RE: libstdc++/9533: Regression: Can't read from tty with ifstream

["Pétur Runólfsson" <peturr02@ru.is>]

The following reply was made to PR libstdc++/9533; it has been noted by GNATS.

From: =?iso-8859-1?Q?P=E9tur_Run=F3lfsson?= <peturr02@ru.is>
To: <paolo@gcc.gnu.org>,
	<gcc-bugs@gcc.gnu.org>,
	<nobody@gcc.gnu.org>,
	=?iso-8859-1?Q?P=E9tur_Run=F3lfsson?= <peturr02@ru.is>,
	<gcc-gnats@gcc.gnu.org>
Cc:  
Subject: RE: libstdc++/9533: Regression: Can't read from tty with ifstream
Date: Sun, 2 Mar 2003 18:23:24 -0000

 >     Something is wrong, agreed, but I cannot reproduce the
 >     regression thing: for me (*), 3.2.2 asks the number but
 >     then hangs upon <newline>. Same behaviour 3.0.4.
 
 Yes, that is the same behaviour I get (with 3.2.1). However,
 mainline fails in a different manner (the program just exits).
 I believe the culprit is this code in basic_file_stdio.cc
 (__basic_file<char>::open), which is not present on the 3.2
 branch:
 
 #if defined (F_SETFL) && defined (O_NONBLOCK)
 	    // Set input to nonblocking for fifos.
 	    if (__mode & ios_base::in)
 	      fcntl(this->fd(), F_SETFL, O_NONBLOCK);
 #endif
 
 This causes fread to return 0 immediately instead of waiting
 for input, which in turn causes underflow to return eof().
 
 Also, I think this counts as a regression, since the hang
 (when compiled with 3.2.x) can be avoided by setting the
 buffer size to 1.
 
 Petur