Add interface number by AurelienBallier · Pull Request #126 · jpnurmi/flutter_libserialport

AurelienBallier · 2025-01-21T16:22:31Z

I'm using Zephyr RTOS CDC driver with 3 serial ports for my USB device, I need a way to differentiate my serial ports as they have the same VID/PID.
An easy way to do that is to use the interface number, this PR add an interface_number coming from the underlying USB device lib.

This PR is related to libserialport.dart PR #87.

This PR also fixes Windows VID/PID null value which could solve libserialport.dart issue #85.

Copilot

Pull Request Overview

This PR adds USB interface number support to libserialport to differentiate between multiple serial ports with the same VID/PID. The interface number is extracted from the underlying USB device information on both Windows and Linux platforms.

Add usb_interface_number field to port structure and API
Extract interface number from hardware IDs on Windows and from sysfs on Linux
Fix Windows VID/PID extraction by parsing hardware IDs instead of using potentially null connection info

Reviewed Changes

Copilot reviewed 6 out of 6 changed files in this pull request and generated 7 comments.

Show a summary per file

File	Description
third_party/libserialport/libserialport.h	Updated API to include interface number parameter
third_party/libserialport/libserialport_internal.h	Added interface number field to port structure
third_party/libserialport/serialport.c	Initialize interface number and updated API implementation
third_party/libserialport/linux.c	Extract interface number from sysfs bInterfaceNumber file
third_party/libserialport/windows.c	Parse interface number, VID, and PID from hardware IDs
pubspec.yaml	Switch to git dependency for testing changes

Copilot · 2025-07-31T22:37:57Z

+				if (CM_Get_DevNode_Registry_PropertyA(dev_inst, CM_DRP_HARDWAREID                  ,
+				                        0, &hardware_ids, &size, 0) == CR_SUCCESS) {
+					//printf("Result hardware ids: %s\n", hardware_ids);


Remove the commented-out printf statement and excessive whitespace in the function call for cleaner code.

Suggested change

if (CM_Get_DevNode_Registry_PropertyA(dev_inst, CM_DRP_HARDWAREID ,

0, &hardware_ids, &size, 0) == CR_SUCCESS) {

//printf("Result hardware ids: %s\n", hardware_ids);

if (CM_Get_DevNode_Registry_PropertyA(dev_inst, CM_DRP_HARDWAREID,

0, &hardware_ids, &size, 0) == CR_SUCCESS) {

Copilot · 2025-07-31T22:37:57Z

+			size_t MI_idx = result - hardware_ids;
+			if((MI_idx >= 0) && ((MI_idx + 4) < sizeof(hardware_ids))) {
+				int a = hardware_ids[MI_idx + 3] - '0';
+				int b = hardware_ids[MI_idx + 4] -'0';
+				port->usb_interface_number = a * 10 + b;
+			}
+
+
+			result = strstr(hardware_ids, "VID_");
+			size_t VID_idx = result - hardware_ids;
+			if((VID_idx >= 0) && ((VID_idx + 7) < sizeof(hardware_ids))) {
+				sscanf((hardware_ids + VID_idx + 4), "%4x", &port->usb_vid);
+			}
+
+			result = strstr(hardware_ids, "PID_");
+			size_t PID_idx = result - hardware_ids;
+			if((PID_idx >= 0) && ((PID_idx + 7) < sizeof(hardware_ids))) {
+				sscanf((hardware_ids + PID_idx + 4), "%4x", &port->usb_pid);


The condition MI_idx >= 0 is always true since MI_idx is of type size_t (unsigned). If strstr returns NULL, this will cause undefined behavior. Check if result is NULL before calculating MI_idx.

Suggested change

size_t MI_idx = result - hardware_ids;

if((MI_idx >= 0) && ((MI_idx + 4) < sizeof(hardware_ids))) {

int a = hardware_ids[MI_idx + 3] - '0';

int b = hardware_ids[MI_idx + 4] -'0';

port->usb_interface_number = a * 10 + b;

}

result = strstr(hardware_ids, "VID_");

size_t VID_idx = result - hardware_ids;

if((VID_idx >= 0) && ((VID_idx + 7) < sizeof(hardware_ids))) {

sscanf((hardware_ids + VID_idx + 4), "%4x", &port->usb_vid);

}

result = strstr(hardware_ids, "PID_");

size_t PID_idx = result - hardware_ids;

if((PID_idx >= 0) && ((PID_idx + 7) < sizeof(hardware_ids))) {

sscanf((hardware_ids + PID_idx + 4), "%4x", &port->usb_pid);

if (result != NULL) {

size_t MI_idx = result - hardware_ids;

if ((MI_idx + 4) < sizeof(hardware_ids)) {

int a = hardware_ids[MI_idx + 3] - '0';

int b = hardware_ids[MI_idx + 4] - '0';

port->usb_interface_number = a * 10 + b;

}

}

result = strstr(hardware_ids, "VID_");

if (result != NULL) {

size_t VID_idx = result - hardware_ids;

if ((VID_idx + 7) < sizeof(hardware_ids)) {

sscanf((hardware_ids + VID_idx + 4), "%4x", &port->usb_vid);

}

}

result = strstr(hardware_ids, "PID_");

if (result != NULL) {

size_t PID_idx = result - hardware_ids;

if ((PID_idx + 7) < sizeof(hardware_ids)) {

sscanf((hardware_ids + PID_idx + 4), "%4x", &port->usb_pid);

}

Copilot · 2025-07-31T22:37:58Z

+			size_t MI_idx = result - hardware_ids;
+			if((MI_idx >= 0) && ((MI_idx + 4) < sizeof(hardware_ids))) {
+				int a = hardware_ids[MI_idx + 3] - '0';
+				int b = hardware_ids[MI_idx + 4] -'0';


Missing space before the minus operator. Should be hardware_ids[MI_idx + 4] - '0' for consistency with the line above.

Suggested change

int b = hardware_ids[MI_idx + 4] -'0';

int b = hardware_ids[MI_idx + 4] - '0';

Copilot · 2025-07-31T22:37:58Z

+
+
+			result = strstr(hardware_ids, "VID_");
+			size_t VID_idx = result - hardware_ids;


Same issue as with MI_idx - if strstr returns NULL, this will cause undefined behavior. Check if result is NULL before calculating VID_idx.

Copilot · 2025-07-31T22:37:58Z

+			size_t MI_idx = result - hardware_ids;
+			if((MI_idx >= 0) && ((MI_idx + 4) < sizeof(hardware_ids))) {
+				int a = hardware_ids[MI_idx + 3] - '0';
+				int b = hardware_ids[MI_idx + 4] -'0';
+				port->usb_interface_number = a * 10 + b;
+			}
+
+
+			result = strstr(hardware_ids, "VID_");
+			size_t VID_idx = result - hardware_ids;
+			if((VID_idx >= 0) && ((VID_idx + 7) < sizeof(hardware_ids))) {
+				sscanf((hardware_ids + VID_idx + 4), "%4x", &port->usb_vid);
+			}
+
+			result = strstr(hardware_ids, "PID_");
+			size_t PID_idx = result - hardware_ids;
+			if((PID_idx >= 0) && ((PID_idx + 7) < sizeof(hardware_ids))) {
+				sscanf((hardware_ids + PID_idx + 4), "%4x", &port->usb_pid);


Same issue as with MI_idx and VID_idx - if strstr returns NULL, this will cause undefined behavior. Check if result is NULL before calculating PID_idx.

Suggested change

size_t MI_idx = result - hardware_ids;

if((MI_idx >= 0) && ((MI_idx + 4) < sizeof(hardware_ids))) {

int a = hardware_ids[MI_idx + 3] - '0';

int b = hardware_ids[MI_idx + 4] -'0';

port->usb_interface_number = a * 10 + b;

}

result = strstr(hardware_ids, "VID_");

size_t VID_idx = result - hardware_ids;

if((VID_idx >= 0) && ((VID_idx + 7) < sizeof(hardware_ids))) {

sscanf((hardware_ids + VID_idx + 4), "%4x", &port->usb_vid);

}

result = strstr(hardware_ids, "PID_");

size_t PID_idx = result - hardware_ids;

if((PID_idx >= 0) && ((PID_idx + 7) < sizeof(hardware_ids))) {

sscanf((hardware_ids + PID_idx + 4), "%4x", &port->usb_pid);

if (result != NULL) {

size_t MI_idx = result - hardware_ids;

if ((MI_idx >= 0) && ((MI_idx + 4) < sizeof(hardware_ids))) {

int a = hardware_ids[MI_idx + 3] - '0';

int b = hardware_ids[MI_idx + 4] - '0';

port->usb_interface_number = a * 10 + b;

}

}

result = strstr(hardware_ids, "VID_");

if (result != NULL) {

size_t VID_idx = result - hardware_ids;

if ((VID_idx >= 0) && ((VID_idx + 7) < sizeof(hardware_ids))) {

sscanf((hardware_ids + VID_idx + 4), "%4x", &port->usb_vid);

}

}

result = strstr(hardware_ids, "PID_");

if (result != NULL) {

size_t PID_idx = result - hardware_ids;

if ((PID_idx >= 0) && ((PID_idx + 7) < sizeof(hardware_ids))) {

sscanf((hardware_ids + PID_idx + 4), "%4x", &port->usb_pid);

}

Copilot · 2025-07-31T22:37:59Z

+			char *result = strstr(hardware_ids, "MI_");
+			size_t MI_idx = result - hardware_ids;
+			if((MI_idx >= 0) && ((MI_idx + 4) < sizeof(hardware_ids))) {
+				int a = hardware_ids[MI_idx + 3] - '0';


No validation that the characters at positions MI_idx+3 and MI_idx+4 are actually digits. This could result in incorrect interface numbers if the hardware ID format is unexpected.

Copilot · 2025-07-31T22:37:59Z

+SP_API enum sp_return sp_get_port_usb_vid_pid(const struct sp_port *port, int *usb_vid, int *usb_pid, int *usb_interface_number);

 /**


This is a breaking API change. Consider adding a new function like sp_get_port_usb_vid_pid_interface instead of modifying the existing function signature to maintain backward compatibility.

Suggested change

SP_API enum sp_return sp_get_port_usb_vid_pid(const struct sp_port *port, int *usb_vid, int *usb_pid, int *usb_interface_number);

/**

SP_API enum sp_return sp_get_port_usb_vid_pid(const struct sp_port *port, int *usb_vid, int *usb_pid);

/**

* Get the USB Vendor ID, Product ID, and Interface Number of a USB serial adapter port.

*

* @param[in] port Pointer to a port structure. Must not be NULL.

* @param[out] usb_vid Pointer to a variable to store the USB VID.

* Can be NULL (in that case it will be ignored).

* @param[out] usb_pid Pointer to a variable to store the USB PID.

* Can be NULL (in that case it will be ignored).

* @param[out] usb_interface_number Pointer to a variable to store the USB interface number.

* Can be NULL (in that case it will be ignored).

*

* @return SP_OK upon success, a negative error code otherwise.

*

* @since 0.1.2

*/

SP_API enum sp_return sp_get_port_usb_vid_pid_interface(const struct sp_port *port, int *usb_vid, int *usb_pid, int *usb_interface_number);

/**

Aurelien Ballier added 3 commits December 13, 2024 13:46

Add USB interface number and Linux grabber

fd4939d

remove rej files

15c1671

Fix VID & PID on Windows, and add Inter_number

aede847

mrdevrobot added the enhancement New feature or request label Feb 10, 2025

mrdevrobot requested a review from Copilot July 31, 2025 22:36

Copilot AI reviewed Jul 31, 2025

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Add interface number - #126

Add interface number#126
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	int b = hardware_ids[MI_idx + 4] -'0';
	int b = hardware_ids[MI_idx + 4] - '0';



		result = strstr(hardware_ids, "VID_");
		size_t VID_idx = result - hardware_ids;

		SP_API enum sp_return sp_get_port_usb_vid_pid(const struct sp_port port, int usb_vid, int usb_pid, int usb_interface_number);

		/**

-SP_API enum sp_return sp_get_port_usb_vid_pid(const struct sp_port *port, int *usb_vid, int *usb_pid, int *usb_interface_number);
-/**
+SP_API enum sp_return sp_get_port_usb_vid_pid(const struct sp_port *port, int *usb_vid, int *usb_pid);
+/**
+ * Get the USB Vendor ID, Product ID, and Interface Number of a USB serial adapter port.
+ *
+ * @param[in] port Pointer to a port structure. Must not be NULL.
+ * @param[out] usb_vid Pointer to a variable to store the USB VID.
+ *                     Can be NULL (in that case it will be ignored).
+ * @param[out] usb_pid Pointer to a variable to store the USB PID.
+ *                     Can be NULL (in that case it will be ignored).
+ * @param[out] usb_interface_number Pointer to a variable to store the USB interface number.
+ *                                  Can be NULL (in that case it will be ignored).
+ *
+ * @return SP_OK upon success, a negative error code otherwise.
+ *
+ * @since 0.1.2
+ */
+SP_API enum sp_return sp_get_port_usb_vid_pid_interface(const struct sp_port *port, int *usb_vid, int *usb_pid, int *usb_interface_number);
+/**

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