Empty Pipe

[PushPop]

Hello
How do I understand when the pipe is empty?
The code is attached
Thank you


.data
    BytesWritten dd 0
.data?
    stinfo STARTUPINFO <>
.code

;++++++++++++++++++++++++++++++++++++++++++++++++++
;invoke Shell,chr$("C:\Windows\system32\cmd.exe"),chr$("dir /S /B D:\masm32\examples\"),addr outbuffer
;+++++++++++++++++++++++++++++++++++++++++++++++++

Shell proc CommandLine :DWORD,Param:DWORD,lpbuffer:DWORD
    LOCAL hChildStd_In_Rd  :DWORD
    LOCAL hChildStd_In_Wr  :DWORD
    LOCAL hChildStd_Out_Rd :DWORD
    LOCAL hChildStd_Out_Wr :DWORD
    LOCAL hParentStd_Out   :DWORD
;   LOCAL pbuffer [1024]:BYTE
    LOCAL security_attrib  :SECURITY_ATTRIBUTES
    LOCAL pinfo :PROCESS_INFORMATION


   mov security_attrib.lpSecurityDescriptor,0
   mov security_attrib.bInheritHandle,TRUE
   mov security_attrib.nLength,sizeof SECURITY_ATTRIBUTES
   
   invoke CreatePipe,addr hChildStd_Out_Rd ,addr hChildStd_Out_Wr,addr security_attrib,0
   or eax,eax
   jz EX
   invoke CreatePipe,addr hChildStd_In_Rd ,addr hChildStd_In_Wr,addr security_attrib,0
   or eax,eax
   jz EX
   invoke SetHandleInformation,hChildStd_Out_Rd,HANDLE_FLAG_INHERIT, 0
   or eax,eax
   jz EX
   invoke SetHandleInformation,hChildStd_In_Wr,HANDLE_FLAG_INHERIT, 0
   or eax,eax
   jz EX
   mov stinfo.cb,sizeof STARTUPINFO
   mov eax,hChildStd_Out_Wr
   mov stinfo.hStdError,eax
   mov stinfo.hStdOutput,eax
   mov eax,hChildStd_In_Rd
   mov stinfo.hStdInput,eax
   mov stinfo.dwFlags,STARTF_USESHOWWINDOW+STARTF_USESTDHANDLES
;   mov stinfo.wShowWindow,SW_HIDE
   invoke CreateProcess,CommandLine,0,0,0,TRUE,NULL,0,0,offset stinfo,addr pinfo
   or eax,eax
   jz EX
   invoke WriteFile,hChildStd_In_Wr,Param,1024,addr BytesWritten,0
   invoke CloseHandle, hChildStd_Out_Wr
   
   invoke Sleep,50
   
   invoke ReadFile,hChildStd_Out_Rd,lpbuffer,1024,addr BytesWritten,0
   EX:
    ret

Shell endp

[TouEnMasm]

Seems you have a simplify version of the pipe.
the readfile must entry in a loop until he received a number of ZERO byte.
Try to find a sample working well in c who perhaps here.

Here a sample (in french ??) http://luce.yves.pagesperso-orange.fr/_tut21.html
copy paste the sample must be enough

[fearless]

I have an example reading a pipe from child process and writing back to parent pipe, which uses a loop to keep peeking, reading and writing whilst there is stuff to read/write: https://github.com/mrfearless/EEexLoader/blob/master/EEex/EEexConsole.asm#L145

[deeR44]

I have an example reading a pipe from child process and writing back to parent pipe, which uses a loop to keep peeking, reading and writing whilst there is stuff to read/write: https://github.com/mrfearless/EEexLoader/blob/master/EEex/EEexConsole.asm#L145

In this link, there is a lot of "EEEX_ALIGN" labels. What is "EEEX_ALIGN"? I have never seen this term before.

[fearless]

Code Select Expand

.CONST
EEEX_ALIGN    TEXTEQU <ALIGN 16>