aya/maps: fix libbpf_pin_by_name

Aligns with libbpf for the special LIBBPF_PIN_BY_NAME
map flag. Specifically if the flag is provided without a pin path
default to "/sys/fs/bpf".

Signed-off-by: astoycos <astoycos@redhat.com>

aya/src/bpf.rs

@@ -477,8 +477,13 @@ impl<'a> BpfLoader<'a> {
             let mut map = match obj.pinning() {
                 PinningType::None => MapData::create(obj, &name, btf_fd)?,
                 PinningType::ByName => {
-                    let path = map_pin_path.as_ref().ok_or(BpfError::NoPinPath)?;
-                    MapData::create_pinned(path, obj, &name, btf_fd)?
+                    // pin maps in /sys/fs/bpf by default to align with libbpf
+                    // behavior https://github.com/libbpf/libbpf/blob/v1.2.2/src/libbpf.c#L2161.
+                    let path = map_pin_path
+                        .as_deref()
+                        .unwrap_or_else(|| Path::new("/sys/fs/bpf"));
+
+                    MapData::create_pinned_by_name(path, obj, &name, btf_fd)?
                 }
             };
             map.finalize()?;
@@ -927,10 +932,6 @@ pub enum BpfError {
         error: io::Error,
     },
 
-    /// Pinning requested but no path provided
-    #[error("pinning requested but no path provided")]
-    NoPinPath,
-
     /// Unexpected pinning type
     #[error("unexpected pinning type {name}")]
     UnexpectedPinningType {

aya/src/maps/mod.rs

@@ -440,7 +440,7 @@ impl MapData {
         Ok(Self { obj, fd })
     }
 
-    pub(crate) fn create_pinned<P: AsRef<Path>>(
+    pub(crate) fn create_pinned_by_name<P: AsRef<Path>>(
         path: P,
         obj: obj::Map,
         name: &str,
@@ -469,7 +469,6 @@ impl MapData {
             }
             Err(_) => {
                 let mut map = Self::create(obj, name, btf_fd)?;
-                let path = path.join(name);
                 map.pin(&path).map_err(|error| MapError::PinError {
                     name: Some(name.into()),
                     error,