1 files changed, 120 insertions, 0 deletions
diff --git a/private/ntos/ex/i386/probe.c b/private/ntos/ex/i386/probe.c
new file mode 100644
index 000000000..e65bd0d9a
--- /dev/null
+++ b/private/ntos/ex/i386/probe.c
@@ -0,0 +1,120 @@
+/*++
+
+Copyright (c) 1989-1993  Microsoft Corporation
+
+Module Name:
+
+    probe.c
+
+Abstract:
+
+    This module contains implements the probe for write function.
+
+Author:
+
+    David N. Cutler (davec) 5-May-1989
+
+Environment:
+
+    Any mode.
+
+Revision History:
+
+--*/
+
+#include "exp.h"
+
+#if defined(ALLOC_PRAGMA)
+#pragma alloc_text(PAGE, ProbeForWrite)
+#endif
+
+
+VOID
+ProbeForWrite (
+    IN PVOID Address,
+    IN ULONG Length,
+    IN ULONG Alignment
+    )
+
+/*++
+
+Routine Description:
+
+    This function probes a structure for write accessibility and ensures
+    correct alignment of the structure. If the structure is not accessible
+    or has incorrect alignment, then an exception is raised.
+
+Arguments:
+
+    Address - Supplies a pointer to the structure to be probed.
+
+    Length - Supplies the length of the structure.
+
+    Alignment - Supplies the required alignment of the structure expressed
+        as the number of bytes in the primitive datatype (e.g., 1 for char,
+        2 for short, 4 for long, and 8 for quad).
+
+Return Value:
+
+    None.
+
+--*/
+
+{
+
+    ULONG StartAddress;
+    ULONG EndAddress;
+
+    //
+    // If the structure has zero length, then do not probe the structure for
+    // write accessibility or alignment.
+    //
+
+    if (Length != 0) {
+
+        //
+        // If the structure is not properly aligned, then raise a data
+        // misalignment exception.
+        //
+
+        ASSERT((Alignment == 1) || (Alignment == 2) ||
+               (Alignment == 4) || (Alignment == 8));
+
+        StartAddress = (ULONG)Address;
+        if ((StartAddress & (Alignment - 1)) == 0) {
+
+            //
+            // Compute the ending address of the structure and probe for
+            // write accessibility.
+            //
+
+            EndAddress = StartAddress + Length - 1;
+            if ((StartAddress <= EndAddress) &
+                (EndAddress < MM_USER_PROBE_ADDRESS)) {
+
+                //
+                // N.B. Only the contents of the buffer may be probed.
+                //      Therefore the starting byte is probed for the
+                //       first page, and then the first byte in the page
+                //      for each succeeding page.
+                //
+
+                EndAddress = (EndAddress & ~(PAGE_SIZE - 1)) + PAGE_SIZE;
+                do {
+                    *(volatile CHAR *)StartAddress = *(volatile CHAR *)StartAddress;
+                    StartAddress = (StartAddress & ~(PAGE_SIZE - 1)) + PAGE_SIZE;
+                } while (StartAddress != EndAddress);
+
+                return;
+
+            } else {
+                ExRaiseStatus(STATUS_ACCESS_VIOLATION);
+            }
+
+        } else {
+            ExRaiseStatus(STATUS_DATATYPE_MISALIGNMENT);
+        }
+    }
+
+    return;
+}