POSIX Device Input and Output option group. More...

Files
file	poll.h
	POSIX poll API (<poll.h>)

file	select.h
	POSIX select API (<sys/select.h>)

Data Structures
struct	sigset_t
	Type representing a set of signals (bitmask). More...

Macros
#define	O_CLOEXEC ZVFS_O_CLOEXEC
	Close file descriptor on exec (open() flag).

#define	O_CREAT ZVFS_O_CREAT
	Create file if it does not exist (open() flag).

#define	O_DIRECTORY ZVFS_O_DIRECTORY
	Fail if path does not name a directory (open() flag).

#define	O_EXCL ZVFS_O_EXCL
	Exclusive creation: fail if file already exists (open() flag, with O_CREAT).

#define	O_NOCTTY ZVFS_O_NOCTTY
	Do not assign a controlling terminal (open() flag).

#define	O_NOFOLLOW ZVFS_O_NOFOLLOW
	Do not follow symbolic links (open() flag).

#define	O_TRUNC ZVFS_O_TRUNC
	Truncate file to zero length on open (open() flag).

#define	O_TTY_INIT ZVFS_O_TTY_INIT
	Initialise terminal to conforming state (open() flag).

#define	O_APPEND ZVFS_O_APPEND
	Write operations append to end of file.

#define	O_DSYNC ZVFS_O_DSYNC
	Write I/O completes as defined for synchronised I/O data integrity.

#define	O_NONBLOCK ZVFS_O_NONBLOCK
	Non-blocking I/O mode.

#define	O_RSYNC ZVFS_O_RSYNC
	Synchronised read I/O (same as O_SYNC for reads).

#define	O_SYNC ZVFS_O_SYNC
	Write I/O completes as defined for synchronised I/O file integrity.

#define	O_EXEC ZVFS_O_EXEC
	Open for execute only (no read, write, or search).

#define	O_RDONLY ZVFS_O_RDONLY
	Open for reading only.

#define	O_RDWR ZVFS_O_RDWR
	Open for reading and writing.

#define	O_SEARCH ZVFS_O_SEARCH
	Open directory for search only.

#define	O_WRONLY ZVFS_O_WRONLY
	Open for writing only.

#define	O_ACCMODE (ZVFS_O_RDONLY \| ZVFS_O_RDWR \| ZVFS_O_WRONLY)
	Mask to extract the file access mode from open flags.

#define	pollfd zvfs_pollfd
	Poll file descriptor structure (alias for zvfs_pollfd).

#define	POLLIN ZVFS_POLLIN
	Data other than high-priority data may be read without blocking.

#define	POLLRDNORM ZVFS_POLLRDNORM
	Normal data may be read without blocking.

#define	POLLRDBAND ZVFS_POLLRDBAND
	Priority data may be read without blocking.

#define	POLLPRI ZVFS_POLLPRI
	High-priority data may be read without blocking.

#define	POLLOUT ZVFS_POLLOUT
	Normal data may be written without blocking.

#define	POLLWRNORM ZVFS_POLLWRNORM
	Equivalent to POLLOUT.

#define	POLLWRBAND ZVFS_POLLWRBAND
	Priority data may be written.

#define	POLLERR ZVFS_POLLERR
	An error has occurred on the file descriptor (output only).

#define	POLLHUP ZVFS_POLLHUP
	The file descriptor has been hung up (output only).

#define	POLLNVAL ZVFS_POLLNVAL
	The file descriptor is not open (output only).

#define	EFD_SEMAPHORE ZVFS_EFD_SEMAPHORE
	Semaphore-mode flag: each read decrements the counter by 1 instead of resetting to 0.

#define	EFD_NONBLOCK ZVFS_EFD_NONBLOCK
	Non-blocking flag: reads and writes return EAGAIN instead of blocking.

#define	FD_SETSIZE ZVFS_FD_SETSIZE
	Maximum number of file descriptors in an fd_set.

#define	SIGRTMAX (SIGRTMIN + CONFIG_POSIX_RTSIG_MAX)
	Largest real-time signal number.

#define	STDERR_FILENO 2
	File descriptor for standard error.

#define	STDIN_FILENO 0
	File descriptor for standard input.

#define	STDOUT_FILENO 1
	File descriptor for standard output.

#define	_POSIX_VDISABLE ('\0')
	Value used to disable a special character in a terminal.

Typedefs
typedef int	nfds_t
	Type for the number of file descriptors passed to poll().

typedef zvfs_eventfd_t	eventfd_t
	Counter value type for eventfd operations.

typedef long	suseconds_t
	Microsecond time component type.

typedef struct zvfs_fd_set	fd_set
	Set of file descriptors for select()/pselect().

Functions
int	creat (const char *path, mode_t mode)
	Create or truncate a file.

int	open (const char *name, int flags,...)
	Open or create a file.

int	openat (int fd, const char *path, int oflag,...)
	Open or create a file relative to a directory file descriptor.

int	poll (struct zvfs_pollfd *fds, nfds_t nfds, int timeout)
	Wait for events on a set of file descriptors.

int	eventfd (unsigned int initval, int flags)
	Create a file descriptor for event notification.

int	eventfd_read (int fd, eventfd_t *value)
	Read the current counter value from an eventfd.

int	eventfd_write (int fd, eventfd_t value)
	Add a value to an eventfd counter.

int	pselect (int nfds, fd_set readfds, fd_set writefds, fd_set exceptfds, const struct timespec timeout, const sigset_t *sigmask)
	Synchronous multiplexed I/O with signal-mask and nanosecond timeout.

int	select (int nfds, fd_set readfds, fd_set writefds, fd_set errorfds, struct timeval timeout)
	Synchronous multiplexed I/O (legacy interface, use pselect() for new code).

void	FD_CLR (int fd, fd_set *fdset)
	Remove a file descriptor from an fd_set.

int	FD_ISSET (int fd, fd_set *fdset)
	Test whether a file descriptor is in an fd_set.

void	FD_SET (int fd, fd_set *fdset)
	Add a file descriptor to an fd_set.

void	FD_ZERO (fd_set *fdset)
	Clear all file descriptors from an fd_set.

int	close (int fildes)
	Close a file descriptor.

int	isatty (int fildes)
	Determine whether a file descriptor refers to a terminal.

ssize_t	pread (int fildes, void *buf, size_t nbyte, off_t offset)
	Read from a file at a given offset without changing the file offset.

ssize_t	pwrite (int fildes, const void *buf, size_t nbyte, off_t offset)
	Write to a file at a given offset without changing the file offset.

ssize_t	read (int fildes, void *buf, size_t nbyte)
	Read from a file descriptor.

char *	ttyname (int fildes)
	Get the name of the terminal associated with a file descriptor.

ssize_t	write (int fildes, const void *buf, size_t nbyte)
	Write to a file descriptor.

Detailed Description

POSIX Device Input and Output option group.

Covers open(), close(), read(), write(), pread(), pwrite(), isatty(), ttyname(), ttyname_r(), and related device-I/O primitives.

Macro Definition Documentation

◆ _POSIX_VDISABLE

#define _POSIX_VDISABLE ('\0')

Value used to disable a special character in a terminal.

Definition at line 123 of file unistd.h.

◆ EFD_NONBLOCK

#define EFD_NONBLOCK ZVFS_EFD_NONBLOCK

Non-blocking flag: reads and writes return EAGAIN instead of blocking.

Definition at line 32 of file eventfd.h.

◆ EFD_SEMAPHORE

#define EFD_SEMAPHORE ZVFS_EFD_SEMAPHORE

Semaphore-mode flag: each read decrements the counter by 1 instead of resetting to 0.

Definition at line 30 of file eventfd.h.

◆ FD_SETSIZE

#define FD_SETSIZE ZVFS_FD_SETSIZE

Maximum number of file descriptors in an fd_set.

Definition at line 30 of file select.h.

◆ O_ACCMODE

#define O_ACCMODE (ZVFS_O_RDONLY | ZVFS_O_RDWR | ZVFS_O_WRONLY)

Mask to extract the file access mode from open flags.

Definition at line 130 of file fcntl.h.

◆ O_APPEND

#define O_APPEND ZVFS_O_APPEND

Write operations append to end of file.

Definition at line 108 of file fcntl.h.

◆ O_CLOEXEC

#define O_CLOEXEC ZVFS_O_CLOEXEC

Close file descriptor on exec (open() flag).

Definition at line 91 of file fcntl.h.

◆ O_CREAT

#define O_CREAT ZVFS_O_CREAT

Create file if it does not exist (open() flag).

Definition at line 93 of file fcntl.h.

◆ O_DIRECTORY

#define O_DIRECTORY ZVFS_O_DIRECTORY

Fail if path does not name a directory (open() flag).

Definition at line 95 of file fcntl.h.

◆ O_DSYNC

#define O_DSYNC ZVFS_O_DSYNC

Write I/O completes as defined for synchronised I/O data integrity.

Definition at line 110 of file fcntl.h.

◆ O_EXCL

#define O_EXCL ZVFS_O_EXCL

Exclusive creation: fail if file already exists (open() flag, with O_CREAT).

Definition at line 97 of file fcntl.h.

◆ O_EXEC

#define O_EXEC ZVFS_O_EXEC

Open for execute only (no read, write, or search).

Definition at line 119 of file fcntl.h.

◆ O_NOCTTY

#define O_NOCTTY ZVFS_O_NOCTTY

Do not assign a controlling terminal (open() flag).

Definition at line 99 of file fcntl.h.

◆ O_NOFOLLOW

#define O_NOFOLLOW ZVFS_O_NOFOLLOW

Do not follow symbolic links (open() flag).

Definition at line 101 of file fcntl.h.

◆ O_NONBLOCK

#define O_NONBLOCK ZVFS_O_NONBLOCK

Non-blocking I/O mode.

Definition at line 112 of file fcntl.h.

◆ O_RDONLY

#define O_RDONLY ZVFS_O_RDONLY

Open for reading only.

Definition at line 121 of file fcntl.h.

◆ O_RDWR

#define O_RDWR ZVFS_O_RDWR

Open for reading and writing.

Definition at line 123 of file fcntl.h.

◆ O_RSYNC

#define O_RSYNC ZVFS_O_RSYNC

Synchronised read I/O (same as O_SYNC for reads).

Definition at line 114 of file fcntl.h.

◆ O_SEARCH

#define O_SEARCH ZVFS_O_SEARCH

Open directory for search only.

Definition at line 125 of file fcntl.h.

◆ O_SYNC

#define O_SYNC ZVFS_O_SYNC

Write I/O completes as defined for synchronised I/O file integrity.

Definition at line 116 of file fcntl.h.

◆ O_TRUNC

#define O_TRUNC ZVFS_O_TRUNC

Truncate file to zero length on open (open() flag).

Definition at line 103 of file fcntl.h.

◆ O_TTY_INIT

#define O_TTY_INIT ZVFS_O_TTY_INIT

Initialise terminal to conforming state (open() flag).

Definition at line 105 of file fcntl.h.

◆ O_WRONLY

#define O_WRONLY ZVFS_O_WRONLY

Open for writing only.

Definition at line 127 of file fcntl.h.

◆ POLLERR

#define POLLERR ZVFS_POLLERR

An error has occurred on the file descriptor (output only).

Definition at line 57 of file poll.h.

◆ pollfd

#define pollfd zvfs_pollfd

Poll file descriptor structure (alias for zvfs_pollfd).

Definition at line 40 of file poll.h.

◆ POLLHUP

#define POLLHUP ZVFS_POLLHUP

The file descriptor has been hung up (output only).

Definition at line 59 of file poll.h.

◆ POLLIN

#define POLLIN ZVFS_POLLIN

Data other than high-priority data may be read without blocking.

Definition at line 43 of file poll.h.

◆ POLLNVAL

#define POLLNVAL ZVFS_POLLNVAL

The file descriptor is not open (output only).

Definition at line 61 of file poll.h.

◆ POLLOUT

#define POLLOUT ZVFS_POLLOUT

Normal data may be written without blocking.

Definition at line 51 of file poll.h.

◆ POLLPRI

#define POLLPRI ZVFS_POLLPRI

High-priority data may be read without blocking.

Definition at line 49 of file poll.h.

◆ POLLRDBAND

#define POLLRDBAND ZVFS_POLLRDBAND

Priority data may be read without blocking.

Definition at line 47 of file poll.h.

◆ POLLRDNORM

#define POLLRDNORM ZVFS_POLLRDNORM

Normal data may be read without blocking.

Definition at line 45 of file poll.h.

◆ POLLWRBAND

#define POLLWRBAND ZVFS_POLLWRBAND

Priority data may be written.

Definition at line 55 of file poll.h.

◆ POLLWRNORM

#define POLLWRNORM ZVFS_POLLWRNORM

Equivalent to POLLOUT.

Definition at line 53 of file poll.h.

◆ SIGRTMAX

#define SIGRTMAX (SIGRTMIN + CONFIG_POSIX_RTSIG_MAX)

Largest real-time signal number.

Definition at line 40 of file select.h.

◆ STDERR_FILENO

#define STDERR_FILENO 2

File descriptor for standard error.

Definition at line 107 of file unistd.h.

◆ STDIN_FILENO

#define STDIN_FILENO 0

File descriptor for standard input.

Definition at line 112 of file unistd.h.

◆ STDOUT_FILENO

#define STDOUT_FILENO 1

File descriptor for standard output.

Definition at line 117 of file unistd.h.

Typedef Documentation

◆ eventfd_t

typedef zvfs_eventfd_t eventfd_t

Counter value type for eventfd operations.

Definition at line 35 of file eventfd.h.

◆ fd_set

typedef struct zvfs_fd_set fd_set

Set of file descriptors for select()/pselect().

Definition at line 88 of file select.h.

◆ nfds_t

typedef int nfds_t

Type for the number of file descriptors passed to poll().

Definition at line 34 of file poll.h.

◆ suseconds_t

typedef long suseconds_t

Microsecond time component type.

Definition at line 55 of file select.h.

Function Documentation

◆ close()

int close ( int fildes )

Close a file descriptor.

See also: https://pubs.opengroup.org/onlinepubs/9699919799/functions/close.html

◆ creat()

int creat	(	const char *	path,
		mode_t	mode
	)

Create or truncate a file.

Equivalent to open(path, O_WRONLY|O_CREAT|O_TRUNC, mode).

Parameters

path	File path.
mode	Permission bits applied if the file is created.

Returns: New file descriptor on success, or -1 with errno set on failure.

See also: https://pubs.opengroup.org/onlinepubs/9699919799/functions/creat.html

◆ eventfd()

int eventfd	(	unsigned int	initval,
		int	flags
	)

Create a file descriptor for event notification.

The returned file descriptor can be used with POSIX read()/write() or with eventfd_read()/eventfd_write(). It also integrates with poll(), allowing a writing thread to wake a polling thread simply by writing to the eventfd.

When using read()/write(), the buffer size must be exactly 8 bytes or the call will fail with EINVAL.

Parameters

initval	Initial counter value.
flags	0, EFD_SEMAPHORE, EFD_NONBLOCK, or their combination.

Returns: New eventfd file descriptor on success, -1 with errno set on failure.

See also: https://pubs.opengroup.org/onlinepubs/9699919799/functions/eventfd.html

◆ eventfd_read()

int eventfd_read	(	int	fd,
		eventfd_t *	value
	)

Read the current counter value from an eventfd.

In normal mode the counter is reset to 0; in EFD_SEMAPHORE mode it is decremented by 1. Blocks if the counter is 0 (unless EFD_NONBLOCK).

Parameters

fd	Eventfd file descriptor.
value	Output: counter value read.

Returns: 0 on success, -1 with errno set on failure.

See also: https://pubs.opengroup.org/onlinepubs/9699919799/functions/eventfd_read.html

◆ eventfd_write()

int eventfd_write	(	int	fd,
		eventfd_t	value
	)

Add a value to an eventfd counter.

Wakes any thread blocked in eventfd_read(), read(), or poll() on fd.

Parameters

fd	Eventfd file descriptor.
value	Value to add to the counter.

Returns: 0 on success, -1 with errno set on failure.

See also: https://pubs.opengroup.org/onlinepubs/9699919799/functions/eventfd_write.html

◆ FD_CLR()

void FD_CLR	(	int	fd,
		fd_set *	fdset
	)

Remove a file descriptor from an fd_set.

Parameters

fd	File descriptor to clear.
fdset	File descriptor set to modify.

See also: https://pubs.opengroup.org/onlinepubs/9699919799/functions/FD_CLR.html

◆ FD_ISSET()

int FD_ISSET	(	int	fd,
		fd_set *	fdset
	)

Test whether a file descriptor is in an fd_set.

Parameters

fd	File descriptor to test.
fdset	File descriptor set.

Returns: Non-zero if fd is set, 0 otherwise.

See also: https://pubs.opengroup.org/onlinepubs/9699919799/functions/FD_ISSET.html

◆ FD_SET()

void FD_SET	(	int	fd,
		fd_set *	fdset
	)

Add a file descriptor to an fd_set.

Parameters

fd	File descriptor to add.
fdset	File descriptor set to modify.

See also: https://pubs.opengroup.org/onlinepubs/9699919799/functions/FD_SET.html

◆ FD_ZERO()

void FD_ZERO ( fd_set * fdset )

Clear all file descriptors from an fd_set.

Parameters

fdset File descriptor set to clear.

See also: https://pubs.opengroup.org/onlinepubs/9699919799/functions/FD_ZERO.html

◆ isatty()

int isatty ( int fildes )

Determine whether a file descriptor refers to a terminal.

See also: https://pubs.opengroup.org/onlinepubs/9699919799/functions/isatty.html

◆ open()

int open	(	const char *	name,
		int	flags,
			...
	)

Open or create a file.

Parameters

name	File path.
flags	Access and creation flags (O_RDONLY, O_WRONLY, O_RDWR, O_CREAT, …).
...	If O_CREAT: mode_t mode.

Returns: New file descriptor on success, or -1 with errno set on failure.

See also: https://pubs.opengroup.org/onlinepubs/9699919799/functions/open.html

◆ openat()

int openat	(	int	fd,
		const char *	path,
		int	oflag,
			...
	)

Open or create a file relative to a directory file descriptor.

Parameters

fd	Directory file descriptor, or AT_FDCWD.
path	File path (relative to `fd`, or absolute).
oflag	Access and creation flags.
...	If O_CREAT: mode_t mode.

Returns: New file descriptor on success, or -1 with errno set on failure.

See also: https://pubs.opengroup.org/onlinepubs/9699919799/functions/openat.html

◆ poll()

int poll	(	struct zvfs_pollfd *	fds,
		nfds_t	nfds,
		int	timeout
	)

Wait for events on a set of file descriptors.

Examines each file descriptor in fds for the events specified in its events field. Blocks until at least one descriptor is ready, the timeout expires, or a signal is caught.

Parameters

fds	Array of `struct` pollfd descriptors to monitor.
nfds	Number of entries in `fds`.
timeout	Timeout in milliseconds; -1 to block indefinitely, 0 to return immediately.

Returns: Number of file descriptors with non-zero revents on success, 0 on timeout, or -1 with errno set on failure.

See also: https://pubs.opengroup.org/onlinepubs/9699919799/functions/poll.html

◆ pread()

ssize_t pread	(	int	fildes,
		void *	buf,
		size_t	nbyte,
		off_t	offset
	)

Read from a file at a given offset without changing the file offset.

See also: https://pubs.opengroup.org/onlinepubs/9699919799/functions/pread.html

◆ pselect()

int pselect	(	int	nfds,
		fd_set *	readfds,
		fd_set *	writefds,
		fd_set *	exceptfds,
		const struct timespec *	timeout,
		const sigset_t *	sigmask
	)

Synchronous multiplexed I/O with signal-mask and nanosecond timeout.

Parameters

nfds	Highest-numbered file descriptor in any set + 1.
readfds	Set of file descriptors to watch for readability, or NULL.
writefds	Set of file descriptors to watch for writability, or NULL.
exceptfds	Set of file descriptors to watch for exceptions, or NULL.
timeout	Maximum wait time, or NULL to block indefinitely.
sigmask	Signal mask to apply during the wait, or NULL.

Returns: Number of ready file descriptors on success, 0 on timeout, or -1 with errno set on failure.

See also: https://pubs.opengroup.org/onlinepubs/9699919799/functions/pselect.html

◆ pwrite()

ssize_t pwrite	(	int	fildes,
		const void *	buf,
		size_t	nbyte,
		off_t	offset
	)

Write to a file at a given offset without changing the file offset.

See also: https://pubs.opengroup.org/onlinepubs/9699919799/functions/pwrite.html

◆ read()

ssize_t read	(	int	fildes,
		void *	buf,
		size_t	nbyte
	)

Read from a file descriptor.

See also: https://pubs.opengroup.org/onlinepubs/9699919799/functions/read.html

◆ select()

int select	(	int	nfds,
		fd_set *	readfds,
		fd_set *	writefds,
		fd_set *	errorfds,
		struct timeval *	timeout
	)

Synchronous multiplexed I/O (legacy interface, use pselect() for new code).

Parameters

nfds	Highest-numbered file descriptor in any set + 1.
readfds	Set of file descriptors to watch for readability, or NULL.
writefds	Set of file descriptors to watch for writability, or NULL.
errorfds	Set of file descriptors to watch for errors, or NULL.
timeout	Maximum wait time, or NULL to block indefinitely.

Returns: Number of ready file descriptors on success, 0 on timeout, or -1 with errno set on failure.

See also: https://pubs.opengroup.org/onlinepubs/9699919799/functions/select.html

◆ ttyname()

char * ttyname ( int fildes )

Get the name of the terminal associated with a file descriptor.

See also: https://pubs.opengroup.org/onlinepubs/9699919799/functions/ttyname.html

◆ write()

ssize_t write	(	int	fildes,
		const void *	buf,
		size_t	nbyte
	)

Write to a file descriptor.

See also: https://pubs.opengroup.org/onlinepubs/9699919799/functions/write.html

Files

Data Structures

Macros

Typedefs

Functions

Detailed Description

Macro Definition Documentation

◆ _POSIX_VDISABLE

◆ EFD_NONBLOCK

◆ EFD_SEMAPHORE

◆ FD_SETSIZE

◆ O_ACCMODE

◆ O_APPEND

◆ O_CLOEXEC

◆ O_CREAT

◆ O_DIRECTORY

◆ O_DSYNC

◆ O_EXCL

◆ O_EXEC

◆ O_NOCTTY

◆ O_NOFOLLOW

◆ O_NONBLOCK

◆ O_RDONLY

◆ O_RDWR

◆ O_RSYNC

◆ O_SEARCH

◆ O_SYNC

◆ O_TRUNC

◆ O_TTY_INIT

◆ O_WRONLY

◆ POLLERR

◆ pollfd

◆ POLLHUP

◆ POLLIN

◆ POLLNVAL

◆ POLLOUT

◆ POLLPRI

◆ POLLRDBAND

◆ POLLRDNORM

◆ POLLWRBAND

◆ POLLWRNORM

◆ SIGRTMAX

◆ STDERR_FILENO

◆ STDIN_FILENO

◆ STDOUT_FILENO

Typedef Documentation

◆ eventfd_t

◆ fd_set

◆ nfds_t

◆ suseconds_t

Function Documentation

◆ close()

◆ creat()

◆ eventfd()

◆ eventfd_read()

◆ eventfd_write()

◆ FD_CLR()

◆ FD_ISSET()

◆ FD_SET()

◆ FD_ZERO()

◆ isatty()

◆ open()

◆ openat()

◆ poll()

◆ pread()

◆ pselect()

◆ pwrite()

◆ read()

◆ select()

◆ ttyname()

◆ write()