process wrapper: move argument parsing in a separate mod.

Author: gigaroby

util/process_wrapper/flags.rs

@@ -119,7 +119,12 @@ impl<'a> Flags<'a> {
         all.sort();
 
         let mut help_text = String::new();
-        writeln!(&mut help_text, "Help for {}", program_name).unwrap();
+        writeln!(
+            &mut help_text,
+            "Help for {}: [options] -- [extra arguments]",
+            program_name
+        )
+        .unwrap();
         for line in all {
             writeln!(&mut help_text, "\t{}", line).unwrap();
         }

util/process_wrapper/main.rs

@@ -13,168 +13,24 @@
 // limitations under the License.
 
 mod flags;
+mod options;
 mod util;
 
-use std::collections::HashMap;
-use std::env;
 use std::fs::{copy, OpenOptions};
 use std::process::{exit, Command, Stdio};
 
-use flags::{Flags, ParseOutcome};
-use util::*;
-
-fn environment_block(
-    environment_file_block: HashMap<String, String>,
-    stamp_mappings: &[(String, String)],
-    subst_mappings: &[(String, String)],
-) -> HashMap<String, String> {
-    // Taking all environment variables from the current process
-    // and sending them down to the child process
-    let mut environment_variables: HashMap<String, String> = std::env::vars().collect();
-    // Have the last values added take precedence over the first.
-    // This is simpler than needing to track duplicates and explicitly override
-    // them.
-    environment_variables.extend(environment_file_block.into_iter());
-    for (f, replace_with) in stamp_mappings {
-        for value in environment_variables.values_mut() {
-            let from = format!("{{{}}}", f);
-            let new = value.replace(from.as_str(), replace_with);
-            *value = new;
-        }
-    }
-    for (f, replace_with) in subst_mappings {
-        for value in environment_variables.values_mut() {
-            let from = format!("${{{}}}", f);
-            let new = value.replace(from.as_str(), replace_with);
-            *value = new;
-        }
-    }
-    environment_variables
-}
-
-fn prepare_args(mut args: Vec<String>, subst_mappings: &[(String, String)]) -> Vec<String> {
-    for (f, replace_with) in subst_mappings {
-        for arg in args.iter_mut() {
-            let from = format!("${{{}}}", f);
-            let new = arg.replace(from.as_str(), replace_with);
-            *arg = new;
-        }
-    }
-    args
-}
+use crate::options::options;
 
 fn main() {
-    // Process argument list until -- is encountered.
-    // Everything after is sent to the child process.
-    let mut subst_mapping_raw = None;
-    let mut volatile_status_file_raw = None;
-    let mut env_file_raw = None;
-    let mut arg_file_raw = None;
-    let mut touch_file_raw = None;
-    let mut copy_output_raw = None;
-    let mut stdout_file_raw = None;
-    let mut stderr_file_raw = None;
-    let mut flags = Flags::new();
-    flags.define_repeated_flag("--subst", "", &mut subst_mapping_raw);
-    flags.define_flag("--volatile-status-file", "", &mut volatile_status_file_raw);
-    flags.define_repeated_flag("--env-file", "", &mut env_file_raw);
-    flags.define_repeated_flag("--arg-file", "", &mut arg_file_raw);
-    flags.define_flag("--touch-file", "", &mut touch_file_raw);
-    flags.define_repeated_flag("--copy-output", "", &mut copy_output_raw);
-    flags.define_flag(
-        "--stdout-file",
-        "Redirect subprocess stdout in this file.",
-        &mut stdout_file_raw,
-    );
-    flags.define_flag(
-        "--stderr-file",
-        "Redirect subprocess stderr in this file.",
-        &mut stderr_file_raw,
-    );
-    let mut child_args = match flags
-        .parse(env::args().collect())
-        .expect("flag parse error")
-    {
-        ParseOutcome::Help(help) => {
-            eprintln!("{}", help);
-            return;
-        }
-        ParseOutcome::Parsed(p) => p,
+    let opts = match options() {
+        Err(err) => panic!("process wrapper error: {}", err),
+        Ok(v) => v,
     };
-    let subst_mappings: Vec<(String, String)> = subst_mapping_raw
-        .unwrap_or_default()
-        .into_iter()
-        .map(|arg| {
-            let (key, val) = arg.split_once('=').unwrap_or_else(|| {
-                panic!(
-                    "process wrapper error: empty key for substitution '{}'",
-                    arg
-                )
-            });
-            let v = if val == "${pwd}" {
-                std::env::current_dir()
-                    .unwrap()
-                    .to_str()
-                    .unwrap()
-                    .to_string()
-            } else {
-                val.to_owned()
-            };
-            (key.to_owned(), v)
-        })
-        .collect();
-    let stamp_mappings =
-        volatile_status_file_raw.map_or_else(Vec::new, |s| read_stamp_status_to_array(s).unwrap());
-    let environment_file_block: HashMap<String, String> = env_file_raw
-        .unwrap_or_default()
-        .into_iter()
-        .flat_map(|path| -> Vec<(String, String)> {
-            let lines = read_file_to_array(path).unwrap();
-            lines
-                .into_iter()
-                .map(|l| {
-                    let splits = l
-                        .split_once('=')
-                        .expect("process wrapper error: environment file invalid");
-                    (splits.0.to_owned(), splits.1.to_owned())
-                })
-                .collect()
-        })
-        .collect();
-    let mut file_arguments: Vec<String> = arg_file_raw
-        .unwrap_or_default()
-        .into_iter()
-        .flat_map(|path| read_file_to_array(path).unwrap())
-        .collect();
-    // Process --copy-output
-    let copy_output = copy_output_raw.map(|co| {
-        if co.len() != 2 {
-            panic!(
-                "process wrapper error: \"--copy-output\" needs exactly 2 parameters, {} provided",
-                co.len()
-            )
-        }
-        let copy_source = &co[0];
-        let copy_dest = &co[1];
-        if copy_source == copy_dest {
-            panic!(
-                "process wrapper error: \"--copy-output\" source ({}) and dest ({}) need to be different.",
-                copy_source, copy_dest
-            )
-        }
-        (copy_source.to_owned(), copy_dest.to_owned())
-    });
-    child_args.append(&mut file_arguments);
-    let child_args = prepare_args(child_args, &subst_mappings);
-
-    let (exec_path, args) = child_args.split_first().expect("process wrapper error: at least one argument after -- is required (the child process path) but none found.");
-    let vars = environment_block(environment_file_block, &stamp_mappings, &subst_mappings);
-
-    let status = Command::new(exec_path)
-        .args(args)
+    let status = Command::new(opts.executable)
+        .args(opts.child_arguments)
         .env_clear()
-        .envs(vars)
-        .stdout(if let Some(stdout_file) = stdout_file_raw {
+        .envs(opts.child_environment)
+        .stdout(if let Some(stdout_file) = opts.stdout_file {
             OpenOptions::new()
                 .create(true)
                 .truncate(true)
@@ -185,7 +41,7 @@ fn main() {
         } else {
             Stdio::inherit()
         })
-        .stderr(if let Some(stderr_file) = stderr_file_raw {
+        .stderr(if let Some(stderr_file) = opts.stderr_file {
             OpenOptions::new()
                 .create(true)
                 .truncate(true)
@@ -200,14 +56,14 @@ fn main() {
         .expect("process wrapper error: failed to spawn child process");
 
     if status.success() {
-        if let Some(tf) = touch_file_raw {
+        if let Some(tf) = opts.touch_file {
             OpenOptions::new()
                 .create(true)
                 .write(true)
                 .open(tf)
                 .expect("process wrapper error: failed to create touch file");
         }
-        if let Some((copy_source, copy_dest)) = copy_output {
+        if let Some((copy_source, copy_dest)) = opts.copy_output {
             copy(&copy_source, &copy_dest).unwrap_or_else(|_| {
                 panic!(
                     "process wrapper error: failed to copy {} into {}",