@section @code{dup2}
@findex dup2
-POSIX specification: @url{http://www.opengroup.org/onlinepubs/9699919799/functions/dup2.html}
+POSIX specification:@* @url{http://www.opengroup.org/onlinepubs/9699919799/functions/dup2.html}
-Gnulib module: dup2
+Gnulib module: dup2 or dup2-obsolete
-Portability problems fixed by Gnulib:
+Portability problems fixed by either Gnulib module @code{dup2} or @code{dup2-obsolete}:
@itemize
@item
This function always returns 0 for success on some platforms:
mingw.
@item
-This function returns 0 for @code(dup2 (1, 1)} on some platforms:
+This function resets the @code{FD_CLOEXEC} flag when duplicating an fd
+to itself on some platforms:
+Haiku.
+
+@item
+This function returns 0 for @code{dup2 (1, 1)} on some platforms:
Cygwin 1.5.x.
@item
This function may return @code{-EBADF} instead of @code{-1} on some platforms:
-Linux releases between July 2008 and May 2009.
+Linux releases between July 2008 and May 2009 (versions 2.6.27 to 2.6.29).
+
+@item
+This function returns @code{EMFILE} instead of @code{EBADF} for
+extremely large targets, which interferes with using
+@code{dup2(fd,fd)==fd)} as the minimal @code{EBADF} filter:
+FreeBSD 6.1, Cygwin 1.5.
+@end itemize
+Portability problems fixed by Gnulib module @code{dup2-obsolete}:
+@itemize
@item
This function is missing on some older platforms.
@end itemize