From a3f9709566543f17f1cc1e62b8435fd8358932b5 Mon Sep 17 00:00:00 2001
From: Kadin Sayani <kadin.sayani@canonical.com>
Date: Wed, 30 Oct 2024 05:54:17 -0600
Subject: [PATCH] lxd/device: Add support for discovering multiple unix hotplug
 devices

Signed-off-by: Kadin Sayani <kadin.sayani@canonical.com>
---
 lxd/device/unix_hotplug.go | 73 ++++++++++++++++++++++----------------
 1 file changed, 42 insertions(+), 31 deletions(-)

diff --git a/lxd/device/unix_hotplug.go b/lxd/device/unix_hotplug.go
index fdd259879028..b3e7e57d8e7d 100644
--- a/lxd/device/unix_hotplug.go
+++ b/lxd/device/unix_hotplug.go
@@ -89,8 +89,7 @@ func (d *unixHotplug) validateConfig(instConf instance.ConfigReader) error {
 
 // Register is run after the device is started or when LXD starts.
 func (d *unixHotplug) Register() error {
-	// Extract variables needed to run the event hook so that the reference to this device
-	// struct is not needed to be kept in memory.
+	// Extract variables needed to run the event hook so that the reference to this device struct is not required to be stored in memory.
 	devicesPath := d.inst.DevicesPath()
 	devConfig := d.config
 	deviceName := d.name
@@ -149,29 +148,36 @@ func (d *unixHotplug) Start() (*deviceConfig.RunConfig, error) {
 	runConf := deviceConfig.RunConfig{}
 	runConf.PostHooks = []func() error{d.Register}
 
-	device := d.loadUnixDevice()
-	if d.isRequired() && device == nil {
+	devices := d.loadUnixDevices()
+	if d.isRequired() && devices == nil {
 		return nil, fmt.Errorf("Required Unix Hotplug device not found")
 	}
 
-	if device == nil {
+	if devices == nil {
 		return &runConf, nil
 	}
 
-	devnum := device.Devnum()
-	major := uint32(devnum.Major())
-	minor := uint32(devnum.Minor())
+	for _, device := range devices {
+		devnum := device.Devnum()
+		major := uint32(devnum.Major())
+		minor := uint32(devnum.Minor())
+
+		// Setup device.
+		var err error
+		if device.Subsystem() == "block" {
+			err = unixDeviceSetupBlockNum(d.state, d.inst.DevicesPath(), "unix", d.name, d.config, major, minor, device.Devnode(), false, &runConf)
+		} else {
+			err = unixDeviceSetupCharNum(d.state, d.inst.DevicesPath(), "unix", d.name, d.config, major, minor, device.Devnode(), false, &runConf)
+		}
 
-	// setup device
-	var err error
-	if device.Subsystem() == "block" {
-		err = unixDeviceSetupBlockNum(d.state, d.inst.DevicesPath(), "unix", d.name, d.config, major, minor, device.Devnode(), false, &runConf)
-	} else {
-		err = unixDeviceSetupCharNum(d.state, d.inst.DevicesPath(), "unix", d.name, d.config, major, minor, device.Devnode(), false, &runConf)
-	}
+		if err != nil {
+			err := unixDeviceRemove(d.inst.DevicesPath(), "unix", d.name, "", &runConf)
+			if err != nil {
+				return nil, err
+			}
 
-	if err != nil {
-		return nil, err
+			return nil, err
+		}
 	}
 
 	return &runConf, nil
@@ -203,9 +209,9 @@ func (d *unixHotplug) postStop() error {
 	return nil
 }
 
-// loadUnixDevice scans the host machine for unix devices with matching product/vendor ids
-// and returns the first matching device with the subsystem type char or block.
-func (d *unixHotplug) loadUnixDevice() *udev.Device {
+// loadUnixDevices scans the host machine for unix devices with matching product/vendor ids
+// and returns the matching devices with subsystem types of char or block.
+func (d *unixHotplug) loadUnixDevices() []*udev.Device {
 	// Find device if exists
 	u := udev.Udev{}
 	e := u.NewEnumerate()
@@ -230,27 +236,32 @@ func (d *unixHotplug) loadUnixDevice() *udev.Device {
 	}
 
 	devices, _ := e.Devices()
-	var device *udev.Device
+	var matchingDevices []*udev.Device
 	for i := range devices {
-		device = devices[i]
+		device := devices[i]
 
-		if device == nil {
+		if device == nil || device.Devnum().Major() == 0 || device.Devnode() == "" || strings.HasPrefix(device.Subsystem(), "usb") {
 			continue
 		}
 
-		devnum := device.Devnum()
-		if devnum.Major() == 0 || devnum.Minor() == 0 {
-			continue
+		match := false
+		vendorIDMatch := device.PropertyValue("ID_VENDOR_ID") == d.config["vendorid"]
+		productIDMatch := device.PropertyValue("ID_MODEL_ID") == d.config["productid"]
+
+		if d.config["vendorid"] != "" && d.config["productid"] != "" {
+			match = vendorIDMatch && productIDMatch
+		} else if d.config["vendorid"] != "" {
+			match = vendorIDMatch
+		} else if d.config["productid"] != "" {
+			match = productIDMatch
 		}
 
-		if device.Devnode() == "" {
+		if !match {
 			continue
 		}
 
-		if !strings.HasPrefix(device.Subsystem(), "usb") {
-			return device
-		}
+		matchingDevices = append(matchingDevices, device)
 	}
 
-	return nil
+	return matchingDevices
 }