Merge pull request #63 from lucab/ups/example-all-caps

examples: show how to introspect all capabilities

examples/all_caps.rs

@@ -0,0 +1,37 @@
+/*!
+A simple example showing how to introspect all available capabilities.
+
+This differentiates between:
+ * library set: the static set hardcoded in the library at build-time.
+ * runtime set: the dynamic set available in the running kernel.
+
+The runtime set can be introspected in two different ways: via procfs
+(faster but not always possible) or via probing (slower). Where both
+mechanisms are available, they produce the exact same result.
+!*/
+
+type ExResult<T> = Result<T, Box<dyn std::error::Error + 'static>>;
+
+fn main() -> ExResult<()> {
+    let library_set = caps::all();
+    let runtime_set = caps::runtime::procfs_all_supported(None).unwrap_or_else(|e| {
+        eprintln!("procfs introspection failed: {}", e);
+        caps::runtime::thread_all_supported()
+    });
+
+    println!("Capabilities tally:");
+    println!(" -> known by this library: {}.", library_set.len());
+    println!(" -> known by the current kernel: {}.\n", runtime_set.len());
+
+    println!("Library vs kernel differences:");
+    println!(
+        " -> newer caps only in the library set: {:?}.",
+        library_set.difference(&runtime_set)
+    );
+    println!(
+        " -> newer caps only in the current kernel set: {:?}.",
+        runtime_set.difference(&library_set)
+    );
+
+    Ok(())
+}