fix(rust_extractor): process env vars and compiler args passed to wra…

…pper (#5014)

* fix(rust_extractor): process env vars and compiler args passed to wrapper

* chore: fix typo

* fix: optimize functions

* fix: simplify further

Co-authored-by: Shahms King <shahms@google.com>

kythe/rust/extractor/src/bin/save_analysis.rs

@@ -12,7 +12,9 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-use anyhow::Result;
+use anyhow::{Context, Result};
+use std::fs::File;
+use std::io::{self, BufRead};
 use std::path::{Path, PathBuf};
 
 /// Generates a save analysis in `output_dir`
@@ -55,5 +57,47 @@ fn generate_arguments(arguments: Vec<String>, output_dir: &Path) -> Result<Vec<S
         output_dir.to_str().ok_or_else(|| anyhow!("Couldn't convert temporary path to string"))?;
     rustc_arguments[outdir_position] = format!("--out-dir={}", outdir_str);
 
+    // Check if there is a file containing environment variables
+    let env_file_position = arguments.iter().position(|arg| arg == "--env-file");
+    if let Some(position) = env_file_position {
+        let env_file = &arguments[position + 1];
+        let path = Path::new(env_file);
+        process_env_file(path).context("Failed to process wrapper environment file")?;
+    }
+
+    // Check if there is a file containing extra compiler arguments
+    let arg_file_position = arguments.iter().position(|arg| arg == "--arg-file");
+    if let Some(position) = arg_file_position {
+        let arg_file = &arguments[position + 1];
+        let path = Path::new(arg_file);
+        let new_arguments =
+            process_arg_file(path).context("Failed to process wrapper argument file")?;
+        rustc_arguments.extend(new_arguments);
+    }
+
     Ok(rustc_arguments)
 }
+
+/// Process an environment variable file passed to the process wrapper
+///
+/// * `path` - The path of the environment variable file
+fn process_env_file(path: &Path) -> Result<()> {
+    let pwd = std::env::current_dir().context("Couldn't determine pwd")?;
+    for line in io::BufReader::new(File::open(path)?).lines() {
+        let line_string = line.context("Failed to read line of env file")?;
+        let split: Vec<&str> = line_string.trim().split('=').collect();
+        let value = split[1].replace("${pwd}", pwd.to_str().unwrap());
+        std::env::set_var(split[0], value);
+    }
+    Ok(())
+}
+
+/// Process a compiler argument file passed to the process wrapper
+///
+/// * `path` - The path of the compiler argument file
+fn process_arg_file(path: &Path) -> Result<Vec<String>> {
+    io::BufReader::new(File::open(path)?)
+        .lines()
+        .map(|line| line.context("Failed to read line of arg file"))
+        .collect()
+}