From 73ca8c09ddfa54eaea53378b35d2cc9d26958721 Mon Sep 17 00:00:00 2001
From: Georg von Zengen <vonzengen@ibr.cs.tu-bs.de>
Date: Thu, 7 Dec 2017 14:43:11 +0100
Subject: [PATCH] libhackrf: counts the open devices, prevents exit if not all
 closed

fixes #435, osmosdr calls hackrf_exit for the last sink and the last
source. If both are in one flow graph the desctructor of the source
fails as the sink already closed the usb context.
This prevents hackrf_exit to close the context if not all devices are closed
---
 host/libhackrf/src/hackrf.c | 25 +++++++++++++++++++------
 host/libhackrf/src/hackrf.h |  1 +
 2 files changed, 20 insertions(+), 6 deletions(-)

diff --git a/host/libhackrf/src/hackrf.c b/host/libhackrf/src/hackrf.c
index 51efae8c..94d25c0d 100644
--- a/host/libhackrf/src/hackrf.c
+++ b/host/libhackrf/src/hackrf.c
@@ -150,6 +150,7 @@ static const uint16_t hackrf_usb_vid = 0x1d50;
 static const uint16_t hackrf_jawbreaker_usb_pid = 0x604b;
 static const uint16_t hackrf_one_usb_pid = 0x6089;
 static const uint16_t rad1o_usb_pid = 0xcc15;
+static uint16_t open_devices = 0;
 
 static libusb_context* g_libusb_context = NULL;
 int last_libusb_error = LIBUSB_SUCCESS;
@@ -347,6 +348,7 @@ extern "C"
 int ADDCALL hackrf_init(void)
 {
 	int libusb_error;
+	open_devices++;
 	if (g_libusb_context != NULL) {
 		return HACKRF_SUCCESS;
 	}
@@ -355,6 +357,7 @@ int ADDCALL hackrf_init(void)
 	if( libusb_error != 0 )
 	{
 		last_libusb_error = libusb_error;
+		open_devices--;
 		return HACKRF_ERROR_LIBUSB;
 	} else {
 		return HACKRF_SUCCESS;
@@ -363,13 +366,19 @@ int ADDCALL hackrf_init(void)
 
 int ADDCALL hackrf_exit(void)
 {
-	if( g_libusb_context != NULL )
-	{
-		libusb_exit(g_libusb_context);
-		g_libusb_context = NULL;
-	}
 
-	return HACKRF_SUCCESS;
+	if( open_devices == 0)
+	{
+        if( g_libusb_context != NULL )
+        {
+            libusb_exit(g_libusb_context);
+            g_libusb_context = NULL;
+        }
+
+        return HACKRF_SUCCESS;
+	} else {
+		return HACKRF_ERROR_NOT_LAST_DEVICE;
+	}
 }
 
 #ifndef LIBRARY_VERSION
@@ -1674,6 +1683,7 @@ int ADDCALL hackrf_close(hackrf_device* device)
 
 		free(device);
 	}
+	open_devices--;
 
 	if (result2 != HACKRF_SUCCESS)
 	{
@@ -1726,6 +1736,9 @@ const char* ADDCALL hackrf_error_name(enum hackrf_error errcode)
 	case HACKRF_ERROR_USB_API_VERSION:
 		return "feature not supported by installed firmware";
 
+	case HACKRF_ERROR_NOT_LAST_DEVICE:
+		return "some hackrf is sill in use";
+
 	case HACKRF_ERROR_OTHER:
 		return "unspecified error";
 
diff --git a/host/libhackrf/src/hackrf.h b/host/libhackrf/src/hackrf.h
index 4c43bffd..476cc571 100644
--- a/host/libhackrf/src/hackrf.h
+++ b/host/libhackrf/src/hackrf.h
@@ -64,6 +64,7 @@ enum hackrf_error {
 	HACKRF_ERROR_STREAMING_STOPPED = -1003,
 	HACKRF_ERROR_STREAMING_EXIT_CALLED = -1004,
 	HACKRF_ERROR_USB_API_VERSION = -1005,
+	HACKRF_ERROR_NOT_LAST_DEVICE = -2000,
 	HACKRF_ERROR_OTHER = -9999,
 };