hashcrypt: minimize panic code paths

[jerrysxie]

This pull request enhances error handling in the hashcrypt hasher implementation by introducing a unified Error type and updating relevant methods to return Result instead of panicking. This makes the code more robust, especially for invalid input scenarios, and improves its safety and reliability in both blocking and asynchronous hashing modes.

Error handling improvements:

• Introduced a new Error enum in src/hashcrypt/mod.rs to represent unsupported configurations and updated code to use this error type instead of panicking.
• Updated internal helper methods in Hasher (such as init_final_data, init_final_block, and init_final_len) to return Result<(), Error> and propagate errors instead of panicking on invalid buffer access.

Blocking hasher API changes:

• Changed public and internal methods in the blocking Hasher implementation (submit_blocks, finalize, hash) to return Result and handle errors gracefully, replacing panics with error returns for invalid input lengths.

Async hasher API changes:

• Updated async Hasher methods (transfer, submit_blocks, finalize, hash) to return Result and propagate errors, ensuring safe handling of invalid conditions such as missing DMA channels or incorrect data lengths. [1] [2] [3]

General code safety improvements:

• Added assertions and explicit error returns to ensure buffer sizes and data lengths are always valid, replacing unchecked unwraps and panics with error handling. [1] [2]

[Copilot]

Pull request overview

This PR refactors the hashcrypt module to replace panic-based error handling with Result-based error handling, introducing a new Error enum and updating all public APIs to return Result<(), Error>.

• Introduces a new Error enum with an UnsupportedConfiguration variant
• Converts internal helper methods to use bounds checking with error returns instead of direct indexing
• Updates all public methods (submit_blocks, finalize, hash) for both blocking and async variants to return Results

Reviewed changes

Copilot reviewed 2 out of 4 changed files in this pull request and generated 5 comments.

File	Description
src/hashcrypt/mod.rs	Adds the new Error enum with UnsupportedConfiguration variant and defmt support
src/hashcrypt/hasher.rs	Converts internal methods and public APIs to return Results, replacing panics with error handling (except one remaining panic in async transfer)
examples/rt685s-evk/src/bin/sha256.rs	Updates example to handle Results with .unwrap() calls on hash operations
examples/rt685s-evk/src/bin/sha256-async.rs	Updates async example to handle Results with .unwrap() calls on hash operations

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[Copilot]

Pull request overview

Copilot reviewed 2 out of 4 changed files in this pull request and generated 3 comments.

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[williampMSFT]

[Copilot]

Pull request overview

Copilot reviewed 2 out of 4 changed files in this pull request and generated 4 comments.

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[jerrysxie]

Announced on Zulip: #embedded-controller > embassy-imxrt breaking hashcrypt API changes @ 💬

[Copilot]

Pull request overview

Copilot reviewed 2 out of 4 changed files in this pull request and generated 3 comments.

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