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   sigsetjmp.3p    ( 3 )

местный goto (local goto)

Пролог (Prolog)

This manual page is part of the POSIX Programmer's Manual.  The
       Linux implementation of this interface may differ (consult the
       corresponding Linux manual page for details of Linux behavior),
       or the interface may not be implemented on Linux.

Имя (Name)

sigsetjmp — set jump point for a non-local goto

Синопсис (Synopsis)

#include <setjmp.h>

int sigsetjmp(sigjmp_buf env, int savemask);


Описание (Description)

The sigsetjmp() function shall be equivalent to the setjmp()
       function, except as follows:

* References to setjmp() are equivalent to sigsetjmp().

* References to longjmp() are equivalent to siglongjmp().

* If the value of the savemask argument is not 0, sigsetjmp() shall also save the current signal mask of the calling thread as part of the calling environment.


Возвращаемое значение (Return value)

If the return is from a successful direct invocation, sigsetjmp()
       shall return 0. If the return is from a call to siglongjmp(),
       sigsetjmp() shall return a non-zero value.

Ошибки (Error)

No errors are defined.

The following sections are informative.


Примеры (Examples)

None.

Использование в приложениях (Application usage)

The distinction between setjmp()/longjmp() and
       sigsetjmp()/siglongjmp() is only significant for programs which
       use sigaction(), sigprocmask(), or sigsuspend().

Note that since this function is defined in terms of setjmp(), if savemask is zero, it is unspecified whether the signal mask is saved.


Обоснование (Rationale)

The ISO C standard specifies various restrictions on the usage of
       the setjmp() macro in order to permit implementors to recognize
       the name in the compiler and not implement an actual function.
       These same restrictions apply to the sigsetjmp() macro.

There are processors that cannot easily support these calls, but this was not considered a sufficient reason to exclude them.

4.2 BSD, 4.3 BSD, and XSI-conformant systems provide functions named _setjmp() and _longjmp() that, together with setjmp() and longjmp(), provide the same functionality as sigsetjmp() and siglongjmp(). On those systems, setjmp() and longjmp() save and restore signal masks, while _setjmp() and _longjmp() do not. On System V Release 3 and in corresponding issues of the SVID, setjmp() and longjmp() are explicitly defined not to save and restore signal masks. In order to permit existing practice in both cases, the relation of setjmp() and longjmp() to signal masks is not specified, and a new set of functions is defined instead.

The longjmp() and siglongjmp() functions operate as in the previous issue provided the matching setjmp() or sigsetjmp() has been performed in the same thread. Non-local jumps into contexts saved by other threads would be at best a questionable practice and were not considered worthy of standardization.


Будущие направления (Future directions)

None.

Смотри также (See also)

pthread_sigmask(3p), siglongjmp(3p), signal(3p), sigsuspend(3p)

The Base Definitions volume of POSIX.1‐2017, setjmp.h(0p)