175 lines
5.6 KiB
C
175 lines
5.6 KiB
C
#ifndef LIBNAGIOS_iobroker_h__
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#define LIBNAGIOS_iobroker_h__
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/**
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* @file iobroker.h
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* @brief I/O broker library function declarations
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*
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* The I/O broker library handles multiplexing between hundreds or
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* thousands of sockets with a few simple calls. It's designed to
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* be as lightweight as possible so as to not cause memory bloat,
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* and is therefore highly suitable for use by processes that are
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* fork()-intensive.
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*
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* @{
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*/
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#undef IOBROKER_USES_EPOLL
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#undef IOBROKER_USES_POLL
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#undef IOBROKER_USES_SELECT
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#if (_POSIX_C_SOURCE - 0) >= 200112L
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#include <poll.h>
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# define IOBROKER_POLLIN POLLIN
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# define IOBROKER_POLLPRI POLLPRI
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# define IOBROKER_POLLOUT POLLOUT
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# define IOBROKER_POLLERR POLLERR
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# define IOBROKER_POLLHUP POLLHUP
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# define IOBROKER_POLLNVAL POLLNVAL
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#else
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# define IOBROKER_POLLIN 0x001 /* there is data to read */
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# define IOBROKER_POLLPRI 0x002 /* there is urgent data to read */
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# define IOBROKER_POLLOUT 0x004 /* writing now will not block */
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# define IOBROKER_POLLERR 0x008 /* error condition */
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# define IOBROKER_POLLHUP 0x010 /* hung up */
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# define IOBROKER_POLLNVAL 0x020 /* invalid polling request */
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#endif
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/** return codes */
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#define IOBROKER_SUCCESS 0
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#define IOBROKER_ENOSET (-1)
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#define IOBROKER_ENOINIT (-2)
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#define IOBROKER_ELIB (-3)
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#define IOBROKER_EALREADY (-EALREADY)
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#define IOBROKER_EINVAL (-EINVAL)
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/** Flags for iobroker_destroy() */
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#define IOBROKER_CLOSE_SOCKETS 1
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/* Opaque type. Callers needn't worry about this */
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struct iobroker_set;
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typedef struct iobroker_set iobroker_set;
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/**
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* Get a string describing the error in the last iobroker call.
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* The returned string must not be free()'d.
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* @param error The error code
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* @return A string describing the meaning of the error code
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*/
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extern const char *iobroker_strerror(int error);
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/**
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* Create a new socket set
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* @return An iobroker_set on success. NULL on errors.
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*/
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extern iobroker_set *iobroker_create(void);
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/**
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* Published utility function used to determine the max number of
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* file descriptors this process can keep open at any one time.
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* @return Max number of filedescriptors we can keep open
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*/
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extern int iobroker_max_usable_fds(void);
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/**
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* Register a socket for input polling with the broker.
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*
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* @param iobs The socket set to add the socket to.
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* @param sd The socket descriptor to add
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* @param arg Argument passed to input handler on available input
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* @param handler The callback function to call when input is available
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*
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* @return 0 on succes. < 0 on errors.
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*/
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extern int iobroker_register(iobroker_set *iobs, int sd, void *arg, int (*handler)(int, int, void *));
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/**
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* Register a socket for output polling with the broker
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* @note There's no guarantee that *ALL* data is writable just
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* because the socket won't block you completely.
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*
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* @param iobs The socket set to add the socket to.
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* @param sd The socket descriptor to add
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* @param arg Argument passed to output handler on ready-to-write
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* @param handler The function to call when output won't block
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*
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* @return 0 on success. < 0 on errors
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*/
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extern int iobroker_register_out(iobroker_set *iobs, int sd, void *arg, int (*handler)(int, int, void *));
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/**
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* Check if a particular filedescriptor is registered with the iobroker set
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* @param[in] iobs The iobroker set the filedescriptor should be member of
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* @param[in] fd The filedescriptor to check for
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* @return 1 if the filedescriptor is registered and 0 otherwise
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*/
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extern int iobroker_is_registered(iobroker_set *iobs, int fd);
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/**
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* Getter function for number of file descriptors registered in
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* the set specified.
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* @param iobs The io broker set to query
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* @return Number of file descriptors registered in the set
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*/
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extern int iobroker_get_num_fds(iobroker_set *iobs);
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/**
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* Getter function for the maximum amount of file descriptors this
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* set can handle.
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* @param iobs The io broker set to query
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* @return Max file descriptor capacity for the set
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*/
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extern int iobroker_get_max_fds(iobroker_set *iobs);
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/**
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* Unregister a socket for input polling with the broker.
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*
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* @param iobs The socket set to remove the socket from
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* @param sd The socket descriptor to remove
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* @return 0 on succes. < 0 on errors.
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*/
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extern int iobroker_unregister(iobroker_set *iobs, int sd);
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/**
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* Deregister a socket for input polling with the broker
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* (this is identical to iobroker_unregister())
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* @param iobs The socket set to remove the socket from
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* @param sd The socket descriptor to remove
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* @return 0 on success. < 0 on errors.
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*/
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extern int iobroker_deregister(iobroker_set *iobs, int sd);
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/**
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* Unregister and close(2) a socket registered for input with the
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* broker. This is a convenience function which exists only to avoid
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* doing multiple calls when read() returns 0, as closed sockets must
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* always be removed from the socket set to avoid consuming tons of
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* cpu power from iterating "too fast" over the file descriptors.
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*
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* @param iobs The socket set to remove the socket from
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* @param sd The socket descriptor to remove and close
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* @return 0 on success. < 0 on errors
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*/
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extern int iobroker_close(iobroker_set *iobs, int sd);
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/**
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* Destroy a socket set as created by iobroker_create
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* @param iobs The socket set to destroy
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* @param flags If set, close(2) all registered sockets
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*/
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extern void iobroker_destroy(iobroker_set *iobs, int flags);
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/**
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* Wait for input on any of the registered sockets.
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* @param iobs The socket set to wait for.
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* @param timeout Timeout in milliseconds. -1 is "wait indefinitely"
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* @return -1 on errors, or number of filedescriptors with input
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*/
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extern int iobroker_poll(iobroker_set *iobs, int timeout);
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#endif /* INCLUDE_iobroker_h__ */
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/** @} */
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