Add support for lirc programs

Signed-off-by: Sean Young <sean@mess.org>

aya/src/bpf.rs

@@ -19,8 +19,9 @@ use crate::{
         Object, ParseError, ProgramKind,
     },
     programs::{
-        CgroupSkb, CgroupSkbAttachType, KProbe, ProbeKind, Program, ProgramData, ProgramError,
-        SchedClassifier, SkMsg, SkSkb, SkSkbKind, SockOps, SocketFilter, TracePoint, UProbe, Xdp,
+        CgroupSkb, CgroupSkbAttachType, KProbe, LircMode2, ProbeKind, Program, ProgramData,
+        ProgramError, SchedClassifier, SkMsg, SkSkb, SkSkbKind, SockOps, SocketFilter, TracePoint,
+        UProbe, Xdp,
     },
     sys::bpf_map_update_elem_ptr,
     util::{possible_cpus, POSSIBLE_CPUS},
@@ -195,6 +196,7 @@ impl Bpf {
                         data,
                         expected_attach_type: Some(CgroupSkbAttachType::Egress),
                     }),
+                    ProgramKind::LircMode2 => Program::LircMode2(LircMode2 { data }),
                 };
 
                 (name, program)

aya/src/obj/mod.rs

@@ -80,6 +80,7 @@ pub enum ProgramKind {
     SchedClassifier,
     CgroupSkbIngress,
     CgroupSkbEgress,
+    LircMode2,
 }
 
 impl FromStr for ProgramKind {
@@ -102,6 +103,7 @@ impl FromStr for ProgramKind {
             "classifier" => SchedClassifier,
             "cgroup_skb/ingress" => CgroupSkbIngress,
             "cgroup_skb/egress" => CgroupSkbEgress,
+            "lirc_mode2" => LircMode2,
             _ => {
                 return Err(ParseError::InvalidProgramKind {
                     kind: kind.to_string(),
@@ -302,7 +304,8 @@ impl Object {
             | &[ty @ "classifier", name]
             | &[ty @ "cgroup_skb/ingress", name]
             | &[ty @ "cgroup_skb/egress", name]
-            | &[ty @ "cgroup/skb", name] => {
+            | &[ty @ "cgroup/skb", name]
+            | &[ty @ "lirc_mode2", name] => {
                 self.programs
                     .insert(name.to_string(), self.parse_program(&section, ty, name)?);
                 if !section.relocations.is_empty() {

aya/src/programs/lirc_mode2.rs

@@ -0,0 +1,101 @@
+use std::os::unix::prelude::{AsRawFd, RawFd};
+
+use crate::{
+    generated::{bpf_attach_type::BPF_LIRC_MODE2, bpf_prog_type::BPF_PROG_TYPE_LIRC_MODE2},
+    programs::{load_program, Link, LinkRef, ProgramData, ProgramError},
+    sys::{bpf_prog_attach, bpf_prog_detach},
+};
+
+use libc::{close, dup};
+
+/// A program used to decode IR into key events for a lirc device.
+///
+/// [`LircMode2`] programs can be used to inspect infrared pulses, spaces,
+/// and timeouts received by a lirc IR receiver.
+///
+/// [lirc]: https://www.kernel.org/doc/html/latest/userspace-api/media/rc/lirc-dev.html
+///
+/// # Examples
+///
+/// ```no_run
+/// use std::fs::File;
+/// use std::convert::TryInto;
+/// use aya::programs::LircMode2;
+///
+/// let file = File::open("/dev/lirc0").unwrap();
+/// let mut bpf = Bpf::load_file("imon_rsc.o").unwrap();
+/// let decoder: &mut LircMode2 = bpf.program_mut("imon_rsc").unwrap().try_into().unwrap();
+/// decoder.load().unwrap();
+/// decoder.attach(file).unwrap();
+/// # Ok::<(), Error>(())
+/// ```
+#[derive(Debug)]
+#[doc(alias = "BPF_PROG_TYPE_LIRC_MODE2")]
+pub struct LircMode2 {
+    pub(crate) data: ProgramData,
+}
+
+impl LircMode2 {
+    /// Loads the program inside the kernel.
+    ///
+    /// See also [`Program::load`](crate::programs::Program::load).
+    pub fn load(&mut self) -> Result<(), ProgramError> {
+        load_program(BPF_PROG_TYPE_LIRC_MODE2, &mut self.data)
+    }
+
+    /// Returns the name of the program.
+    pub fn name(&self) -> String {
+        self.data.name.to_string()
+    }
+
+    /// Attaches the program to the given lirc device.
+    pub fn attach<T: AsRawFd>(&mut self, lircdev: T) -> Result<LinkRef, ProgramError> {
+        let prog_fd = self.data.fd_or_err()?;
+        let lircdev_fd = lircdev.as_raw_fd();
+
+        bpf_prog_attach(prog_fd, lircdev_fd, BPF_LIRC_MODE2).map_err(|(_, io_error)| {
+            ProgramError::SyscallError {
+                call: "bpf_prog_attach".to_owned(),
+                io_error,
+            }
+        })?;
+
+        Ok(self.data.link(LircLink::new(prog_fd, lircdev_fd)))
+    }
+}
+
+#[derive(Debug)]
+struct LircLink {
+    prog_fd: Option<RawFd>,
+    target_fd: Option<RawFd>,
+}
+
+impl LircLink {
+    pub(crate) fn new(prog_fd: RawFd, target_fd: RawFd) -> LircLink {
+        LircLink {
+            prog_fd: Some(prog_fd),
+            target_fd: Some(unsafe { dup(target_fd) }),
+        }
+    }
+}
+
+impl Link for LircLink {
+    fn detach(&mut self) -> Result<(), ProgramError> {
+        if let Some(prog_fd) = self.prog_fd.take() {
+            let target_fd = self.target_fd.take().unwrap();
+            let _ = bpf_prog_detach(prog_fd, target_fd, BPF_LIRC_MODE2);
+            unsafe { close(target_fd) };
+            Ok(())
+        } else {
+            Err(ProgramError::AlreadyDetached)
+        }
+    }
+}
+
+impl Drop for LircLink {
+    fn drop(&mut self) {
+        if let Some(target_fd) = self.target_fd.take() {
+            unsafe { close(target_fd) };
+        }
+    }
+}

aya/src/programs/mod.rs

@@ -38,6 +38,7 @@
 //! [`maps`]: crate::maps
 mod cgroup_skb;
 mod kprobe;
+mod lirc_mode2;
 mod perf_attach;
 mod probe;
 mod sk_msg;
@@ -55,6 +56,7 @@ use thiserror::Error;
 
 pub use cgroup_skb::{CgroupSkb, CgroupSkbAttachType};
 pub use kprobe::{KProbe, KProbeError};
+pub use lirc_mode2::LircMode2;
 use perf_attach::*;
 pub use probe::ProbeKind;
 pub use sk_msg::SkMsg;
@@ -170,6 +172,7 @@ pub enum Program {
     SockOps(SockOps),
     SchedClassifier(SchedClassifier),
     CgroupSkb(CgroupSkb),
+    LircMode2(LircMode2),
 }
 
 impl Program {
@@ -201,6 +204,7 @@ impl Program {
             Program::SockOps(_) => BPF_PROG_TYPE_SOCK_OPS,
             Program::SchedClassifier(_) => BPF_PROG_TYPE_SCHED_CLS,
             Program::CgroupSkb(_) => BPF_PROG_TYPE_CGROUP_SKB,
+            Program::LircMode2(_) => BPF_PROG_TYPE_LIRC_MODE2,
         }
     }
 
@@ -221,6 +225,7 @@ impl Program {
             Program::SockOps(p) => &p.data,
             Program::SchedClassifier(p) => &p.data,
             Program::CgroupSkb(p) => &p.data,
+            Program::LircMode2(p) => &p.data,
         }
     }
 
@@ -236,6 +241,7 @@ impl Program {
             Program::SockOps(p) => &mut p.data,
             Program::SchedClassifier(p) => &mut p.data,
             Program::CgroupSkb(p) => &mut p.data,
+            Program::LircMode2(p) => &mut p.data,
         }
     }
 }
@@ -482,7 +488,8 @@ impl_program_fd!(
     SkMsg,
     SkSkb,
     SchedClassifier,
-    CgroupSkb
+    CgroupSkb,
+    LircMode2
 );
 
 macro_rules! impl_try_from_program {
@@ -523,5 +530,6 @@ impl_try_from_program!(
     SkSkb,
     SockOps,
     SchedClassifier,
-    CgroupSkb
+    CgroupSkb,
+    LircMode2
 );