[BOOT:LIB] Implement EfiInitpConvertEfiFilePath()

Also implemented RtlULongSub() and EfiInitpAppendPathString()

BOOT/ENVIRON/LIB/EFI/efiinit.c

@@ -24,6 +24,106 @@ UCHAR EfiInitScratch[2048];
 const EFI_GUID EfiLoadedImageProtocol = LOADED_IMAGE_PROTOCOL;
 const EFI_GUID EfiDevicePathProtocol = DEVICE_PATH_PROTOCOL;
 
+NTSTATUS
+EfiInitpAppendPathString (
+    IN PWCHAR Destination,
+    IN ULONG BufferSize,
+    IN PWCHAR Source,
+    IN ULONG SourceSize,
+    IN OUT PULONG BufferUsed
+    )
+
+/*++
+
+Routine Description:
+
+    Appends a soure path to a destination path.
+
+Arguments:
+
+    Destination - the path to append to.
+
+    BufferSize - the maximum number of bytes to append.
+
+    Source - the source path to append to Destination.
+
+    SourceSize - the size of Source, in bytes.
+
+    BufferUsed - pointer to a ULONG to store the number of bytes appended in.
+
+Return Value:
+
+    STATUS_SUCCESS if successful,
+    STATUS_INVALID_PARAMETER if Destination is not valid,
+    STATUS_BUFFER_TOO_SMALL if BufferSize is too small.
+
+--*/
+
+{
+    ULONG Position;
+
+    //
+    // Verify that Source uses wide characters.
+    //
+    if (SourceSize % sizeof(WCHAR) != 0) {
+        return STATUS_INVALID_PARAMETER;
+    }
+
+    //
+    // Remove NULL terminator.
+    //
+    if (SourceSize >= sizeof(WCHAR)) {
+        Position = (SourceSize / sizeof(WCHAR)) - 1;
+        if (Source[Position] == UNICODE_NULL) {
+            SourceSize -= sizeof(UNICODE_NULL);
+        }
+    }
+
+    //
+    // Remove leading separator.
+    //
+    if (SourceSize >= sizeof(WCHAR)) {
+        if (Source[0] == L'\\') {
+            Source++;
+            SourceSize -= sizeof(WCHAR);
+        }
+    }
+
+    //
+    // Remove trailing separator.
+    //
+    if (SourceSize >= sizeof(WCHAR)) {
+        Position = (SourceSize / sizeof(WCHAR)) - 1;
+        if (Source[Position] == L'\\') {
+            SourceSize -= sizeof(WCHAR);
+        }
+    }
+
+    //
+    // Check if Source is empty.
+    //
+    if (SourceSize == 0) {
+        *BufferUsed = 0;
+        return STATUS_SUCCESS;
+    }
+
+    //
+    // Make sure the buffer is large enough.
+    //
+    if (BufferSize < SourceSize + sizeof(WCHAR)) {
+        return STATUS_BUFFER_TOO_SMALL;
+    }
+
+    //
+    // Append separator and Source to Destination.
+    //
+    Destination[0] = L'\\';
+    RtlCopyMemory(Destination + 1, Source, SourceSize);
+
+    *BufferUsed = SourceSize + sizeof(WCHAR);
+    return STATUS_SUCCESS;
+}
+
 EFI_DEVICE_PATH *
 EfiInitpGetDeviceNode (
     IN EFI_DEVICE_PATH *DevicePath
@@ -287,10 +387,70 @@ Return Value:
 --*/
 
 {
-    (VOID)EfiFilePath;
-    (VOID)OptionType;
-    (VOID)Option;
-    (VOID)BufferSize;
+    NTSTATUS Status;
+    EFI_DEVICE_PATH *Node;
+    PWCHAR PathStart, Position;
+    ULONG BufferRemaining, Length, Appended;
+
+    //
+    // Check for available buffer space.
+    //
+    if (BufferSize < sizeof(BOOT_APPLICATION_ENTRY_OPTION)) {
+        return STATUS_INVALID_PARAMETER;
+    }
+
+    //
+    // Set up option structure.
+    //
+    RtlZeroMemory(Option, sizeof(BOOT_APPLICATION_ENTRY_OPTION));
+    Option->Type = OptionType;
+    Option->DataOffset = sizeof(BOOT_APPLICATION_ENTRY_OPTION);
+
+    //
+    // Add to the path one file path node at a time.
+    //
+    Option->DataSize = 0;
+    BufferRemaining = BufferSize - sizeof(BOOT_APPLICATION_ENTRY_OPTION);
+    Node = EfiFilePath;
+    PathStart = (PWCHAR)((PUCHAR)Option + Option->DataOffset);
+    Position = PathStart;
+    while (!IsDevicePathEndType(Node)) {
+        if (DevicePathType(Node) != MEDIA_DEVICE_PATH || DevicePathSubType(Node) != MEDIA_FILEPATH_DP) {
+            Node = NextDevicePathNode(Node);
+            continue;
+        }
+
+        Status = RtlULongSub(DevicePathNodeLength(Node), FIELD_OFFSET(FILEPATH_DEVICE_PATH, PathName), &Length);
+        if (!NT_SUCCESS(Status)) {
+            return Status;
+        }
+
+        Status = EfiInitpAppendPathString(Position, BufferRemaining, &((FILEPATH_DEVICE_PATH *)Node)->PathName[0], Length, &Appended);
+        if (!NT_SUCCESS(Status)) {
+            return Status;
+        }
+
+        Option->DataSize += Appended;
+        BufferRemaining -= Appended;
+        Position = (PWCHAR)((PUCHAR)Position + Appended);
+        Node = NextDevicePathNode(Node);
+    }
+
+    //
+    // Terminate path string.
+    //
+    if (BufferRemaining < sizeof(UNICODE_NULL)) {
+        return STATUS_INVALID_PARAMETER;
+    }
+    *Position = L'\0';
+    Option->DataSize += sizeof(UNICODE_NULL);
+
+    //
+    // The path option is invalid if the path is NULL.
+    //
+    if (Position == PathStart) {
+        Option->IsInvalid = TRUE;
+    }
 
     return STATUS_SUCCESS;
 }

SDK/INC/NT/ntrtl.h

@@ -18,6 +18,7 @@ Abstract:
 
 #include <string.h>
 #include <ntdef.h>
+#include <ntstatus.h>
 
 //
 // Memory operations.
@@ -27,6 +28,47 @@ Abstract:
 #define RtlFillMemory(Destination, Length, Fill)   memset((Destination), (Fill), (Length))
 #define RtlZeroMemory(Destination, Length)         memset((Destination), 0, (Length))
 
+#define ULONG_ERROR 0xFFFFFFFFUL
+
+FORCEINLINE
+NTSTATUS
+RtlULongSub (
+   IN ULONG ulMinuend,
+   IN ULONG ulSubtrahend,
+   IN OUT PULONG pulResult
+   )
+
+/*++
+
+Routine Description:
+
+    Calculates the difference of two ULONG values.
+
+Arguments:
+
+    ulMinuend - The value to subtract ulSubtrahend from.
+
+    ulSubtrahend - The value to subtract from ulMinuend.
+
+    pulResult - Pointer to a ULONG to store the difference in.
+
+Return Value:
+
+    STATUS_SUCCESS if successful.
+    STATUS_INTEGER_OVERFLOW if unsuccessful.
+
+--*/
+
+{
+    if (ulMinuend >= ulSubtrahend) {
+        *pulResult = ulMinuend - ulSubtrahend;
+        return STATUS_SUCCESS;
+    }
+
+    *pulResult = ULONG_ERROR;
+    return STATUS_INTEGER_OVERFLOW;
+}
+
 VOID
 NTAPI
 RtlInitUnicodeString (

SDK/INC/NT/ntstatus.h

@@ -29,6 +29,7 @@ Abstract:
 #define STATUS_DISK_CORRUPT_ERROR      ((NTSTATUS) 0xC0000032L)
 #define STATUS_DEVICE_ALREADY_ATTACHED ((NTSTATUS) 0xC0000038L)
 #define STATUS_DISK_FULL               ((NTSTATUS) 0xC000007FL)
+#define STATUS_INTEGER_OVERFLOW        ((NTSTATUS) 0xC0000095L)
 #define STATUS_INSUFFICIENT_RESOURCES  ((NTSTATUS) 0xC000009AL)
 #define STATUS_MEDIA_WRITE_PROTECTED   ((NTSTATUS) 0xC00000A2L)
 #define STATUS_DEVICE_NOT_READY        ((NTSTATUS) 0xC00000A3L)