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From:	"Rod Pemberton" <do_not_have AT nohavenot DOT cmm>
Newsgroups:	comp.os.msdos.djgpp
Subject:	setmode
Date:	Thu, 2 Apr 2009 19:02:06 -0400
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To:	djgpp AT delorie DOT com
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Ok, I have a program which normally outputs to a file as binary.  I'd like
to optionally output to stdout when no output file is specified.  However,
stdout is in text mode.  Therefore, when the output of the program is
redirected to a file from the DOS command line an extra ASCII CR 0x0D is
being inserted into the file's saved output for every newline, i.e., 0x0D
0x0D 0x0A instead of 0x0D 0x0A.  The following setmode() line corrects the
problem, but it isn't ANSI C:

    setmode(fileno(stdout), O_BINARY);

First, is there an equivalent to this in ANSI C?

Second, shouldn't I be able to do the exactly same as the setmode() line
with ANSI C's freopen()?  I.e., if I freopen() stdout as "wb", shouldn't
this be functionally identical?

Third, if there isn't an ANSI C equivalent, is there a way to
surrepticiously do the equivalent to that setmode line in DJGPP - which uses
some combination of ANSI C functions?  E.g., freopen() calls open() which
then calls setmode().  So, shouldn't there be some way to do the same the
setmode() line above using freopen()?

So far, I've tried the following with freopen():

/* fails, captures extra CR when stdout redirected to file */
    freopen(NULL,"wb",stdout);

/* fails, sends to screen, but won't redirect from screen to file */
    freopen("CON","wb",stdout);

/* fails, sends to screen, but won't redirect from screen to file*/
    freopen("/dev/tty","wb",stdout);

/* fails, sends to file CONOUT$, not to screen */
    freopen("CONOUT$","wb",stdout);

/* fails, sends to file asdf, not to screen */
    freopen("asdf","wb",stdout);

How do I get both redirection capability and binary output with stdout when
using ANSI C functions such as freopen()?...


Rod Pemberton

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