[PATCH v2 2/2] efi_loader: create boot options without file path

[Heinrich Schuchardt]

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.g...@gmx.de>
---
v2:
        update the function description of efi_dp_from_file()
---
 lib/efi_loader/efi_device_path.c | 33 +++++++++++++++++++++++---------
 1 file 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;

--
2.36.1