Author: fireball
Date: Wed Mar 16 09:49:07 2011
New Revision: 51059
URL: http://svn.reactos.org/svn/reactos?rev=51059&view=rev
Log:
[RTL]
- Implement LdrVerifyMappedImageChecksum (copied from ntdll/ldr/utils.c).
Modified:
trunk/reactos/lib/rtl/image.c
Modified: trunk/reactos/lib/rtl/image.c
URL:
http://svn.reactos.org/svn/reactos/trunk/reactos/lib/rtl/image.c?rev=51059&r1=51058&r2=51059&view=diff
==============================================================================
--- trunk/reactos/lib/rtl/image.c [iso-8859-1] (original)
+++ trunk/reactos/lib/rtl/image.c [iso-8859-1] Wed Mar 16 09:49:07 2011
@@ -24,11 +24,78 @@
NTAPI
LdrVerifyMappedImageMatchesChecksum(
IN PVOID BaseAddress,
- IN ULONG NumberOfBytes,
+ IN ULONG ImageSize,
IN ULONG FileLength)
{
- /* FIXME: TODO */
- return TRUE;
+ PIMAGE_NT_HEADERS Header;
+ PUSHORT Ptr;
+ ULONG Sum;
+ ULONG CalcSum;
+ ULONG HeaderSum;
+ ULONG i;
+
+ /* Get NT header to check if it's an image at all */
+ Header = RtlImageNtHeader (BaseAddress);
+ if (!Header) return FALSE;
+
+ /* Get checksum to match */
+ HeaderSum = Header->OptionalHeader.CheckSum;
+
+ /* Zero checksum seems to be accepted */
+ if (HeaderSum == 0) return TRUE;
+
+ /* Calculate the checksum */
+ Sum = 0;
+ Ptr = (PUSHORT) BaseAddress;
+ for (i = 0; i < ImageSize / sizeof (USHORT); i++)
+ {
+ Sum += (ULONG)*Ptr;
+ if (HIWORD(Sum) != 0)
+ {
+ Sum = LOWORD(Sum) + HIWORD(Sum);
+ }
+ Ptr++;
+ }
+
+ if (ImageSize & 1)
+ {
+ Sum += (ULONG)*((PUCHAR)Ptr);
+ if (HIWORD(Sum) != 0)
+ {
+ Sum = LOWORD(Sum) + HIWORD(Sum);
+ }
+ }
+
+ CalcSum = (USHORT)(LOWORD(Sum) + HIWORD(Sum));
+
+ /* Subtract image checksum from calculated checksum. */
+ /* fix low word of checksum */
+ if (LOWORD(CalcSum) >= LOWORD(HeaderSum))
+ {
+ CalcSum -= LOWORD(HeaderSum);
+ }
+ else
+ {
+ CalcSum = ((LOWORD(CalcSum) - LOWORD(HeaderSum)) & 0xFFFF) - 1;
+ }
+
+ /* Fix high word of checksum */
+ if (LOWORD(CalcSum) >= HIWORD(HeaderSum))
+ {
+ CalcSum -= HIWORD(HeaderSum);
+ }
+ else
+ {
+ CalcSum = ((LOWORD(CalcSum) - HIWORD(HeaderSum)) & 0xFFFF) - 1;
+ }
+
+ /* Add file length */
+ CalcSum += ImageSize;
+
+ if (CalcSum != HeaderSum)
+ DPRINT1("Image %p checksum mismatches! 0x%x != 0x%x\n", BaseAddress,
CalcSum, HeaderSum);
+
+ return (BOOLEAN)(CalcSum == HeaderSum);
}
/*
