Guardian Procedure Calls Reference Manual (G06.25+)

Guardian Procedure Calls (S)
Guardian Procedure Calls Reference Manual—522629-013
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SIGLONGJMP_ Procedure
specifies the value to be returned at the destination of the long jump; that is, at the
location of the corresponding SIGSETJMP_ call. If this value is set to 0D, then 1D
is returned; otherwise
value is returned.
Considerations
•
SIGLONGJMP_ is the TAL or pTAL procedure name for the C siglongjmp()
function. The C
siglongjmp() function complies with the POSIX.1 standard.
•
SIGLONGJMP_ does not return. Normally, return is made through the
corresponding SIGSETJMP_ procedure.
•
Restoring the signal mask with this procedure enables a native process to receive
multiple occurrences of the same nondeferrable signal when this procedure is used
to exit a signal handler. If the signal mask is not restored and the same
nondeferrable signal occurs a second time, then the process terminates.
See the SIGACTION_INIT_ procedure description for details on deferrable and
nondeferrable signals.
•
The buffer pointed to by env is assumed to be valid and initialized by an earlier call
to SIGSETJMP_. If an illegal address is passed or if the caller modifies the jump
buffer, the result is undefined and could cause the system to deliver a
nondeferrable signal to the process.
•
If SIGLONGJMP_ detects an error, a SIGABRT or SIGILL signal is raised.
•
If SIGLONGJMP_ is passed a jump buffer initialized by SETJMP_, then a simple
long jump (without restoring the signal mask) is executed.
•
The jump buffer must be accessible to both the long jump procedure call and the
associated set jump procedure call.
•
The procedure that invoked the corresponding call to SIGSETJMP_ must still be
active. That is, the activation record of the procedure that called SIGSETJMP_
must still be on the stack.
•
A long jump across a transition boundary between the TNS and native mode
environments, in either direction, is not permitted. Any attempt to do so will be fatal
to the process.
•
A nonprivileged caller cannot jump to a privileged area. Any attempt to do so will
be fatal to the process. A privileged caller, however, can execute a long jump
across the privilege boundary; privileges are automatically turned off before control
returns to the SIGSETJMP_ procedure.
•
As a result of optimization, the values of nonvolatile local variables in the
procedure that calls SIGSETJMP_ might not be the same as they were when
SIGLONGJMP_ was called if the variables are modified between the calls to
SIGSETJMP_ and SIGLONGJMP_. C and pTAL programs can declare variables
with the volatile type qualifier; this is the only safe way of preserving local variables