From 686caf4ca401f4db14e64e5e52393c9cec6187a6 Mon Sep 17 00:00:00 2001
From: Lorenz Meier <lm@inf.ethz.ch>
Date: Wed, 16 Sep 2015 17:10:24 +0200
Subject: [PATCH] Fix semaphore handling for device on Mac OS

---
 Build/.keep                         |  0
 src/drivers/device/device_posix.cpp | 24 +++++++++++++++++++++++-
 src/drivers/device/vdev.cpp         |  2 +-
 src/drivers/device/vdev.h           |  7 ++++---
 4 files changed, 28 insertions(+), 5 deletions(-)
 delete mode 100644 Build/.keep

diff --git a/Build/.keep b/Build/.keep
deleted file mode 100644
index e69de29bb2..0000000000
diff --git a/src/drivers/device/device_posix.cpp b/src/drivers/device/device_posix.cpp
index 5fc6a595ad..97cf2c8254 100644
--- a/src/drivers/device/device_posix.cpp
+++ b/src/drivers/device/device_posix.cpp
@@ -44,6 +44,7 @@
 #include <drivers/drv_device.h>
 #include <stdio.h>
 #include <unistd.h>
+#include <sys/stat.h>
 
 namespace device
 {
@@ -54,7 +55,24 @@ Device::Device(const char *name) :
 	_name(name),
 	_debug_enabled(false)
 {
-	sem_init(&_lock, 0, 1);
+	#ifndef __PX4_DARWIN
+		_lock = new sem_t;
+		int ret = sem_init(_lock, 0, 1);
+
+		if (ret != 0) {
+			PX4_WARN("SEM INIT FAIL: ret %d, %s", ret, strerror(errno));
+		}
+	#else
+		_lock_name = new char[strlen(_name) + 2];
+		_lock_name[0] = '/';
+		strcpy(&_lock_name[1], _name);
+		/* not using O_EXCL as the device handles are unique */
+		_lock = sem_open(_lock_name, O_CREAT, 0777, 1);
+
+		if (_lock == SEM_FAILED) {
+			PX4_WARN("SEM INIT FAIL: %s", strerror(errno));
+		}
+	#endif
         
 	/* setup a default device ID. When bus_type is UNKNOWN the
 	   other fields are invalid */
@@ -67,7 +85,11 @@ Device::Device(const char *name) :
 
 Device::~Device()
 {
+	#ifdef __PX4_DARWIN
+	sem_unlink(_name);
+	#else
 	sem_destroy(&_lock);
+	#endif
 }
 
 int
diff --git a/src/drivers/device/vdev.cpp b/src/drivers/device/vdev.cpp
index 507cebbf83..430b121c09 100644
--- a/src/drivers/device/vdev.cpp
+++ b/src/drivers/device/vdev.cpp
@@ -64,7 +64,7 @@ private:
 	px4_dev_t() {}
 };
 
-#define PX4_MAX_DEV 200
+#define PX4_MAX_DEV 500
 static px4_dev_t *devmap[PX4_MAX_DEV];
 
 /*
diff --git a/src/drivers/device/vdev.h b/src/drivers/device/vdev.h
index c39857bbf0..3b4aae01ed 100644
--- a/src/drivers/device/vdev.h
+++ b/src/drivers/device/vdev.h
@@ -161,6 +161,7 @@ public:
 
 protected:
 	const char	*_name;			/**< driver name */
+	char		*_lock_name;		/**< name of the semaphore */
 	bool		_debug_enabled;		/**< if true, debug messages are printed */
 	union DeviceId	_device_id;             /**< device identifier information */
 
@@ -180,7 +181,7 @@ protected:
 	 */
 	void		lock() {
 		DEVICE_DEBUG("lock");
-		do {} while (sem_wait(&_lock) != 0);
+		do {} while (sem_wait(_lock) != 0);
 	}
 
 	/**
@@ -188,11 +189,11 @@ protected:
 	 */
 	void		unlock() {
 		DEVICE_DEBUG("unlock");
-		sem_post(&_lock);
+		sem_post(_lock);
 	}
 
 private:
-	sem_t		_lock;
+	sem_t		* _lock;
 
 	/** disable copy construction for this and all subclasses */
 	Device(const Device &);