121 lines
5.9 KiB
C
121 lines
5.9 KiB
C
/**
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* @defgroup poll Poll
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* @ingroup libc
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*/
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#ifndef _POLL_H
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#define _POLL_H
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#ifdef __cplusplus
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extern "C" {
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#endif
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#include <features.h>
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#include <bits/poll.h>
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#define POLLIN 0x001
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#define POLLPRI 0x002
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#define POLLOUT 0x004
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#define POLLERR 0x008
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#define POLLHUP 0x010
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#define POLLNVAL 0x020
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#define POLLRDNORM 0x040
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#define POLLRDBAND 0x080
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#ifndef POLLWRNORM
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#define POLLWRNORM 0x100
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#define POLLWRBAND 0x200
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#endif
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#ifndef POLLMSG
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#define POLLMSG 0x400
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#define POLLRDHUP 0x2000
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#endif
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typedef unsigned long nfds_t;
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#include "poll_adapt.h"
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/**
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* @ingroup poll
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* @par Description:
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*
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* The poll function provides applications with a mechanism for multiplexing input/output over a set of file descriptors. For each member of the
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* array pointed to by fds, the poll examines the given file descriptor for the event(s) specified in events. The poll identifies those file descriptors
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* on which an application can read or write data, or on which certain events have occurred.\n\n
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*
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* The fds argument specifies the file descriptors to be examined and the events of interest for each file descriptor. It is a pointer to an array with
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* one member for each open file descriptor of interest. The array's members are pollfd structures within which fd specifies an open file descriptor
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* and events and revents are bitmasks constructed by OR'ing a combination of the following event flags:\n
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* POLLIN -- There is data to read.\n
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* POLLOUT -- Writing is now possible, though a write larger that the available space in a socket or pipe will still block (unless O_NONBLOCK is set).\n
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* POLLERR -- Error condition (only returned in revents; ignored in events).\n
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* POLLRDHUP -- Stream socket peer closed connection, or shut down writing half of connection.\n
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* POLLHUP -- Hang up (only returned in revents; ignored in events). Note that when reading from a channel such as a stream socket, this event
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* merely indicates that the peer closed its end of the channel. Subsequent reads from the channel will return 0 (end of file) only after all outstanding
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* data in the channel has been consumed.\n\n
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*
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* @param fds [IN/OUT] The field fd contains a file descriptor for an open file. The field events is an input parameter, a bit mask specifying
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* the events the application is interested in for the file descriptor fd. This field can be specified as zero, in which case the only events that can be
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* returned in revents are POLLHUP and POLLERR. The field revents is an output parameter, filled by LiteOS kernel with the events that actually occurred.
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* The bits returned in revents can include any of those specified in events, or one of the values POLLERR or POLLHUP.
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* @param nfds [IN] the number of items in the fds.
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* @param timeout [IN] the number of milliseconds that the poll should block waiting for a file descriptor to become ready. The call will block until
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* either a file descriptor becomes ready or the timeout expires. If the value of timeout is 0, poll just check the file descriptors and return immediately,
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* even if no file descriptors are ready. If the value of timeout is -1, poll blocks until a requested event occurs.
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*
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* @attention
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* <ul>
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* <li>Unlike Linux or other operation system, LiteOS does not support signal mechanism, so the poll function can't be interrupted by signal.</li>
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* <li>Other events which supported on Linux, such as POLLRDNORM, POLLWRNORM, POLLRDBAND, POLLWRBAND and POLLNVAL, are not supported on LiteOS.</li>
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* <li>On LiteOS, the user must make sure all the file descriptors supplied in fds are valid, else the poll function returns failure immediately. On Linux or
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* other platform, if the file descriptor is negative or invalid, the corresponding events field is ignored and the revents field returns zero.</li>
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* <li>It is recommended that the poll function is preferred than the select as the implementation of select is based on the pool, so the poll function is more efficient.</li>
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* <li>If a file descriptor being monitored by poll is closed in another thread, the result is unspecified. On some UNIX systems, poll unblocks and returns
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* with an indication that the file descriptor is ready. On LiteOS, closing the file descriptor in another thread has no effect on poll. In summary,
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* any application that relies on a particular behavior in this scenario must be considered buggy.</li>
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* <li>The timeout will be rounded up to the system clock granularity, on LiteOS, it's the system scheduling tick. So the minimal poll timeout is one
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* scheduling tick on LiteOS.</li>
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* <li>LiteOS does not support TCP urgent data(also used as the out-of-band data), so user cannot use the poll function with POLLPRI to examine the TCP urgent data.</li>
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* </ul>
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*
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* @retval #>=0 On success, a positive number is returned; this is the number of structures which have nonzero revents fields (in other words,
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* those descriptors with events or errors reported). A value of 0 indicates that the call timed out and no file descriptors were ready.
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* @retval #-1 On failure, -1 is returned, and errno is set to indicate the error.
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*
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* @par Errors
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* <ul>
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* <li><b>EBADF</b>: One of the file descriptor supplied in fds is invalid.</li>
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* <li><b>EINVAL</b>: The fds is a null pointer.</li>
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* <li><b>ENOMEM</b>: There was no space to allocate file descriptor tables.</li>
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* <li><b>ENOSYS</b>: One or more of the file descriptor sets specified a file descriptor don't support poll operation</li>
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* </ul>
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*
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* @par Dependency:
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* <ul><li>poll.h</li></ul>
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*
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* @see accept | connect | select | read | recv | send | write
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*
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* @since Huawei LiteOS V100R001C00
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*/
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int poll (struct pollfd *, nfds_t, int);
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#ifdef _GNU_SOURCE
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#define __NEED_time_t
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#define __NEED_struct_timespec
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#define __NEED_sigset_t
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#include <bits/alltypes.h>
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int ppoll(struct pollfd *, nfds_t, const struct timespec *, const sigset_t *);
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#endif
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#if _REDIR_TIME64
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#ifdef _GNU_SOURCE
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__REDIR(ppoll, __ppoll_time64);
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#endif
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#endif
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#ifdef __cplusplus
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}
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#endif
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#endif
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