bug in freopen
Fri Jul 15 07:32:00 GMT 2005
> -----Original Message-----
> From: firstname.lastname@example.org
> [mailto:email@example.com] On Behalf Of Eric Blake
> Sent: Friday, July 15, 2005 1:14 AM
> To: firstname.lastname@example.org; email@example.com
> Subject: bug in freopen
> 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.
Just to be pedantic: POSIX allows system interfaces to set <errno> to
values additional to those documented in the standard, so this in itself
is not necessarily a bug.
Of course, freopen() should not be calling open() with NULL, it appears
this case has not been implemented in newlib.
> #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,
> 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.
> Eric Blake
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