POSIX select

Select implementation for RIOT. More...

Detailed Description

Select implementation for RIOT.

See also

[The Open Group Base Specification Issue 7] (https://pubs.opengroup.org/onlinepubs/9699919799.2018edition/)

Todo:

Omitted from original specification for now:

• Inclusion of <signal.h>; no POSIX signal handling implemented in RIOT yet
• pselect() as it uses sigset_t from <signal.h>
• handling of the writefds and errorfds parameters of select()

Currently, only sockets are supported

Modules
	POSIX wrapper compile configurations

Files
file	select.h
	Select types.

Data Structures
struct	fd_set
	The fd_set structure. More...

Macros
#define	POSIX_SELECT_THREAD_FLAG   (1U << 3)
	Thread Flags for POSIX select
#define	FD_SETSIZE   (CONFIG_POSIX_FD_SET_SIZE)
	Maximum number of file descriptors in an fd_set structure.

Functions
static void	FD_CLR (int fd, fd_set *fdsetp)
	Removes a file descriptor from an fd_set if it is a member.
static int	FD_ISSET (int fd, fd_set *fdsetp)
	Checks if a file descriptor is a member of an fd_set
static void	FD_SET (int fd, fd_set *fdsetp)
	Adds a file descriptor from an fd_set if it is not already a member.
static void	FD_ZERO (fd_set *fdsetp)
	Initializes the descriptor set as an empty set.
int	select (int nfds, fd_set *readfds, fd_set *writefds, fd_set *errorfds, struct timeval *timeout)
	Examines the given file descriptor sets if they are ready for their respective operation.

Macro Definition Documentation

FD_SETSIZE

#define FD_SETSIZE   (CONFIG_POSIX_FD_SET_SIZE)

Maximum number of file descriptors in an fd_set structure.

POSIX-compliant version.

Definition at line 74 of file select.h.

POSIX_SELECT_THREAD_FLAG

#define POSIX_SELECT_THREAD_FLAG   (1U << 3)

Thread Flags for POSIX select

Definition at line 65 of file select.h.

Function Documentation

FD_CLR()

static void FD_CLR ( int  fd, fd_set *  fdsetp  )

inlinestatic

Removes a file descriptor from an fd_set if it is a member.

Parameters

[in]	fd	A file descriptor
[in]	fdsetp	An fd_set

Definition at line 90 of file select.h.

FD_ISSET()

static int FD_ISSET ( int  fd, fd_set *  fdsetp  )

inlinestatic

Checks if a file descriptor is a member of an fd_set

Parameters

[in]	fd	A file descriptor
[in]	fdsetp	An fd_set

Returns

non-zero value, if fd is a member of fdsetp

0, if fd is not a member of fdsetp

Definition at line 104 of file select.h.

FD_SET()

static void FD_SET ( int  fd, fd_set *  fdsetp  )

inlinestatic

Adds a file descriptor from an fd_set if it is not already a member.

Parameters

[in]	fd	A file descriptor
[in]	fdsetp	An fd_set

Definition at line 116 of file select.h.

FD_ZERO()

static void FD_ZERO ( fd_set *  fdsetp )

inlinestatic

Initializes the descriptor set as an empty set.

Parameters

[in]

fdsetp

An fd_set

Definition at line 126 of file select.h.

select()

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

Examines the given file descriptor sets if they are ready for their respective operation.

Parameters

[in]	nfds	The range of descriptors tested. The first nfds descriptors shall be checked in each set; that is, the descriptors from zero through nfds - 1 in the descriptor sets shall be examined.
[in,out]	readfds	The set of file descriptors to be checked for being ready to read. Indicates on output which file descriptors are ready to read. May be NULL to check no file descriptors.
[in,out]	writefds	The set of file descriptors to be checked for being ready to write. Indicates on output which file descriptors are ready to write. May be NULL to check no file descriptors. As only sockets are supported for now, these will be ignored
[in,out]	errorfds	The set of file descriptors to be checked for being error conditions pending. Indicates on output which file descriptors have error conditions pending. May be NULL to check no file descriptors. As only sockets are supported for now, these will be ignored
[in]	timeout	Timeout for select to block until one or more of the checked file descriptors is ready. Set timeout to all-zero to return immediately without blocking. May be NULL to block indefinitely.

Returns

number of members added to the file descriptor sets on success.

-1 on error, errno is set to indicate the error.