Re: question about uefi shell pipe.

[Andrew Fish <afish@apple.com>]

Krishnal,

Thanks for including the code. You are overflowing the buffer. In C sizeof(Buffer) will be 80*25*4*2 since sizeof(UINT16) is 2. Your code is passing in double the size of the buffer. 

UINT16 Buffer[80*25*4]; //tool's buffer;
UINTN BufferSize=sizeof(Buffer);
UINTN BufferByteSize=BufferSize*sizeof(UINT16);

This should work:

UINT16 Buffer[80*25*4]; //tool's buffer;
UINTN BufferByteSize = sizeof(Buffer);

Thanks,

Andrew Fish

> On Jul 4, 2018, at 2:15 AM, krishnaLee <sssky307@163.com> wrote:
> 
> Hi,
> I wrote this shell application(smalltest.efi),did some pipe function test,find some strange result.
> boot into shell:
> 
> 
> # test-1,the follow two command should has the same output ,but infact not the same in QEMU,and the second command failed WriteFile in real machine(AMI bios uefi 2.6):
> ls | smalltest.efi
> ls | smalltest.efi | smalltest.efi             # the ls command directory only has one file(this tool),so the tool's buffer 80x25*4 won't overflow.
> 
> 
> #test-2
> run smalltest.efi,
> just key in  some chars and Enter,nothing output,why?
> 
> 
> my test environment:
> UDK2018 + vs2015
> QEMU emulator version 2.10.95
> OVMF_X64.fd( x64,release build)
> 
> 
> the tool's build command:
> D:\edk2-vUDK2018>build -p ShellPkg\ShellPkg.dsc -m ShellPkg\Application2\smalltest\smalltest.inf -a X64 -b RELEASE
> 
> 
> //--------code---smalltest.c-------------
> 
> 
> #include <Uefi.h>
> #include <Library/UefiApplicationEntryPoint.h>
> #include <Library/UefiLib.h>
> #include <Library/UefiBootServicesTableLib.h>//global gST gBS gImageHandle
> #include <Library/BaseMemoryLib.h>
> #include <Library/MemoryAllocationLib.h>
> 
> 
> #include <Protocol/Shell.h>
> #include <Protocol/ShellParameters.h>
> 
> 
> 
> EFI_STATUS
> EFIAPI
> UefiMain (
> IN EFI_HANDLE ImageHandle,
> IN EFI_SYSTEM_TABLE *SystemTable
> )
> {
> EFI_STATUS status;
> EFI_SHELL_PROTOCOL* gShell;
> EFI_SHELL_PARAMETERS_PROTOCOL*gParameters;
> UINT16 Buffer[80*25*4]; //tool's buffer;
> UINTN BufferSize=sizeof(Buffer);
> UINTN BufferByteSize=BufferSize*sizeof(UINT16);
> 
> 
> status=gBS->HandleProtocol(gImageHandle,&gEfiShellParametersProtocolGuid,&gParameters);
> if(status!=EFI_SUCCESS)
> {
> Print(L"locate gEfiShellParametersProtocolGuid failed.\n");
> return status;
> }
> 
> 
> status=gBS->LocateProtocol(&gEfiShellProtocolGuid,NULL,&gShell);
> if(status!=EFI_SUCCESS)
> {
> Print(L"locate gEfiShellProtocolGuid failed.\n");
> return status;
> }
> 
> 
> status=gShell->ReadFile(gParameters->StdIn,&BufferByteSize,(VOID*)Buffer);
> if(status!=EFI_SUCCESS)
> {
> Print(L"read from gParameters->StdIn failed.\n");
> return status;
> }
> 
> 
> status=gShell->WriteFile(gParameters->StdOut,&BufferByteSize,(VOID*)Buffer);
> if(status!=EFI_SUCCESS)
> {
> Print(L"wirte gParameters->StdOut failed\n");
> return status;
> }
> 
> 
> gShell->FlushFile(gParameters->StdOut);
> 
> 
> return EFI_SUCCESS;
> }
> 
> 
> //--------code---smalltest.inf-------------
> 
> 
> [Defines]
>  INF_VERSION                    = 0x00010005
>  BASE_NAME                      = smalltest
>  FILE_GUID                      = 8F7D7B1D-0E1C-4c98-B12E-4EC99C400704
>  MODULE_TYPE                    = UEFI_APPLICATION
>  VERSION_STRING                 = 1.0
>  ENTRY_POINT                    = UefiMain
> 
> 
> [Sources]
>  smalltest.c
> 
> 
> [Packages]
>  MdePkg/MdePkg.dec
> 
> 
> [Protocols]
> gEfiShellProtocolGuid
> gEfiShellParametersProtocolGuid
> 
> 
> [LibraryClasses]
>  UefiApplicationEntryPoint
>  UefiLib
> //--------code---end----------------------------------------------------------
> 
> 
> 
> 
> 
> 
> thank you, 
> by krishna.
> _______________________________________________
> edk2-devel mailing list
> edk2-devel@lists.01.org
> https://lists.01.org/mailman/listinfo/edk2-devel