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5e9dc714ca
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: 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. * 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. |
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| .. | ||
| ice-9 | ||
| autogen.sh | ||
| ChangeLog-2008 | ||
| configure.in | ||
| LIBGUILEREADLINE-VERSION | ||
| Makefile.am | ||
| readline-activator.scm | ||
| readline.c | ||
| readline.h | ||