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10.254 fcntl

POSIX specification:
https://pubs.opengroup.org/onlinepubs/9699919799/functions/fcntl.html

LSB specification:
https://refspecs.linuxbase.org/LSB_5.0.0/LSB-Core-generic/LSB-Core-generic/baselib-fcntl-3.html

Gnulib module: fcntl

Portability problems fixed by Gnulib:

• This function is missing on some platforms: mingw, MSVC 14.
• This function does not support F_DUPFD_CLOEXEC on some platforms: glibc with Linux kernels before 2.6.24, Mac OS X 10.5, FreeBSD 6.0, NetBSD 5.0, OpenBSD 6.7, AIX 7.1, HP-UX 11, IRIX 6.5, Solaris 11 2010-11, Cygwin 1.7.1. Note that the gnulib replacement code is functional but not atomic.
• The F_DUPFD_CLOEXEC action of this function does not set the FD_CLOEXEC flag on some platforms: NetBSD 9.0.
• The F_DUPFD_CLOEXEC action of this function sets the FD_CLOEXEC flag on the wrong file descriptor on some platforms: Haiku.
• The F_DUPFD action of this function does not reject out-of-range targets properly on some platforms: AIX 7.1, Cygwin 1.5.x, Haiku.
• The F_DUPFD action of this function mistakenly clears FD_CLOEXEC on the source descriptor on some platforms: Haiku.

Portability problems not fixed by Gnulib:

• The replacement function does not support F_SETFD, F_GETFL, F_SETFL, F_GETOWN, F_SETOWN, F_GETLK, F_SETLK, and F_SETLKW on some platforms: mingw, MSVC 14.
• When a file does not support locking (such as on an NFS file system that does not support file locking), calls with F_SETLK and F_SETLKW fail with errno set to different values on different systems: EINVAL on OpenIndiana (as suggested by the POSIX 1003.1-2017 fcntl specification), ENOLCK on GNU/Linux, and EOPNOTSUPP on FreeBSD.