[efi] Allow downloaded images to take precedence over constructed files

Try searching for a matching registered image before checking for
fixed filenames (such as "initrd.magic" for the dynamically generated
magic initrd file).  This minimises surprise by ensuring that an
explicitly downloaded image will always be used verbatim.

Signed-off-by: Michael Brown <mcb30@ipxe.org>

1 files changed, 33 insertions, 22 deletions

diff --git a/src/interface/efi/efi_file.c b/src/interface/efi/efi_file.c
index b232591..2ac6e2b 100644
--- a/src/interface/efi/efi_file.c
+++ b/src/interface/efi/efi_file.c
@@ -321,6 +321,33 @@ static void efi_file_image ( struct efi_file *file, struct image *image ) {
 }
 
 /**
+ * Open image-backed file
+ *
+ * @v image		Image
+ * @v new		New EFI file
+ * @ret efirc		EFI status code
+ */
+static EFI_STATUS efi_file_open_image ( struct image *image,
+					EFI_FILE_PROTOCOL **new ) {
+	struct efi_file *file;
+
+	/* Allocate and initialise file */
+	file = zalloc ( sizeof ( *file ) );
+	if ( ! file )
+		return EFI_OUT_OF_RESOURCES;
+	ref_init ( &file->refcnt, efi_file_free );
+	memcpy ( &file->file, &efi_file_root.file, sizeof ( file->file ) );
+	memcpy ( &file->load, &efi_file_root.load, sizeof ( file->load ) );
+	efi_file_image ( file, image_get ( image ) );
+
+	/* Return opened file */
+	*new = &file->file;
+
+	DBGC ( file, "EFIFILE %s opened\n", efi_file_name ( file ) );
+	return 0;
+}
+
+/**
  * Open file
  *
  * @v this		EFI file
@@ -335,7 +362,6 @@ efi_file_open ( EFI_FILE_PROTOCOL *this, EFI_FILE_PROTOCOL **new,
 		CHAR16 *wname, UINT64 mode, UINT64 attributes __unused ) {
 	struct efi_file *file = container_of ( this, struct efi_file, file );
 	char buf[ wcslen ( wname ) + 1 /* NUL */ ];
-	struct efi_file *new_file;
 	struct image *image;
 	char *name;
 
@@ -367,31 +393,16 @@ efi_file_open ( EFI_FILE_PROTOCOL *this, EFI_FILE_PROTOCOL **new,
 		return EFI_WRITE_PROTECTED;
 	}
 
+	/* Allow registered images to be opened */
+	if ( ( image = efi_file_find ( name ) ) != NULL )
+		return efi_file_open_image ( image, new );
+
 	/* Allow magic initrd to be opened */
 	if ( strcasecmp ( name, efi_file_initrd.file.name ) == 0 )
 		return efi_file_open_fixed ( &efi_file_initrd.file, new );
 
-	/* Identify image */
-	image = efi_file_find ( name );
-	if ( ! image ) {
-		DBGC ( file, "EFIFILE %s does not exist\n", name );
-		return EFI_NOT_FOUND;
-	}
-
-	/* Allocate and initialise file */
-	new_file = zalloc ( sizeof ( *new_file ) );
-	if ( ! new_file )
-		return EFI_OUT_OF_RESOURCES;
-	ref_init ( &file->refcnt, efi_file_free );
-	memcpy ( &new_file->file, &efi_file_root.file,
-		 sizeof ( new_file->file ) );
-	memcpy ( &new_file->load, &efi_file_root.load,
-		 sizeof ( new_file->load ) );
-	efi_file_image ( new_file, image_get ( image ) );
-	*new = &new_file->file;
-	DBGC ( new_file, "EFIFILE %s opened\n", efi_file_name ( new_file ) );
-
-	return 0;
+	DBGC ( file, "EFIFILE %s does not exist\n", name );
+	return EFI_NOT_FOUND;
 }
 
 /**