Hi,
Normally from a C app, I'd use printf and if I ran the app from the console as follows:
myapp.exe param > out.txt
The printf calls would be redirected to file.
However, using msvcrt.lib/masm32 include etc from an asm program the same does not work.
normal calls to print / StdOut macro ARE being redirected, however all printf's stay on screen...
Any ideas?
Thanks
John
I'm wondering if the C app does some CRT init that allows the printf redirection to work?
Jpohn,
If you have MASM32 version 11, just use the "printf" macro, it works very close to the C original. Michael Webster wrote the original macro and it has had a UNICODE version added as well. Both call functions from MSVCRT.
is the subsystem = CONSOLE or did you use AllocConsole()? - allocated consoles requires to set CRT's I/O handles (http://www.masm32.com/board/index.php?topic=15984.0).
Quote from: johnsa on February 02, 2012, 10:50:57 AM
I'm wondering if the C app does some CRT init that allows the printf redirection to work?
Can't check right now but that's probably the issue.
subsystem = console.
I really think it's something to do with CRt startup..
If the printf macro also calls msvcrt it's going to have the same problem?
you might try using setvbuf to set the buffering mode - the CRT startup code may well do this
http://msdn.microsoft.com/en-us/library/86cebhfs%28v=vs.80%29.aspx
i found this example in C
http://www.pixelbeat.org/programming/stdio_buffering/obuffer.c
you may show us your code ...
John,
Try this with MASM32 version 11.
; ¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤
__UNICODE__ equ 1
include \masm32\include\masm32rt.inc
; ¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤
.code
start:
; ¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤
call main
inkey
exit
; ¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤
main proc
printf("this is the MASM32 default version of \qprintf\q\n\n");
printf("It handles numbers using the normal C escapes\n\n");
printf("%X or %x or %u or %d\n\n",1234,1234,1234,-1234);
ret
main endp
; ¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤
end start
This is the output to the console.
this is the MASM32 default version of "printf"
It handles numbers using the normal C escapes
4D2 or 4d2 or 1234 or -1234
Press any key to continue ...
...if Hutch's example doesn't work...
i found some code by qWord that uses setvbuf for piping...
http://www.masm32.com/board/index.php?topic=15984.msg132047#msg132047
Just a guess (unable to check right now)...
If printf is using WriteConsole, then redirection will fail.
Using WriteFile with GetStdHandle(STD_OUTPUT_HANDLE) as the file-handle does work correctly (output goes to the console by default, or to a file if redirected to one, etc.)
out of curiosity, i made a small app using printf
it redirects with no problems
maybe it's the specific format you are using - or, perhaps, the environment
are you running in a virtual environment or something ?
This KB article shows a way to do it programmatically in C/C++:
http://support.microsoft.com/kb/58667
But I could not find a way to do it from a MASM app until I found this:
http://www.masm32.com/board/index.php?topic=17326.msg145357#msg145357
;==============================================================================
include \masm32\include\masm32rt.inc
;==============================================================================
_iobuf STRUCT
_ptr DWORD ?
_cnt DWORD ?
_base DWORD ?
_flag DWORD ?
_file DWORD ?
_charbuf DWORD ?
_bufsiz DWORD ?
_tmpfname DWORD ?
_iobuf ENDS
FILE TYPEDEF _iobuf
stdout MACRO
call crt___p__iob
add eax, SIZEOF FILE
EXITM <eax>
ENDM
;==============================================================================
.data
.code
;==============================================================================
start:
printf("before redirect\n");
invoke crt_freopen, chr$("file.txt"), chr$("w"), stdout()
printf("after redirect\n");
invoke crt_freopen, chr$("CON"), chr$("w"), stdout()
printf("after re-redirect\n");
inkey
exit
;==============================================================================
end start
stdout MACRO
call crt___p__iob
add eax, SIZEOF FILE
EXITM <eax>
ENDM
that's the part i could not figure out from the documentation
mainly because the C compiler does it for you - little need to document what goes on under the hood :P
what i don't get with that code is that you are using a "printf" macro from someplace
in Erol's code, he uses fprintf
i am gonna steal your stdout macro :bg
i'd be interested to know if this code works under windows 7
i am guessing the problem is due to the fact that, under win 7, the console is run in a virtualized environment
EDIT: corrected the code - see post #15
Quote from: dedndave on February 03, 2012, 04:30:09 AM
stdout MACRO
call crt___p__iob
add eax, SIZEOF FILE
EXITM <eax>
ENDM
that's the part i could not figure out from the documentation
mainly because the C compiler does it for you - little need to document what goes on under the hood :P
what i don't get with that code is that you are using a "printf" macro from someplace
in Erol's code, he uses fprintf
I'm using the printf macro from MASM32 v11r.
I should have included some additional information that I got from the Microsoft header files when I was trying to figure out how I could get the address of the CRT's iob (i/o buffer) array.
struct _iobuf {
char *_ptr;
int _cnt;
char *_base;
int _flag;
int _file;
int _charbuf;
int _bufsiz;
char *_tmpfname;
};
typedef struct _iobuf FILE;
/* Declare _iob[] array */
#ifndef _STDIO_DEFINED
_CRTIMP extern FILE _iob[];
#endif /* _STDIO_DEFINED */
#define stdin (&_iob[0])
#define stdout (&_iob[1])
#define stderr (&_iob[2])
updated and corrected code from post #13:
.XCREF
.NOLIST
INCLUDE \masm32\include\masm32rt.inc
.LIST
;#################################################################################
IFNDEF _IONBF
_IONBF EQU 4
ENDIF
;*********************************************************************************
IFNDEF _iobuf
_iobuf STRUCT
_ptr dd ?
_cnt dd ?
_base dd ?
_flag dd ?
_file dd ?
_charbuf dd ?
_bufsiz dd ?
_tmpfname dd ?
_iobuf ENDS
ENDIF
;*********************************************************************************
IFNDEF FILE
FILE TYPEDEF _iobuf
ENDIF
;#################################################################################
.DATA
szDelim db 13,10,'%s setvbuf',13,10,0
szBefor db 'Before',0
szAfter db 'After',0
;*********************************************************************************
; .DATA?
;#################################################################################
.CODE
;*********************************************************************************
_main PROC
INVOKE crt_printf,offset szDelim,offset szBefor
CALL crt___p__iob
add eax,sizeof FILE
INVOKE crt_setvbuf,eax,NULL,_IONBF,NULL
INVOKE crt_printf,offset szDelim,offset szAfter
INVOKE ExitProcess,0
_main ENDP
;#################################################################################
END _main