POSIX_DEVICE_IO

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>)

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

Typedefs
typedef int	nfds_t
	Type for the number of file descriptors passed to poll().
typedef long	suseconds_t
	Microsecond time component type.
typedef struct zvfs_fd_set	fd_set
	Set of file descriptors for select()/pselect().

Functions
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.
FILE *	fdopen (int fd, const char *mode)
	Associate a stream with an open file descriptor.
int	fileno (FILE *stream)
	Return the file descriptor associated with a stream.
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.
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.
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(), select(), poll(), and related device-I/O primitives.

Macro Definition Documentation

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.

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

fd_set

typedef struct zvfs_fd_set fd_set

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

Definition at line 90 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 57 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

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

fdopen()

FILE * fdopen	(	int	fd,
		const char *	mode
	)

Associate a stream with an open file descriptor.

Parameters

fd	File descriptor to associate with the stream.
mode	Mode string as for fopen().

Returns

Pointer to the stream, or NULL on failure.

See also

https://pubs.opengroup.org/onlinepubs/9699919799/functions/fdopen.html

fileno()

int fileno

(

FILE *

stream

)

Return the file descriptor associated with a stream.

Parameters

stream

Stream to query.

Returns

File descriptor associated with stream.

See also

https://pubs.opengroup.org/onlinepubs/9699919799/functions/fileno.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

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