[SETUPLIB] Improve the bootloader 'validity' checks -- Addendum to f06734e5 (r74512).

[reactos.git] / base / setup / lib / bootsup.c

diff --git a/base/setup/lib/bootsup.c b/base/setup/lib/bootsup.c
index 0ef4e82..5f0f694 100644 (file)
--- a/base/setup/lib/bootsup.c
+++ b/base/setup/lib/bootsup.c
@@ -551,7 +551,6 @@ IsThereAValidBootSector(
     HANDLE FileHandle;
     LARGE_INTEGER FileOffset;
     PUCHAR BootSector;
-    ULONG Instruction;
 
     /* Allocate buffer for bootsector */
     BootSector = RtlAllocateHeap(ProcessHeap, 0, SECTORSIZE);
@@ -593,17 +592,18 @@ IsThereAValidBootSector(
     if (!NT_SUCCESS(Status))
         goto Quit;
 
-    /* Check the instruction; we use a ULONG to read three bytes */
-    Instruction = (*(PULONG)BootSector) & 0x00FFFFFF;
-    IsValid = (Instruction != 0x00000000);
-
-    /* Check the bootsector signature */
-    IsValid &= (*(PUSHORT)(BootSector + 0x1fe) == 0xaa55);
+    /* Check for the existence of the bootsector signature */
+    IsValid = (*(PUSHORT)(BootSector + 0x1FE) == 0xAA55);
+    if (IsValid)
+    {
+        /* Check for the first instruction encoded on three bytes */
+        IsValid = (((*(PULONG)BootSector) & 0x00FFFFFF) != 0x00000000);
+    }
 
 Quit:
     /* Free the boot sector */
     RtlFreeHeap(ProcessHeap, 0, BootSector);
-    return IsValid; // Status;
+    return IsValid;
 }
 
 static
@@ -883,9 +883,9 @@ InstallMbrBootCodeToDisk(
 
 #if 0
     WCHAR DestinationDevicePathBuffer[MAX_PATH];
-    StringCchPrintfW(DestinationDevicePathBuffer, ARRAYSIZE(DestinationDevicePathBuffer),
-            L"\\Device\\Harddisk%d\\Partition0",
-            DiskNumber);
+    RtlStringCchPrintfW(DestinationDevicePathBuffer, ARRAYSIZE(DestinationDevicePathBuffer),
+                        L"\\Device\\Harddisk%d\\Partition0",
+                        DiskNumber);
 #endif
 
     CombinePaths(SourceMbrPathBuffer, ARRAYSIZE(SourceMbrPathBuffer), 2,