aya: add helper to return all loaded maps

This mirrors the already existing approach to returning all of the
currently loaded programs.

aya/src/maps/mod.rs

@@ -68,7 +68,7 @@ use crate::{
     sys::{
         bpf_create_map, bpf_get_object, bpf_map_freeze, bpf_map_get_fd_by_id,
         bpf_map_get_info_by_fd, bpf_map_get_next_key, bpf_map_update_elem_ptr, bpf_pin_object,
-        SyscallError,
+        iter_map_ids, SyscallError,
     },
     util::{nr_cpus, KernelVersion},
     PinningType, Pod,
@@ -820,6 +820,41 @@ impl<T: Pod> Deref for PerCpuValues<T> {
     }
 }
 
+/// Returns an iterator over all loaded bpf maps.
+///
+/// This differs from [`crate::Bpf::maps`] since it will return all maps
+/// listed on the host system and not only maps for a specific [`crate::Bpf`] instance.
+///
+/// # Example
+/// ```
+/// # use aya::maps::loaded_maps;
+///
+/// for m in loaded_maps() {
+///     match m {
+///         Ok(map) => match map.name() {
+///             Ok(name) => println!("{}",name),
+///             Err(e) => println!("Error querying map name: {:?}", e),
+///         }
+///         Err(e) => println!("Error iterating maps: {:?}", e),
+///     }
+/// }
+/// ```
+///
+/// # Errors
+///
+/// Returns [`MapError::SyscallError`] if any of the syscalls required to either get
+/// next map id, get the map fd, or the [`MapData`] fail. In cases where
+/// iteration can't be performed, for example the caller does not have the necessary privileges,
+/// a single item will be yielded containing the error that occurred.
+pub fn loaded_maps() -> impl Iterator<Item = Result<MapData, MapError>> {
+    iter_map_ids()
+        .map(|id| {
+            let id = id?;
+            bpf_map_get_fd_by_id(id)
+        })
+        .map(|fd| MapData::from_fd(fd?))
+}
+
 #[cfg(test)]
 mod tests {
     use std::os::fd::AsRawFd as _;

aya/src/sys/bpf.rs

@@ -1049,6 +1049,10 @@ pub(crate) fn iter_link_ids() -> impl Iterator<Item = Result<u32, SyscallError>>
     iter_obj_ids(bpf_cmd::BPF_LINK_GET_NEXT_ID, "bpf_link_get_next_id")
 }
 
+pub(crate) fn iter_map_ids() -> impl Iterator<Item = Result<u32, SyscallError>> {
+    iter_obj_ids(bpf_cmd::BPF_MAP_GET_NEXT_ID, "bpf_map_get_next_id")
+}
+
 pub(crate) fn retry_with_verifier_logs<T>(
     max_retries: usize,
     f: impl Fn(&mut [u8]) -> SysResult<T>,