rust: various build script fixes

lang/rust/helpers/src/bin/buildscript-runner.rs

@@ -0,0 +1,70 @@
+use std::{
+    collections::HashMap,
+    env::{var, var_os},
+    fs::{File, create_dir},
+    io::{Read, Write},
+    os::unix::process::CommandExt,
+    process::Command,
+};
+
+fn parse(data: &str) -> HashMap<String, String> {
+    let mut out = HashMap::new();
+
+    let mut parse_one = |key: &str, value: String, fallback| match key {
+        "metadata" => {
+            let (left, right) = value
+                .split_once('=')
+                .expect("missing '=' for cargo::metadata");
+            out.insert(left.to_string(), right.to_string());
+        }
+
+        _ if fallback => {
+            out.insert(key.to_string(), value);
+        }
+
+        _ => {}
+    };
+
+    for line in data.lines() {
+        if let Some(data) = line.strip_prefix("cargo::") {
+            let (key, value) = data.split_once('=').expect("missing '=' on cargo:: line");
+            parse_one(key, value.to_string(), false);
+        } else if let Some(data) = line.strip_prefix("cargo:") {
+            let (key, value) = data.split_once('=').expect("missing '=' on cargo: line");
+            parse_one(key, value.to_string(), true);
+        }
+    }
+
+    out
+}
+
+fn main() {
+    create_dir(var_os("OUT_DIR").unwrap()).unwrap();
+
+    let mut f = File::create(var_os("out").unwrap()).unwrap();
+    writeln!(&mut f, "zilch: OUT_DIR={:?}", var("OUT_DIR").unwrap()).unwrap();
+
+    let mut cmd = Command::new(var_os("script").unwrap());
+
+    cmd.stdout(f).current_dir(var_os("cwd").unwrap());
+
+    if let Ok(inherit) = var("_zilch_links") {
+        if !inherit.is_empty() {
+            for v in inherit.split('!') {
+                let (path, name) = v.split_once(':').unwrap();
+                let mut file = File::open(path).unwrap();
+                let mut data = String::new();
+                file.read_to_string(&mut data).unwrap();
+
+                let data = parse(&data);
+                for (k, v) in data {
+                    let mut name = format!("DEP_{}_{}", name, k);
+                    name.make_ascii_uppercase();
+                    cmd.env(name.replace('-', "_"), v);
+                }
+            }
+        }
+    }
+
+    panic!("failed to exec: {:?}", cmd.exec())
+}