GetStdHandle related question

[themughal]

Hi,

I am writing masm32 console code using win32 api, the program prints an intro line and ask user name, then try to print the name, for intro I am using STD_OUTPUT_HANDLE and for getting user input I am using STD_INPUT_HANDLE. All goes well except the last greet output with username, the code is below:
=======================================================================
.Data
hInstOut    HINSTANCE    NULL
hInstIn        HINSTANCE    NULL
intro        db    "Hi, What is your name: ",0
greet        db    "Welcome to WinAssembly "
mname        db    50 dup (0)
.Code

start:
    Invoke GetStdHandle, STD_OUTPUT_HANDLE
    Mov hInstOut, Eax
   
    Invoke GetStdHandle, STD_INPUT_HANDLE
    Mov hInstIn, Eax
   
    Invoke WriteConsole, hInstOut, addr intro, sizeof intro, NULL, NULL
    Invoke ReadConsole, hInstIn, addr mname, 50, NULL, NULL
    Invoke WriteConsole, hInstOut, addr greet, 60, NULL, NULL
    Invoke ExitProcess, 0
End start
========================================================
The expected last line "Welcome to WinAssembly USERNAME" is not printing.

[zedd151]

The string greet is not zero terminated.

Oh, I see you want to concatenate the user name to it. At first glance I did not notice, but did notice after I posted.

I am not at my computer at the moment, but on my iPad. Else I would have looked at it further.... maybe later today.

Welcome back, Professor.

[zedd151]

Code Select Expand

include \masm32\include\masm32rt.inc

.Data
hInstOut    HINSTANCE    NULL
hInstIn        HINSTANCE    NULL
intro        db    "Hi, What is your name: ",0
greet        db    "Welcome to WinAssembly "
mname        db    50 dup (0)
bread        dd 0
.Code

start:
    Invoke GetStdHandle, STD_OUTPUT_HANDLE
    Mov hInstOut, Eax
 
    Invoke GetStdHandle, STD_INPUT_HANDLE
    Mov hInstIn, Eax
   
    Invoke WriteConsole, hInstOut, addr intro, sizeof intro, NULL, NULL
    Invoke ReadConsole, hInstIn, addr mname, 50, addr bread, NULL
   
    invoke lstrlen, addr greet
    Invoke WriteConsole, hInstOut, addr greet, eax, NULL, NULL
    inkey
    Invoke ExitProcess, 0
end start
three things:
I used lstrlen to get the proper concatenated length of "greet", it is in eax after returning from lstrlen.

Also added variable bread for number of bytes read. mname was not getting copied into buffer.

And added macro call inkey to wait for user to press any key before exit, to pause before exiting. I am assuming that you have masm32 SDK installed. Link in upper right corner, if not.


Free tip: Get yourself a stepping debugger such as ollydbg 1.10 or  x32dbg or similar to assist in troubleshooting. Invaluable for debugging.

[Vortex]

Hi themughal,

Here is another example, the StdOut function using GetStdHandle :

Code Select Expand

\masm32\m32lib\stdout.asm

Code Select Expand

StdOut proc lpszText:DWORD

    LOCAL hOutPut  :DWORD
    LOCAL bWritten :DWORD
    LOCAL sl       :DWORD

    invoke GetStdHandle,STD_OUTPUT_HANDLE
    mov hOutPut, eax

    invoke StrLen,lpszText
    mov sl, eax

    invoke WriteFile,hOutPut,lpszText,sl,ADDR bWritten,NULL

    mov eax, bWritten
    ret

StdOut endp

[NoCforMe]

Instead of having to mess with getting all those handles and passing them to WriteFile(), I like to use the simplified functions that Steve provided for us in the MASM32 package:

Code Select Expand

INVOKE StdOut, OFFSET CompressedErrMsg

It's there if you include masm32rt.inc and takes care of getting the handles for you. All you need to provide is the offset of the string to display. (There's a complementary function that reads from the console as well, don't know it's exact name at the moment.)

[NoCforMe]

I'm guessing it's StdIn().

[jj2007]

Invoke ReadConsole, hInstIn, addr mname, 50, NULL, NULL

mov [edi], eax some where in ReadConsole, and edi==0

The "characters read" variable is not optional. Read the docs.