173 lines
3.6 KiB
C
173 lines
3.6 KiB
C
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/*++
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Copyright (c) 1994 Microsoft Corporation
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Module Name:
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callback.c
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Abstract:
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This module implements user mode call back services.
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Author:
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David N. Cutler (davec) 29-Oct-1994
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Environment:
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Kernel mode only.
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Revision History:
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--*/
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#include "ki.h"
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#ifdef ALLOC_PRAGMA
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#pragma alloc_text (PAGE, KeUserModeCallback)
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#endif
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NTSTATUS
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KeUserModeCallback (
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IN ULONG ApiNumber,
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IN PVOID InputBuffer,
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IN ULONG InputLength,
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OUT PVOID *OutputBuffer,
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IN PULONG OutputLength
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)
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/*++
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Routine Description:
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This function call out from kernel mode to a user mode function.
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Arguments:
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ApiNumber - Supplies the API number.
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InputBuffer - Supplies a pointer to a structure that is copied
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to the user stack.
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InputLength - Supplies the length of the input structure.
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Outputbuffer - Supplies a pointer to a variable that receives
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the address of the output buffer.
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Outputlength - Supplies a pointer to a variable that receives
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the length of the output buffer.
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Return Value:
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If the callout cannot be executed, then an error status is
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returned. Otherwise, the status returned by the callback function
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is returned.
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--*/
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{
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ULONG Length;
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ULONG NewStack;
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ULONG OldStack;
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NTSTATUS Status;
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PULONG UserStack;
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PVOID ValueBuffer;
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ULONG ValueLength;
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ULONG GdiBatchCount;
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PEXCEPTION_REGISTRATION_RECORD ExceptionList;
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PTEB Teb;
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ASSERT(KeGetPreviousMode() == UserMode);
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ASSERT(KeGetCurrentThread()->ApcState.KernelApcInProgress == FALSE);
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//
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// Get the user mode stack pointer and attempt to copy input buffer
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// to the user stack.
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//
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UserStack = KiGetUserModeStackAddress();
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OldStack = *UserStack;
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try {
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//
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// Compute new user mode stack address, probe for writability,
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// and copy the input buffer to the user stack.
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//
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Length = (InputLength + sizeof(CHAR) - 1) & ~(sizeof(CHAR) - 1);
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NewStack = OldStack - Length;
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ProbeForWrite((PCHAR)(NewStack - 16), Length + 16, sizeof(CHAR));
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RtlCopyMemory((PVOID)NewStack, InputBuffer, Length);
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//
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// Push arguments onto user stack.
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//
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*(PULONG)(NewStack - 4) = (ULONG)InputLength;
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*(PULONG)(NewStack - 8) = (ULONG)NewStack;
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*(PULONG)(NewStack - 12) = ApiNumber;
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*(PULONG)(NewStack - 16) = 0;
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NewStack -= 16;
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//
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// Save the exception list in case another handler is defined during
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// the callout.
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//
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Teb = (PTEB)KeGetCurrentThread()->Teb;
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ExceptionList = Teb->NtTib.ExceptionList;
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//
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// Call user mode.
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//
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*UserStack = NewStack;
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Status = KiCallUserMode(OutputBuffer, OutputLength);
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//
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// Restore exception list.
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//
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Teb->NtTib.ExceptionList = ExceptionList;
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//
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// If an exception occurs during the probe of the user stack, then
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// always handle the exception and return the exception code as the
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// status value.
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//
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} except (EXCEPTION_EXECUTE_HANDLER) {
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return GetExceptionCode();
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}
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//
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// When returning from user mode, any drawing done to the GDI TEB
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// batch must be flushed. If the TEB cannot be accessed then blindly
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// flush the GDI batch anyway.
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//
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GdiBatchCount = 1;
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try {
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GdiBatchCount = Teb->GdiBatchCount;
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} except (EXCEPTION_EXECUTE_HANDLER) {
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NOTHING;
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}
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if (GdiBatchCount > 0) {
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//
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// call GDI batch flush routine
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//
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*UserStack -= 256;
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KeGdiFlushUserBatch();
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}
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*UserStack = OldStack;
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return Status;
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}
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