Handle STDERR, in addition to STDOUT

This patch overhauls the reading and reciting of verses, such that the
redirection of STDERR (in addition to STDOUT, which was already a
feature), is now possible.

Removed the 'stdout' argument from recite(), since it is no longer
needed with how incantations function.

A verse's couplet indicator is now a u8, instead of a bool, with certain
values corresponding to types of couplets, for instance:

  ls | grep Ca | lolcat
  ^    ^         ^
  |    |         2: right side of a couplet
  |    3: both sides of a couplet
  1: left side of a couplet

Incantions are no longer hanlded in rune.rs, and the task macros have
been removed. Now, a verse incants itself, matching on its own meter to
determine how to handle the next verse.

The following runes were added to help with handling STDERR:
  Write2 -> 2>
  WriteAll -> &>
  Addendum2 -> 2>>
  AddendumAll -> &>>

The 'io' field in verse was changed from an Option<Rune>, to an array of
Runes, since a single verse might have multiple IO operations.

The following fields were added to Verse, to assist with handling
STDERR:
  ip -> List of filenames to read into STDIN
  op -> List of filenames to send STDOUT to
  ep -> List of filenames to send STDERR to

Keep track of channels when reading a poem. Channels are relating to IO
operations. If channel is None, words get pushed to the verse's primary
stanza (i.e. the verb or the clause). If a channel is selected, words
are pushed to one of the aforementioned new fields in Verse.
  Read -> ip
  Write/Addedum -> op
  Write2/Addedum2 -> ep
  WriteAll/AddendumAll -> op and ep

2 files changed, 289 insertions, 335 deletions

diff --git a/src/poem/elements/rune.rs b/src/poem/elements/rune.rs
index 2307519..1322ca5 100644
--- a/src/poem/elements/rune.rs
+++ b/src/poem/elements/rune.rs
@@ -1,14 +1,4 @@
-use super::verse::Verse;
-use crate::iobtask;
-use crate::{btask, ctask, task};
 use core::fmt;
-use libc::waitpid;
-use libc::WNOHANG;
-use std::fs::OpenOptions;
-use std::io::{self, Read, Write};
-use std::os::unix::process::CommandExt;
-use std::process::{Command, Stdio};
-use std::sync::{Arc, Mutex};
 
 /// Describes one or two characters from the input
 ///
@@ -40,21 +30,25 @@ use std::sync::{Arc, Mutex};
 /// * `Else` - Any other character
 #[derive(Debug, PartialEq, Eq, Copy, Clone)]
 pub enum Rune {
-    None,     // No meter (the end of a poem)
-    Pause,    // A space
-    Path,     // A forward slash
-    Remark,   // A comment
-    String,   // Interpret the following as one large [Word]
-    Poem,     // Run a sub-poem before the main one
-    Read,     // Read files into STDIN
-    Write,    // Send STDOUT to a file
-    Addendum, // Append STDOUT to a file
-    Couplet,  // Pipe the output of this command into the next
-    Quiet,    // Fork the command into the background
-    And,      // Run the next command only if this succeeds
-    Continue, // Run the next command, even if this doesn't succeed
-    Home,     // Interpret '~' as $HOME
-    Else,     // Any other character
+    None,        // No meter (the end of a poem)
+    Pause,       // A space
+    Path,        // A forward slash
+    Remark,      // A comment
+    String,      // Interpret the following as one large [Word]
+    Poem,        // Run a sub-poem before the main one
+    Read,        // Read files into STDIN
+    Write,       // Send STDOUT to a file
+    Write2,      // Send STDERR to a file
+    WriteAll,    // Send STDOUT and STDERR to a file
+    Addendum,    // Append STDOUT to a file
+    Addendum2,   // Append STDERR to a file
+    AddendumAll, // Append STDOUT and STDERR to a file
+    Couplet,     // Pipe the output of this command into the next
+    Quiet,       // Fork the command into the background
+    And,         // Run the next command only if this succeeds
+    Continue,    // Run the next command, even if this doesn't succeed
+    Home,        // Interpret '~' as $HOME
+    Else,        // Any other character
 }
 
 impl fmt::Display for Rune {
@@ -71,7 +65,11 @@ impl fmt::Display for Rune {
             Rune::Poem => "`",
             Rune::Read => "<",
             Rune::Write => ">",
+            Rune::Write2 => "2>",
+            Rune::WriteAll => "&>",
             Rune::Addendum => ">>",
+            Rune::Addendum2 => "2>>",
+            Rune::AddendumAll => "&>>",
             Rune::Couplet => "|",
             Rune::Quiet => "&",
             Rune::And => "&&",
@@ -83,294 +81,3 @@ impl fmt::Display for Rune {
         write!(f, "{}", rune)
     }
 }
-
-impl Rune {
-    /// Recite a verse with [Rune::None]
-    ///
-    /// Call this function on a [Verse] with a meter of type [Rune::None].
-    /// This forks into a child process, calls the `verb()` (i.e. program)
-    /// that was specified in the [Verse], then waits for that program to
-    /// complete. If the last [Verse] piped its contents into `out`, it will
-    /// be piped into the STDIN of this [Verse]. If all Rust code is called
-    /// successfully, return the exit code of the process. Otherwise, return a
-    /// [std::io::Error].
-    ///
-    /// # Arguments
-    /// * `verse: &Verse` - The verse to recite
-    /// * `out: &mut String` - A string that may have output from the last command
-    pub fn incant_none(verse: &Verse, out: &mut Vec<u8>) -> Result<i32, io::Error> {
-        let child = task!(verse, out);
-
-        let output = child.wait_with_output()?;
-
-        if !output.status.success() {
-            return Ok(output.status.code().unwrap_or(-1));
-        }
-
-        Ok(output.status.code().unwrap_or(0))
-    }
-
-    /// Recite a verse with [Rune::Couplet]
-    ///
-    /// Call this function on a [Verse] with a meter of type [Rune::Couplet].
-    /// This forks into a child process, calls the `verb` (i.e. program)
-    /// that was specified in the [Verse], then waits for that program to
-    /// complete. If the last [Verse] piped its contents into `out`, it will
-    /// be piped into the STDIN of this [Verse]. Then, the contents of this
-    /// processes' STDOUT are stored in `out`. If all Rust code is called
-    /// successfully, return the exit code of the process. Otherwise, return a
-    /// [std::io::Error].
-    ///
-    /// # Arguments
-    /// * `verse: &Verse` - The verse to recite
-    /// * `out: &mut String` - A string that may have output from the last command
-    pub fn incant_couplet(verse: &Verse, out: &mut Vec<u8>) -> Result<i32, io::Error> {
-        let child = ctask!(verse, out);
-
-        let mut output = child.wait_with_output()?;
-
-        if !output.status.success() {
-            return Ok(output.status.code().unwrap_or(-1));
-        }
-
-        out.append(&mut output.stdout);
-
-        Ok(output.status.code().unwrap_or(0))
-    }
-
-    /// Recite a verse with [Rune::Quiet]
-    ///
-    /// Call this function on a [Verse] with a meter of type [Rune::Quiet].
-    /// This forks a child process into the background. It then registers a
-    /// `SIGCHLD` handler, making sure to do so for each PID in the `pids`
-    /// Vec. If the last [Verse] piped its contents into `out`, it will be
-    /// piped into the STDIN of this [Verse]. If all Rust code is called
-    /// successfully, return the exit code of the process. Otherwise, return a
-    /// [std::io::Error].
-    ///
-    /// # Arguments
-    /// * `verse: &Verse` - The verse to recite
-    /// * `out: &mut String` - A string that may have output from the last command
-    /// * `pids: Arc<Mutex<Vec<i32>>>` - A vector that stores the PIDs of all background processes that belong to the shell
-    pub fn incant_quiet(
-        verse: &Verse,
-        out: &mut Vec<u8>,
-        pids: &mut Arc<Mutex<Vec<i32>>>,
-    ) -> Result<i32, io::Error> {
-        let child = btask!(verse, out);
-        println!("[&]  {}", child.id());
-
-        pids.lock().unwrap().push(child.id() as i32);
-        let stanza = verse.stanza.join(" ").to_string();
-        let pids = Arc::clone(pids);
-
-        unsafe {
-            signal_hook::low_level::register(signal_hook::consts::SIGCHLD, move || {
-                for pid in pids.lock().unwrap().iter() {
-                    let mut pid = *pid;
-                    let mut status: i32 = 0;
-                    pid = waitpid(pid, &mut status, WNOHANG);
-                    if pid > 0 {
-                        print!("\n[&]  + done    {}", stanza);
-                        io::stdout().flush().unwrap();
-                    }
-                }
-            })
-            .unwrap();
-        }
-
-        Ok(0)
-    }
-
-    /// Alias to [Rune::incant_none]
-    pub fn incant_and(verse: &Verse, out: &mut Vec<u8>) -> Result<i32, io::Error> {
-        Rune::incant_none(verse, out)
-    }
-
-    /// Alias to [Rune::incant_none]
-    pub fn incant_continue(verse: &Verse, out: &mut Vec<u8>) -> Result<i32, io::Error> {
-        Rune::incant_none(verse, out)
-    }
-
-    /// Recite a verse with [Rune::Read]
-    ///
-    /// Call this function on a [Verse] with a meter of type [Rune::Read].
-    /// This reads the specified files into `out`, then makes a call to
-    /// [Rune::incant_none] with all the contents of `out`. Anything piped to
-    /// this command will appear in `out` first, and any subsequent files will
-    /// be appended.
-    ///
-    /// # Arguments
-    /// * `verse: &Verse` - The verse to recite
-    /// * `paths: &Verse` - The next verse (i.e. the file paths)
-    /// * `out: &mut String` - A string that may have output from the last command,
-    ///                        and that will be used to store the contents of the
-    ///                        file paths in `next`
-    pub fn incant_read(
-        verse: &mut Verse,
-        out: &mut Vec<u8>,
-        pids: &mut Arc<Mutex<Vec<i32>>>,
-    ) -> Result<i32, io::Error> {
-        // Split the verse from the paths
-        let paths = verse.split("<");
-
-        // Read all file specified in the next verse into 'out', since there
-        // may also be piped output from the last command
-        for path in paths.iter() {
-            let mut file = OpenOptions::new().read(true).open(path)?;
-            let mut contents = String::new();
-            file.read_to_string(&mut contents)?;
-            out.append(&mut contents.as_bytes().to_vec());
-        }
-
-        // Alias incant_<meter>
-        match verse.meter {
-            Rune::None => Rune::incant_none(&verse, out),
-            Rune::Couplet => Rune::incant_couplet(&verse, out),
-            Rune::Quiet => Rune::incant_quiet(&verse, out, pids),
-            Rune::And => Rune::incant_and(&verse, out),
-            Rune::Continue => Rune::incant_continue(&verse, out),
-            _ => unreachable!(),
-        }
-    }
-
-    /// Recite a verse with [Rune::Write]
-    ///
-    /// Call this function on a [Verse] with a meter of type [Rune::Write].
-    /// This writes the output of the verse into the specified files, after
-    /// making a call to [Rune::incant_couplet].
-    ///
-    /// # Arguments
-    /// * `verse: &Verse` - The verse to recite
-    /// * `paths: &Verse` - The next verse (i.e. the file paths)
-    /// * `out: &mut String` - A string that may have output from the last command,
-    ///                        and that will be used to store the contents of the
-    ///                        file paths in `next`
-    pub fn incant_write(
-        verse: &mut Verse,
-        out: &mut Vec<u8>,
-        pids: &mut Arc<Mutex<Vec<i32>>>,
-    ) -> Result<i32, io::Error> {
-        // Split the verse from the paths
-        let mut paths = Arc::new(Mutex::new(verse.split("<")));
-
-        // Alias incant_<meter>
-        // let status = Rune::incant_couplet(&verse, out)?;
-        let status = match verse.meter {
-            Rune::None => Rune::incant_couplet(&verse, out)?,
-            Rune::Couplet => Rune::incant_couplet(&verse, out)?,
-            Rune::Quiet => Rune::incant_quiet_io(&verse, out, pids, &mut paths)?,
-            Rune::And => Rune::incant_couplet(&verse, out)?,
-            Rune::Continue => Rune::incant_couplet(&verse, out)?,
-            _ => unreachable!(),
-        };
-
-        // Write output to each file specified in the next verse
-        for path in paths.lock().unwrap().iter() {
-            let mut file = OpenOptions::new().create(true).write(true).open(path)?;
-            file.write(out)?;
-        }
-
-        // Clear out
-        out.clear();
-
-        // Return the exit status
-        Ok(status)
-    }
-
-    /// Recite a verse with [Rune::Addendum]
-    ///
-    /// Same as [Rune::Write], except it appends to the file(s) specified,
-    /// instead of overwriting them.
-    ///
-    /// # Arguments
-    /// * `verse: &Verse` - The verse to recite
-    /// * `paths: &Verse` - The next verse (i.e. the file paths)
-    /// * `out: &mut String` - A string that may have output from the last command,
-    ///                        and that will be used to store the contents of the
-    ///                        file paths in `next`
-    pub fn incant_addendum(
-        verse: &mut Verse,
-        out: &mut Vec<u8>,
-        pids: &mut Arc<Mutex<Vec<i32>>>,
-    ) -> Result<i32, io::Error> {
-        // Split the verse from the paths
-        let mut paths = Arc::new(Mutex::new(verse.split("<")));
-
-        // Alias incant_<meter>
-        // let status = Rune::incant_couplet(&verse, out)?;
-        let status = match verse.meter {
-            Rune::None => Rune::incant_couplet(&verse, out)?,
-            Rune::Couplet => Rune::incant_couplet(&verse, out)?,
-            Rune::Quiet => Rune::incant_quiet_io(&verse, out, pids, &mut paths)?,
-            Rune::And => Rune::incant_couplet(&verse, out)?,
-            Rune::Continue => Rune::incant_couplet(&verse, out)?,
-            _ => unreachable!(),
-        };
-
-        // Write output to each file specified in the next verse
-        for path in paths.lock().unwrap().iter() {
-            let mut file = OpenOptions::new().create(true).append(true).open(path)?;
-            file.write(out)?;
-        }
-
-        // Clear out
-        out.clear();
-
-        // Return the exit status
-        Ok(status)
-    }
-
-    /// Same as incant_quiet, except capture STDOUT into `out`
-    pub fn incant_quiet_io(
-        verse: &Verse,
-        out: &mut Vec<u8>,
-        pids: &mut Arc<Mutex<Vec<i32>>>,
-        paths: &mut Arc<Mutex<Vec<String>>>,
-    ) -> Result<i32, io::Error> {
-        let child = Arc::new(Mutex::new(iobtask!(verse, out)));
-        println!("[&]  {}", child.lock().unwrap().id());
-
-        pids.lock().unwrap().push(child.lock().unwrap().id() as i32);
-        let stanza = verse.stanza.join(" ").to_string();
-        let pids = Arc::clone(pids);
-        let paths = Arc::clone(paths);
-        let io = Arc::new(verse.io);
-
-        unsafe {
-            signal_hook::low_level::register(signal_hook::consts::SIGCHLD, move || {
-                for pid in pids.lock().unwrap().iter() {
-                    let mut pid = *pid;
-                    let mut status: i32 = 0;
-                    pid = waitpid(pid, &mut status, WNOHANG);
-                    if pid > 0 {
-                        print!("\n[&]  + done    {}", stanza);
-                        let mut bytes: Vec<u8> = Vec::new();
-                        let mut child = child.lock().unwrap();
-                        child
-                            .stdout
-                            .as_mut()
-                            .unwrap()
-                            .read_to_end(&mut bytes)
-                            .unwrap();
-                        for path in paths.lock().unwrap().iter() {
-                            let file = if io == Rune::Write.into() {
-                                OpenOptions::new().create(true).write(true).open(path)
-                            } else if io == Rune::Addendum.into() {
-                                OpenOptions::new().create(true).append(true).open(path)
-                            } else {
-                                unreachable!();
-                            };
-
-                            let _ = file.unwrap().write(&bytes);
-                        }
-                        io::stdout().flush().unwrap();
-                    }
-                }
-            })
-            .unwrap();
-        }
-
-        Ok(0)
-    }
-}
diff --git a/src/poem/elements/verse.rs b/src/poem/elements/verse.rs
index e857676..307ebc8 100644
--- a/src/poem/elements/verse.rs
+++ b/src/poem/elements/verse.rs
@@ -2,7 +2,13 @@ use super::rune::Rune;
 use super::stanza::Stanza;
 use super::word::Word;
 use crate::poem::Poem;
+use libc::{waitpid, WNOHANG};
+use std::fs::OpenOptions;
+use std::io::{self, Read, Write};
+use std::os::unix::process::CommandExt;
 use std::path::Path;
+use std::process::{Command, Output, Stdio};
+use std::sync::{Arc, Mutex};
 
 /// A [Stanza] and it's [meter](Rune)
 ///
@@ -12,8 +18,11 @@ use std::path::Path;
 #[derive(Debug, Clone)]
 pub struct Verse {
     pub stanza: Stanza,
-    pub couplet: bool,
-    pub io: Rune,
+    pub couplet: u8,
+    pub io: Vec<Rune>,
+    pub ip: Stanza,
+    pub op: Stanza,
+    pub ep: Stanza,
     pub poems: Vec<Poem>,
     pub meter: Rune,
 }
@@ -26,8 +35,11 @@ impl Verse {
     pub fn new() -> Self {
         Verse {
             stanza: Stanza::new(),
-            couplet: false,
-            io: Rune::None,
+            couplet: 0,
+            io: Vec::new(),
+            ip: Stanza::new(),
+            op: Stanza::new(),
+            ep: Stanza::new(),
             poems: Vec::new(),
             meter: Rune::None,
         }
@@ -64,6 +76,8 @@ impl Verse {
     /// Alias to [Verse].stanza.clear()
     pub fn clear(&mut self) {
         self.stanza.clear();
+        self.io.clear();
+        self.poems.clear();
     }
 
     /// Check if the [Verse] contains any internal poems
@@ -79,25 +93,26 @@ impl Verse {
     /// Push a word to the [Stanza] after performing a few extra checks, such
     /// as whether or not the word is empty, or if the word should be
     /// interpreted as an environment variable.
-    pub fn add(&mut self, word: &mut Word) {
-        if !word.is_empty() {
-            // Push the word, and clear the stack
-            self.push(word.iter().collect());
-            word.clear();
+    pub fn add(&mut self, word: &mut Word, channel: Option<Rune>) {
+        // Do nothing if the stack is empty
+        if word.is_empty() {
+            return;
         }
-    }
 
-    /// Split a [Verse] into two different [Verse]s
-    ///
-    /// This is useful for [Rune::Read], [Rune::Write], and [Rune::Addendum].
-    pub fn split(&mut self, c: &str) -> Vec<String> {
-        for (i, s) in self.stanza.iter().enumerate() {
-            if *s == c {
-                let split = self.stanza.split_off(i);
-                return split[1..].to_vec();
+        // Push the word
+        match channel {
+            Some(Rune::Read) => self.ip.push(word.iter().collect()),
+            Some(Rune::Write) | Some(Rune::Addendum) => self.op.push(word.iter().collect()),
+            Some(Rune::Write2) | Some(Rune::Addendum2) => self.ep.push(word.iter().collect()),
+            Some(Rune::WriteAll) | Some(Rune::AddendumAll) => {
+                self.op.push(word.iter().collect());
+                self.ep.push(word.iter().collect());
             }
+            Some(_) | None => self.push(word.iter().collect()),
         }
-        vec![]
+
+        // Clear the stack
+        word.clear();
     }
 
     /// Check if the `verb()` exists in the `$PATH`
@@ -156,4 +171,236 @@ impl Verse {
         // Return true if the full path or relative path exists
         true
     }
+
+    pub fn incant(
+        &mut self,
+        out: &mut Vec<u8>,
+        pids: &mut Arc<Mutex<Vec<i32>>>,
+    ) -> Result<i32, io::Error> {
+        // Read files into 'out' if Rune::Read is present in the verse's IO
+        if self.io.contains(&Rune::Read) {
+            // Enable piping on stdin
+            self.couplet += 2;
+
+            // Read all files specified after '<' into 'out', since there may
+            // also be piped output from the last command
+            for path in self.ip.iter() {
+                let mut file = OpenOptions::new().read(true).open(path)?;
+                let mut contents = String::new();
+                file.read_to_string(&mut contents)?;
+                out.append(&mut contents.as_bytes().to_vec());
+            }
+        }
+
+        // Build the command
+        let mut command = Command::new(self.verb());
+        command.args(self.clause().unwrap_or(vec![]));
+
+        // Determine couplet status
+        if self.couplet == 1 {
+            // Verse is the left half of a couplet
+            command.stdout(Stdio::piped());
+        } else if self.couplet == 2 {
+            // Verse is the right half of a couplet
+            command.stdin(Stdio::piped());
+        } else if self.couplet == 3 {
+            // Verse is taking in and piping out output
+            command.stdout(Stdio::piped());
+            command.stdin(Stdio::piped());
+        }
+
+        // Setup for other IO
+        if self.io.contains(&Rune::Write) || self.io.contains(&Rune::Addendum) {
+            command.stdout(Stdio::piped());
+        }
+        if self.io.contains(&Rune::Write2) || self.io.contains(&Rune::Addendum2) {
+            command.stderr(Stdio::piped());
+        }
+        if self.io.contains(&Rune::WriteAll) || self.io.contains(&Rune::AddendumAll) {
+            command.stdout(Stdio::piped());
+            command.stderr(Stdio::piped());
+        }
+
+        // Detach the process group, if in the [Rune::Quiet] meter
+        if self.meter == Rune::Quiet {
+            command.process_group(0);
+        }
+
+        // Spawn the process
+        let mut child = command.spawn()?;
+
+        // Pipe in command, if we're the right side of a couplet
+        if self.couplet > 1 {
+            let stdin = child.stdin.as_mut().ok_or(io::ErrorKind::BrokenPipe)?;
+            stdin.write_all(&out)?;
+            out.clear();
+        }
+
+        // Determine what to do based on the meter
+        let mut output: Output;
+        let mut err: Vec<u8> = Vec::new();
+        match self.meter {
+            Rune::None | Rune::And | Rune::Continue => {
+                output = child.wait_with_output()?;
+                if self.io.contains(&Rune::Write) || self.io.contains(&Rune::Addendum) {
+                    out.append(&mut output.stdout);
+                }
+                if self.io.contains(&Rune::Write2) || self.io.contains(&Rune::Addendum2) {
+                    err.append(&mut output.stderr);
+                }
+                if self.io.contains(&Rune::WriteAll) || self.io.contains(&Rune::AddendumAll) {
+                    out.append(&mut output.stdout);
+                    err.append(&mut output.stderr);
+                }
+            }
+            Rune::Couplet => {
+                output = child.wait_with_output()?;
+                out.append(&mut output.stdout);
+                if self.io.contains(&Rune::Write2) || self.io.contains(&Rune::Addendum2) {
+                    err.append(&mut output.stderr);
+                }
+                if self.io.contains(&Rune::WriteAll) || self.io.contains(&Rune::AddendumAll) {
+                    err.append(&mut output.stderr);
+                }
+            }
+            Rune::Quiet => {
+                println!("[&]  {}", child.id());
+
+                pids.lock().unwrap().push(child.id() as i32);
+                let stanza = self.stanza.join(" ").to_string();
+                let pids = Arc::clone(pids);
+
+                unsafe {
+                    signal_hook::low_level::register(signal_hook::consts::SIGCHLD, move || {
+                        for pid in pids.lock().unwrap().iter() {
+                            let mut pid = *pid;
+                            let mut status: i32 = 0;
+                            pid = waitpid(pid, &mut status, WNOHANG);
+                            if pid > 0 {
+                                print!("\n[&]  + done    {}", stanza);
+                                io::stdout().flush().unwrap();
+                            }
+                        }
+                    })
+                    .unwrap();
+                }
+
+                return Ok(0);
+            }
+            _ => unreachable!(),
+        }
+
+        // Perform IO operations
+        let mut oi = 0;
+        let mut ei = 0;
+        self.io.retain(|rune| *rune != Rune::Read);
+        for io in self.io.iter() {
+            let (f, f2) = match *io {
+                Rune::Write => {
+                    oi += 1;
+                    (
+                        Some(
+                            OpenOptions::new()
+                                .create(true)
+                                .write(true)
+                                .open(&self.op[oi - 1])?,
+                        ),
+                        None,
+                    )
+                }
+                Rune::Write2 => {
+                    ei += 1;
+                    (
+                        None,
+                        Some(
+                            OpenOptions::new()
+                                .create(true)
+                                .write(true)
+                                .open(&self.ep[ei - 1])?,
+                        ),
+                    )
+                }
+                Rune::WriteAll => {
+                    oi += 1;
+                    ei += 1;
+                    (
+                        Some(
+                            OpenOptions::new()
+                                .create(true)
+                                .write(true)
+                                .open(&self.op[oi - 1])?,
+                        ),
+                        Some(
+                            OpenOptions::new()
+                                .create(true)
+                                .write(true)
+                                .open(&self.ep[ei - 1])?,
+                        ),
+                    )
+                }
+                Rune::Addendum => {
+                    oi += 1;
+                    (
+                        Some(
+                            OpenOptions::new()
+                                .create(true)
+                                .append(true)
+                                .open(&self.op[oi - 1])?,
+                        ),
+                        None,
+                    )
+                }
+                Rune::Addendum2 => {
+                    ei += 1;
+                    (
+                        None,
+                        Some(
+                            OpenOptions::new()
+                                .create(true)
+                                .append(true)
+                                .open(&self.ep[ei - 1])?,
+                        ),
+                    )
+                }
+                Rune::AddendumAll => {
+                    oi += 1;
+                    ei += 1;
+                    (
+                        Some(
+                            OpenOptions::new()
+                                .create(true)
+                                .append(true)
+                                .open(&self.op[oi - 1])?,
+                        ),
+                        Some(
+                            OpenOptions::new()
+                                .create(true)
+                                .append(true)
+                                .open(&self.ep[ei - 1])?,
+                        ),
+                    )
+                }
+                _ => unreachable!(),
+            };
+
+            match f {
+                Some(mut file) => file.write(out)?,
+                None => 0,
+            };
+
+            match f2 {
+                Some(mut file) => file.write(&err)?,
+                None => 0,
+            };
+        }
+
+        if !output.status.success() {
+            return Ok(output.status.code().unwrap_or(-1));
+        }
+
+        out.clear();
+        err.clear();
+
+        Ok(output.status.code().unwrap_or(0))
+    }
 }