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)
