Add a kill function to the select extension, and check whether sigprocmask is available.

5 files changed, 77 insertions, 7 deletions

diff --git a/extension/ChangeLog b/extension/ChangeLog
index efb38249..49c100e4 100644
--- a/extension/ChangeLog
+++ b/extension/ChangeLog
@@ -1,3 +1,14 @@
+2013-07-05         Andrew J. Schorr     <aschorr@telemetry-investments.com>
+
+	* configure.ac (AC_CHECK_FUNCS): Add kill and sigprocmask.
+	* select.c (get_signal_number): Change error messages since now may
+	be called by "kill" as well as "select_signal".
+	(do_signal): Add a lint warning if there are more than 2 args.
+	(do_kill): Add new function to send a signal.
+	(do_select): Support platforms where sigprocmask is not available.
+	There will be a race condition on such platforms, but that is not
+	easily avoided.
+
 2013-07-02         Andrew J. Schorr     <aschorr@telemetry-investments.com>
 
 	* select.c (do_select): Now that the API flatten_array call has been
diff --git a/extension/configh.in b/extension/configh.in
index a7212dc1..aa5c71e1 100644
--- a/extension/configh.in
+++ b/extension/configh.in
@@ -66,6 +66,9 @@
 /* Define to 1 if you have the <inttypes.h> header file. */
 #undef HAVE_INTTYPES_H
 
+/* Define to 1 if you have the `kill' function. */
+#undef HAVE_KILL
+
 /* Define to 1 if you have the <limits.h> header file. */
 #undef HAVE_LIMITS_H
 
@@ -84,6 +87,9 @@
 /* Define to 1 if you have the <signal.h> header file. */
 #undef HAVE_SIGNAL_H
 
+/* Define to 1 if you have the `sigprocmask' function. */
+#undef HAVE_SIGPROCMASK
+
 /* Define to 1 if you have the <stdint.h> header file. */
 #undef HAVE_STDINT_H
 
diff --git a/extension/configure b/extension/configure
index 02ff3dc8..c9cb9a28 100755
--- a/extension/configure
+++ b/extension/configure
@@ -14018,7 +14018,7 @@ done
 
 
 for ac_func in fdopendir fnmatch gettimeofday \
-		getdtablesize nanosleep select sigaction \
+		getdtablesize kill nanosleep select sigaction sigprocmask \
 		GetSystemTimeAsFileTime
 do :
   as_ac_var=`$as_echo "ac_cv_func_$ac_func" | $as_tr_sh`
diff --git a/extension/configure.ac b/extension/configure.ac
index 5b95f966..aca856a0 100644
--- a/extension/configure.ac
+++ b/extension/configure.ac
@@ -71,7 +71,7 @@ AC_CHECK_HEADERS(dirent.h fnmatch.h limits.h time.h sys/time.h sys/select.h \
 		sys/param.h signal.h)
 
 AC_CHECK_FUNCS(fdopendir fnmatch gettimeofday \
-		getdtablesize nanosleep select sigaction \
+		getdtablesize kill nanosleep select sigaction sigprocmask \
 		GetSystemTimeAsFileTime)
 
 GAWK_FUNC_DIRFD
diff --git a/extension/select.c b/extension/select.c
index 89dbf6c3..261d8ebd 100644
--- a/extension/select.c
+++ b/extension/select.c
@@ -127,7 +127,7 @@ get_signal_number(awk_value_t signame)
 	case AWK_NUMBER:
 		x = signame.num_value;
 		if ((x != signame.num_value) || ! IS_VALID_SIGNAL(x)) {
-			update_ERRNO_string(_("select_signal: invalid signal number"));
+			update_ERRNO_string(_("invalid signal number"));
 			return -1;
 		}
 		return x;
@@ -139,10 +139,10 @@ get_signal_number(awk_value_t signame)
 			if ((integer_string(signame.str_value.str, &z) == 0) && IS_VALID_SIGNAL(z))
 				return z;
 		}
-		update_ERRNO_string(_("select_signal: invalid signal name"));
+		update_ERRNO_string(_("invalid signal name"));
 		return -1;
 	default:
-		update_ERRNO_string(_("select_signal: signal name argument must be string or numeric"));
+		update_ERRNO_string(_("signal name argument must be string or numeric"));
 		return -1;
 	}
 }
@@ -157,6 +157,8 @@ do_signal(int nargs, awk_value_t *result)
 	int signum;
 	struct sigaction sa;
 
+	if (do_lint && nargs > 2)
+		lintwarn(ext_id, _("select_signal: called with too many arguments"));
 	if (! get_argument(0, AWK_UNDEFINED, & signame)) {
 		update_ERRNO_string(_("select_signal: missing required signal name argument"));
 		return make_number(-1, result);
@@ -190,6 +192,43 @@ do_signal(int nargs, awk_value_t *result)
 #endif
 }
 
+/*  do_kill --- send a signal */
+
+static awk_value_t *
+do_kill(int nargs, awk_value_t *result)
+{
+#ifdef HAVE_KILL
+	awk_value_t pidarg, signame;
+	pid_t pid;
+	int signum;
+	int rc;
+
+	if (do_lint && nargs > 2)
+		lintwarn(ext_id, _("kill: called with too many arguments"));
+	if (! get_argument(0, AWK_NUMBER, & pidarg)) {
+		update_ERRNO_string(_("kill: missing required pid argument"));
+		return make_number(-1, result);
+	}
+	pid = pidarg.num_value;
+	if (pid != pidarg.num_value) {
+		update_ERRNO_string(_("kill: pid argument must be an integer"));
+		return make_number(-1, result);
+	}
+	if (! get_argument(1, AWK_UNDEFINED, & signame)) {
+		update_ERRNO_string(_("kill: missing required signal name argument"));
+		return make_number(-1, result);
+	}
+	if ((signum = get_signal_number(signame)) < 0)
+		return make_number(-1, result);
+	if ((rc = kill(pid, signum)) < 0)
+		update_ERRNO_int(errno);
+	return make_number(rc, result);
+#else
+	update_ERRNO_string(_("kill: not supported on this platform"));
+	return make_number(-1, result);
+#endif
+}
+
 /*  do_select --- I/O multiplexing */
 
 static awk_value_t *
@@ -290,13 +329,26 @@ do_select(int nargs, awk_value_t *result)
 
 	if (dosig && caught.flag) {
 		int i;
-		sigset_t set, oldset, trapped;
+		sigset_t trapped;
+#ifdef HAVE_SIGPROCMASK
+		/*
+		 * Block signals while we copy and reset the mask to eliminate
+		 * a race condition whereby a signal could be missed.
+		 */
+		sigset_t set, oldset;
 		sigfillset(& set);
 		sigprocmask(SIG_SETMASK, &set, &oldset);
+#endif
+		/*
+		 * Reset flag to 0 first.  If we don't have sigprocmask,
+		 * that may reduce the chance of missing a signal.
+		 */
+		caught.flag = 0;
 		trapped = caught.mask;
 		sigemptyset(& caught.mask);
-		caught.flag = 0;
+#ifdef HAVE_SIGPROCMASK
 		sigprocmask(SIG_SETMASK, &oldset, NULL);
+#endif
 		/* populate sigarr with trapped signals */
 		/*
 		 * XXX this is very inefficient!  Note that get_signal_number
@@ -391,6 +443,7 @@ static awk_ext_func_t func_table[] = {
 	{ "select", do_select, 5 },
 	{ "select_signal", do_signal, 2 },
 	{ "set_non_blocking", do_set_non_blocking, 2 },
+	{ "kill", do_kill, 2 },
 };
 
 /* define the dl_load function using the boilerplate macro */