map: move keys() helper from Map to MapHandle

Before the introduction of MapHandle it was possible to create a Map
using libbpf_rs and to iterate over its keys (with care). But now the
helper is only available for Map as it was not moved alongside the
other public functions. Fix this by moving the keys() helper to
MapHandle, still allowing Map objects to use it thanks to the Deref
impl.

For the above to work, make MapKeyIter reference a MapHandle.

Signed-off-by: Antoine Tenart <[email protected]>

Author: atenart

libbpf-rs/CHANGELOG.md

@@ -1,3 +1,9 @@
+Unreleased
+----------
+- Enabled key iteration on `MapHandle` objects (formerly possible only on `Map`
+  objects)
+
+
 0.21.1
 ------
 - Fixed build failures on 32 bit x86 and aarch32

libbpf-rs/src/map.rs

@@ -285,15 +285,6 @@ impl Map {
         util::parse_ret(ret)
     }
 
-    /// Returns an iterator over keys in this map
-    ///
-    /// Note that if the map is not stable (stable meaning no updates or deletes) during iteration,
-    /// iteration can skip keys, restart from the beginning, or duplicate keys. In other words,
-    /// iteration becomes unpredictable.
-    pub fn keys(&self) -> MapKeyIter<'_> {
-        MapKeyIter::new(self, self.key_size())
-    }
-
     /// Attach a struct ops map
     pub fn attach_struct_ops(&self) -> Result<Link> {
         if self.map_type() != MapType::StructOps {
@@ -842,6 +833,15 @@ impl MapHandle {
             Err(e) => Err(Error::Internal(format!("remove pin map failed: {e}"))),
         }
     }
+
+    /// Returns an iterator over keys in this map
+    ///
+    /// Note that if the map is not stable (stable meaning no updates or deletes) during iteration,
+    /// iteration can skip keys, restart from the beginning, or duplicate keys. In other words,
+    /// iteration becomes unpredictable.
+    pub fn keys(&self) -> MapKeyIter<'_> {
+        MapKeyIter::new(self, self.key_size())
+    }
 }
 
 impl AsFd for MapHandle {
@@ -938,13 +938,13 @@ impl MapType {
 
 #[derive(Debug)]
 pub struct MapKeyIter<'a> {
-    map: &'a Map,
+    map: &'a MapHandle,
     prev: Option<Vec<u8>>,
     next: Vec<u8>,
 }
 
 impl<'a> MapKeyIter<'a> {
-    fn new(map: &'a Map, key_size: u32) -> Self {
+    fn new(map: &'a MapHandle, key_size: u32) -> Self {
         Self {
             map,
             prev: None,