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9.12 fcntl.h ¶

POSIX specification:
https://pubs.opengroup.org/onlinepubs/9799919799/basedefs/fcntl.h.html

Gnulib module: fcntl-h

Portability problems fixed by Gnulib:

• The type pid_t is not defined on some platforms: MSVC 14.
• The type mode_t is not defined on some platforms: MSVC 14.
• The type off64_t is not defined on some platforms: macOS 14, FreeBSD 10.4, NetBSD 10.0, OpenBSD 7.5, MSVC 14, Cygwin, Haiku, Minix 3.3.
• ‘O_CLOEXEC’ is not defined on some platforms: Mac OS X 10.6, FreeBSD 8.4, NetBSD 5.1, OpenBSD 4.9, Minix 3.1.8, AIX 7.1, HP-UX 11.31, Solaris 10, Cygwin 1.7.1, mingw, MSVC 14.
• ‘O_DSYNC’, ‘O_NOCTTY’, ‘O_NOFOLLOW’, ‘O_RSYNC’, ‘O_SYNC’, and ‘O_TTY_INIT’ are not defined on some platforms. When not otherwise defined, Gnulib defines these macros to 0, which is generally safe.
• ‘O_NONBLOCK’ is not defined on some platforms. If the ‘nonblocking’ module is in use, gnulib guarantees a working non-zero value; otherwise, the gnulib replacement is 0.
• ‘O_EXEC’ is not defined on some platforms: glibc 2.41, macOS 12, FreeBSD 7.4, NetBSD 9.4, OpenBSD 7.5, HP-UX 11, Solaris 10, Cygwin 1.5.x, mingw, MSVC 14, Android. However, glibc does define ‘O_EXEC’ on GNU/Hurd. When not otherwise defined, Gnulib defines this macro to ‘O_RDONLY’, which is typically 0.

  Note: ‘O_EXEC’ is not suitable for opening a file descriptor that you want to use with fchmod later, because musl libc defines ‘O_EXEC’ to O_PATH and Linux fchmod fails with error EBADF when given such a file descriptor.

• ‘O_SEARCH’ is not defined on some platforms: glibc 2.41, macOS 12, FreeBSD 12.4, NetBSD 6.1, OpenBSD 7.5, AIX 6.1, HP-UX 11, Solaris 10, Cygwin 1.5.x, mingw, MSVC 14, Android. When not otherwise defined, Gnulib defines this macro to ‘O_RDONLY’, which is typically 0.
• ‘O_SEARCH’ is defined to O_PATH on some platforms: musl libc.
• ‘O_ACCMODE’ is not defined on some platforms: MSVC 14.
• The ‘O_ACCMODE’ mask mistakenly omits ‘O_SEARCH’ and ‘O_EXEC’ on some platforms: Cygwin.
• ‘O_BINARY’, ‘O_TEXT’ (not specified by POSIX, but essential for portability to native Windows platforms) are defined on some platforms but not on others. Gnulib defines these macros to 0 on GNU and other platforms that do not distinguish between text and binary I/O.
• ‘O_CLOEXEC’, ‘O_NOFOLLOW’, and ‘O_TTY_INIT’ are defined to values that are too large for an int on some platforms: AIX 7.1 with XL C 12.1.
• ‘O_DIRECT’, ‘O_IGNORE_CTTY’, ‘O_NDELAY’, ‘O_NOATIME’, ‘O_NOLINK’, ‘O_NOLINKS’, and ‘O_NOTRANS’ (not specified by POSIX) are defined on some platforms but not on others. When not otherwise defined, Gnulib defines these macros to 0, which is generally safe.
• ‘O_DIRECTORY’ is not defined on some platforms: glibc 2.0, Mac OS X 10.4, FreeBSD 7.4, NetBSD 4.0.1, OpenBSD 4.9, HP-UX 11, Solaris 10, Cygwin 1.5.x, mingw, MSVC 14.
• ‘FD_CLOEXEC’, ‘F_DUPFD’, and ‘F_GETFD’ are not defined on some platforms: mingw, MSVC 14.
• ‘F_DUPFD_CLOEXEC’ is not defined on some platforms: Mac OS X 10.5, FreeBSD 6.0, NetBSD 5.0, OpenBSD 7.5, AIX 5.1, HP-UX 11, Solaris 11 2010-11, Cygwin 1.7.1, mingw, MSVC 14.
• ‘AT_FDCWD’, ‘AT_EACCESS’, ‘AT_SYMLINK_NOFOLLOW’, ‘AT_SYMLINK_FOLLOW’, and ‘AT_REMOVEDIR’ are not defined on many platforms: glibc 2.3.6, Mac OS X 10.5, FreeBSD 6.0, NetBSD 5.0, OpenBSD 7.5, AIX 5.1, HP-UX 11, Cygwin 1.5.x, mingw, MSVC 14.
• ‘AT_FDCWD’ is defined with a value too large for an int on some platforms: Solaris 11.3.

Portability problems not fixed by Gnulib:

• On some platforms, ‘O_NOATIME’ and ‘O_NOFOLLOW’ are defined but do not work. To help work around the resulting portability problems, the fcntl-h module defines ‘HAVE_WORKING_O_NOATIME’ to 1 on platforms where ‘O_NOATIME’ is known to work, and to 0 otherwise; and similarly for ‘HAVE_WORKING_O_NOFOLLOW’ and ‘O_NOFOLLOW’: Mac OS X 10.3.
• ‘O_PATH’ is not defined on some platforms: glibc 2.13, macOS 13, FreeBSD 13.0, NetBSD 9.2, OpenBSD 7.1, Minix 3.3.0, AIX 7.3, HP-UX 11.31, Solaris 11.4, Cygwin 2.9, mingw, MSVC 14.
• Although POSIX.1-2024 standardized O_CLOFORK, FD_CLOFORK and F_DUPFD_CLOFORK, they are not defined on most platforms: glibc 2.41, musl libc, macOS 15.5, FreeBSD 14.2, NetBSD 10.1, OpenBSD 7.7, Minix 3.3.0, AIX 7.3, Solaris 11.3, Cygwin 3.6.2, mingw, MSVC 14.
• ‘F_SETFD’, ‘F_GETFL’, ‘F_SETFL’, ‘F_GETLK’, ‘F_SETLK’, ‘F_SETLKW’, ‘F_GETOWN’, and ‘F_SETOWN’ are not defined on some platforms: mingw, MSVC 14.
• ‘POSIX_FADV_DONTNEED’, ‘POSIX_FADV_NOREUSE’, ‘POSIX_FADV_NORMAL’, ‘POSIX_FADV_RANDOM’, ‘POSIX_FADV_SEQUENTIAL’, and ‘POSIX_FADV_WILLNEED’ are not defined on some platforms.