From: Rodrigo Kumpera <kumpera@gmail.com>
Date: Mon, 16 Nov 2015 05:22:56 +0000 (-0500)
Subject: [android] Add fallback for thread bounds calculation for Android.
X-Git-Url: http://wien.tomnetworks.com/gitweb/?a=commitdiff_plain;h=2a7be75dfb7a1d2afb9ef3e9780398fb52ede841;p=mono.git

[android] Add fallback for thread bounds calculation for Android.

On some junk Samsung x86 device, pthread_attr_getstack is completely broken.

If the returned value is not sane, we parse /proc/self/maps to find the right
memory regions for the current stack.

Fixes BXC #21550 and DESK #83333.

List of original contributors:

Rodrigo Kumpera <kumpera@gmail.com>
---

diff --git a/mono/utils/mono-threads-android.c b/mono/utils/mono-threads-android.c
index a72ee81a560..fa82387f26f 100644
--- a/mono/utils/mono-threads-android.c
+++ b/mono/utils/mono-threads-android.c
@@ -2,8 +2,55 @@
 
 #if defined(PLATFORM_ANDROID)
 
-#ifdef ENABLE_EXTENSION_MODULE
-#include "../../../mono-extensions/mono/utils/mono-threads-android.c"
-#endif
+#include <pthread.h>
+#include <stdio.h>
+#include <inttypes.h>
+#include "glib.h"
+
+static void
+slow_get_thread_bounds (guint8 *current, guint8 **staddr, size_t *stsize)
+{
+	char buff [1024];
+	FILE *f = fopen ("/proc/self/maps", "r");
+	if (!f)
+		g_error ("Could not determine thread bounds, failed to open /proc/self/maps");
+
+	while (fgets (buff, sizeof (buff), f)) {
+		intmax_t low, high;
+		char *ptr = buff;
+		char *end = NULL;
+		//each line starts with the range we want: f7648000-f7709000
+		low = strtoimax (ptr, &end, 16);
+		if (end) {
+			ptr = end + 1; //skip the dash to make sure we don't get a negative number
+			end = NULL;
+			high = strtoimax (ptr, &end, 16);
+		}
+		if (end && low <= (intmax_t)(size_t)current && high > (intmax_t)(size_t)current) {
+			*staddr = (guint8 *)(size_t)low;
+			*stsize = (size_t)(high - low);
+			fclose (f);
+			return;
+		}
+	}
+	g_error ("Could not determine thread bounds, failed to find current stack pointer in /proc/self/maps");
+}
+
+void
+mono_threads_core_get_stack_bounds (guint8 **staddr, size_t *stsize)
+{
+	pthread_attr_t attr;
+	guint8 *current = (guint8*)&attr;
+
+	*staddr = NULL;
+	*stsize = (size_t)-1;
+
+	pthread_getattr_np (pthread_self (), &attr);
+	pthread_attr_getstack (&attr, (void**)staddr, stsize);
+	pthread_attr_destroy (&attr);
+
+	if (*staddr && ((current <= *staddr) || (current > *staddr + *stsize)))
+		slow_get_thread_bounds (current, staddr, stsize);
+}
 
 #endif