typedef char *(*myFunc)(char*,char*);
 
     // Import Symbol named funcName
-    myFunc MyImport = (myFunc)symLoad(handle, funcName);
+    myFunc MyImport = (myFunc)loadSymbol(path, funcName);
 
     // The C# function will return a pointer
     char *result = MyImport(firstString, secondString);
-
-    // CoreRT libraries do not support unloading
-    // See https://github.com/dotnet/corert/issues/7887
     return result;
 }
