vs里面的/***
*_PHNDLR signal(signum, sigact) - Define a signal handler
*
*Purpose:
* The signal routine allows the user to define what action should
* be taken when various signals occur. The Win32/Dosx32 implementation
* supports seven signals, divided up into three general groups
*
* 1. Signals corresponding to OS exceptions. These are:
* SIGFPE
* SIGILL
* SIGSEGV
* Signal actions for these signals are installed by altering the
* XcptAction and SigAction fields for the appropriate entry in the
* exception-action table (XcptActTab[]).
*
* 2. Signals corresponding to ^C and ^Break. These are:
* SIGINT
* SIGBREAK
* Signal actions for these signals are installed by altering the
* _ctrlc_action and _ctrlbreak_action variables.
*
* 3. Signals which are implemented only in the runtime. That is, they
* occur only as the result of a call to raise().
* SIGABRT
* SIGTERM
*
*
*Entry:
* int signum signal type. recognized signal types are:
*
* SIGABRT (ANSI)
* SIGBREAK
* SIGFPE (ANSI)
* SIGILL (ANSI)
* SIGINT (ANSI)
* SIGSEGV (ANSI)
* SIGTERM (ANSI)
* SIGABRT_COMPAT
*
* _PHNDLR sigact signal handling function or action code. the action
* codes are:
*
* SIG_DFL - take the default action, whatever that may
* be, upon receipt of this type type of signal.
*
* SIG_DIE - *** ILLEGAL ***
* special code used in the XcptAction field of an
* XcptActTab[] entry to indicate that the runtime is
* to terminate the process upon receipt of the exception.
* not accepted as a value for sigact.
*
* SIG_IGN - ignore this type of signal
*
* [function address] - transfer control to this address
* when a signal of this type occurs.
*
*Exit:
* Good return:
* Signal returns the previous value of the signal handling function
* (e.g., SIG_DFL, SIG_IGN, etc., or [function address]). This value is
* returned in DX:AX.
*
* Error return:
* Signal returns -1 and errno is set to EINVAL. The error return is
* generally taken if the user submits bogus input values.
*
*Exceptions:
* None.
*
*******************************************************************************/
_PHNDLR __cdecl signal(
int signum,
_PHNDLR sigact
)
{
struct _XCPT_ACTION *pxcptact;
_PHNDLR oldsigact;
int Error=0;
_ptiddata ptd;
BOOL SetConsoleCtrlError = FALSE;
/*
* Check for values of sigact supported on other platforms but not
* on this one. Also, make sure sigact is not SIG_DIE
*/
if ( (sigact == SIG_ACK) || (sigact == SIG_SGE) )
goto sigreterror;
/*
* Take care of all signals which do not correspond to exceptions
* in the host OS. Those are:
*
* SIGINT
* SIGBREAK
* SIGABRT
* SIGTERM
*
*/
if ( (signum == SIGINT) || (signum == SIGBREAK) || (signum == SIGABRT)
|| (signum == SIGABRT_COMPAT) || (signum == SIGTERM) ) {
_mlock( _SIGNAL_LOCK );
__try {
/*
* if SIGINT or SIGBREAK, make sure the handler is installed
* to capture ^C and ^Break events.
*/
if ( ((signum == SIGINT) || (signum == SIGBREAK)) &&
!ConsoleCtrlHandler_Installed )
{
if ( SetConsoleCtrlHandler(ctrlevent_capture, TRUE)
== TRUE )
{
ConsoleCtrlHandler_Installed = TRUE;
}
else
{
_doserrno = GetLastError();
SetConsoleCtrlError=TRUE;
}
}
switch (signum) {
case SIGINT:
oldsigact = (_PHNDLR) DecodePointer(ctrlc_action);
if(sigact!=SIG_GET)
{
ctrlc_action = (_PHNDLR) EncodePointer(sigact);
}
break;
case SIGBREAK:
oldsigact = (_PHNDLR) DecodePointer(ctrlbreak_action);
if(sigact!=SIG_GET)
{
ctrlbreak_action = (_PHNDLR) EncodePointer(sigact);
}
break;
case SIGABRT:
case SIGABRT_COMPAT:
oldsigact = (_PHNDLR) DecodePointer(abort_action);
if(sigact!=SIG_GET)
{
abort_action = (_PHNDLR) EncodePointer(sigact);
}
break;
case SIGTERM:
oldsigact = (_PHNDLR) DecodePointer(term_action);
if(sigact!=SIG_GET)
{
term_action = (_PHNDLR) EncodePointer(sigact);
}
break;
}
}
__finally {
_munlock( _SIGNAL_LOCK );
}
if (SetConsoleCtrlError) {
goto sigreterror;
}
goto sigretok;
}
/*
* If we reach here, signum is supposed to be one the signals which
* correspond to exceptions in the host OS. Those are:
*
* SIGFPE
* SIGILL
* SIGSEGV
*/
/*
* Make sure signum is one of the remaining supported signals.
*/
if ( (signum != SIGFPE) && (signum != SIGILL) && (signum != SIGSEGV) )
goto sigreterror;
/*
* Fetch the tid data table entry for this thread
*/
ptd = _getptd_noexit();
if (!ptd)
goto sigreterror;
/*
* Check that there a per-thread instance of the exception-action
* table for this thread. if there isn't, create one.
*/
if ( ptd->_pxcptacttab == _XcptActTab )
/*
* allocate space for an exception-action table
*/
if ( (ptd->_pxcptacttab = _malloc_crt(_XcptActTabSize)) != NULL )
/*
* initialize the table by copying over the contents
* of _XcptActTab[]
*/
(void) memcpy(ptd->_pxcptacttab, _XcptActTab,
_XcptActTabSize);
else
/*
* cannot create exception-action table, return
* error to caller
*/
goto sigreterror;
/*
* look up the proper entry in the exception-action table. note that
* if several exceptions are mapped to the same signal, this returns
* the pointer to first such entry in the exception action table. it
* is assumed that the other entries immediately follow this one.
*/
if ( (pxcptact = siglookup(signum, ptd->_pxcptacttab)) == NULL )
goto sigreterror;
/*
* SIGSEGV, SIGILL and SIGFPE all have more than one exception mapped
* to them. the code below depends on the exceptions corresponding to
* the same signal being grouped together in the exception-action
* table.
*/
/*
* store old signal action code for return value
*/
oldsigact = pxcptact->XcptAction;
if(sigact!=SIG_GET)
{
/*
* loop through all entries corresponding to the
* given signal and update the SigAction and XcptAction
* fields as appropriate
*/
while ( pxcptact->SigNum == signum ) {
/*
* take care of the SIG_IGN and SIG_DFL action
* codes
*/
pxcptact->XcptAction = sigact;
/*
* make sure we don't run off the end of the table
*/
if ( ++pxcptact >= ((struct _XCPT_ACTION *)(ptd->_pxcptacttab)
+ _XcptActTabCount) )
break;
}
}
sigretok:
return(oldsigact);
sigreterror:
switch(signum)
{
case _SIGHUP_IGNORE:
case _SIGQUIT_IGNORE:
case _SIGPIPE_IGNORE:
case _SIGIOINT_IGNORE:
case _SIGSTOP_IGNORE:
return SIG_ERR;
default:
_VALIDATE_RETURN(("Invalid signal or error", 0), EINVAL, SIG_ERR);
/* should never happen, but compiler can't tell */
return SIG_ERR;
}
}
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