Commit fdd1b511 authored by Eric Blake's avatar Eric Blake

dup2, dup3: work around another cygwin crasher

Cygwin 1.7.25 can crash due to an off-by-one bug on an attempt to
duplicate a file into the current RLIMIT_NOFILE soft limit, when
that limit is smaller than the hard limit.  The intent in the
cygwin code was to allow the dup and auto-increase the soft limit,
which is itself questionable (and which we work around in the
gnulib getdtablesize module); but avoiding the crash is worth
doing even if the soft limit semantics are wrong.

http://cygwin.com/ml/cygwin/2013-09/msg00397.html
http://cygwin.com/ml/cygwin-developers/2013-q3/msg00010.html

* m4/dup2.m4 (gl_FUNC_DUP2): Expose the bug.
* m4/dup3.m4 (gl_FUNC_DUP3): Likewise.
* tests/test-dup2.c (main): Likewise.
* lib/dup2.c (rpl_dup2): Use setdtablesize to avoid it.
* lib/dup3.c (dup3): Likewise.
* doc/posix-functions/dup2.texi (dup2): Document it.
* doc/glibc-functions/dup3.texi (dup3): Likewise.
Signed-off-by: default avatarEric Blake <eblake@redhat.com>
parent 3bd0d48d
2013-09-26 Eric Blake <eblake@redhat.com>
dup2, dup3: work around another cygwin crasher
* m4/dup2.m4 (gl_FUNC_DUP2): Expose the bug.
* m4/dup3.m4 (gl_FUNC_DUP3): Likewise.
* tests/test-dup2.c (main): Likewise.
* lib/dup2.c (rpl_dup2): Use setdtablesize to avoid it.
* lib/dup3.c (dup3): Likewise.
* doc/posix-functions/dup2.texi (dup2): Document it.
* doc/glibc-functions/dup3.texi (dup3): Likewise.
getdtablesize: work around cygwin issue
* m4/getdtablesize.m4 (gl_FUNC_GETDTABLESIZE): Detect problem.
* modules/getdtablesize (configure.ac): Build replacement.
......@@ -10,6 +10,10 @@ Portability problems fixed by Gnulib:
This function is missing on many non-glibc platforms:
Mac OS X 10.5, FreeBSD 6.0, NetBSD 5.0, OpenBSD 3.8, Minix 3.1.8, AIX 5.1, HP-UX 11,
IRIX 6.5, OSF/1 5.1, Solaris 11 2011-11, Cygwin 1.7.1, mingw, MSVC 9, Interix 3.5, BeOS.
@item
This function can crash on some platforms:
Cygwin 1.7.25.
@end itemize
Portability problems not fixed by Gnulib:
......
......@@ -20,6 +20,10 @@ mingw, MSVC 9.
This function crashes when invoked with invalid arguments on some platforms:
Cygwin 1.7.17, MSVC 9.
@item
This function crashes when invoked with valid arguments on some platforms:
Cygwin 1.7.25.
@item
This function resets the @code{FD_CLOEXEC} flag when duplicating an fd
to itself on some platforms:
......
......@@ -96,7 +96,11 @@ rpl_dup2 (int fd, int desired_fd)
/* On Linux kernels 2.6.26-2.6.29, dup2 (fd, fd) returns -EBADF.
On Cygwin 1.5.x, dup2 (1, 1) returns 0.
On Cygwin 1.7.17, dup2 (1, -1) dumps core.
On Cygwin 1.7.25, dup2 (1, 256) can dump core.
On Haiku, dup2 (fd, fd) mistakenly clears FD_CLOEXEC. */
# if HAVE_SETDTABLESIZE
setdtablesize (desired_fd + 1);
# endif
if (desired_fd < 0)
fd = desired_fd;
if (fd == desired_fd)
......
......@@ -30,6 +30,10 @@ dup3 (int oldfd, int newfd, int flags)
{
#if HAVE_DUP3
# undef dup3
# if HAVE_SETDTABLESIZE
/* Avoid a cygwin crasher. */
setdtablesize (newfd + 1);
# endif
/* Try the system call first, if it exists. (We may be running with a glibc
that has the function but with an older kernel that lacks it.) */
{
......
#serial 19
#serial 20
dnl Copyright (C) 2002, 2005, 2007, 2009-2013 Free Software Foundation, Inc.
dnl This file is free software; the Free Software Foundation
dnl gives unlimited permission to copy and/or distribute it,
......@@ -39,9 +39,11 @@ AC_DEFUN([gl_FUNC_DUP2],
/* Many gnulib modules require POSIX conformance of EBADF. */
if (dup2 (2, 1000000) == -1 && errno != EBADF)
result |= 16;
/* Flush out a cygwin core dump. */
/* Flush out some cygwin core dumps. */
if (dup2 (2, -1) != -1 || errno != EBADF)
result |= 32;
dup2 (2, 255);
dup2 (2, 256);
return result;
])
],
......@@ -65,6 +67,7 @@ AC_DEFUN([gl_FUNC_DUP2],
*yes) ;;
*)
REPLACE_DUP2=1
AC_CHECK_FUNCS([setdtablesize])
;;
esac
fi
......
# dup3.m4 serial 4
# dup3.m4 serial 5
dnl Copyright (C) 2009-2013 Free Software Foundation, Inc.
dnl This file is free software; the Free Software Foundation
dnl gives unlimited permission to copy and/or distribute it,
......@@ -11,7 +11,7 @@ AC_DEFUN([gl_FUNC_DUP3],
dnl Persuade glibc <unistd.h> to declare dup3().
AC_REQUIRE([AC_USE_SYSTEM_EXTENSIONS])
AC_CHECK_FUNCS_ONCE([dup3])
AC_CHECK_FUNCS_ONCE([dup3 setdtablesize])
if test $ac_cv_func_dup3 != yes; then
HAVE_DUP3=0
fi
......
......@@ -150,6 +150,15 @@ main (void)
errno = 0;
ASSERT (dup2 (fd, -2) == -1);
ASSERT (errno == EBADF);
if (bad_fd > 256)
{
ASSERT (dup2 (fd, 255) == 255);
ASSERT (dup2 (fd, 256) == 256);
ASSERT (close (255) == 0);
ASSERT (close (256) == 0);
}
ASSERT (dup2 (fd, bad_fd - 1) == bad_fd - 1);
ASSERT (close (bad_fd - 1) == 0);
errno = 0;
ASSERT (dup2 (fd, bad_fd) == -1);
ASSERT (errno == EBADF);
......
......@@ -124,6 +124,15 @@ main ()
errno = 0;
ASSERT (dup3 (fd, -2, o_flags) == -1);
ASSERT (errno == EBADF);
if (bad_fd > 256)
{
ASSERT (dup3 (fd, 255, 0) == 255);
ASSERT (dup3 (fd, 256, 0) == 256);
ASSERT (close (255) == 0);
ASSERT (close (256) == 0);
}
ASSERT (dup3 (fd, bad_fd - 1, 0) == bad_fd - 1);
ASSERT (close (bad_fd - 1) == 0);
errno = 0;
ASSERT (dup3 (fd, bad_fd, o_flags) == -1);
ASSERT (errno == EBADF);
......
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