fcntl.h

Go to the documentation of this file.

#ifndef __LINUX_FCNTL_H__
#define __LINUX_FCNTL_H__
 
/*
 * DCL <linux/fcntl.h> -- open(2) flags and the F_* commands.
 *
 * Ported from mainline's uapi/asm-generic/fcntl.h (what arm64 uses), values
 * verbatim. The header exists because <linux/tty.h> tests file->f_flags:
 * tty_io_nonblock() is `file->f_flags & O_NONBLOCK || ...`, and an undefined
 * O_NONBLOCK would turn into an implicit declaration of an identifier the
 * preprocessor never saw -- it would not be "always false", it would not
 * compile.
 *
 * ---------------------------------------------------------------------------
 * KNOWN DIVERGENCE, recorded here because the day it matters will be the day
 * someone opens /dev/ttyS0 with O_NONBLOCK from userspace.
 *
 * Xeneva's userspace libc (Libs/XEClib/includes/fcntl.h) assigns a different
 * bit layout entirely:
 *
 *     userspace (XEClib)      this header (asm-generic)
 *       O_NONBLOCK  0x0080       O_NONBLOCK  0x0800  (1 << 11)
 *       O_NOCTTY    0x0004       O_NOCTTY    0x0100  (1 << 8)
 *       O_RDWR      0x0800       O_RDWR      0x0002
 *       F_SETFL     0x0010       F_SETFL     0x0004
 *
 * This header follows mainline for two reasons: every ported file is written
 * against mainline's numbers, and DCL's own cdev bridge already picked one --
 * linux_cdev_shim.c:507 defines DCL_O_NONBLOCK as 0x800 with the comment
 * "asm-generic fcntl.h: 00004000". Changing it now would silently change
 * behaviour that already works.
 *
 * It is safe *today* because nothing yet carries a userspace flag into
 * f_flags: there is no `f_flags =` assignment anywhere in the tree (the only
 * writer is that cdev selftest, which ORs the value in by hand), so every
 * open file reads as flags == 0 and the tty layer behaves blocking, which is
 * the correct default. The reconciliation -- most likely teaching XEClib the
 * Linux layout, since ported code assumes it -- belongs with the stage that
 * first wires a real open() through to tty_open(). It is listed in the
 * tracker rather than resolved here, because guessing which side should move
 * without a working open path would be exactly that: a guess.
 * ---------------------------------------------------------------------------
 */
 
#define O_ACCMODE   3
#define O_RDONLY    0
#define O_WRONLY    (1 << 0)
#define O_RDWR      (1 << 1)
#ifndef O_CREAT
#define O_CREAT     (1 << 6)    /* not fcntl */
#endif
#ifndef O_EXCL
#define O_EXCL      (1 << 7)    /* not fcntl */
#endif
#ifndef O_NOCTTY
#define O_NOCTTY    (1 << 8)    /* not fcntl */
#endif
#ifndef O_TRUNC
#define O_TRUNC     (1 << 9)    /* not fcntl */
#endif
#ifndef O_APPEND
#define O_APPEND    (1 << 10)
#endif
#ifndef O_NONBLOCK
#define O_NONBLOCK  (1 << 11)
#endif
#ifndef O_DSYNC
#define O_DSYNC     (1 << 12)
#endif
#ifndef FASYNC
#define FASYNC      (1 << 13)   /* fcntl, for BSD compatibility */
#endif
#ifndef O_DIRECT
#define O_DIRECT    (1 << 14)
#endif
#ifndef O_LARGEFILE
#define O_LARGEFILE (1 << 15)
#endif
#ifndef O_DIRECTORY
#define O_DIRECTORY (1 << 16)
#endif
#ifndef O_NOFOLLOW
#define O_NOFOLLOW  (1 << 17)
#endif
#ifndef O_NOATIME
#define O_NOATIME   (1 << 18)
#endif
#ifndef O_CLOEXEC
#define O_CLOEXEC   (1 << 19)
#endif
#ifndef O_SYNC
#define __O_SYNC    (1 << 20)
#define O_SYNC      (__O_SYNC | O_DSYNC)
#endif
#ifndef O_PATH
#define O_PATH      (1 << 21)
#endif
#ifndef __O_TMPFILE
#define __O_TMPFILE (1 << 22)
#endif
#ifndef O_EMPTYPATH
#define O_EMPTYPATH (1 << 26)
#endif
 
#define O_TMPFILE (__O_TMPFILE | O_DIRECTORY)
 
#ifndef O_NDELAY
#define O_NDELAY    O_NONBLOCK
#endif
 
#define F_DUPFD     0   /* dup */
#define F_GETFD     1   /* get close_on_exec */
#define F_SETFD     2   /* set/clear close_on_exec */
#define F_GETFL     3   /* get file->f_flags */
#define F_SETFL     4   /* set file->f_flags */
#ifndef F_GETLK
#define F_GETLK     5
#define F_SETLK     6
#define F_SETLKW    7
#endif
#ifndef F_SETOWN
#define F_SETOWN    8   /* for sockets. */
#define F_GETOWN    9   /* for sockets. */
#endif
#ifndef F_SETSIG
#define F_SETSIG    10  /* for sockets. */
#define F_GETSIG    11  /* for sockets. */
#endif
#ifndef F_GETLK64
#define F_GETLK64   12
#define F_SETLK64   13
#define F_SETLKW64  14
#endif
#ifndef F_SETOWN_EX
#define F_SETOWN_EX 15
#define F_GETOWN_EX 16
#endif
#ifndef F_GETOWNER_UIDS
#define F_GETOWNER_UIDS 17
#endif
 
#define FD_CLOEXEC  1   /* actually anything with low bit set goes */
 
#ifndef F_RDLCK
#define F_RDLCK     0
#define F_WRLCK     1
#define F_UNLCK     2
#endif
 
#define LOCK_SH     1   /* shared lock */
#define LOCK_EX     2   /* exclusive lock */
#define LOCK_NB     4   /* or'd with one of the above to prevent
                 * blocking */
#define LOCK_UN     8   /* remove lock */
 
#define F_LINUX_SPECIFIC_BASE   1024
 
/*
 * Deliberately *not* <linux/types.h>, which mainline's fcntl.h does include.
 *
 * mainline needs it because the full uapi surface carries types: struct
 * flock, struct f_owner_ex, flock64, struct falloc and the __kernel_* types
 * they are built from. DCL's port is every #define above and nothing else --
 * grep for a non-# line in this file and there are none -- so types.h was
 * carrying nothing.
 *
 * It was carrying something, though, and it is worth recording why it is
 * gone: types.h's only include is <linux/kernel.h> (types.h:21), which is the
 * aggregator -- virtio.h, completion.h, wait.h, sched.h. So a header of
 * numeric constants was reaching <linux/sched.h>, which `#undef current` and
 * redefines the word as a macro. struct __VFS_NODE__ (BaseHdr/Fs/vfs.h:105)
 * has a `uint64_t current` member, so a file that includes <Fs/vfs.h> after
 * anything which touched this header came out with "field declared as a
 * function" pointing at that member. linux_cdev_shim.c hit exactly that: it
 * includes <linux/file.h> at line 9 and <Fs/vfs.h> at line 11, and file.h
 * owes this header because mainline's fs.h includes it.
 *
 * If anyone adds struct flock or any other type here, <linux/types.h> comes
 * back with it, and the collision comes back with that. The way round it
 * then is to include <linux/fcntl.h> before <Fs/vfs.h>, not to make the
 * member go away -- Xeneva's VFS layout is not this tree's to move.
 */
 
#endif /* __LINUX_FCNTL_H__ */