standards/164787: dirfd() function not available when _POSIX_C_SOURCE is defined

Eric Wong normalperson at
Sun Feb 5 07:30:10 UTC 2012

>Number:         164787
>Category:       standards
>Synopsis:       dirfd() function not available when _POSIX_C_SOURCE is defined
>Confidential:   no
>Severity:       non-critical
>Priority:       medium
>Responsible:    freebsd-standards
>State:          open
>Class:          sw-bug
>Submitter-Id:   current-users
>Arrival-Date:   Sun Feb 05 07:30:09 UTC 2012
>Originator:     Eric Wong
>Release:        8.2-RELEASE
FreeBSD f82 8.2-RELEASE FreeBSD 8.2-RELEASE #0: Thu Feb 17 02:41:51 UTC 2011     root at  amd64
dirfd(3) is now specified in POSIX.1-2008, so it should be available
when the _POSIX_C_SOURCE macro is defined to >= 200809L

However, /usr/include/dirent.h only exposes the dirfd() macro if
__BSD_VISIBLE is defined.  However, __BSD_VISIBLE appears to be false
if _POSIX_C_SOURCE is defined.

 * To build + link:
 *   gcc -o dirfdtest dirfdtest.c
 * having _POSIX_C_SOURCE defined will cause this to fail link
#define _POSIX_C_SOURCE 200809L
#include <dirent.h>
int main(void)
        DIR *dir = opendir(".");


        return 0;

It's probably best to add dirfd() as a function to libc, allowing the opacity
of the struct _dir_desc to be preserved.


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