bug in freopen

Dave Korn dave.korn@artimi.com
Fri Jul 15 10:38:00 GMT 2005

----Original Message----
>From: Eric Blake
>Sent: 15 July 2005 00:14

> POSIX requires that freopen(NULL, mode, f) reopen f in the new
> mode, and allows implementations the option of not even closing
> f in the first place.  But in cygwin, it is failing with EFAULT, which is
> not even one of the errors allowed by POSIX.
> http://www.opengroup.org/susv3xsh/freopen.html
> #include <stdio.h>
> #include <errno.h>
> int main(void)
> {
>    FILE* f = freopen (NULL, "rb", stdin); /* Ensure that stdin is binary
>    */ printf ("file is %s, errno %d:%s\n", f ? "good" : "null", errno,
>            strerror(errno));
>    return 0;
> }
> CVS coreutils recently switched to this idiom, replacing its former
> use of the nonstandard <io.h> and setmode() with something
> that is required by the standards.  But until this bug is fixed, CVS
> coreutils will not work with cygwin.  The strace in cygwin shows
> that newlib tried to perform open(NULL), which is the cause of
> the EFAULT.

  I could take a look at this over the weekend if nobody gets to it first :)

Can't think of a witty .sigline today....

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