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/*

FUNCTION

<<signal>>---specify handler subroutine for a signal

INDEX

        signal

INDEX

        _signal_r

INDEX

        raise

INDEX

        _raise_r

ANSI_SYNOPSIS

        #include <signal.h>

        void ( * signal(int <[sig]>, void(*<[func]>)(int)) )(int);

        void ( * _signal_r(void *<[reent]>,

                           int <[sig]>, void(*<[func]>)(int)) )(int);

        int raise (int <[sig]>);

        int _raise_r (void *<[reent]>, int <[sig]>);

TRAD_SYNOPSIS

        #include <signal.h>

        char ( * signal(<[sig]>, <[func]>) )()

        int <[sig]>;

        char ( * <[func]> )();

        char ( * _signal_r(<[reent]>, <[sig]>, <[func]>) )()

        char *<[reent]>;

        int <[sig]>;

        char ( * <[func]> )();

        int raise (<[sig]>)()

        int <[sig]>;

        int _raise_r (<[reent]>, <[sig]>)()

        char *<[reent]>;

        int <[sig]>;

DESCRIPTION

<<signal, raise>> provide a simple signal/raise implementation for embedded

targets.

<<signal>> allows you to request changed treatment for a particular

signal <[sig]>.  You can use one of the predefined macros <<SIG_DFL>>

(select system default handling) or <<SIG_IGN>> (ignore this signal)

as the value of <[func]>; otherwise, <[func]> is a function pointer

that identifies a subroutine in your program as the handler for this signal.

Some of the execution environment for signal handlers is

unpredictable; notably, the only library function required to work

correctly from within a signal handler is @code{signal} itself, and

only when used to redefine the handler for the current signal value.

Static storage is likewise unreliable for signal handlers, with one

exception: if you declare a static storage location as `<<volatile

sig_atomic_t>>', then you may use that location in a signal handler to

store signal values.

If your signal handler terminates using <<return>> (or implicit

return), your program's execution continues at the point

where it was when the signal was raised (whether by your program

itself, or by an external event).  Signal handlers can also

use functions such as <<exit>> and <<abort>> to avoid returning.

<<raise>> sends the signal sig to the executing program.  It returns zero if

successful, non-zero if unsuccessful.

The alternate functions <<_signal_r, _raise_r>> are the reentrant versions.

The extra argument <[reent]> is a pointer to a reentrancy structure.

@c FIXME: do we have setjmp.h and assoc fns?

RETURNS

If your request for a signal handler cannot be honored, the result is

<<SIG_ERR>>; a specific error number is also recorded in <<errno>>.

Otherwise, the result is the previous handler (a function pointer or

one of the predefined macros).

PORTABILITY

ANSI C requires <<raise>>, <<signal>>.

No supporting OS subroutines are required to link with <<signal>>, but

it will not have any useful effects, except for software generated signals,

without an operating system that can actually raise exceptions.

*/

/*

 * signal.c

 * Original Author:     G. Haley

 *

 * signal associates the function pointed to by func with the signal sig. When

 * a signal occurs, the value of func determines the action taken as follows:

 * if func is SIG_DFL, the default handling for that signal will occur; if func

 * is SIG_IGN, the signal will be ignored; otherwise, the default handling for

 * the signal is restored (SIG_DFL), and the function func is called with sig

 * as its argument. Returns the value of func for the previous call to signal

 * for the signal sig, or SIG_ERR if the request fails.

 */

/* _init_signal initialises the signal handlers for each signal. This function

   is called by crt0 at program startup.  */

#ifdef SIGNAL_PROVIDED

int _dummy_simulated_signal;

#else

#include <errno.h>

#include <signal.h>

#include <stddef.h>

#include <stdlib.h>

#include <reent.h>

#include <_syslist.h>

int

_DEFUN (_init_signal_r, (ptr),

        struct _reent *ptr)

{

  int i;

  if (ptr->_sig_func == NULL)

    {

      ptr->_sig_func = (_sig_func_ptr *)_malloc_r (ptr, sizeof (_sig_func_ptr) * NSIG);

      if (ptr->_sig_func == NULL)

        return -1;

      for (i = 0; i < NSIG; i++)

        ptr->_sig_func[i] = SIG_DFL;

    }

  return 0;

}

_sig_func_ptr

_DEFUN (_signal_r, (ptr, sig, func),

        struct _reent *ptr _AND

        int sig _AND

        _sig_func_ptr func)

{

  _sig_func_ptr old_func;

  if (sig < 0 || sig >= NSIG)

    {

      ptr->_errno = EINVAL;

      return SIG_ERR;

    }

  if (ptr->_sig_func == NULL && _init_signal_r (ptr) != 0)

    return SIG_ERR;

  old_func = ptr->_sig_func[sig];

  ptr->_sig_func[sig] = func;

  return old_func;

}

int

_raise_r (ptr, sig)

     struct _reent *ptr;

     int sig;

{

  _sig_func_ptr func;

  if (sig < 0 || sig >= NSIG)

    {

      ptr->_errno = EINVAL;

      return -1;

    }

  if (ptr->_sig_func == NULL && _init_signal_r (ptr) != 0)

    return -1;

  func = ptr->_sig_func[sig];

  if (func == SIG_DFL)

    return _kill_r (ptr, _getpid_r (ptr), sig);

  else if (func == SIG_IGN)

    return 0;

  else if (func == SIG_ERR)

    {

      ptr->_errno = EINVAL;

      return 1;

    }

  else

    {

      ptr->_sig_func[sig] = SIG_DFL;

      func (sig);

      return 0;

    }

}

int

__sigtramp_r (ptr, sig)

     struct _reent *ptr;

     int sig;

{

  _sig_func_ptr func;

  if (sig < 0 || sig >= NSIG)

    {

      return -1;

    }

  if (ptr->_sig_func == NULL && _init_signal_r (ptr) != 0)

    return -1;

  func = ptr->_sig_func[sig];

  if (func == SIG_DFL)

    return 1;

  else if (func == SIG_ERR)

    return 2;

  else if (func == SIG_IGN)

    return 3;

  else

    {

      ptr->_sig_func[sig] = SIG_DFL;

      func (sig);

      return 0;

    }

}

#ifndef _REENT_ONLY

int

raise (sig)

     int sig;

{

  return _raise_r (_REENT, sig);

}

_sig_func_ptr

_DEFUN (signal, (sig, func),

        int sig _AND

        _sig_func_ptr func)

{

  return _signal_r (_REENT, sig, func);

}

int

_init_signal ()

{

  return _init_signal_r (_REENT);

}

int

__sigtramp (int sig)

{

  return __sigtramp_r (_REENT, sig);

}

#endif

#endif /* !SIGNAL_PROVIDED */