efi_loader: create boot options without file path

Allow the efidebug command to create boot options without file path, e.g.

    efidebug boot add -b 0001 'short dev only' host 0:1 ''
    efidebug boot add -B 0002 'long dev only' host 0:1 ''

Signed-off-by: Heinrich Schuchardt <xypron.glpk@gmx.de>

1 files changed, 24 insertions, 9 deletions

diff --git a/lib/efi_loader/efi_device_path.c b/lib/efi_loader/efi_device_path.c
index 50a988c561..171661b897 100644
--- a/lib/efi_loader/efi_device_path.c
+++ b/lib/efi_loader/efi_device_path.c
@@ -973,9 +973,22 @@ static void path_to_uefi(void *uefi, const char *src)
 	*pos = 0;
 }
 
-/*
- * If desc is NULL, this creates a path with only the file component,
- * otherwise it creates a full path with both device and file components
+/**
+ * efi_dp_from_file() - create device path for file
+ *
+ * The function creates a device path from the block descriptor @desc and the
+ * partition number @part and appends a device path node created describing the
+ * file path @path.
+ *
+ * If @desc is NULL, the device path will not contain nodes describing the
+ * partition.
+ * If @path is an empty string "", the device path will not contain a node
+ * for the file path.
+ *
+ * @desc:	block device descriptor or NULL
+ * @part:	partition number
+ * @path:	file path on partition or ""
+ * Return:	device path or NULL in case of an error
  */
 struct efi_device_path *efi_dp_from_file(struct blk_desc *desc, int part,
 		const char *path)
@@ -1002,12 +1015,14 @@ struct efi_device_path *efi_dp_from_file(struct blk_desc *desc, int part,
 		buf = dp_part_fill(buf, desc, part);
 
 	/* add file-path: */
-	fp = buf;
-	fp->dp.type = DEVICE_PATH_TYPE_MEDIA_DEVICE;
-	fp->dp.sub_type = DEVICE_PATH_SUB_TYPE_FILE_PATH;
-	fp->dp.length = (u16)fpsize;
-	path_to_uefi(fp->str, path);
-	buf += fpsize;
+	if (*path) {
+		fp = buf;
+		fp->dp.type = DEVICE_PATH_TYPE_MEDIA_DEVICE;
+		fp->dp.sub_type = DEVICE_PATH_SUB_TYPE_FILE_PATH;
+		fp->dp.length = (u16)fpsize;
+		path_to_uefi(fp->str, path);
+		buf += fpsize;
+	}
 
 	*((struct efi_device_path *)buf) = END;