impl Debug for descriptors

examples/descriptors.rs

@@ -20,35 +20,19 @@ fn inspect_device(dev: DeviceInfo) {
     let dev = match dev.open() {
         Ok(dev) => dev,
         Err(e) => {
-            println!("  Failed to open device: {}", e);
+            println!("Failed to open device: {}", e);
             return;
         }
     };
 
     match dev.active_configuration() {
-        Ok(config) => println!("  Active configuration is {}", config.configuration_value()),
+        Ok(config) => println!("Active configuration is {}", config.configuration_value()),
         Err(e) => println!("Unknown active configuration: {e}"),
     }
 
     for config in dev.configurations() {
-        println!("  Configuration {}", config.configuration_value());
-        for intf in config.interfaces() {
-            for alt in intf.alt_settings() {
-                println!(
-                    "    Interface {}, alt setting {}",
-                    alt.interface_number(),
-                    alt.alternate_setting()
-                );
-                for ep in alt.endpoints() {
-                    println!(
-                        "      Endpoint {:02x} {:?} {:?}",
-                        ep.address(),
-                        ep.transfer_type(),
-                        ep.direction()
-                    );
-                }
-            }
-        }
+        println!("{config:#?}");
     }
     println!("");
+    println!("");
 }

fuzz/fuzz_targets/descriptors.rs

@@ -5,12 +5,7 @@ use libfuzzer_sys::fuzz_target;
 fuzz_target!(|data: &[u8]| {
     for config in nusb::descriptors::fuzz_parse_concatenated_config_descriptors(data) {
         let config = nusb::descriptors::Configuration::new(config);
-        for interface in config.interfaces() {
-            for alt in interface.alt_settings() {
-                for endpoint in alt.endpoints() {
-                    std::hint::black_box(endpoint);
-                }
-            }
-        }
+        let s = format!("{config:?}");
+        std::hint::black_box(s);
     }
 });

src/descriptors.rs

@@ -2,7 +2,7 @@
 //!
 //! Descriptors are blocks of data that describe the functionality of a USB device.
 
-use std::{collections::BTreeMap, fmt::Display, io::ErrorKind, iter, ops::Deref};
+use std::{collections::BTreeMap, fmt::{Display, Debug}, io::ErrorKind, iter, ops::Deref};
 
 use log::warn;
 
@@ -285,6 +285,27 @@ impl<'a> Configuration<'a> {
     }
 }
 
+struct DebugEntries<F>(F);
+
+impl<F, I> Debug for DebugEntries<F> where F: Fn() -> I, I: Iterator, I::Item: Debug {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        f.debug_list().entries(self.0()).finish()
+    }
+}
+
+impl<'a> Debug for Configuration<'a> {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        f.debug_struct("Configuration")
+            .field("configuration_value", &self.configuration_value())
+            .field("num_interfaces", &self.num_interfaces())
+            .field("attributes", &self.attributes())
+            .field("max_power", &self.max_power())
+            .field("string_index", &self.string_index())
+            .field("interface_alt_settings", &DebugEntries(|| self.interface_alt_settings()))
+            .finish()
+    }
+}
+
 /// Interface descriptors for alternate settings, grouped by the interface number.
 #[derive(Clone)]
 pub struct InterfaceGroup<'a> {
@@ -371,6 +392,21 @@ impl<'a> InterfaceAltSetting<'a> {
     }
 }
 
+impl<'a> Debug for InterfaceAltSetting<'a> {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        f.debug_struct("InterfaceAltSetting")
+            .field("interface_number", &self.interface_number())
+            .field("alternate_setting", &self.alternate_setting())
+            .field("num_endpoints", &self.num_endpoints())
+            .field("class", &self.class())
+            .field("subclass", &self.subclass())
+            .field("protocol", &self.protocol())
+            .field("string_index", &self.string_index())
+            .field("endpoints", &DebugEntries(|| self.endpoints()))
+            .finish()
+    }
+}
+
 /// Information about a USB endpoint, with access to any associated descriptors.
 pub struct Endpoint<'a>(&'a [u8]);
 
@@ -435,6 +471,19 @@ descriptor_fields! {
     }
 }
 
+impl<'a> Debug for Endpoint<'a> {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        f.debug_struct("Endpoint")
+            .field("address", &format_args!("0x{:02X}", self.address()))
+            .field("direction", &self.direction())
+            .field("transfer_type", &self.transfer_type())
+            .field("max_packet_size", &self.max_packet_size())
+            .field("packets_per_microframe", &self.packets_per_microframe())
+            .field("interval", &self.interval())
+            .finish()
+    }
+}
+
 /// Error from [`crate::Device::active_configuration`]
 #[derive(Copy, Clone, Debug, PartialEq, Eq)]
 pub struct ActiveConfigurationError {