1 files changed, 203 insertions, 0 deletions
diff --git a/src/runner/command.rs b/src/runner/command.rs
new file mode 100644
index 0000000..cbc8dee
--- /dev/null
+++ b/src/runner/command.rs
@@ -0,0 +1,203 @@
+use crate::runner::prelude::*;
+
+pub struct Command {
+    inner: Inner,
+    exe: std::path::PathBuf,
+    redirects: Vec<crate::parse::Redirect>,
+    pre_exec: Option<
+        Box<dyn FnMut() -> std::io::Result<()> + Send + Sync + 'static>,
+    >,
+}
+
+impl Command {
+    pub fn new(exe: crate::parse::Exe, io: super::builtins::Io) -> Self {
+        let exe_path = exe.exe().to_path_buf();
+        let redirects = exe.redirects().to_vec();
+        Self {
+            inner: super::builtins::Command::new(exe, io).map_or_else(
+                |exe| Self::new_binary(&exe).inner,
+                Inner::Builtin,
+            ),
+            exe: exe_path,
+            redirects,
+            pre_exec: None,
+        }
+    }
+
+    pub fn new_binary(exe: &crate::parse::Exe) -> Self {
+        let exe_path = exe.exe().to_path_buf();
+        let redirects = exe.redirects().to_vec();
+        let mut cmd = tokio::process::Command::new(exe.exe());
+        cmd.args(exe.args());
+        Self {
+            inner: Inner::Binary(cmd),
+            exe: exe_path,
+            redirects,
+            pre_exec: None,
+        }
+    }
+
+    pub fn new_builtin(
+        exe: crate::parse::Exe,
+        io: super::builtins::Io,
+    ) -> Self {
+        let exe_path = exe.exe().to_path_buf();
+        let redirects = exe.redirects().to_vec();
+        Self {
+            inner: super::builtins::Command::new(exe, io)
+                .map_or_else(|_| todo!(), Inner::Builtin),
+            exe: exe_path,
+            redirects,
+            pre_exec: None,
+        }
+    }
+
+    pub fn stdin(&mut self, fh: std::fs::File) {
+        match &mut self.inner {
+            Inner::Binary(cmd) => {
+                cmd.stdin(fh);
+            }
+            Inner::Builtin(cmd) => {
+                cmd.stdin(fh);
+            }
+        }
+    }
+
+    pub fn stdout(&mut self, fh: std::fs::File) {
+        match &mut self.inner {
+            Inner::Binary(cmd) => {
+                cmd.stdout(fh);
+            }
+            Inner::Builtin(cmd) => {
+                cmd.stdout(fh);
+            }
+        }
+    }
+
+    pub fn stderr(&mut self, fh: std::fs::File) {
+        match &mut self.inner {
+            Inner::Binary(cmd) => {
+                cmd.stderr(fh);
+            }
+            Inner::Builtin(cmd) => {
+                cmd.stderr(fh);
+            }
+        }
+    }
+
+    // Safety: see pre_exec in tokio::process::Command (this is just a
+    // wrapper)
+    pub unsafe fn pre_exec<F>(&mut self, f: F)
+    where
+        F: 'static + FnMut() -> std::io::Result<()> + Send + Sync,
+    {
+        self.pre_exec = Some(Box::new(f));
+    }
+
+    pub fn spawn(self, env: &Env) -> Result<Child> {
+        let Self {
+            inner,
+            exe,
+            redirects,
+            pre_exec,
+        } = self;
+
+        #[allow(clippy::as_conversions)]
+        let pre_exec = pre_exec.map_or_else(
+            || {
+                let redirects = redirects.clone();
+                Box::new(move || {
+                    apply_redirects(&redirects)?;
+                    Ok(())
+                })
+                    as Box<dyn FnMut() -> std::io::Result<()> + Send + Sync>
+            },
+            |mut pre_exec| {
+                let redirects = redirects.clone();
+                Box::new(move || {
+                    apply_redirects(&redirects)?;
+                    pre_exec()?;
+                    Ok(())
+                })
+            },
+        );
+        match inner {
+            Inner::Binary(mut cmd) => {
+                // Safety: open, dup2, and close are async-signal-safe
+                // functions
+                unsafe { cmd.pre_exec(pre_exec) };
+                Ok(Child::Binary(cmd.spawn().map_err(|e| {
+                    anyhow!(
+                        "{}: {}",
+                        crate::format::io_error(&e),
+                        exe.display()
+                    )
+                })?))
+            }
+            Inner::Builtin(mut cmd) => {
+                // Safety: open, dup2, and close are async-signal-safe
+                // functions
+                unsafe { cmd.pre_exec(pre_exec) };
+                cmd.apply_redirects(&redirects);
+                Ok(Child::Builtin(cmd.spawn(env)?))
+            }
+        }
+    }
+}
+
+pub enum Inner {
+    Binary(tokio::process::Command),
+    Builtin(super::builtins::Command),
+}
+
+pub enum Child {
+    Binary(tokio::process::Child),
+    Builtin(super::builtins::Child),
+}
+
+impl Child {
+    pub fn id(&self) -> Option<u32> {
+        match self {
+            Self::Binary(child) => child.id(),
+            Self::Builtin(child) => child.id(),
+        }
+    }
+
+    pub fn status(
+        self,
+    ) -> std::pin::Pin<
+        Box<
+            dyn std::future::Future<Output = Result<std::process::ExitStatus>>
+                + Send
+                + Sync,
+        >,
+    > {
+        Box::pin(async move {
+            match self {
+                // this case is handled by waitpid
+                Self::Binary(_) => unreachable!(),
+                Self::Builtin(child) => Ok(child.status().await?),
+            }
+        })
+    }
+}
+
+fn apply_redirects(
+    redirects: &[crate::parse::Redirect],
+) -> std::io::Result<()> {
+    for redirect in redirects {
+        match &redirect.to {
+            crate::parse::RedirectTarget::Fd(fd) => {
+                nix::unistd::dup2(*fd, redirect.from)?;
+            }
+            crate::parse::RedirectTarget::File(path) => {
+                let fd = redirect.dir.open(path)?;
+                if fd != redirect.from {
+                    nix::unistd::dup2(fd, redirect.from)?;
+                    nix::unistd::close(fd)?;
+                }
+            }
+        }
+    }
+    Ok(())
+}