figure out hash

src/main.rs

@@ -0,0 +1,76 @@
+#![feature(string_from_utf8_lossy_owned)]
+
+use std::{env, path::Path};
+use std::process::Command;
+use std::path::PathBuf;
+
+use serde::{Deserialize, Serialize};
+use serde_json;
+use log::debug;
+
+const UPSTREAM_CACHES: &'static [&'static str] = &[
+    "https://cache.nixos.org",
+    "https://nix-community.cachix.org",
+    "https://nixcache.cy7.sh",
+];
+
+// nix path-info --derivation --json
+#[derive(Debug, Serialize, Deserialize)]
+#[serde(rename_all = "camelCase")]
+struct PathInfo {
+    ca: String,
+    nar_hash: String,
+    nar_size: u32,
+    path: String,
+    references: Vec<String>,
+    registration_time: u32,
+    valid: bool,
+}
+
+impl PathInfo {
+    // find store paths related to derivation
+    fn get_store_paths(&self) -> Vec<String> {
+        let mut store_paths: Vec<String> = Vec::new();
+        let nix_store_cmd = Command::new("nix-store")
+            .arg("--query")
+            .arg("--requisites")
+            .arg("--include-outputs")
+            .arg(&self.path)
+            .output()
+            .expect("nix-store cmd failed");
+
+        let nix_store_out = String::from_utf8(nix_store_cmd.stdout).unwrap();
+        for store_path in nix_store_out.split_whitespace().map(ToString::to_string) {
+            store_paths.push(store_path);
+        }
+        store_paths
+    }
+}
+
+fn main() {
+    env_logger::init();
+    let args: Vec<String> = env::args().collect();
+    let package = &args[1];
+    println!("package: {}", package);
+
+    // find derivations related to package
+    let path_infos = Command::new("nix")
+        .arg("path-info")
+        .arg("--derivation")
+        .arg("--json")
+        .arg(package)
+        .output()
+        .expect("path-info failed");
+
+    let path_infos: Vec<PathInfo> = serde_json::from_slice(&path_infos.stdout).unwrap();
+    debug!("PathInfo's from nix path-info: {:#?}", path_infos);
+
+
+    // filter out store paths that exist in upstream caches
+    let store_paths = path_infos[0].get_store_paths();
+    for store_path in store_paths {
+        let basename = Path::new(&store_path).file_name().unwrap().to_str().unwrap().to_string();
+        let hash = basename.split("-").nth(0).unwrap();
+        println!("hash: {}", hash);
+    }
+}