From a4b6335e57ceea1caf7c8da33579ae45901d22d8 Mon Sep 17 00:00:00 2001
From: Carl Philipp Klemm <philipp@uvos.xyz>
Date: Tue, 7 May 2024 11:48:55 +0200
Subject: [PATCH] usb_shm: correct refcounting

---
 eismultiplexer.c |  6 +-----
 usbshm.c         | 45 +++++++++++++++++++++++++++++----------------
 usbshm.h         |  6 ++----
 3 files changed, 32 insertions(+), 25 deletions(-)

diff --git a/eismultiplexer.c b/eismultiplexer.c
index 5248c97..fc542f5 100644
--- a/eismultiplexer.c
+++ b/eismultiplexer.c
@@ -40,10 +40,6 @@ int eismultiplexer_connect(struct eismultiplexer* muliplexer, uint16_t serial)
 	muliplexer->priv = malloc(sizeof(*muliplexer->priv));
 	if(!muliplexer->priv)
 		return -1;
-	
-	ret = usbshm_init(muliplexer->priv);
-	if(ret)
-		return -2;
 
 	unsigned char serialStr[5];
 	snprintf((char*)serialStr, sizeof(serialStr), "%04hu", serial);
@@ -112,7 +108,7 @@ uint16_t eismultiplexer_read_eeprom(struct eismultiplexer* muliplexer, uint16_t
 
 void eismultiplexer_disconnect(struct eismultiplexer* muliplexer)
 {
-	usbshm_distroy(muliplexer->priv);
+	usbshm_close(muliplexer->priv);
 	free(muliplexer->priv);
 	muliplexer->priv = NULL;
 }
diff --git a/usbshm.c b/usbshm.c
index d953225..52ddc4f 100644
--- a/usbshm.c
+++ b/usbshm.c
@@ -44,20 +44,7 @@
 static int object_counter = 0;
 static struct libusb_context* context = NULL;
 
-void usbshm_distroy(struct usbshm* instance)
-{
-	pthread_mutex_lock(instance->mutex);
-	libusb_close(instance->handle);
-	if(instance->serial)
-		free(instance->serial);
-}
-
-bool usbshm_is_open(struct usbshm* instance)
-{
-	return instance->handle != NULL;
-}
-
-int usbshm_init(struct usbshm* instance)
+static int usbshm_init(struct usbshm* instance)
 {
 	int ret = 0;
 	if(object_counter == 0)
@@ -76,12 +63,38 @@ int usbshm_init(struct usbshm* instance)
 	return ret < 0 ? USBSHM_ERROR_ERR : 0;
 }
 
+static void usbshm_exit(void)
+{
+	if(--object_counter == 0)
+	{
+		libusb_exit(context);
+		context = NULL;
+	}
+}
+
+void usbshm_close(struct usbshm* instance)
+{
+	pthread_mutex_lock(instance->mutex);
+	libusb_close(instance->handle);
+	if(instance->serial)
+		free(instance->serial);
+	usbshm_exit();
+}
+
+bool usbshm_is_open(struct usbshm* instance)
+{
+	return instance->handle != NULL;
+}
+
 int usbshm_open(struct usbshm* instance, int vendorID, int productID, const unsigned char* serial)
 {
 	if(instance->handle)
 		return USBSHM_ERROR_ALLREADY_CONNECTED;
-	if(!context)
-		return USBSHM_ERROR_NOT_CONNECTED;
+
+	int ret = usbshm_init(instance);
+	if(ret < 0)
+		return ret;
+
 	pthread_mutex_lock(instance->mutex);
 	libusb_device** list;
 	int count = libusb_get_device_list(context, &list);
diff --git a/usbshm.h b/usbshm.h
index 1b0bca2..1e72b69 100644
--- a/usbshm.h
+++ b/usbshm.h
@@ -48,12 +48,10 @@ struct usbshm {
 	pthread_mutex_t* mutex;
 };
 
-void usbshm_distroy(struct usbshm* instance);
-
-int usbshm_init(struct usbshm* instance);
-
 int usbshm_open(struct usbshm* instance, int vendorID, int productID, const unsigned char* serial);
 
+void usbshm_close(struct usbshm* instance);
+
 bool usbshm_is_open(struct usbshm* instance);
 
 void usbshm_reset(struct usbshm* instance);