Added the 'Callbacks' struct, as a simple generic implementation of the 'FapiCallbacks' trait.

Author: danieltrick

CHANGELOG.md

@@ -4,6 +4,16 @@ All notable changes to this project will be documented in this file.
 
 The format is based on [Keep a Changelog](http://keepachangelog.com/).
 
+## [0.10.0] - 2026-01-21
+
+### Added
+
+- Added the `Callbacks` struct, as a simple generic implementation of the `FapiCallbacks` trait.
+
+### Changed
+
+- The `FapiCallbacks` trait **no** longer has the `Debug` trait bound.
+
 ## [0.9.0] - 2026-01-20
 
 ### Added

Cargo.lock

@@ -1,6 +1,6 @@
 [package]
 name = "tss2-fapi-rs"
-version = "0.9.0"
+version = "0.10.0"
 edition = "2024"
 rust-version = "1.85"
 description = "Provides a Rust interface to the TSS2.0 Feature API (FAPI)"

Cargo.toml

@@ -7,7 +7,7 @@
 use env_logger::Builder as EnvLogger;
 use log::{LevelFilter, debug, info, warn};
 use std::borrow::Cow;
-use tss2_fapi_rs::{AuthCbParam, BaseErrorCode, ErrorCode, FapiCallbacks, FapiContext, KeyFlags};
+use tss2_fapi_rs::{BaseErrorCode, Callbacks, ErrorCode, FapiContext, KeyFlags};
 
 const MY_KEYFLAG: &[KeyFlags] = &[KeyFlags::Sign, KeyFlags::NoDA];
 const MY_KEYPATH: &str = "HS/SRK/myTestKey";
@@ -44,7 +44,8 @@ fn main() {
     info!("FAPI context created. ({})", context);
 
     // Add authorization callback function
-    match context.set_callbacks(MyCallbacks { password: MY_AUTHVAL }) {
+    // Will be called by the FAPI in order to request authorization values!
+    match context.set_callbacks(Callbacks::with_auth(|_| Some(Cow::Borrowed(MY_AUTHVAL)))) {
         Ok(_) => info!("Success."),
         Err(error) => panic!("Failed to set up AUTH callback function: {:?}", error),
     }
@@ -82,19 +83,3 @@ fn main() {
     // Exit
     info!("Shutting down...");
 }
-
-/// Struct to implement our application-defined callback functions
-#[derive(Debug)]
-struct MyCallbacks {
-    password: &'static str,
-}
-
-impl FapiCallbacks for MyCallbacks {
-    /// This function will be called by FAPI in order to request authorization values from the application.
-    ///
-    /// *Note:* For simplicity, in this example, the callback function always returns our password, regardless of the requested object path.
-    fn auth_cb(&self, param: AuthCbParam) -> Option<Cow<'static, str>> {
-        info!("Authorization for object at {:?} has been requested.", param.object_path);
-        Some(Cow::from(self.password))
-    }
-}

examples/3_auth_callback.rs

@@ -129,14 +129,17 @@ impl<T: Any> AsAny for T {
 
 /// Represents the set of application-defined callback functions that the FAPI invokes.
 ///
+/// An implementation is **not** required to override *all* callback functions, as the trait provides “blank” default implementations.
+///
+/// Generally, an application overrides only the callback functions that it actually needs.
+///
 /// Implementations of this trait are registered with a FAPI context via the [**`FapiContext::set_callbacks()`**](crate::FapiContext::set_callbacks) function.
 ///
 /// ### Example
 ///
 /// Applications shall implement this trait as follows:
 ///
 /// ```
-/// #[derive(Debug)]
 /// pub struct MyCallbacks;
 ///
 /// impl FapiCallbacks for MyCallbacks {
@@ -157,7 +160,7 @@ impl<T: Any> AsAny for T {
 ///     }
 /// }
 /// ```
-pub trait FapiCallbacks: AsAny + Send + Debug + 'static {
+pub trait FapiCallbacks: AsAny + Send + 'static {
     /// A callback function that allows the FAPI to request authorization values.
     ///
     /// The default implementation of this function returns `None`. Please override the function as needed!
@@ -201,11 +204,96 @@ pub trait FapiCallbacks: AsAny + Send + Debug + 'static {
     }
 }
 
+// ==========================================================================
+// Callbacks implementation
+// ==========================================================================
+
+/// Provides a simple implementation of the [`FapiCallbacks`](crate::FapiCallbacks) trait.
+#[allow(clippy::type_complexity)]
+pub struct Callbacks {
+    auth_fn: Box<dyn Fn(AuthCbParam) -> Option<Cow<'static, str>> + Send>,
+    sign_fn: Box<dyn Fn(SignCbParam) -> Option<Vec<u8>> + Send>,
+    branch_fn: Box<dyn Fn(BranchCbParam) -> Option<usize> + Send>,
+    policy_action_fn: Box<dyn Fn(PolicyActionCbParam) -> bool + Send>,
+}
+
+impl Callbacks {
+    /// Creates a new `Callbacks` instance with application-defined callback functions.
+    ///
+    /// Instances of this struct are registered with a FAPI context via the [**`FapiContext::set_callbacks()`**](crate::FapiContext::set_callbacks) function.
+    pub fn new<AuthFn, SignFn, BranchFn, PolicyActionFn>(auth_fn: AuthFn, sign_fn: SignFn, branch_fn: BranchFn, policy_action_fn: PolicyActionFn) -> Self
+    where
+        AuthFn: Fn(AuthCbParam) -> Option<Cow<'static, str>> + Send + 'static,
+        SignFn: Fn(SignCbParam) -> Option<Vec<u8>> + Send + 'static,
+        BranchFn: Fn(BranchCbParam) -> Option<usize> + Send + 'static,
+        PolicyActionFn: Fn(PolicyActionCbParam) -> bool + Send + 'static,
+    {
+        Self { auth_fn: Box::new(auth_fn), sign_fn: Box::new(sign_fn), branch_fn: Box::new(branch_fn), policy_action_fn: Box::new(policy_action_fn) }
+    }
+
+    /// Creates a `Callbacks` instance with an application-defined [`auth_cb`](crate::FapiCallbacks::auth_cb) callback function.
+    ///
+    /// All other callback functions will use the default implementation.
+    pub fn with_auth<F>(auth_fn: F) -> Self
+    where
+        F: Fn(AuthCbParam) -> Option<Cow<'static, str>> + Send + 'static,
+    {
+        Self::new(auth_fn, |_| None, |_| None, |_| false)
+    }
+
+    /// Creates a `Callbacks` instance with an application-defined [`sign_cb`](crate::FapiCallbacks::sign_cb) callback function.
+    ///
+    /// All other callback functions will use the default implementation.
+    pub fn with_sign<F>(sign_fn: F) -> Self
+    where
+        F: Fn(SignCbParam) -> Option<Vec<u8>> + Send + 'static,
+    {
+        Self::new(|_| None, sign_fn, |_| None, |_| false)
+    }
+
+    /// Creates a `Callbacks` instance with an application-defined [`branch_cb`](crate::FapiCallbacks::branch_cb) callback function.
+    ///
+    /// All other callback functions will use the default implementation.
+    pub fn with_branch<F>(branch_fn: F) -> Self
+    where
+        F: Fn(BranchCbParam) -> Option<usize> + Send + 'static,
+    {
+        Self::new(|_| None, |_| None, branch_fn, |_| false)
+    }
+
+    /// Creates a `Callbacks` instance with an application-defined [`policy_action_cb`](crate::FapiCallbacks::policy_action_cb) callback function.
+    ///
+    /// All other callback functions will use the default implementation.
+    pub fn with_policy_action<F>(policy_action_fn: F) -> Self
+    where
+        F: Fn(PolicyActionCbParam) -> bool + Send + 'static,
+    {
+        Self::new(|_| None, |_| None, |_| None, policy_action_fn)
+    }
+}
+
+impl FapiCallbacks for Callbacks {
+    fn auth_cb(&self, param: AuthCbParam) -> Option<Cow<'static, str>> {
+        (self.auth_fn)(param)
+    }
+
+    fn sign_cb(&self, param: SignCbParam) -> Option<Vec<u8>> {
+        (self.sign_fn)(param)
+    }
+
+    fn branch_cb(&self, param: BranchCbParam) -> Option<usize> {
+        (self.branch_fn)(param)
+    }
+
+    fn policy_action_cb(&self, param: PolicyActionCbParam) -> bool {
+        (self.policy_action_fn)(param)
+    }
+}
+
 // ==========================================================================
 // Callbacks manager
 // ==========================================================================
 
-#[derive(Debug)]
 pub struct CallbackManager {
     inner: Box<dyn FapiCallbacks>,
     auth_value: Option<CStringHolder>,
@@ -283,6 +371,16 @@ impl CallbackManager {
     }
 }
 
+impl Debug for CallbackManager {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        f.debug_struct("CallbackManager")
+            .field("inner", &self.inner.as_any().type_id())
+            .field("auth_value", &self.auth_value)
+            .field("sign_data", &self.sign_data)
+            .finish()
+    }
+}
+
 // ==========================================================================
 // Unit tests
 // ==========================================================================

src/callback.rs

@@ -66,41 +66,29 @@
 //! ```rust no_run
 //! use log::info;
 //! use std::borrow::Cow;
-//! use tss2_fapi_rs::{AuthCbParam, FapiCallbacks, FapiContext};
+//! use tss2_fapi_rs::{Callbacks, FapiContext};
 //!
 //! fn main() {
 //!     // Create a new FAPI context
 //!     let mut context = FapiContext::new().expect("Failed to create context!");
 //!
-//!     // Add callback functions
-//!     match context.set_callbacks(MyCallbacks { password: "my_password" }) {
+//!     // Register "auth" callback function
+//!     match context.set_callbacks(Callbacks::with_auth(|_| Some(Cow::from("my_password")))) {
 //!         Ok(_) => info!("Success."),
 //!         Err(error) => panic!("Failed to set up AUTH callback function: {:?}", error),
 //!     }
 //! }
-//!
-//! /// Application-defined callback functions
-//! #[derive(Debug)]
-//! struct MyCallbacks {
-//!     password: &'static str,
-//! }
-//!
-//! impl FapiCallbacks for MyCallbacks {
-//!     /// Function that will be called by the FAPI to request authorization values
-//!     fn auth_cb(&self, param: AuthCbParam) -> Option<Cow<'static, str>> {
-//!         info!("Authorization for object at {:?} requested.", param.object_path);
-//!         Some(Cow::from(self.password))
-//!     }
-//! }
 //! ```
 //!
+//! Please see the **[`FapiCallbacks`]** documentation for more details!
+//!
 //! ### Usage instructions
 //!
 //! In order to use the **`tss2-fapi-rs`** library in your Rust project, simply add it to your `Cargo.toml` file:
 //!
 //! ```toml
 //! [dependencies]
-//! tss2-fapi-rs = "0.9.0"
+//! tss2-fapi-rs = "0.10.0"
 //! ```
 //!
 //! **Note:** Please also consider the [prerequisites](#prerequisites) that are required to use the `tss2-fapi-rs` library!
@@ -451,7 +439,7 @@ mod types;
 mod version;
 
 pub use algorithm_id::HashAlgorithm;
-pub use callback::{AsAny, AuthCbParam, BranchCbParam, FapiCallbacks, PolicyActionCbParam, SignCbParam};
+pub use callback::{AsAny, AuthCbParam, BranchCbParam, Callbacks, FapiCallbacks, PolicyActionCbParam, SignCbParam};
 pub use context::FapiContext;
 pub use error::{BaseErrorCode, ErrorCode, InternalError, Tpm2ErrFmt0, Tpm2ErrFmt1, Tpm2ErrorCode, Tpm2Warning};
 pub use flags::{BlobType, KeyFlags, NvFlags, PaddingFlags, QuoteFlags, SealFlags};