Bug #21128: dir.c defines O_CLOEXEC before it is defined by the system.

• Status: Closed
• Assignee: -
• Target version: -
• Backport: 3.1: UNKNOWN, 3.2: UNKNOWN, 3.3: UNKNOWN, 3.4: UNKNOWN

[collinfunk (Collin Funk)]

Building from master commit hash bfcf36fe2243d34a01b5707754be9164849150c9 on GNU/Linux, I see:

compiling dir.c
In file included from /usr/include/bits/fcntl.h:61,
                 from /usr/include/fcntl.h:35,
                 from dir.c:39:
/usr/include/bits/fcntl-linux.h:144:10: warning: "O_CLOEXEC" redefined
  144 | # define O_CLOEXEC      __O_CLOEXEC     /* Set close_on_exec.  */
      |          ^~~~~~~~~
dir.c:26:11: note: this is the location of the previous definition
   26 | #  define O_CLOEXEC 0
      |           ^~~~~~~~~

This is because the file includes unistd.h before falling back to 0 for O_CLOEXEC. But glibc requires inclusion of fcntl.h for O_CLOEXEC. Since that file is included after, it is redefined.

The C standard leaves the behavior of redefining a variable undefined and it is a simple fix, so I will create a pull request.

[collinfunk (Collin Funk)]

Opened a pull request [1].

Also, POSIX requires unistd.h to define O_CLOEXEC, so this is a glibc bug that is easy to reproduce [2]. I'll have a look at fixing it in glibc and gnulib.

[1] https://github.com/ruby/ruby/pull/12735
[2] https://pubs.opengroup.org/onlinepubs/9799919799/basedefs/unistd.h.html

[collinfunk (Collin Funk)]

• Status changed from Open to Closed

Applied in changeset git|c1c7934b63d7682216fed9dd7c9ddff5b72fea89.

---

[Bug #21128] Include fcntl.h before checking for O_CLOEXEC

On glibc O_CLOEXEC is defined in fcntl.h and not unistd.h so this change
prevents the macro from being redefined.