From 075d3b80578e00e848368d58a96120b66a27012c Mon Sep 17 00:00:00 2001
From: Tiago Castro <tiagolobocastro@gmail.com>
Date: Thu, 25 Jul 2024 23:23:18 +0100
Subject: [PATCH] feat(monitor/kernel): allow monitoring kernel events

Allows monitoring events from the kernel source.
This allows clients to select which source they want to use, similar
to udevadm monitor for example.
Default remains udev.

Signed-off-by: Tiago Castro <tiagolobocastro@gmail.com>
---
 src/monitor.rs | 28 ++++++++++++++++++++++++++--
 1 file changed, 26 insertions(+), 2 deletions(-)

diff --git a/src/monitor.rs b/src/monitor.rs
index 7dac6c9..dd6513f 100644
--- a/src/monitor.rs
+++ b/src/monitor.rs
@@ -50,8 +50,14 @@ impl Drop for Builder {
 
 as_ffi_with_context!(Builder, monitor, ffi::udev_monitor, ffi::udev_monitor_ref);
 
+/// The event source to monitor.
+pub(crate) enum EventSource {
+    Udev,
+    Kernel,
+}
+
 impl Builder {
-    /// Creates a new `Monitor`.
+    /// Creates a new udev event `Monitor`.
     pub fn new() -> Result<Self> {
         // Create a new Udev context for this monitor
         // It would be more efficient to allow callers to create just one context and use multiple
@@ -59,9 +65,27 @@ impl Builder {
         Self::with_udev(Udev::new()?)
     }
 
+    /// Creates a new kernel event `Monitor`.
+    pub fn new_kernel() -> Result<Self> {
+        Self::with_kernel(Udev::new()?)
+    }
+
     /// Creates a new `Monitor` using an existing `Udev` instance
     pub(crate) fn with_udev(udev: Udev) -> Result<Self> {
-        let name = b"udev\0".as_ptr() as *const libc::c_char;
+        Self::with_source(udev, EventSource::Udev)
+    }
+
+    /// Creates a new kernel event `Monitor` using an existing `Udev` instance.
+    pub(crate) fn with_kernel(udev: Udev) -> Result<Self> {
+        Self::with_source(udev, EventSource::Kernel)
+    }
+
+    /// Creates a `Monitor` for the given source, using an existing `Udev` instance.
+    pub(crate) fn with_source(udev: Udev, source: EventSource) -> Result<Self> {
+        let name = match source {
+            EventSource::Udev => b"udev\0".as_ptr() as *const libc::c_char,
+            EventSource::Kernel => b"kernel\0".as_ptr() as *const libc::c_char,
+        };
 
         let ptr = try_alloc!(unsafe { ffi::udev_monitor_new_from_netlink(udev.as_raw(), name) });