[fallback] For HD() device paths, use just the media node and later.

UEFI 2.x section 3.1.2 provides for "short-form device path", where the
first element specified is a "hard drive media device path", so that you
can move a disk around on different buses without invalidating your
device path.  Fallback has not been using this option, though in most
cases efibootmgr has.

Note that we still keep the full device path, because LoadImage()
isn't necessarily the layer where HD() works - one some systems BDS is
responsible for resolving the full path and passes that to LoadImage()
instead.  So we have to do LoadImage() with the full path.

fallback.c

@@ -14,6 +14,27 @@
 
 EFI_LOADED_IMAGE *this_image = NULL;
 
+static EFI_STATUS
+FindSubDevicePath(EFI_DEVICE_PATH *In, UINT8 Type, UINT8 SubType,
+		  EFI_DEVICE_PATH **Out)
+{
+	EFI_DEVICE_PATH *dp = In;
+	if (!In || !Out)
+		return EFI_INVALID_PARAMETER;
+
+	for (dp = In; !IsDevicePathEnd(dp); dp = NextDevicePathNode(dp)) {
+		if (DevicePathType(dp) == Type &&
+				DevicePathSubType(dp) == SubType) {
+			*Out = DuplicateDevicePath(dp);
+			if (!*Out)
+				return EFI_OUT_OF_RESOURCES;
+			return EFI_SUCCESS;
+		}
+	}
+	*Out = NULL;
+	return EFI_NOT_FOUND;
+}
+
 static EFI_STATUS
 get_file_size(EFI_FILE_HANDLE fh, UINTN *retsize)
 {
@@ -93,7 +114,9 @@ make_full_path(CHAR16 *dirname, CHAR16 *filename, CHAR16 **out, UINT64 *outlen)
 {
 	UINT64 len;
 	
-	len = StrLen(dirname) + StrLen(filename) + StrLen(L"\\EFI\\\\") + 2;
+	len = StrLen(L"\\EFI\\") + StrLen(dirname)
+	    + StrLen(L"\\") + StrLen(filename)
+	    + 2;
 
 	CHAR16 *fullpath = AllocateZeroPool(len*sizeof(CHAR16));
 	if (!fullpath) {
@@ -119,7 +142,8 @@ VOID *first_new_option_args = NULL;
 UINTN first_new_option_size = 0;
 
 EFI_STATUS
-add_boot_option(EFI_DEVICE_PATH *dp, CHAR16 *filename, CHAR16 *label, CHAR16 *arguments)
+add_boot_option(EFI_DEVICE_PATH *hddp, EFI_DEVICE_PATH *fulldp,
+		CHAR16 *filename, CHAR16 *label, CHAR16 *arguments)
 {
 	static int i = 0;
 	CHAR16 varname[] = L"Boot0000";
@@ -136,24 +160,31 @@ add_boot_option(EFI_DEVICE_PATH *dp, CHAR16 *filename, CHAR16 *label, CHAR16 *ar
 		void *var = LibGetVariable(varname, &global);
 		if (!var) {
 			int size = sizeof(UINT32) + sizeof (UINT16) +
-				StrLen(label)*2 + 2 + DevicePathSize(dp) +
+				StrLen(label)*2 + 2 + DevicePathSize(hddp) +
-				StrLen(arguments) * 2 + 2;
+				StrLen(arguments) * 2;
 
 			CHAR8 *data = AllocateZeroPool(size);
 			CHAR8 *cursor = data;
 			*(UINT32 *)cursor = LOAD_OPTION_ACTIVE;
 			cursor += sizeof (UINT32);
-			*(UINT16 *)cursor = DevicePathSize(dp);
+			*(UINT16 *)cursor = DevicePathSize(hddp);
 			cursor += sizeof (UINT16);
 			StrCpy((CHAR16 *)cursor, label);
 			cursor += StrLen(label)*2 + 2;
-			CopyMem(cursor, dp, DevicePathSize(dp));
+			CopyMem(cursor, hddp, DevicePathSize(hddp));
-			cursor += DevicePathSize(dp);
+			cursor += DevicePathSize(hddp);
 			StrCpy((CHAR16 *)cursor, arguments);
 
 			Print(L"Creating boot entry \"%s\" with label \"%s\" "
 					L"for file \"%s\"\n",
 				varname, label, filename);
+
+			if (!first_new_option) {
+				first_new_option = DuplicateDevicePath(fulldp);
+				first_new_option_args = arguments;
+				first_new_option_size = StrLen(arguments) * sizeof (CHAR16);
+			}
+
 			rc = uefi_call_wrapper(RT->SetVariable, 5, varname,
 				&global, EFI_VARIABLE_NON_VOLATILE |
 					 EFI_VARIABLE_BOOTSERVICE_ACCESS |
@@ -254,7 +285,10 @@ add_to_boot_list(EFI_FILE_HANDLE fh, CHAR16 *dirname, CHAR16 *filename, CHAR16 *
 	if (EFI_ERROR(rc))
 		return rc;
 	
-	EFI_DEVICE_PATH *dph = NULL, *dpf = NULL, *dp = NULL;
+	EFI_DEVICE_PATH *dph = NULL;
+	EFI_DEVICE_PATH *file = NULL;
+	EFI_DEVICE_PATH *full_device_path = NULL;
+	EFI_DEVICE_PATH *dp = NULL;
 	
 	dph = DevicePathFromHandle(this_image->DeviceHandle);
 	if (!dph) {
@@ -262,19 +296,31 @@ add_to_boot_list(EFI_FILE_HANDLE fh, CHAR16 *dirname, CHAR16 *filename, CHAR16 *
 		goto err;
 	}
 
-	dpf = FileDevicePath(fh, fullpath);
+	file = FileDevicePath(fh, fullpath);
-	if (!dpf) {
+	if (!file) {
 		rc = EFI_OUT_OF_RESOURCES;
 		goto err;
 	}
 
-	dp = AppendDevicePath(dph, dpf);
+	full_device_path = AppendDevicePath(dph, file);
-	if (!dp) {
+	if (!full_device_path) {
 		rc = EFI_OUT_OF_RESOURCES;
 		goto err;
 	}
 
+	rc = FindSubDevicePath(full_device_path,
+				MEDIA_DEVICE_PATH, MEDIA_HARDDRIVE_DP, &dp);
+	if (EFI_ERROR(rc)) {
+		if (rc == EFI_NOT_FOUND) {
+			dp = full_device_path;
+		} else {
+			rc = EFI_OUT_OF_RESOURCES;
+			goto err;
+		}
+	}
+
 #ifdef DEBUG_FALLBACK
+	{
 	UINTN s = DevicePathSize(dp);
 	int i;
 	UINT8 *dpv = (void *)dp;
@@ -287,20 +333,16 @@ add_to_boot_list(EFI_FILE_HANDLE fh, CHAR16 *dirname, CHAR16 *filename, CHAR16 *
 
 	CHAR16 *dps = DevicePathToStr(dp);
 	Print(L"device path: \"%s\"\n", dps);
-#endif
-	if (!first_new_option) {
-		CHAR16 *dps = DevicePathToStr(dp);
-		Print(L"device path: \"%s\"\n", dps);
-		first_new_option = DuplicateDevicePath(dp);
-		first_new_option_args = arguments;
-		first_new_option_size = StrLen(arguments) * sizeof (CHAR16);
 	}
+#endif
 
-	add_boot_option(dp, fullpath, label, arguments);
+	add_boot_option(dp, full_device_path, fullpath, label, arguments);
 
 err:
-	if (dpf)
+	if (file)
-		FreePool(dpf);
+		FreePool(file);
+	if (full_device_path)
+		FreePool(full_device_path);
 	if (dp)
 		FreePool(dp);
 	if (fullpath)
@@ -629,8 +671,19 @@ try_start_first_option(EFI_HANDLE parent_image_handle)
 			       first_new_option, NULL, 0,
 			       &image_handle);
 	if (EFI_ERROR(rc)) {
-		Print(L"LoadImage failed: %d\n", rc);
+		CHAR16 *dps = DevicePathToStr(first_new_option);
-		uefi_call_wrapper(BS->Stall, 1, 2000000);
+		UINTN s = DevicePathSize(first_new_option);
+		int i;
+		UINT8 *dpv = (void *)first_new_option;
+		Print(L"LoadImage failed: %d\nDevice path: \"%s\"\n", rc, dps);
+		for (i = 0; i < s; i++) {
+			if (i > 0 && i % 16 == 0)
+				Print(L"\n");
+			Print(L"%02x ", dpv[i]);
+		}
+		Print(L"\n");
+
+		uefi_call_wrapper(BS->Stall, 1, 500000000);
 		return rc;
 	}
 
@@ -644,7 +697,7 @@ try_start_first_option(EFI_HANDLE parent_image_handle)
 	rc = uefi_call_wrapper(BS->StartImage, 3, image_handle, NULL, NULL);
 	if (EFI_ERROR(rc)) {
 		Print(L"StartImage failed: %d\n", rc);
-		uefi_call_wrapper(BS->Stall, 1, 2000000);
+		uefi_call_wrapper(BS->Stall, 1, 500000000);
 	}
 	return rc;
 }