Reuben Thomas wrote:
> (SIGPOLL is mandated by POSIX).
This is not true. Look at
<http://pubs.opengroup.org/onlinepubs/9699919799/basedefs/signal.h.html>
In the table, SIGPOLL is marked with OB and XSR.
- [OB] means obsolescent.
- [XSR] means XSI STREAMS. This is an optional part of POSIX that only
few systems implement, namely glibc, SVR4 based systems, and AIX.
BSD systems don't implement XSI STREAMS.
> I'm writing Lua bindings for POSIX APIs
What can signals like SIGPOLL bring you in this use-case? Given that
you can't evaluate Lua code from within a signal handler (a consequence
of Lua's interpreter using malloc()/realloc(), and malloc()/realloc() not
being safe to be called from a signal handler), what can the user do with
a C binding that offers signals?
> Also, gnulib does not define _POSIX_C_SOURCE on Darwin, which is
> necessary in order to get some POSIX features.
It is better *not* to fiddle with _POSIX_C_SOURCE, because on many
systems _POSIX_C_SOURCE has the effect of hiding many platform specific
extensions.
For example, on glibc systems <features.h> contains:
/* If nothing (other than _GNU_SOURCE) is defined,
define _BSD_SOURCE and _SVID_SOURCE. */
#if (!defined __STRICT_ANSI__ && !defined _ISOC99_SOURCE && \
!defined _POSIX_SOURCE && !defined _POSIX_C_SOURCE && \
!defined _XOPEN_SOURCE && !defined _XOPEN_SOURCE_EXTENDED && \
!defined _BSD_SOURCE && !defined _SVID_SOURCE)
# define _BSD_SOURCE 1
# define _SVID_SOURCE 1
#endif
On MacOS X systems <sys/cdefs.h> contains:
* STRICT Defining _POSIX_C_SOURCE or _XOPEN_SOURCE restricts the
* available APIs to exactly the set of APIs defined by the
* corresponding standard, based on the value defined.
Similarly, on OpenBSD, the presence of _POSIX_C_SOURCE hides some functions:
#if (!defined(_POSIX_C_SOURCE) && !defined(_XOPEN_SOURCE)) || \
(_XOPEN_VERSION - 0) >= 500
ssize_t pread(int, void *, size_t, off_t);
ssize_t pwrite(int, const void *, size_t, off_t);
#endif
> Is there anything to be done in gnulib
No. SIGPOLL is definitely not in the scope of the common, widely used
Unix APIs that gnulib cares about.
Bruno
