[NativeAOT] Do not use private APIs on iOS/macOS (#90430)

* Use custom implementation of _dyld_find_unwind_sections on Apple
platforms since it's a private API and it blocks uploads to TestFlight,
iOS App Store, and Mac App Store.

* Link against local ICU libraries on iOS-like platforms

* Update src/coreclr/nativeaot/BuildIntegration/Microsoft.NETCore.Native.Unix.targets

* Add comment

* Update src/coreclr/nativeaot/Runtime/unix/UnwindHelpers.cpp

Co-authored-by: Jan Kotas <jkotas@microsoft.com>

---------

Co-authored-by: Jan Kotas <jkotas@microsoft.com>

src/coreclr/nativeaot/BuildIntegration/Microsoft.NETCore.Native.Unix.targets

@@ -69,6 +69,9 @@ The .NET Foundation licenses this file to you under the MIT license.
       <NetCoreAppNativeLibrary Include="System.Security.Cryptography.Native.Apple" Condition="'$(_IsApplePlatform)' == 'true'" />
       <!-- Not compliant for iOS-like platforms -->
       <NetCoreAppNativeLibrary Include="System.Security.Cryptography.Native.OpenSsl" Condition="'$(StaticOpenSslLinking)' != 'true' and '$(_IsiOSLikePlatform)' != 'true'" />
+      <NetCoreAppNativeLibrary Include="icudata" Condition="'$(_IsiOSLikePlatform)' == 'true' and '$(InvariantGlobalization)' != 'true'" />
+      <NetCoreAppNativeLibrary Include="icui18n" Condition="'$(_IsiOSLikePlatform)' == 'true' and '$(InvariantGlobalization)' != 'true'" />
+      <NetCoreAppNativeLibrary Include="icuuc" Condition="'$(_IsiOSLikePlatform)' == 'true' and '$(InvariantGlobalization)' != 'true'" />
     </ItemGroup>
 
     <ItemGroup>

src/coreclr/nativeaot/Runtime/unix/UnwindHelpers.cpp

@@ -8,7 +8,7 @@
 #define UNW_STEP_SUCCESS 1
 #define UNW_STEP_END     0
 
-#ifdef __APPLE__
+#if defined(TARGET_APPLE)
 #include <mach-o/getsect.h>
 #endif
 
@@ -883,3 +883,34 @@ bool UnwindHelpers::GetUnwindProcInfo(PCODE pc, UnwindInfoSections &uwInfoSectio
     uc.getInfo(procInfo);
     return true;
 }
+
+#if defined(TARGET_APPLE)
+// Apple considers _dyld_find_unwind_sections to be private API that cannot be used
+// by apps submitted to App Store and TestFlight, both for iOS-like and macOS platforms.
+// We reimplement it using public API surface.
+//
+// Ref: https://github.com/llvm/llvm-project/blob/c37145cab12168798a603e22af6b6bf6f606b705/libunwind/src/AddressSpace.hpp#L67-L93
+bool _dyld_find_unwind_sections(void* addr, dyld_unwind_sections* info)
+{
+    // Find mach-o image containing address.
+    Dl_info dlinfo;
+    if (!dladdr(addr, &dlinfo))
+      return false;
+
+    const struct mach_header_64 *mh = (const struct mach_header_64 *)dlinfo.dli_fbase;
+
+    // Initialize the return struct
+    info->mh = (const struct mach_header *)mh;
+    info->dwarf_section = getsectiondata(mh, "__TEXT", "__eh_frame", &info->dwarf_section_length);
+    info->compact_unwind_section = getsectiondata(mh, "__TEXT", "__unwind_info", &info->compact_unwind_section_length);
+
+    if (!info->dwarf_section) {
+        info->dwarf_section_length = 0;
+    }
+    if (!info->compact_unwind_section) {
+        info->compact_unwind_section_length = 0;
+    }
+
+    return true;
+}
+#endif