Re: question about uefi shell pipe.

[krishnaLee <sssky307@163.com>]

Andrew Fish,
Yes,some times I am work in C++,thanks for correct this,but if I use this:
UINT16 Buffer[80*25*4]; //tool's buffer;
UINTN BufferByteSize = sizeof(Buffer);
it still cannot work.
I had checked the read size( gShell->ReadFile(gParameters->StdIn,...)) before I post my question,it just read  some hundred of bytes,It seems the question is not about overflow...
so I want to know if I'm wrong or it is a bug?


thank you,
by krishna.







At 2018-07-04 22:55:27, "Andrew Fish" <afish@apple.com> wrote:
>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.
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