From: Rodrigo Kumpera <kumpera@gmail.com>
Date: Fri, 3 Mar 2017 18:15:49 +0000 (-0800)
Subject: [runtime] Make sure we use lower numbered signals on Android.
X-Git-Url: http://wien.tomnetworks.com/gitweb/?a=commitdiff_plain;ds=sidebyside;h=3a5adbd2aff0e0f72ceb58f4d953c1a552cb6a9e;p=mono.git

[runtime] Make sure we use lower numbered signals on Android.

Android on 32bits arm shipped broken headers that made sigset_t be 32 bits instead of 64.

This means that it's not possible to use signals whose value are >= 32. The default implementation
uses RT signals when available (and they are on Android). But RT signals don't work as expected
as their value is >= 32.

This fix hardcodes some safe signals on Android and add asserts about their values to avoid regressions.

See 5005c6f3fbc1da584c6a550281689cc23f59fe6d for more details.
---

diff --git a/mono/utils/mono-threads-posix-signals.c b/mono/utils/mono-threads-posix-signals.c
index c19ef8fe402..a4de7746d9f 100644
--- a/mono/utils/mono-threads-posix-signals.c
+++ b/mono/utils/mono-threads-posix-signals.c
@@ -80,7 +80,9 @@ abort_signal_get (void)
 static int
 suspend_signal_get (void)
 {
-#ifdef SIGRTMIN
+#if defined(PLATFORM_ANDROID)
+	return SIGPWR;
+#elif defined (SIGRTMIN)
 	static int suspend_signum = -1;
 	if (suspend_signum == -1)
 		suspend_signum = mono_threads_suspend_search_alternative_signal ();
@@ -97,7 +99,9 @@ suspend_signal_get (void)
 static int
 restart_signal_get (void)
 {
-#ifdef SIGRTMIN
+#if defined(PLATFORM_ANDROID)
+	return SIGXCPU;
+#elif defined (SIGRTMIN)
 	static int restart_signum = -1;
 	if (restart_signum == -1)
 		restart_signum = mono_threads_suspend_search_alternative_signal ();
@@ -236,6 +240,16 @@ mono_threads_suspend_init_signals (void)
 
 	/* ensure all the new signals are unblocked */
 	sigprocmask (SIG_UNBLOCK, &signal_set, NULL);
+
+	/*
+	On 32bits arm Android, signals with values >=32 are not usable as their headers ship a broken sigset_t.
+	See 5005c6f3fbc1da584c6a550281689cc23f59fe6d for more details.
+	*/
+#ifdef PLATFORM_ANDROID
+	g_assert (suspend_signal_num < 32);
+	g_assert (restart_signal_num < 32);
+	g_assert (abort_signal_num < 32);
+#endif
 }
 
 gint