diff options
| -rw-r--r-- | ShellPkg/Library/UefiShellLib/UefiShellLib.c | 22 |
1 files changed, 20 insertions, 2 deletions
diff --git a/ShellPkg/Library/UefiShellLib/UefiShellLib.c b/ShellPkg/Library/UefiShellLib/UefiShellLib.c index 835d0f88ca..9f07a58eb2 100644 --- a/ShellPkg/Library/UefiShellLib/UefiShellLib.c +++ b/ShellPkg/Library/UefiShellLib/UefiShellLib.c @@ -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));
//
|