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<p>
</p>
<p>
<b>Input Parameters:</b>
</p>
<ul>
<li><code>sockfd</code>: Socket descriptor of socket
<li><code>buf</code>: Data to send
<li><code>len</code>: Length of data to send
<li><code>flags</code>: Send flags
<li><code>to</code>: Address of recipient
<li><code>tolen</code>: The length of the address structure
</ul>
<p>
<b>Returned Values:</b>
On success, returns the number of characters sent. On error, -1 is returned, and<code>errno</code>is set appropriately:
</p>
<ul>
<li><code>EAGAIN</code> or <code>EWOULDBLOCK</code>.
The socket is marked non-blocking and the requested operation would block.
<li><code>EBADF</code>.
An invalid descriptor was specified.
<li><code>ECONNRESET</code>.
Connection reset by peer.
<li><code>EDESTADDRREQ</code>.
The socket is not connection-mode, and no peer address is set.
<li><code>EFAULT</code>.
An invalid user space address was specified for a parameter.
<li><code>EINTR</code>.
A signal occurred before any data was transmitted.
<li><code>EINVAL</code>.
Invalid argument passed.
<li><code>EISCONN</code>.
The connection-mode socket was connected already but a recipient
was specified. (Now either this error is returned, or the recipient
specification is ignored.)
<li><code>EMSGSIZE</code>.
The socket type requires that message be sent atomically, and the
size of the message to be sent made this impossible.
<li><code>ENOBUFS</code>.
The output queue for a network interface was full. This generally
indicates that the interface has stopped sending, but may be
caused by transient congestion.
<li><code>ENOMEM</code>.
No memory available.
<li><code>ENOTCONN</code>.
The socket is not connected, and no target has been given.
<li><code>ENOTSOCK</code>.
The argument s is not a socket.
<li><code>EOPNOTSUPP</code>.
Some bit in the flags argument is inappropriate for the socket type.
<li><code>EPIPE</code>.
The local end has been shut down on a connection oriented socket.
In this case the process will also receive a SIGPIPE unless
MSG_NOSIGNAL is set.
</ul>
<h3><a name="recv">2.12.6 <code>recv</code></a></h3>
<p>
<b>Function Prototype:</b>
</p>
<pre>
#include <sys/socket.h>
ssize_t recv(int sockfd, void *buf, size_t len, int flags);
</pre>
<p>
<b>Description:</b>
The <code>recv()</code> call is identical to
<a href="#recvfrom"><code>recvfrom()</code></a> with a NULL
<code>from</code> parameter.
<p>
</p>
<p>
<b>Input Parameters:</b>
</p>
<ul>
</li>
<li>sockfd</code>: Socket descriptor of socket </li>
<li>buf</code>: Buffer to receive data </li>
<li>len</code>: Length of buffer </li>
<li>flags</code>: Receive flags </li>
</ul>
<p>
<b>Returned Values:</b>
see <a href="#recvfrom"><code>recvfrom()</code></a>.
Zero on success.
</p>
<h3><a name="recvfrom">2.12.7 <code>recvfrom</code></a></h3>
<p>
<b>Function Prototype:</b>
</p>
<pre>
#include <sys/socket.h>
ssize_t recvfrom(int sockfd, void *buf, size_t len, int flags,
struct sockaddr *from, socklen_t *fromlen);
</pre>
<p>
<b>Description:</b>
<code>recvfrom()</code> receives messages from a socket, and may be used to receive
data on a socket whether or not it is connection-oriented.
</p>
<p>
If <code>from</code> is not NULL, and the underlying protocol provides the source
address, this source address is filled in. The argument <code>fromlen</code>
initialized to the size of the buffer associated with <code>from</code>, and modified
on return to indicate the actual size of the address stored there.
</p>
<p>
<b>Input Parameters:</b>
</p>
<ul>
<li><code>sockfd</code>: Socket descriptor of socket.</li>
<li><code>buf</code>: Buffer to receive data.</li>
<li><code>len</code>: Length of buffer.</li>
<li><code>flags</code>: Receive flags.</li>
<li><code>from</code>: Address of source.</li>
<li><code>fromlen</code>: The length of the address structure.</li>
</ul>
<p>
<b>Returned Values:</b>
On success, returns the number of characters sent.
On error, -1 is returned, and errno is set appropriately:
</p>
<ul>
<li><code>EAGAIN</code>.
The socket is marked non-blocking and the receive operation would block,
or a receive timeout had been set and the timeout expired before data
was received.
<li><code>EBADF</code>.
The argument <code>sockfd</code> is an invalid descriptor.
<li><code>ECONNREFUSED</code>.
A remote host refused to allow the network connection (typically because
it is not running the requested service).
<li><code>EFAULT</code>.
The receive buffer pointer(s) point outside the process's address space.
<li><code>EINTR</code>.
The receive was interrupted by delivery of a signal before any data were
available.
<li><code>EINVAL</code>.
Invalid argument passed.
<li><code>ENOMEM</code>.
Could not allocate memory.
<li><code>ENOTCONN</code>.
The socket is associated with a connection-oriented protocol and has
not been connected.
<li><code>ENOTSOCK</code>.
The argument <code>sockfd</code> does not refer to a socket.
</ul>
<h3><a name="setsockopt">2.12.8 <code>setsockopt</code></a></h3>
<p>
<b>Function Prototype:</b>
</p>
<pre>
#include <sys/socket.h>
int setsockopt(int sockfd, int level, int option,
const void *value, socklen_t value_len);
</pre>
<p>
<b>Description:</b>
<code>setsockopt()</code> sets the option specified by the <code>option</code> argument,
at the protocol level specified by the <code>level</code> argument, to the value
pointed to by the <code>value</code> argument for the socket associated with the
file descriptor specified by the <code>sockfd</code> argument.
</p>
<p>
The <code>level</code> argument specifies the protocol level of the option. To set
options at the socket level, specify the level argument as SOL_SOCKET.
</p>
<p>
See <sys/socket.h> a complete list of values for the <code>option</code> argument.
</p>
<p>
<b>Input Parameters:</b>
</p>
<ul>
<li><code>sockfd</code>: Socket descriptor of socket
<li><code>level</code>: Protocol level to set the option
<li><code>option</code>: identifies the option to set
<li><code>value</code>: Points to the argument value
<li><code>value_len</code>: The length of the argument value
</ul>
<p>
<b>Returned Values:</b>
On success, returns the number of characters sent.
On error, -1 is returned, and errno is set appropriately:
</p>
<ul>
<li><code>BADF</code>.
The <code>sockfd</code> argument is not a valid socket descriptor.
<li><code>DOM</code>.
The send and receive timeout values are too big to fit into the
timeout fields in the socket structure.
<li><code>INVAL</code>.
The specified option is invalid at the specified socket <code>level</code> or the
socket has been shut down.
<li><code>ISCONN</code>.
The socket is already connected, and a specified option cannot be set
while the socket is connected.
<li><code>NOPROTOOPT</code>.
The <code>option</code> is not supported by the protocol.
<li><code>NOTSOCK</code>.
The <code>sockfd</code> argument does not refer to a socket.
<li><code>NOMEM</code>.
There was insufficient memory available for the operation to complete.
<li><code>NOBUFS</code>.
Insufficient resources are available in the system to complete the call.
</ul>
<h3><a name="getsockopt">2.12.9 <code>getsockopt</code></a></h3>
<p>
<b>Function Prototype:</b>
</p>
<pre>
#include <sys/socket.h>
int getsockopt(int sockfd, int level, int option,
void *value, socklen_t *value_len);
</pre>
<p>
<b>Description:</b>
<code>getsockopt()</code> retrieve thse value for the option specified by the
<code>option</code> argument for the socket specified by the <code>sockfd</code> argument. If
the size of the option value is greater than <code>value_len</code>, the value
stored in the object pointed to by the <code>value</code> argument will be silently
truncated. Otherwise, the length pointed to by the <code>value_len</code> argument
will be modified to indicate the actual length of the<code>value</code>.
</p>
<p>
The <code>level</code> argument specifies the protocol level of the option. To
retrieve options at the socket level, specify the level argument as
SOL_SOCKET.
</p>
<p>
See <sys/socket.h> a complete list of values for the <code>option</code> argument.
</p>
<p>
<b>Input Parameters:</b>
</p>
<ul>
<li><code>sockfd Socket descriptor of socket
<li><code>level Protocol level to set the option
<li><code>option identifies the option to get
<li><code>value Points to the argument value
<li><code>value_len The length of the argument value
</ul>
<p>
<b>Returned Values:</b>
On success, returns the number of characters sent.
On error, -1 is returned, and errno is set appropriately:
</p>
<ul>
<li><code>BADF</code>.
The <code>sockfd</code> argument is not a valid socket descriptor.</li>
<li><code>INVAL</code>.
The specified option is invalid at the specified socket <code>level</code> or the
socket has been shutdown.</li>
<li><code>NOPROTOOPT</code>.
The <code>option</code> is not supported by the protocol.</li>
<li><code>NOTSOCK</code>.
The <code>sockfd</code> argument does not refer to a socket.</li>
<li><code>NOBUFS
Insufficient resources are available in the system to complete the call.</li>
</ul>
<hr>
<h1>3.0 <A NAME="Data_Structures">OS Data Structures</a></h1>
Many of the types used to communicate with NuttX are simple
scalar types. These types are used to provide architecture independence
of the OS from the application. The scalar types used at the NuttX
<ul>
<li>pid_t
<li>size_t
<li>sigset_t
<li>STATUS
<li>time_t
</ul>
Several of the types used to interface with NuttX are
structures that are intended to be hidden from the application.
From the standpoint of the application, these structures (and
structure pointers) should be treated as simple handles to reference
OS resources. These hidden structures include:
<ul>
<li>_TCB
<li>mqd_t
<li>sem_t
<li>WDOG_ID
<li>pthread_key_t
</ul>
<p>
In order to maintain portability, applications should not reference
specific elements within these hidden structures. These hidden
structures will not be described further in this user's manual.
A pointer to the thread-specific <I>errno</I>. value is available through a
function call:
<pre> int *get_errno_ptr( void )</pre>
<p>
<b>Description</b>: <I>osGetErrnorPtr()</I> returns a pointer to
This differs somewhat from the use for<code>errno</code>in a multi-threaded process environment:
Each pthread will have its own private copy of<code>errno</code>and the<code>errno</code>will not be shared
<p>
<b>Input Parameters</b>: None
<p>
<b>Returned Values</b>:
<p>
<ul>
<li>A pointer to the thread-specific <I>errno</I> value.
</ul>
<p>
main_t defines the type of a task entry point. main_t is declared
in sys/types.h as:
This structure is used to pass scheduling priorities to and from
NuttX;
NuttX and a user application:
struct timespec
{
time_t tv_sec; /* Seconds */
long tv_nsec; /* Nanoseconds */
};
between NuttX and a MoBY application:
struct mq_attr {
size_t mq_maxmsg; /* Max number of messages in queue */
size_t mq_msgsize; /* Max message size */
unsigned mq_flags; /* Queue flags */
size_t mq_curmsgs; /* Number of messages currently in queue */
};
The following structure defines the action to take for given signal:
struct sigaction
{
union
{
void (*_sa_handler)(int);
void (*_sa_sigaction)(int, siginfo_t *, void *);
} sa_u;
sigset_t sa_mask;
int sa_flags;
};
#define sa_handler sa_u._sa_handler
#define sa_sigaction sa_u._sa_sigaction
The following types is used to pass parameters to/from signal
handlers:
typedef struct siginfo
{
int si_signo;
int si_code;
union sigval si_value;
} siginfo_t;
This defines the type of the struct siginfo si_value field and
is used to pass parameters with signals.
union sigval
{
int sival_int;
void *sival_ptr;
};
The following is used to attach a signal to a message queue to
notify a task when a message is available on a queue.
struct sigevent
{
int sigev_signo;
union sigval sigev_value;
int sigev_notify;
};
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<H3>3.4.9 Watchdog Data Types</H3>
<p>
When a watchdog expires, the callback function with this
type is called:
</p>
<pre>
typedef void (*wdentry_t)(int argc, ...);
</pre>
<p>
Where argc is the number of uint32 type arguments that follow.
</p>
The arguments are passed as uint32 values.
For systems where the sizeof(pointer) < sizeof(uint32), the
following union defines the alignment of the pointer within the
uint32. For example, the SDCC MCS51 general pointer is
24-bits, but uint32 is 32-bits (of course).
</p>
<pre>
union wdparm_u
{
void *pvarg;
uint32 *dwarg;
};
typedef union wdparm_u wdparm_t;
</pre>
<p>
For most 32-bit systems, pointers and uint32 are the same size
For systems where sizeof(pointer) > sizeof(uint32), we will
have to do some redesign.
</p>
<table width="100%">
<tr>
<td>
<li><a href="#bind">bind</a></li>
<li><a href="#clockgetres">clock_getres</a></li>
<li><a href="#clockgettime">clock_gettime</a></li>
<li><a href="#ClocksNTimers">Clocks</a></li>
<li><a href="#clocksettime">clock_settime</a></li>
<li><a href="#Data_Structures">Data structures</a></li>
<li><a href="#directoryoperations">Directory operations</a></li>
<li><a href="#driveroperations">Driver operations</a></li>
<li><a href="#FileSystem">Filesystem interfaces</a></li>
<li><a href="#gmtimer">gmtime_r</a></li>
<li><a href="#Introduction">Introduction</a>
<li><a href="#kill">kill</a></li>
<li><a href="#localtimer">localtime_r</a></li>
<li><a href="#mktime">mktime</a></li>
<li><a href="#mqclose">mq_close</a></li>
<li><a href="#mqgetattr">mq_getattr</a></li>
<li><a href="#mqnotify">mq_notify</a></li>
<li><a href="#mqopen">mq_open</a></li>
<li><a href="#mqreceive">mq_receive</a></li>
<li><a href="#mqsend">mq_send</a></li>
<li><a href="#mqsetattr">mq_setattr</a></li>
<li><a href="#mqtimedreceive">mq_timedreceive</a></li>
<li><a href="#mqtimedsend">mq_timedsend</a></li>
<li><a href="#pthreadattrdestroy">pthread_attr_destroy</a></li>
<li><a href="#pthreadattrgetinheritsched">pthread_attr_getinheritsched</a></li>
<li><a href="#pthreadattrgetschedparam">pthread_attr_getschedparam</a></li>
<li><a href="#pthreadattrgetschedpolicy">pthread_attr_getschedpolicy</a></li>
<li><a href="#pthreadattrgetstacksize">0 pthread_attr_getstacksize</a></li>
<li><a href="#pthreadattrinit">pthread_attr_init</a></li>
<li><a href="#pthreadattrsetinheritsched">pthread_attr_setinheritsched</a></li>
<li><a href="#pthreadattrsetschedparam">pthread_attr_setschedparam</a></li>
<li><a href="#pthreadattrsetschedpolity">pthread_attr_setschedpolicy</a></li>
<li><a href="#pthreadattrsetstacksize">pthread_attr_setstacksize</a></li>
<li><a href="#pthreadbarrierattrinit">pthread_barrierattr_init</a></li>
<li><a href="#pthreadbarrierattrdestroy">pthread_barrierattr_destroy</a></li>
<li><a href="#pthreadbarrierattrgetpshared">pthread_barrierattr_getpshared</a></li>
<li><a href="#pthreadbarrierattrsetpshared">pthread_barrierattr_setpshared</a></li>
<li><a href="#pthreadbarrierdestroy">pthread_barrier_destroy</a></li>
<li><a href="#pthreadbarrierinit">pthread_barrier_init</a></li>
<li><a href="#pthreadbarrierwait">pthread_barrier_wait</a></li>
<li><a href="#pthreadcancel">pthread_cancel</a></li>
<li><a href="#pthreadconaddrinit">pthread_condattr_init</a></li>
<li><a href="#pthreadcondbroadcast">pthread_cond_broadcast</a></li>
<li><a href="#pthreadconddestroy">pthread_cond_destroy</a></li>
<li><a href="#pthreadcondinit">pthread_cond_init</a></li>
<li><a href="#pthreadcondsignal">pthread_cond_signal</a></li>
<li><a href="#pthreadcondtimedwait">pthread_cond_timedwait</a></li>
<li><a href="#pthreadcondwait">pthread_cond_wait</a></li>
<li><a href="#pthreadcreate">pthread_create</a></li>
<li><a href="#pthreaddetach">pthread_detach</a></li>
<li><a href="#pthreadexit">pthread_exit</a></li>
<li><a href="#pthreadgetschedparam">pthread_getschedparam</a></li>
<li><a href="#pthreadgetspecific">pthread_getspecific</a></li>
<li><a href="#Pthread"><i>pthreads</i></a> share some resources.
<li><a href="#pthreadjoin">pthread_join</a></li>
<li><a href="#pthreadkeycreate">pthread_key_create</a></li>
<li><a href="#pthreadkeydelete">pthread_key_delete</a></li>
<li><a href="#pthreadmutexattrdestroy">pthread_mutexattr_destroy</a></li>
<li><a href="#pthreadmutexattrgetpshared">pthread_mutexattr_getpshared</a></li>
<li><a href="#pthreadmutexattrinit">pthread_mutexattr_init</a></li>
<li><a href="#pthreadmutexattrsetpshared">pthread_mutexattr_setpshared</a></li>
<li><a href="#pthreadmutexdestrory">pthread_mutex_destroy</a></li>
<li><a href="#pthreadmutexinit">pthread_mutex_init</a></li>
<li><a href="#pthreadmutexlock">pthread_mutex_lock</a></li>
<li><a href="#pthreadmutextrylock">pthread_mutex_trylock</a></li>
<li><a href="#pthreadmutexunlock">pthread_mutex_unlock</a></li>
<li><a href="#pthreadocndattrdestroy">pthread_condattr_destroy</a></li>
<li><a href="#pthreadself">pthread_self</a></li>
<li><a href="#pthreadsetcancelstate">pthread_setcancelstate</a></li>
<li><a href="#pthreadsetschedparam">pthread_setschedparam</a></li>
<li><a href="#pthreadsetspecific">pthread_setspecific</a></li>
<li><a href="#pthreadsigmask">pthread_sigmask</a></li>
<li><a href="#pthreadtestcancelstate">pthread_testcancelstate</a></li>
<li><a href="#pthreadyield">pthread_yield</a></li>
<li><a href="#recv">recv</a></li>
<li><a href="#recvfrom">recvfrom</a></li>
6561
6562
6563
6564
6565
6566
6567
6568
6569
6570
6571
6572
6573
6574
6575
6576
6577
6578
6579
6580
6581
<li><a href="#schedgetparam">sched_getparam</a></li>
<li><a href="#schedgetprioritymax">sched_get_priority_max</a></li>
<li><a href="#schedgetprioritymin">sched_get_priority_min</a></li>
<li><a href="#schedgetrrinterval">sched_get_rr_interval</a></li>
<li><a href="#schedlockcount">sched_lockcount</a></li>
<li><a href="#schedlock">sched_lock</a></li>
<li><a href="#schedsetparam">sched_setparam</a></li>
<li><a href="#schedsetscheduler">sched_setscheduler</a></li>
<li><a href="#schedunlock">sched_unlock</a></li>
<li><a href="#sched_yield">sched_yield</a></li>
<li><a href="#Semaphores">Counting Semaphore Interfaces</a>
<li><a href="#semclose">sem_close</a></li>
<li><a href="#semdestroy">sem_destroy</a></li>
<li><a href="#semgetvalue">sem_getvalue</a></li>
<li><a href="#seminit">sem_init</a></li>
<li><a href="#semopen">sem_open</a></li>
<li><a href="#sempost">sem_post</a></li>
<li><a href="#semtrywait">sem_trywait</a></li>
<li><a href="#semunlink">sem_unlink</a></li>
<li><a href="#semwait">sem_wait</a></li>
<li><a href="#setgetscheduler">sched_getscheduler</a></li>
<li><a href="#send">send</a></li>
<li><a href="#sendto">sendto</a></li>
<li><a href="#setsockopt">setsockopt</a></li>
<li><a href="#sigaction">sigaction</a></li>
<li><a href="#sigaddset">sigaddset</a></li>
<li><a href="#sigdelset">sigdelset</a></li>
<li><a href="#sigemptyset">sigemptyset</a></li>
<li><a href="#sigfillset">sigfillset</a></li>
<li><a href="#sigismember">sigismember</a></li>
<li><a href="#Signals">Signal Interfaces</a>
<li><a href="#sigpending">sigpending</a></li>
<li><a href="#sigprocmask">sigprocmask</a></li>
<li><a href="#sigqueue">sigqueue</a></li>
<li><a href="#sigsuspend">sigsuspend</a></li>
<li><a href="#sigtimedwait">sigtimedwait</a></li>
<li><a href="#sigwaitinfo">sigwaitinfo</a></li>
<li><a href="#standardio">Standard I/O</a></li>
<li><a href="#taskactivate">task_activate</a></li>
<li><a href="#Task_Control">Task Control Interfaces</a>
<li><a href="#taskcreate">task_create</a></li>
<li><a href="#taskdelete">task_delete</a></li>
<li><a href="#taskinit">task_init</a></li>
<li><a href="#taskrestart">task_restart</a></li>
<li><a href="#Task_Schedule">Task Scheduling Interfaces</a>
<li><a href="#Task_Switch">Task Switching Interfaces</a>
<li><a href="#timercreate">timer_create</a></li>
<li><a href="#timerdelete">timer_delete</a></li>
<li><a href="#timergetoverrun">timer_getoverrun</a></li>
<li><a href="#timergettime">timer_gettime</a></li>
<li><a href="#ClocksNTimers">Timers</a></li>
<li><a href="#timersettime">timer_settime</a></li>
<li><a href="#Watchdogs">Watchdog Timer Interfaces</a>
<li><a href="#wdcancel">wd_cancel</a></li>
<li><a href="#wdcreate">wd_create</a></li>
<li><a href="#wddelete">wd_delete</a></li>
<li><a href="#wdgettime">wd_gettime</a></li>