http://bugs.gentoo.org/250342 http://sources.redhat.com/bugzilla/show_bug.cgi?id=9685 we cant assume sock_cloexec and pipe2 are bound together as the former defines are found in glibc only while the latter are a combo of kernel headers and glibc. so if we do a runtime detection of SOCK_CLOEXEC, but pipe2() is a stub inside of glibc, we hit a problem. for example: #include #include main() { getgrnam("portage"); if (!popen("ls", "r")) perror("popen()"); } getgrnam() will detect that the kernel supports SOCK_CLOEXEC and then set both __have_sock_cloexec and __have_pipe2 to true. but if glibc was built against older kernel headers where __NR_pipe2 does not exist, glibc will have a ENOSYS stub for it. so popen() will always fail as glibc assumes pipe2() works. diff -durN glibc-2.10.1.orig/include/unistd.h glibc-2.10.1/include/unistd.h --- glibc-2.10.1.orig/include/unistd.h 2008-07-27 20:23:17.000000000 +0200 +++ glibc-2.10.1/include/unistd.h 2009-11-13 00:50:15.000000000 +0100 @@ -167,9 +167,6 @@ extern int __pause_nocancel (void) attribute_hidden; extern int __have_sock_cloexec; -/* At lot of other functionality became available at the same time as - SOCK_CLOEXEC. Avoid defining separate variables for all of them - unless it is really necessary. */ -#define __have_pipe2 __have_sock_cloexec +extern int __have_pipe2; #endif diff -durN glibc-2.10.1.orig/socket/have_sock_cloexec.c glibc-2.10.1/socket/have_sock_cloexec.c --- glibc-2.10.1.orig/socket/have_sock_cloexec.c 2008-07-25 18:46:23.000000000 +0200 +++ glibc-2.10.1/socket/have_sock_cloexec.c 2009-11-13 00:50:15.000000000 +0100 @@ -16,9 +16,14 @@ Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA. */ +#include #include #include #if defined SOCK_CLOEXEC && !defined __ASSUME_SOCK_CLOEXEC int __have_sock_cloexec; #endif + +#if defined O_CLOEXEC && !defined __ASSUME_PIPE2 +int __have_pipe2; +#endif