From 718f45492a4b2c31a67458c13c4cd4b3268703bc Mon Sep 17 00:00:00 2001
From: Rory Dudley
Date: Thu, 29 Feb 2024 01:40:27 -0700
Subject: Fix handling of SIGINT

Keep track of a new atomic variable: at_prompt, which is set to true
just before blocking on io::stdin.read_line, and set to false just
calling Poem::read. Additionally, for background tasks, there is a new
ps macro called btask, which changes the process group of commands that
are forked into the background, so that they don't receive SIGINT from
the keyboard.
---
 src/main.rs      | 21 +++++++++++++++++----
 src/recite.rs    |  5 +++--
 src/recite/ps.rs | 33 +++++++++++++++++++++++++++++++++
 3 files changed, 53 insertions(+), 6 deletions(-)

diff --git a/src/main.rs b/src/main.rs
index 3cb2a74..04d58eb 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -3,6 +3,7 @@ use recite::path::prefresh;
 use recite::Poem;
 use std::io::{self, Write};
 use std::path::Path;
+use std::sync::{Arc, Mutex};
 
 /// Starts the main shell loop
 ///
@@ -20,7 +21,7 @@ use std::path::Path;
 ///     repl(&path, prompt);
 /// }
 /// ```
-fn repl(path: &Vec<&Path>, prompt: &str) {
+fn repl(path: &Vec<&Path>, prompt: &str, at_prompt: &mut Arc<Mutex<bool>>) {
     // Initial path refresh on startup
     let mut bins: Vec<String> = prefresh(path);
 
@@ -30,6 +31,9 @@ fn repl(path: &Vec<&Path>, prompt: &str) {
         print!("{}", prompt);
         io::stdout().flush().unwrap();
 
+        // At the prompt
+        *at_prompt.lock().unwrap() = true;
+
         // Wait for user input
         let mut poetry = String::new();
         let bytes = io::stdin()
@@ -50,6 +54,9 @@ fn repl(path: &Vec<&Path>, prompt: &str) {
             continue;
         }
 
+        // Not at the prompt
+        *at_prompt.lock().unwrap() = false;
+
         // Parse a poem
         let poem = Poem::read(poetry);
         match poem {
@@ -80,16 +87,22 @@ fn main() {
 
     // Set the prompt
     let prompt = "|> ";
+    let mut at_prompt = Arc::new(Mutex::new(false));
 
     // Handle signals
     unsafe {
+        let at_prompt = Arc::clone(&at_prompt);
         signal_hook::low_level::register(signal_hook::consts::SIGINT, move || {
-            print!("\n{}", prompt);
-            io::stdout().flush().unwrap();
+            if *at_prompt.lock().unwrap() {
+                print!("\n{}", prompt);
+                io::stdout().flush().unwrap();
+            } else {
+                println!();
+            }
         })
         .unwrap();
     };
 
     // Begin evaluating commands
-    repl(&path, prompt);
+    repl(&path, prompt, &mut at_prompt);
 }
diff --git a/src/recite.rs b/src/recite.rs
index bd72b67..1aa1a62 100644
--- a/src/recite.rs
+++ b/src/recite.rs
@@ -1,10 +1,11 @@
 pub mod path;
 mod ps;
-use crate::{ctask, task};
+use crate::{btask, ctask, task};
 use core::fmt;
 use libc::{waitpid, WNOHANG};
 use path::prefresh;
 use std::io::{self, Write};
+use std::os::unix::process::CommandExt;
 use std::path::Path;
 use std::process::{exit, Command, Stdio};
 use std::sync::{Arc, Mutex};
@@ -125,7 +126,7 @@ impl Meter {
         out: &mut String,
         pids: &mut Arc<Mutex<Vec<i32>>>,
     ) -> Result<i32, io::Error> {
-        let child = task!(verse, out);
+        let child = btask!(verse, out);
         println!("[&]  {}", child.id());
 
         pids.lock().unwrap().push(child.id() as i32);
diff --git a/src/recite/ps.rs b/src/recite/ps.rs
index d0e2435..bb18b3f 100644
--- a/src/recite/ps.rs
+++ b/src/recite/ps.rs
@@ -60,3 +60,36 @@ macro_rules! ctask {
         }
     };
 }
+
+#[macro_export]
+/// Fork into a background process from a Verse
+///
+/// Figures out whether or not the given Verse is a couplet. If it is, fork
+/// into a backgournd process, and pipe the contents of out `out` into STDIN.
+/// If not, then simply fork into the background process.
+///
+/// # Arguments
+/// * `$verse: &Verse` - The verse to fork into
+/// * `$out: &mut String` - If the $verse is a couplet, the contents of STDOUT from the last verse
+macro_rules! btask {
+    ($verse:expr, $out:expr) => {
+        if $verse.couplet {
+            let mut child = Command::new($verse.verb())
+                .args($verse.clause())
+                .stdin(Stdio::piped())
+                .process_group(0)
+                .spawn()?;
+
+            let stdin = child.stdin.as_mut().ok_or(io::ErrorKind::BrokenPipe)?;
+            stdin.write_all(&$out.as_bytes())?;
+            $out.clear();
+
+            child
+        } else {
+            Command::new($verse.verb())
+                .args($verse.clause())
+                .process_group(0)
+                .spawn()?
+        }
+    };
+}
-- 
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