npub127…n5r64 on Nostr: //! A simple command-line tool that calculates and displays the SHA-256 hash of //! ...

//! A simple command-line tool that calculates and displays the SHA-256 hash of
//! its own source file.
//!
//! This utility demonstrates how to use the `get_file_hash!` macro to obtain
//! the hash of a specified file at compile time and incorporate it into runtime
//! logic.

use get_file_hash_core::get_file_hash;
use sha2::{Digest, Sha256};

const README_TEMPLATE_PART1: &str = r##"# `get_file_hash` macro

This project provides a Rust procedural macro, `get_file_hash!`, designed to compute the SHA-256 hash of a specified file at compile time. This hash is then embedded directly into your compiled executable. This feature is invaluable for:

* **Integrity Verification:** Ensuring the deployed code hasn't been tampered with.
* **Versioning:** Embedding a unique identifier linked to the exact source code version.
* **Cache Busting:** Generating unique names for assets based on their content.

## Project Structure

* `get_file_hash_core`: A foundational crate containing the `get_file_hash!` macro definition.
* `get_file_hash`: The main library crate that re-exports the macro.
* `src/bin/get_file_hash.rs`: An example executable demonstrating the macro's usage by hashing its own source file and updating this `README.md`.
* `build.rs`: A build script that also utilizes the `get_file_hash!` macro to hash `Cargo.toml` during the build process.

## Usage of `get_file_hash!` Macro

To use the `get_file_hash!` macro, ensure you have `get_file_hash` (or `get_file_hash_core` for direct usage) as a dependency in your `Cargo.toml`.

### Example

```rust
use get_file_hash::get_file_hash;
use sha2::{Digest, Sha256};

fn main() {
// The macro resolves the path relative to CARGO_MANIFEST_DIR
let file_hash = get_file_hash!("src/lib.rs");
println!("The SHA-256 hash of src/lib.rs is: {}", file_hash);
}
```

"##;

const README_TEMPLATE_PART2: &str = r"## Setup and Building

1. **Clone the repository:**
```bash
git clone <repository-url>
cd <repository-name>
```
2. **Build the project:**
```bash
cargo build
```
During the build, `build.rs` will execute and print the hash of `Cargo.toml`.
3. **Run the example executable:**
```bash
cargo run --bin get_file_hash
```
This will print the hash of `src/bin/get_file_hash.rs` to your console.

## Updating this `README.md`

The hash information in this `README.md` is automatically generated by running the example executable.
To update it, execute:

```bash
cargo run --bin get_file_hash > README.md
```

## Current File Hash Information (of `src/bin/get_file_hash.rs`)

* **Target File:** `src/bin/get_file_hash.rs`
";

/// The main entry point of the application.
///
/// This function calculates the SHA-256 hash of the `get_file_hash.rs` source
/// file using a custom procedural macro and then prints the hash to the
/// console. It also includes a basic integrity verification check.
fn main() {
// Calculate the SHA-256 hash of the current file (`get_file_hash.rs`) at
// compile time. The `get_file_hash!` macro reads the file content and
// computes its hash.
let self_hash = get_file_hash!("get_file_hash.rs");

let status_message = if self_hash.starts_with("e3b0") {
"Warning: This hash represents an empty file."
} else {
"Integrity Verified."
};

print!("{}{}", README_TEMPLATE_PART1, README_TEMPLATE_PART2);
println!("* **SHA-256 Hash:** `{}`", self_hash);
println!("* **Status:** {}.\n", status_message);
}