chore(code): sbat section generator build tool

crates/build/src/lib.rs

@@ -0,0 +1,76 @@
+use std::path::PathBuf;
+use std::{env, fs};
+
+/// Block size of the sbat section.
+const SBAT_BLOCK_SIZE: usize = 512;
+
+/// Template contents for the sbat.generated.rs file.
+const SBAT_RS_TEMPLATE: &str = include_str!("sbat.template.rs");
+
+/// Pad with zeros the given `data` to a multiple of `block_size`.
+fn block_pad(data: &mut Vec<u8>, block_size: usize) {
+    let needed = data.len().div_ceil(block_size).max(1) * block_size;
+
+    if needed != data.len() {
+        data.resize(needed, 0);
+    }
+}
+
+/// Generate an .sbat link section module. This should be coupled with including the sbat module in
+/// the crate that intends to embed the sbat section.
+/// We intake a sbat.template.csv file in the calling crate and output a sbat.dat
+/// which is included by a generated sbat.generated.rs file.
+pub fn generate_sbat_module() {
+    // Notify Cargo that if the version changes, we need to regenerate the sbat.out file.
+    println!("cargo:rerun-if-env-changed=CARGO_PKG_VERSION");
+
+    // The version of the package.
+    let version = env::var("CARGO_PKG_VERSION").expect("CARGO_PKG_VERSION not set");
+
+    // The output directory to place the sbat.csv into.
+    let output_dir = PathBuf::from(env::var("OUT_DIR").expect("OUT_DIR not set"));
+
+    // The output path to the sbat.out file.
+    let out_file = output_dir.join("sbat.out");
+
+    // The output path to the sbat.generated.rs file.
+    let rs_file = output_dir.join("sbat.generated.rs");
+
+    // The path to the root of the crate.
+    let crate_root =
+        PathBuf::from(env::var("CARGO_MANIFEST_DIR").expect("CARGO_MANIFEST_DIR not set"));
+
+    // The path to the sbat.template.tsv file is in the source directory of the crate.
+    let sbat_template_file = crate_root.join("src/sbat.csv");
+
+    // Notify Cargo that if sbat.csv changes, we need to regenerate the sbat.out file.
+    println!(
+        "cargo:rerun-if-changed={}",
+        sbat_template_file
+            .to_str()
+            .expect("unable to convert sbat template path file to a string")
+    );
+
+    // Read the sbat.csv template file.
+    let sbat_template =
+        fs::read_to_string(&sbat_template_file).expect("unable to read sbat.csv file");
+
+    // Replace the version placeholder in the template with the actual version.
+    let sbat = sbat_template.replace("{version}", &version);
+
+    // Encode the sbat.csv as bytes.
+    let mut encoded = sbat.as_bytes().to_vec();
+
+    // Pad the sbat.csv to the required block size.
+    block_pad(&mut encoded, SBAT_BLOCK_SIZE);
+
+    // Write the sbat.out file to the output directory.
+    fs::write(&out_file, &encoded).expect("unable to write sbat.out");
+
+    // Generate the contents of the sbat.generated.rs file.
+    // The size must tbe size of the encoded sbat.out file.
+    let sbat_rs = SBAT_RS_TEMPLATE.replace("{size}", &encoded.len().to_string());
+
+    // Write the sbat.generated.rs file to the output directory.
+    fs::write(&rs_file, sbat_rs).expect("unable to write sbat.generated.rs");
+}