tyler.durden/audk
1
0
Fork 0
mirror of https://github.com/acidanthera/audk.git synced 2025-04-08 17:05:09 +02:00
Code Issues Packages Projects Releases Wiki Activity

ShellPkg/UefiShellLib: clarify workaround for unfixable EdkShell bug

Browse Source 
The EDK 1 Shell (available at <https://github.com/tianocore/edk-Shell>)
has a bug in its EFI_SHELL_ENVIRONMENT2.Execute() implementation that
edk2's UefiShellLib has no choice but to work around.

Improve the explanation in the code. Also, document the implicit
EFI_HANDLE -> (EFI_HANDLE*) conversion, which happens implicitly after
dereferencing ParentHandle, with an explicit cast.

In practice, this patch is a no-op.

Cc: Jaben Carsey <jaben.carsey@intel.com>
Cc: Ray Ni <ray.ni@intel.com>
Cc: Zhichao Gao <zhichao.gao@intel.com>
Signed-off-by: Laszlo Ersek <lersek@redhat.com>
Reviewed-by: Zhichao Gao <zhichao.gao@intel.com>
Reviewed-by: Jaben Carsey <jaben.carsey@intel.com>
This commit is contained in:
Laszlo Ersek 2019-09-07 00:19:29 +02:00
parent d5e35fddec
commit 7eb6160d4f
1 changed files with 20 additions and 2 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

22
ShellPkg/Library/UefiShellLib/UefiShellLib.c
View File

@ -1291,9 +1291,27 @@ ShellExecute (
if (mEfiShellEnvironment2 != NULL) {
//
// Call EFI Shell version.
// Due to oddity in the EFI shell we want to dereference the ParentHandle here
//
CmdStatus = (mEfiShellEnvironment2->Execute(*ParentHandle,
// Due to an unfixable bug in the EdkShell implementation, we must
// dereference "ParentHandle" here:
//
// 1. The EFI shell installs the EFI_SHELL_ENVIRONMENT2 protocol,
// identified by gEfiShellEnvironment2Guid.
// 2. The Execute() member function takes "ParentImageHandle" as first
// parameter, with type (EFI_HANDLE*).
// 3. In the EdkShell implementation, SEnvExecute() implements the
// Execute() member function. It passes "ParentImageHandle" correctly to
// SEnvDoExecute().
// 4. SEnvDoExecute() takes the (EFI_HANDLE*), and passes it directly --
// without de-referencing -- to the HandleProtocol() boot service.
// 5. But HandleProtocol() takes an EFI_HANDLE.
//
// Therefore we must
// - de-reference "ParentHandle" here, to mask the bug in
// SEnvDoExecute(), and
// - pass the resultant EFI_HANDLE as an (EFI_HANDLE*).
//
CmdStatus = (mEfiShellEnvironment2->Execute((EFI_HANDLE *)*ParentHandle,
CommandLine,
Output));
//