Add operation_kill_switch and ptp_report_error example

src/camlib.h

@@ -115,11 +115,12 @@ struct PtpPropAvail {
 /// @brief Represents a single device connection
 /// @struct PtpRuntime
 struct PtpRuntime {
-	/// @brief Set to 1 to kill all IO operations. By default, this is 1. When a valid connection
-	/// is achieved by libusb, libwpd, and tcp backends, it will be set to 0. On IO error, it
-	/// will be set to 1.
+	/// @brief Set to 1 when it is no longer safe to send any data to the device (socket closed, device unplugged)
 	uint8_t io_kill_switch;
 
+	/// @brief Set to 1 when it is no longer safe to run operations (device is unresponsive, pipe issues)
+	uint8_t operation_kill_switch;
+
 	/// @brief One of enum PtpConnType
 	/// @note Is set to USB by default
 	uint8_t connection_type;

src/error.c

@@ -0,0 +1,40 @@
+// Example implementation of function to safely kill the connection in a multithreaded application.
+// Copyright 2024 by Daniel C (https://github.com/petabyt/camlib)
+
+#include <camlib.h>
+
+void ptp_report_error(struct PtpRuntime *r, char *reason, int code) {
+	if (r->io_kill_switch) return;
+	// Prevent any further operations if this is intentional
+	if (code != 0) {
+		r->operation_kill_switch = 1;
+	}
+	// Wait until we have a lock
+	ptp_mutex_lock(r);
+	// If io_kill_switch was set while waiting for a lock
+	if (r->io_kill_switch) {
+		ptp_mutex_unlock(r);
+		return;
+	}
+
+	// Safely disconnect if intentional
+	if (code == 0) {
+		ptp_verbose_log("Closing session\n");
+		ptp_close_session(r);
+	}
+
+	r->operation_kill_switch = 1;
+	r->io_kill_switch = 1;
+
+	ptp_mutex_unlock(r);
+
+	if (reason == NULL) {
+		if (code == PTP_IO_ERR) {
+			ptp_verbose_log("Disconnected: IO Error\n");
+		} else {
+			ptp_verbose_log("Disconnected: Runtime error\n");
+		}
+	} else {
+		ptp_verbose_log("Disconnected: %s\n", reason);
+	}
+}

src/ip.c

@@ -177,6 +177,7 @@ int ptpip_connect(struct PtpRuntime *r, const char *addr, int port, int extra_tm
 	if (fd > 0) {
 		b->fd = fd;
 		r->io_kill_switch = 0;
+		r->operation_kill_switch = 0;
 		return 0;
 	} else {
 		b->fd = 0;

src/lib.c

@@ -11,8 +11,9 @@
 void ptp_reset(struct PtpRuntime *r) {
 	if (r == NULL) abort();
 	r->io_kill_switch = 1;
+	r->operation_kill_switch = 1;
 	r->transaction = 0;
-	r->session = 0;	
+	r->session = 0;
 	r->connection_type = PTP_USB;
 	r->response_wait_default = 1;
 	r->wait_for_response = 1;
@@ -180,7 +181,12 @@ static int ptp_send_try(struct PtpRuntime *r, struct PtpCommand *cmd) {
 
 // Perform a generic command transaction - no data phase
 int ptp_send(struct PtpRuntime *r, struct PtpCommand *cmd) {
+	if (r->operation_kill_switch) return PTP_IO_ERR;
 	ptp_mutex_lock(r);
+	if (r->operation_kill_switch) {
+		ptp_mutex_unlock(r);
+		return PTP_IO_ERR;
+	}
 
 	r->data_phase_length = 0;
 
@@ -190,11 +196,13 @@ int ptp_send(struct PtpRuntime *r, struct PtpCommand *cmd) {
 		rc = ptp_send_try(r, cmd);
 		if (rc) {
 			ptp_verbose_log("Command ignored again.\n");
+			r->operation_kill_switch = 1;
 			ptp_mutex_unlock(r);
 			return PTP_IO_ERR;
 		}
 	} else if (rc) {
 		ptp_mutex_unlock(r);
+		r->operation_kill_switch = 1;
 		return PTP_IO_ERR;
 	}
 
@@ -240,9 +248,14 @@ static int ptp_send_data_try(struct PtpRuntime *r, struct PtpCommand *cmd, void
 
 // Perform a command request with a data phase to the camera
 int ptp_send_data(struct PtpRuntime *r, struct PtpCommand *cmd, void *data, int length) {
+	if (r->operation_kill_switch) return PTP_IO_ERR;
 	ptp_mutex_lock(r);
+	if (r->operation_kill_switch) {
+		ptp_mutex_unlock(r);
+		return PTP_IO_ERR;
+	}
 
-	// Required for libWPD and PTP/IP
+	// Required for PTP/IP
 	r->data_phase_length = length;
 
 	// Resize buffer if needed
@@ -258,11 +271,13 @@ int ptp_send_data(struct PtpRuntime *r, struct PtpCommand *cmd, void *data, int
 		rc = ptp_send_data_try(r, cmd, data, length);
 		if (rc) {
 			ptp_verbose_log("Command ignored again.\n");
+			r->operation_kill_switch = 1;
 			ptp_mutex_unlock(r);
 			return PTP_IO_ERR;
 		}
 	} else if (rc) {
 		ptp_mutex_unlock(r);
+		r->operation_kill_switch = 1;
 		return PTP_IO_ERR;
 	}
 
@@ -275,7 +290,7 @@ int ptp_send_data(struct PtpRuntime *r, struct PtpCommand *cmd, void *data, int
 
 int ptp_device_type(struct PtpRuntime *r) {
 	struct PtpDeviceInfo *di = r->di;
-	if (di == NULL) return PTP_DEV_EMPTY; // TODO: panic?
+	if (di == NULL) return PTP_DEV_EMPTY; // panic?
 	if (!strcmp(di->manufacturer, "Canon Inc.")) {
 		if (ptp_check_opcode(r, PTP_OC_EOS_GetStorageIDs)) {
 			return PTP_DEV_EOS;

src/libusb.c

@@ -238,6 +238,7 @@ int ptp_device_open(struct PtpRuntime *r, struct PtpDeviceEntry *entry) {
 	}
 
 	r->io_kill_switch = 0;
+	r->operation_kill_switch = 0;
 
 	ptp_mutex_unlock(r);
 	return 0;
@@ -279,12 +280,14 @@ int ptp_device_init(struct PtpRuntime *r) {
 	}
 
 	r->io_kill_switch = 0;
+	r->operation_kill_switch = 0;
 
 	return 0;
 }
 
 int ptp_device_close(struct PtpRuntime *r) {
 	r->io_kill_switch = 1;
+	r->operation_kill_switch = 1;
 	struct LibUSBBackend *backend = (struct LibUSBBackend *)r->comm_backend;
 	if (libusb_release_interface(backend->handle, 0)) {
 		return 1;

src/libwpd.c

@@ -57,6 +57,7 @@ int ptp_device_init(struct PtpRuntime *r) {
 		ptp_verbose_log("Found device of type: %d\n", type);
 		if (type == WPD_DEVICE_TYPE_CAMERA) {
 			r->io_kill_switch = 0;
+			r->operation_kill_switch = 0;
 			ptp_mutex_unlock(r);
 			return 0;
 		}

src/transport.c

@@ -329,7 +329,6 @@ int ptpipusb_receive_bulk_packets(struct PtpRuntime *r) {
 }
 
 int ptp_receive_all_packets(struct PtpRuntime *r) {
-	if (r->io_kill_switch) return -1;
 	if (r->connection_type == PTP_IP) {
 		return ptpip_receive_bulk_packets(r);
 	} else if (r->connection_type == PTP_USB) {