NuttxUserGuide.html

    <code>EPERM</code>.
    The thread does not have permission to send the signal to the target thread.
  </li>
  <li>
    <code>ESRCH</code>.
    No thread could be found corresponding to that specified by the given thread ID.
  </li>
  <li>
    <code>ENOSYS</code>.
    Do not support sending signals to process groups.
  </li>
</ul>
<p>
  <b>Assumptions/Limitations:</b>
</p>
<p>
  <b>POSIX Compatibility:</b> Comparable to the POSIX interface of the same name.
</p>

<h3><a name="pthreadsigmask">2.9.52 pthread_sigmask</a></h3>
<p>
  <b>Function Prototype:</b>
</p>
<pre>
    #include &lt;signal.h&gt;
    #include &lt;pthread.h&gt;
    int pthread_sigmask(int how, FAR const sigset_t *set, FAR sigset_t *oset);
</pre>
<p>
  <b>Description:</b>
  This function is a simple wrapper around <code>sigprocmask()</code>.
  See the <code>sigprocmask()</code> function description for further information.
</p>
<p>
  <b>Input Parameters:</b>
</p>
<p>
<ul>
  <li>
    <code>how</code>. How the signal mast will be changed:
    <ul>
      <li>
        <code>SIG_BLOCK</code>:
        The resulting set is the union of the current set and the signal set pointed to by <code>set</code>.
      </li>
      <li>
        <code>SIG_UNBLOCK</code>:
        The resulting set is the intersection of the current set and the complement of the signal set pointed to by <code>set</code>.
      </li>
      <li>
        <code>SIG_SETMASK</code>:
        The resulting set is the signal set pointed to by <code>set</code>.
      </li>
    </ul>
  </li>
  <li>
    <code>set</code>. Location of the new signal mask.
  </li>
  <li>
    <code>oset</code>. Location to store the old signal mask.
  </li>
</ul>
<p>
  <b>Returned Values:</b>
</p>
<p>
  0 (OK) on succes or EINVAL if <code>how</code> is invalid.
</p>
<p>
  <b>Assumptions/Limitations:</b>
</p>
<p>
  <b>POSIX Compatibility:</b> Comparable to the POSIX interface of the same name.
</p>

<HR>
<H1>3.0 <A NAME="Data_Structures">OS Data Structures</A></H1>
<H2>3.1 Scalar types</H2>
<P>
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
interface include:
<UL>
<LI>pid_t
<LI>size_t
<LI>sigset_t
<LI>STATUS
<LI>time_t
</UL>

<H2>3.2 Hidden Interface Structures</H2>
<P>
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.
<P>

<H2>3.3. Access to the <I>errno</I> Variable</H2>
<P>
A pointer to the thread-specific <I>errno</I>. value is available through a
function call:
<P>
<B>Function Prototype:</B>
<P>
<PRE>    int *get_errno_ptr( void )</PRE>
<P>
<B>Description</B>:  <I>osGetErrnorPtr()</I> returns a pointer to
the thread-specific <I>errno</I> value.
<P>
This differs somewhat from the use for errno in a multi-threaded process environment:
Each pthread will have its own private copy of errno and the errno will not be shared
between pthreads.
<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>

<H2>3.4 User Interface Structures</H2>
<P>
<H3>3.4.1 main_t</H3>
<P>
main_t defines the type of a task entry point. main_t is declared
in sys/types.h as:
<PRE>
    typedef int (*main_t)(int argc, char *argv[]);
</PRE>

<H3>3.4.2 struct sched_param</H3>

<P>
This structure is used to pass scheduling priorities to and from
NuttX;
<PRE>
    struct sched_param
    {
      int sched_priority;
    };
</PRE>

<H3>3.4.3 struct timespec</H3>

<P>
This structure is used to pass timing information between the
NuttX and a user application:
<PRE>
    struct timespec
    {
      time_t tv_sec;  /* Seconds */
      long   tv_nsec; /* Nanoseconds */
    };
</PRE>

<H3>3.4.4 struct mq_attr</H3>

<P>
This structure is used to communicate message queue attributes
between NuttX and a MoBY application:
<PRE>
    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 */
    };
</PRE>

<H3>3.4.5 struct sigaction</H3>

<P>
The following structure defines the action to take for given signal:
<PRE>
    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
</PRE>

<H3>3.4.6 struct siginfo/siginfo_t</H3>

<P>
The following types is used to pass parameters to/from signal
handlers:
<PRE>
    typedef struct siginfo
    {
      int          si_signo;
      int          si_code;
      union sigval si_value;
   } siginfo_t;
</PRE>

<H3>3.4.7 union sigval</H3>

<P>
This defines the type of the struct siginfo si_value field and
is used to pass parameters with signals.
<PRE>
    union sigval
    {
      int   sival_int;
      void *sival_ptr;
    };
</PRE>

<H3>3.4.8 struct sigevent</H3>

<P>
The following is used to attach a signal to a message queue to
notify a task when a message is available on a queue.
<PRE>
    struct sigevent
    {
      int          sigev_signo;
      union sigval sigev_value;
      int          sigev_notify;
    };
</PRE>

<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) &lt; 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>

<h1><a name="FileSystem">2.10 Filesystem Interfaces</a></h1>
<p>
  The NuttX filesystem is very simple; it does not involve any block drivers or
  particular filesystem (like FAT or EXT2 etc.).
  The NuttX filesystem simply supports a set a filesystem APIs
  (<code>open()</code>, <code>close()</code>, <code>read()</code>, <code>write</code>, etc.)
  and a registration mechanism that allows devices drivers to a associated with <i>nodes</i>
  in a file-system-like name space.
</p>

<h2><a name="driveroperations">2.10.1 Driver Operations</a></h2>
<ul><pre>
  #include &lt;fcntl.h&gt;
  int open(const char *path, int oflag, ...);
</pre></ul>

<ul><pre>
  #include &lt;unistd.h&gt;
  int   close(int fd);
  int   dup(int fildes);
  int   dup2(int fildes1, int fildes2);
  off_t lseek(int fd, off_t offset, int whence);           /* Prototyped but not implemented */
  int   read(int fd, void *buf, unsigned int nbytes);
  int   unlink(const char *path);
  int   write(int fd, const void *buf, unsigned int nbytes);
</pre></ul>

<ul><pre>
  #include &lt;sys/ioctl.h&gt;
  int    ioctl(int fd, int req, unsigned long arg);
</pre></ul>

<h2><a name="directoryoperations">2.10.2 Directory Operations</a></h2>
<ul><pre>
  #include &lt;dirent.h&gt;
  int        closedir(DIR *dirp);
  FAR DIR   *opendir(const char *path);
  FAR struct dirent *readdir(FAR DIR *dirp);
  int        readdir_r(FAR DIR *dirp, FAR struct dirent *entry, FAR struct dirent **result);
  void       rewinddir(FAR DIR *dirp);
  void       seekdir(FAR DIR *dirp, int loc);
  int        telldir(FAR DIR *dirp);
</pre></ul>

<h2><a name="standardio">2.10.3 Standard I/O</a></h2>
<ul><pre>
  #include &lt;stdio.h&gt;
  int    fclose(FILE *stream);
  int    fflush(FILE *stream);
  int    feof(FILE *stream);                               /* Prototyped but not implemented */
  int    ferror(FILE *stream);                             /* Prototyped but not implemented */
  int    fgetc(FILE *stream);
  char  *fgets(char *s, int n, FILE *stream);
  FILE  *fopen(const char *path, const char *type);
  int    fprintf(FILE *stream, const char *format, ...);
  int    fputc(int c, FILE *stream);
  int    fputs(const char *s, FILE *stream);
  size_t fread(void *ptr, size_t size, size_t n_items, FILE *stream);
  int    fseek(FILE *stream, long int offset, int whence); /* Prototyped but not implemented */
  size_t fwrite(const void *ptr, size_t size, size_t n_items, FILE *stream);
  char  *gets(char *s);

  int    printf(const char *format, ...);
  int    puts(const char *s);
  int    rename(const char *source, const char *target);   /* Prototyped but not implemented */
  int    sprintf(char *dest, const char *format, ...);
  int    ungetc(int c, FILE *stream);
  int    vprintf(const char *s, va_list ap);
  int    vfprintf(FILE *stream, const char *s, va_list ap);
  int    vsprintf(char *buf, const char *s, va_list ap);

  int    chdir(const char *path);                          /* Prototyped but not implemented */
  FILE  *fdopen(int fd, const char *type);
  int    fstat(int fd, FAR struct stat *buf);              /* Prototyped but not implemented */
  char  *getcwd(FAR char *buf, size_t size);               /* Prototyped but not implemented */
  int    mkdir(const char *path, mode_t mode);             /* Prototyped but not implemented */
  int    rmdir(const char *path);                          /* Prototyped but not implemented */
  int    stat(const char *path, FAR struct stat *buf);     /* Prototyped but not implemented */
  int    statfs(const char *path, FAR struct statfs *buf); /* Prototyped but not implemented */
</pre></ul>

<h1><a name="index">Index</a></h1>
<ul>
  <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="#exit">exit</a></li>
  <li><a href="#FileSystem">Filesystem interfaces</a></li>
  <li><a href="#getpid">getpid</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="#Message_Queue">Named Message Queue Interfaces</a>
  <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="#mqunlink">mq_unlink</a></li>
  <li><a href="#OS_Interfaces">OS Interfaces</a>
  <li><a href="#Pthread">Pthread Interfaces</a>
  <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="#pthreadkill">pthread_kill</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="#pthreadonce">pthread_once</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="#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="#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>
  <li><a href="#wdstart">wd_start</a></li>
</ul>

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