As the Autoconf documentation says, "These days portable programs
[...] should not rely on `HAVE_RESTARTABLE_SYSCALLS', since nowadays
whether a system call is restartable is a dynamic issue, not a
configuration-time issue."
In other words, if we ever rely on HAVE_RESTARTABLE_SYSCALLS, we are
at the mercy of any code that Guile happens to be linked with, because
that code could install a signal handler without the SA_RESTART flag,
and then a Guile system call could unexpectedly return EINTR.
The readline part of this goes back to this problem report:
http://sources.redhat.com/ml/guile/2000-05/msg00177.html; and is an
excellent example of the above paragraph. It was noted during the
discussion that undefining HAVE_RESTARTABLE_SYSCALLS would fix the
problem, but that solution wasn't adopted - I guess because Guile was
still using cooperative threads then (not pthreads) and so there was a
significant concern (whether founded or not) that not using
restartable syscalls (where available) could lead to a loss of
performance.
Now Guile's default mode of operation is with pthreads, where we
already don't assume that HAVE_RESTARTABLE_SYSCALLS is reliable, so
there is no possible further performance loss. And in any case we
really have no choice, if we want correct operation.
Thanks to Sylvain Beucler for reporting this and suggesting the fix.
* configure.in (AC_SYS_RESTARTABLE_SYSCALLS): Removed.
* doc/ref/posix.texi (Signals): Remove statement that Guile always
sets SA_RESTART flag.
* guile-readline/configure.in (GUILE_SIGWINCH_SA_RESTART_CLEARED):
Remove this setting, together with its test code.
(HAVE_RL_PRE_INPUT_HOOK): Remove this setting and its code, as no
longer needed.
* guile-readline/readline.c (sigwinch_enable_restart): Removed.
(scm_init_readline): Remove setting of rl_pre_input_hook.
* libguile/_scm.h (SCM_SYSCALL): Remove the definition that relies on
HAVE_RESTARTABLE_SYSCALLS.
* libguile/scmsigs.c (scm_sigaction_for_thread): Don't always set the
SA_RESTART flag if available. Update docstring accordingly.
(scm_init_scmsigs): Remove code that sets SA_RESTART flag for all
signals.
* THANKS: Add Sylvain.
This patch uses the AC_LIB_LINKFLAGS macro, provided by Gnulib's
havelib module, to provide --with-gmp-prefix and
--with-readline-prefix configure options. Many thanks to Bruno Haible
for suggesting and explaining this to me.
* configure.in (top level): Add AC_LIB_LINKFLAGS(gmp).
* guile-readline/configure.in (AC_CONFIG_AUX_DIR): Change to
../build-aux, to share the main build-aux directory and so avoid
having to distribute multiple copies of config.rpath.
(top level): Add AC_LIB_LINKFLAGS(readline).
* lib/Makefile.am, m4/gnulib-cache.m4: Regenerated by gnulib-tool for
new import of the `havelib' module.
if HAVE_RL_GET_KEYMAP.
(init_bouncing_parens, find_matching_paren, match_paren): Compile
out if ! HAVE_RL_GET_KEYMAP.
* configure.in: Add check for rl_get_keymap.
(continuation-prompt): Renamed from "prompt2".
(make-readline-port, readline, set-readline-prompt!): Reflect above renamings.
(activate-readline): Rename locals "read-hook" and "prompt" to
"repl-read-hook" and "repl-prompt", to disambiguate them from
globals. Save and restore the new-input- and continuation-
prompts around the REPL read call.
Added LIBGUILEREADLINE_MAJOR variable for inclusion in the name of
the shared library.
* configure.in: AC_SUBST it.
* Makefile.am: Substitute it into name of library.
* ice-9/readline.scm: Use new name with load-extension.
Added LIBGUILEREADLINE_MAJOR variable for inclusion in the name of
the shared library.
* configure.in: AC_SUBST it.
* Makefile.am: Substitute it into name of library.
