MdePkg/UefiLib: don't special-case EFI_FILE_MODE_CREATE in OpenMode

While reviewing the patch that would land as 768b611136d0
("MdePkg/UefiLib: introduce EfiOpenFileByDevicePath()", 2018-08-16), Ray
pointed out that distinguishing EFI_FILE_MODE_CREATE was wasteful. Per
spec, if the file to create exists, then EFI_FILE_MODE_CREATE is ignored
by EFI_FILE_PROTOCOL.Open(), and the existent file is opened.

Therefore we don't need an attempt to "open-but-not-create" first, and a
fallback to "open-and-create-too" second -- that behavior is internal to
EFI_FILE_PROTOCOL.Open(). Remove the special-casing of
EFI_FILE_MODE_CREATE.

Cc: Liming Gao <liming.gao@intel.com>
Cc: Michael D Kinney <michael.d.kinney@intel.com>
Cc: Ruiyu Ni <ruiyu.ni@intel.com>
Suggested-by: Ruiyu Ni <ruiyu.ni@intel.com>
Ref: https://bugzilla.tianocore.org/show_bug.cgi?id=1074
Contributed-under: TianoCore Contribution Agreement 1.1
Signed-off-by: Laszlo Ersek <lersek@redhat.com>
Reviewed-by: Liming Gao <liming.gao@intel.com>

1 files changed, 3 insertions, 16 deletions

diff --git a/MdePkg/Include/Library/UefiLib.h b/MdePkg/Include/Library/UefiLib.h
index f950f1c..f80067f 100644
--- a/MdePkg/Include/Library/UefiLib.h
+++ b/MdePkg/Include/Library/UefiLib.h
@@ -1533,12 +1533,7 @@ EfiLocateProtocolBuffer (
 

   On the remaining device path, the longest initial sequence of

   FILEPATH_DEVICE_PATH nodes is node-wise traversed with

-  EFI_FILE_PROTOCOL.Open(). For the pathname fragment specified by each

-  traversed FILEPATH_DEVICE_PATH node, EfiOpenFileByDevicePath() first masks

-  EFI_FILE_MODE_CREATE out of OpenMode, and passes 0 for Attributes. If

-  EFI_FILE_PROTOCOL.Open() fails, and OpenMode includes EFI_FILE_MODE_CREATE,

-  then the operation is retried with the caller's OpenMode and Attributes

-  unmodified.

+  EFI_FILE_PROTOCOL.Open().

 

   (As a consequence, if OpenMode includes EFI_FILE_MODE_CREATE, and Attributes

   includes EFI_FILE_DIRECTORY, and each FILEPATH_DEVICE_PATH specifies a single

@@ -1570,18 +1565,10 @@ EfiLocateProtocolBuffer (
                            the last node in FilePath.

 

   @param[in] OpenMode      The OpenMode parameter to pass to

-                           EFI_FILE_PROTOCOL.Open(). For each

-                           FILEPATH_DEVICE_PATH node in FilePath,

-                           EfiOpenFileByDevicePath() first opens the specified

-                           pathname fragment with EFI_FILE_MODE_CREATE masked

-                           out of OpenMode and with Attributes set to 0, and

-                           only retries the operation with EFI_FILE_MODE_CREATE

-                           unmasked and Attributes propagated if the first open

-                           attempt fails.

+                           EFI_FILE_PROTOCOL.Open().

 

   @param[in] Attributes    The Attributes parameter to pass to

-                           EFI_FILE_PROTOCOL.Open(), when EFI_FILE_MODE_CREATE

-                           is propagated unmasked in OpenMode.

+                           EFI_FILE_PROTOCOL.Open().

 

   @retval EFI_SUCCESS            The file or directory has been opened or

                                  created.