feat: use show-derivation

src/main.rs

@@ -9,6 +9,9 @@ extern crate clap;
 
 use clap::Parser;
 
+mod nix;
+mod sbom;
+
 /// nix2sbom extracts the SBOM (Software Bill of Materials) from a Nix derivation
 #[derive(Parser)]
 #[clap(name = "nix2sbom")]

src/nix.rs

@@ -0,0 +1,13 @@
+use std::io::Error;
+use std::process::Command;
+
+pub fn get_derivation(file: &str) -> Result<Vec<u8>, Error> {
+    let output = Command::new("nix")
+        .arg("show-derivation")
+        .arg("-r")
+        .arg("-f")
+        .arg(file)
+        .output()?;
+
+    Ok(output.stdout)
+}

src/sbom.rs

@@ -0,0 +1,4 @@
+enum Format {
+    SPDX,
+    CycloneDX,
+}