Rewrite core of the XTLDR boot loader

Reviewed-on: #7
Reviewed-by: Piotr Likoski <likoski@noreply.codingworkshop.git>
Co-authored-by: Rafal Kupiec <belliash@codingworkshop.eu.org>
Co-committed-by: Rafal Kupiec <belliash@codingworkshop.eu.org>

xtldr/library/modproto.c

@@ -0,0 +1,80 @@
+/**
+ * PROJECT:         ExectOS
+ * COPYRIGHT:       See COPYING.md in the top level directory
+ * FILE:            xtldr/library/modproto.c
+ * DESCRIPTION:     XT Boot Loader protocol support for XTLDR modules
+ * DEVELOPERS:      Rafal Kupiec <belliash@codingworkshop.eu.org>
+ */
+
+#include <xtldr.h>
+
+
+/**
+ * Finds and opens the XT Boot Loader protocol. This routine should be called by module to access XTLDR protocol.
+ *
+ * @param SystemTable
+ *        Provides the EFI system table.
+ *
+ * @param ImageHandle
+ *        Firmware-allocated handle that identifies the image.
+ *
+ * @param ProtocolHandler
+ *        Receives the pointer to the XT Boot Loader protocol.
+ *
+ * @return This routine returns a status code.
+ *
+ * @since XT 1.0
+ */
+XTCDECL
+EFI_STATUS
+BlGetXtLdrProtocol(IN PEFI_SYSTEM_TABLE SystemTable,
+                   IN EFI_HANDLE ImageHandle,
+                   OUT PXTBL_LOADER_PROTOCOL *ProtocolHandler)
+{
+    EFI_GUID ProtocolGuid = XT_BOOT_LOADER_PROTOCOL_GUID;
+    PEFI_HANDLE Handles = NULL;
+    EFI_STATUS Status;
+    UINT_PTR Count;
+    UINT Index;
+
+    /* Try to locate the handles */
+    Status = SystemTable->BootServices->LocateHandleBuffer(ByProtocol, &ProtocolGuid, NULL, &Count, &Handles);
+    if(Status != STATUS_EFI_SUCCESS)
+    {
+        /* Unable to get handles */
+        return Status;
+    }
+
+    /* Check if any handles returned */
+    if(Count > 0)
+    {
+        /* Iterate through all given handles */
+        for(Index = 0; Index < Count; Index++)
+        {
+            /* Try to open protocol */
+            Status = SystemTable->BootServices->OpenProtocol(Handles[Index], &ProtocolGuid,
+                                                             (PVOID*)ProtocolHandler, ImageHandle, NULL,
+                                                             EFI_OPEN_PROTOCOL_BY_HANDLE_PROTOCOL);
+
+            /* Check if successfully opened the loader protocol */
+            if(Status == STATUS_EFI_SUCCESS)
+            {
+                /* Protocol found and successfully opened */
+                break;
+            }
+        }
+    }
+
+    /* Free handles */
+    SystemTable->BootServices->FreePool(Handles);
+
+    /* Make sure the loaded protocol has been found */
+    if(*ProtocolHandler == NULL)
+    {
+        /* Protocol not found */
+        return STATUS_EFI_NOT_FOUND;
+    }
+
+    /* Return success */
+	return STATUS_EFI_SUCCESS;
+}