ntdll: Implement RtlLocateLegacyContext().

dlls/api-ms-win-core-xstate-l1-1-0/api-ms-win-core-xstate-l1-1-0.spec

@@ -4,5 +4,5 @@
 @ stub RtlGetExtendedFeaturesMask
 @ stdcall RtlInitializeExtendedContext(ptr long ptr) ntdll.RtlInitializeExtendedContext
 @ stdcall RtlLocateExtendedFeature(ptr long ptr) ntdll.RtlLocateExtendedFeature
-@ stub RtlLocateLegacyContext
+@ stdcall RtlLocateLegacyContext(ptr ptr) ntdll.RtlLocateLegacyContext
 @ stub RtlSetExtendedFeaturesMask

dlls/ntdll/exception.c

@@ -850,3 +850,14 @@ void * WINAPI RtlLocateExtendedFeature( CONTEXT_EX *context_ex, ULONG feature_id
 {
     return RtlLocateExtendedFeature2( context_ex, feature_id, &user_shared_data->XState, length );
 }
+
+/**********************************************************************
+ *              RtlLocateLegacyContext      (NTDLL.@)
+ */
+void * WINAPI RtlLocateLegacyContext( CONTEXT_EX *context_ex, ULONG *length )
+{
+    if (length)
+        *length = context_ex->Legacy.Length;
+
+    return (BYTE *)context_ex + context_ex->Legacy.Offset;
+}

dlls/ntdll/ntdll.spec

@@ -828,6 +828,7 @@
 @ stdcall RtlLocaleNameToLcid(wstr ptr long)
 @ stdcall RtlLocateExtendedFeature(ptr long ptr)
 @ stdcall RtlLocateExtendedFeature2(ptr long ptr ptr)
+@ stdcall RtlLocateLegacyContext(ptr ptr)
 # @ stub RtlLockBootStatusData
 @ stdcall RtlLockHeap(long)
 # @ stub RtlLockMemoryStreamRegion

dlls/ntdll/tests/exception.c

@@ -52,6 +52,7 @@ static NTSTATUS  (WINAPI *pRtlInitializeExtendedContext)(void *context, ULONG co
 static NTSTATUS  (WINAPI *pRtlInitializeExtendedContext2)(void *context, ULONG context_flags, CONTEXT_EX **context_ex,
         ULONG64 compaction_mask);
 static void *    (WINAPI *pRtlLocateExtendedFeature)(CONTEXT_EX *context_ex, ULONG feature_id, ULONG *length);
+static void *    (WINAPI *pRtlLocateLegacyContext)(CONTEXT_EX *context_ex, ULONG *length);
 static NTSTATUS  (WINAPI *pNtReadVirtualMemory)(HANDLE, const void*, void*, SIZE_T, SIZE_T*);
 static NTSTATUS  (WINAPI *pNtTerminateProcess)(HANDLE handle, LONG exit_code);
 static NTSTATUS  (WINAPI *pNtQueryInformationProcess)(HANDLE, PROCESSINFOCLASS, PVOID, ULONG, PULONG);
@@ -6307,6 +6308,18 @@ static void test_extended_context(void)
             ok(!context_ex->XState.Length,
                     "Got unexpected Length %#x, flags %#x.\n", context_ex->XState.Length, flags);
 
+            if (0)
+            {
+                /* Crashes on Windows. */
+                pRtlLocateLegacyContext(NULL, NULL);
+            }
+            p = pRtlLocateLegacyContext(context_ex, NULL);
+            ok(p == context, "Got unexpected p %p, flags %#x.\n", p, flags);
+            length2 = 0xdeadbeef;
+            p = pRtlLocateLegacyContext(context_ex, &length2);
+            ok(p == context && length2 == context_ex->Legacy.Length,
+                    "Got unexpected p %p, length %#x, flags %#x.\n", p, length2, flags);
+            length2 = expected_length;
 
             for (j = 0; j < context_arch[test].flags_offset; ++j)
             {
@@ -6738,6 +6751,7 @@ START_TEST(exception)
     X(RtlInitializeExtendedContext);
     X(RtlInitializeExtendedContext2);
     X(RtlLocateExtendedFeature);
+    X(RtlLocateLegacyContext);
 #undef X
 
 #define X(f) p##f = (void*)GetProcAddress(hkernel32, #f)

dlls/ntoskrnl.exe/ntoskrnl.exe.spec

@@ -1176,6 +1176,7 @@
 @ stdcall RtlLocalTimeToSystemTime(ptr ptr)
 @ stdcall RtlLocateExtendedFeature(ptr long ptr)
 @ stdcall RtlLocateExtendedFeature2(ptr long ptr ptr)
+@ stdcall RtlLocateLegacyContext(ptr ptr)
 @ stub RtlLockBootStatusData
 @ stdcall RtlLookupAtomInAtomTable(ptr wstr ptr)
 @ stub RtlLookupElementGenericTable

include/ddk/wdm.h

@@ -1842,6 +1842,7 @@ NTSTATUS  WINAPI RtlInitializeExtendedContext2(void*,ULONG,CONTEXT_EX**,ULONG64)
 ULONG64   WINAPI RtlGetEnabledExtendedFeatures(ULONG64);
 NTSTATUS  WINAPI RtlGetExtendedContextLength(ULONG,ULONG*);
 NTSTATUS  WINAPI RtlGetExtendedContextLength2(ULONG,ULONG*,ULONG64);
+void *    WINAPI RtlLocateLegacyContext(CONTEXT_EX*,ULONG*);
 void *    WINAPI RtlLocateExtendedFeature(CONTEXT_EX*,ULONG,ULONG*);
 void *    WINAPI RtlLocateExtendedFeature2(CONTEXT_EX*,ULONG,XSTATE_CONFIGURATION*,ULONG*);
 #endif