First cut at signal handling support.

* Makefile (OBJS-y): Include signal.o if have_posix_sigs is "y".

* configure (have_posix_sigs): New variable, set by detecting POSIX
signal stuff.

* dep.mk: Regenerated.

* arith.c, debug.c, eval.c, filter.c, hash.c, match.c, parser.y,
parser.l, rand.c, regex.c, syslog.c, txr.c, utf8.c: Include new
signal.h header, now required by unwind, and the <signal.h> system
header.

* eval.c (exit_wrap): New function.
(eval_init): New functions registered as intrinsics: exit_wrap,
set_sig_handler, get_sig_handler, sig_check.

* gc.c (release): Unused functions removed.

* gc.h (release): Declaration removed.

* lib.c (init): Call sig_init.

* stream.c (set_putc, se_getc, se_fflush): New static functions.
(stdio_put_char_callback, stdio_get_char_callback, stdio_put_byte,
stdio_flush, stdio_get_byte): Use new functions to enable
signals when blocked on I/O.
(tail_strategy): Allow signals across sleep.
(pipev_close): Allow signals across waitpid.
(se_pclose): New static function.
(pipe_close): Use new function to enable signals across pclose.

* unwind.c (uw_unwind_to_exit_point): use extended_longjmp instead of
longjmp.

* unwind.h (struct uw_block, struct uw_catch): jb member changes from
jmp_buf to extended_jmp_buf.
(uw_block_begin, uw_simple_catch_begin, uw_catch_begin): Use
extended_setjmp instead of setjmp.

* signal.c: New file.

* signal.h: New file.

1 files changed, 135 insertions, 0 deletions

diff --git a/signal.c b/signal.c
new file mode 100644
index 00000000..05ad9eb6
--- /dev/null
+++ b/signal.c
@@ -0,0 +1,135 @@
+/* Copyright 2013-2014
+ * Kaz Kylheku <kaz@kylheku.com>
+ * Vancouver, Canada
+ * All rights reserved.
+ *
+ * BSD License:
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ *   1. Redistributions of source code must retain the above copyright
+ *      notice, this list of conditions and the following disclaimer.
+ *   2. Redistributions in binary form must reproduce the above copyright
+ *      notice, this list of conditions and the following disclaimer in
+ *      the documentation and/or other materials provided with the
+ *      distribution.
+ *   3. The name of the author may not be used to endorse or promote
+ *      products derived from this software without specific prior
+ *      written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
+ * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
+ * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
+ */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <stdarg.h>
+#include <setjmp.h>
+#include <wchar.h>
+#include <dirent.h>
+#include <signal.h>
+#include "config.h"
+#include "lib.h"
+#include "stream.h"
+#include "hash.h"
+#include "gc.h"
+#include "signal.h"
+#include "unwind.h"
+
+#define MAX_SIG 32
+
+volatile sig_atomic_t async_sig_enabled = 0;
+
+static val sig_lambda[MAX_SIG];
+volatile unsigned long sig_deferred;
+
+static void sig_handler(int sig)
+{
+  val lambda = sig_lambda[sig];
+  if (lambda) {
+    if (async_sig_enabled) {
+      async_sig_enabled = 0;
+      funcall1(lambda, num_fast(sig));
+      async_sig_enabled = 1;
+    } else {
+      sig_deferred |= (1UL << sig);
+    }
+  }
+}
+
+void sig_init(void)
+{
+  int i;
+
+  for (i = 0; i < MAX_SIG; i++) {
+    /* t means SIG_DFL, which is what signals
+     * are before we manipulate them. */
+    sig_lambda[i] = t; 
+    prot1(&sig_lambda[i]);
+  }
+}
+
+val set_sig_handler(val signo, val lambda)
+{
+  cnum sig = c_num(signo);
+  val old_lambda;
+
+  if (sig < 0 || sig >= MAX_SIG)
+    uw_throwf(error_s, lit("set-sig-handler: signal ~s out of range\n"), sig, nao);
+
+  old_lambda = sig_lambda[sig];
+
+  if (lambda != old_lambda) {
+    if (lambda == nil) {
+      signal(sig, SIG_IGN);
+    } else if (lambda == t) {
+      signal(sig, SIG_DFL);
+    } else {
+      struct sigaction sa = { 0 };
+
+      type_check(lambda, FUN);
+
+      sa.sa_flags = SA_RESTART;
+      sa.sa_handler = sig_handler;
+      sigfillset(&sa.sa_mask);
+      sigaction(sig, &sa, 0);
+    }
+
+    sig_lambda[sig] = lambda;
+  }
+
+  return old_lambda;
+}
+
+val get_sig_handler(val signo)
+{
+  cnum sig = c_num(signo);
+
+  if (sig < 0 || sig >= MAX_SIG)
+    uw_throwf(error_s, lit("get-sig-handler: signal ~s out of range\n"), sig, nao);
+
+  return sig_lambda[sig];
+}
+
+val sig_check(void)
+{
+  unsigned long sd;
+  int i;
+
+  if ((sd = sig_deferred) == 0)
+    return nil;
+
+  for (i = 0; i < MAX_SIG; i++) {
+    unsigned long mask = 1UL << i;
+    if ((sd & mask) != 0) {
+      sd &= ~mask;
+      sig_deferred = sd;
+      funcall1(sig_lambda[i], num_fast(i));
+    }
+  }
+
+  return t;
+}