split miscellaneous code into a new command_helpers module

src/command_helpers.rs

@@ -0,0 +1,336 @@
+//! Miscellaneous helpers for running commands
+
+use std::{
+    collections::hash_map,
+    ffi::OsString,
+    fmt::Display,
+    fs::{self, File},
+    hash::Hasher,
+    io::{self, BufRead, BufReader, Read, Write},
+    path::Path,
+    process::{Child, Command, Stdio},
+    sync::Arc,
+    thread::{self, JoinHandle},
+};
+
+use crate::{Error, ErrorKind, Object};
+
+#[derive(Clone, Debug)]
+pub(crate) struct CargoOutput {
+    pub(crate) metadata: bool,
+    pub(crate) warnings: bool,
+}
+
+impl CargoOutput {
+    pub(crate) const fn new() -> Self {
+        Self {
+            metadata: true,
+            warnings: true,
+        }
+    }
+
+    pub(crate) fn print_metadata(&self, s: &dyn Display) {
+        if self.metadata {
+            println!("{}", s);
+        }
+    }
+
+    pub(crate) fn print_warning(&self, arg: &dyn Display) {
+        if self.warnings {
+            println!("cargo:warning={}", arg);
+        }
+    }
+
+    pub(crate) fn print_thread(&self) -> Result<Option<PrintThread>, Error> {
+        self.warnings.then(PrintThread::new).transpose()
+    }
+}
+
+pub(crate) struct PrintThread {
+    handle: Option<JoinHandle<()>>,
+    pipe_writer: Option<File>,
+}
+
+impl PrintThread {
+    pub(crate) fn new() -> Result<Self, Error> {
+        let (pipe_reader, pipe_writer) = crate::os_pipe::pipe()?;
+
+        // Capture the standard error coming from compilation, and write it out
+        // with cargo:warning= prefixes. Note that this is a bit wonky to avoid
+        // requiring the output to be UTF-8, we instead just ship bytes from one
+        // location to another.
+        let print = thread::spawn(move || {
+            let mut stderr = BufReader::with_capacity(4096, pipe_reader);
+            let mut line = Vec::with_capacity(20);
+            let stdout = io::stdout();
+
+            // read_until returns 0 on Eof
+            while stderr.read_until(b'\n', &mut line).unwrap() != 0 {
+                {
+                    let mut stdout = stdout.lock();
+
+                    stdout.write_all(b"cargo:warning=").unwrap();
+                    stdout.write_all(&line).unwrap();
+                    stdout.write_all(b"\n").unwrap();
+                }
+
+                // read_until does not clear the buffer
+                line.clear();
+            }
+        });
+
+        Ok(Self {
+            handle: Some(print),
+            pipe_writer: Some(pipe_writer),
+        })
+    }
+
+    /// # Panics
+    ///
+    /// Will panic if the pipe writer has already been taken.
+    pub(crate) fn take_pipe_writer(&mut self) -> File {
+        self.pipe_writer.take().unwrap()
+    }
+
+    /// # Panics
+    ///
+    /// Will panic if the pipe writer has already been taken.
+    pub(crate) fn clone_pipe_writer(&self) -> Result<File, Error> {
+        self.try_clone_pipe_writer().map(Option::unwrap)
+    }
+
+    pub(crate) fn try_clone_pipe_writer(&self) -> Result<Option<File>, Error> {
+        self.pipe_writer
+            .as_ref()
+            .map(File::try_clone)
+            .transpose()
+            .map_err(From::from)
+    }
+}
+
+impl Drop for PrintThread {
+    fn drop(&mut self) {
+        // Drop pipe_writer first to avoid deadlock
+        self.pipe_writer.take();
+
+        self.handle.take().unwrap().join().unwrap();
+    }
+}
+
+fn wait_on_child(cmd: &Command, program: &str, child: &mut Child) -> Result<(), Error> {
+    let status = match child.wait() {
+        Ok(s) => s,
+        Err(e) => {
+            return Err(Error::new(
+                ErrorKind::ToolExecError,
+                format!(
+                    "Failed to wait on spawned child process, command {:?} with args {:?}: {}.",
+                    cmd, program, e
+                ),
+            ));
+        }
+    };
+    println!("{}", status);
+
+    if status.success() {
+        Ok(())
+    } else {
+        Err(Error::new(
+            ErrorKind::ToolExecError,
+            format!(
+                "Command {:?} with args {:?} did not execute successfully (status code {}).",
+                cmd, program, status
+            ),
+        ))
+    }
+}
+
+/// Find the destination object path for each file in the input source files,
+/// and store them in the output Object.
+pub(crate) fn objects_from_files(files: &[Arc<Path>], dst: &Path) -> Result<Vec<Object>, Error> {
+    let mut objects = Vec::with_capacity(files.len());
+    for file in files {
+        let basename = file
+            .file_name()
+            .ok_or_else(|| {
+                Error::new(
+                    ErrorKind::InvalidArgument,
+                    "No file_name for object file path!",
+                )
+            })?
+            .to_string_lossy();
+        let dirname = file
+            .parent()
+            .ok_or_else(|| {
+                Error::new(
+                    ErrorKind::InvalidArgument,
+                    "No parent for object file path!",
+                )
+            })?
+            .to_string_lossy();
+
+        // Hash the dirname. This should prevent conflicts if we have multiple
+        // object files with the same filename in different subfolders.
+        let mut hasher = hash_map::DefaultHasher::new();
+        hasher.write(dirname.to_string().as_bytes());
+        let obj = dst
+            .join(format!("{:016x}-{}", hasher.finish(), basename))
+            .with_extension("o");
+
+        match obj.parent() {
+            Some(s) => fs::create_dir_all(s)?,
+            None => {
+                return Err(Error::new(
+                    ErrorKind::InvalidArgument,
+                    "dst is an invalid path with no parent",
+                ));
+            }
+        };
+
+        objects.push(Object::new(file.to_path_buf(), obj));
+    }
+
+    Ok(objects)
+}
+
+fn run_inner(cmd: &mut Command, program: &str, pipe_writer: Option<File>) -> Result<(), Error> {
+    let mut child = spawn(cmd, program, pipe_writer)?;
+    wait_on_child(cmd, program, &mut child)
+}
+
+pub(crate) fn run(
+    cmd: &mut Command,
+    program: &str,
+    print: Option<&PrintThread>,
+) -> Result<(), Error> {
+    let pipe_writer = print.map(PrintThread::clone_pipe_writer).transpose()?;
+    run_inner(cmd, program, pipe_writer)?;
+
+    Ok(())
+}
+
+pub(crate) fn run_output(
+    cmd: &mut Command,
+    program: &str,
+    cargo_output: &CargoOutput,
+) -> Result<Vec<u8>, Error> {
+    cmd.stdout(Stdio::piped());
+
+    let mut print = cargo_output.print_thread()?;
+    let mut child = spawn(
+        cmd,
+        program,
+        print.as_mut().map(PrintThread::take_pipe_writer),
+    )?;
+
+    let mut stdout = vec![];
+    child
+        .stdout
+        .take()
+        .unwrap()
+        .read_to_end(&mut stdout)
+        .unwrap();
+
+    wait_on_child(cmd, program, &mut child)?;
+
+    Ok(stdout)
+}
+
+pub(crate) fn spawn(
+    cmd: &mut Command,
+    program: &str,
+    pipe_writer: Option<File>,
+) -> Result<Child, Error> {
+    struct ResetStderr<'cmd>(&'cmd mut Command);
+
+    impl Drop for ResetStderr<'_> {
+        fn drop(&mut self) {
+            // Reset stderr to default to release pipe_writer so that print thread will
+            // not block forever.
+            self.0.stderr(Stdio::inherit());
+        }
+    }
+
+    println!("running: {:?}", cmd);
+
+    let cmd = ResetStderr(cmd);
+    let child = cmd
+        .0
+        .stderr(pipe_writer.map_or_else(Stdio::null, Stdio::from))
+        .spawn();
+    match child {
+        Ok(child) => Ok(child),
+        Err(ref e) if e.kind() == io::ErrorKind::NotFound => {
+            let extra = if cfg!(windows) {
+                " (see https://github.com/rust-lang/cc-rs#compile-time-requirements \
+for help)"
+            } else {
+                ""
+            };
+            Err(Error::new(
+                ErrorKind::ToolNotFound,
+                format!("Failed to find tool. Is `{}` installed?{}", program, extra),
+            ))
+        }
+        Err(e) => Err(Error::new(
+            ErrorKind::ToolExecError,
+            format!(
+                "Command {:?} with args {:?} failed to start: {:?}",
+                cmd.0, program, e
+            ),
+        )),
+    }
+}
+
+pub(crate) fn command_add_output_file(
+    cmd: &mut Command,
+    dst: &Path,
+    cuda: bool,
+    msvc: bool,
+    clang: bool,
+    gnu: bool,
+    is_asm: bool,
+    is_arm: bool,
+) {
+    if msvc && !clang && !gnu && !cuda && !(is_asm && is_arm) {
+        let mut s = OsString::from("-Fo");
+        s.push(dst);
+        cmd.arg(s);
+    } else {
+        cmd.arg("-o").arg(dst);
+    }
+}
+
+#[cfg(feature = "parallel")]
+pub(crate) fn try_wait_on_child(
+    cmd: &Command,
+    program: &str,
+    child: &mut Child,
+    stdout: &mut dyn io::Write,
+) -> Result<Option<()>, Error> {
+    match child.try_wait() {
+        Ok(Some(status)) => {
+            let _ = writeln!(stdout, "{}", status);
+
+            if status.success() {
+                Ok(Some(()))
+            } else {
+                Err(Error::new(
+                    ErrorKind::ToolExecError,
+                    format!(
+                        "Command {:?} with args {:?} did not execute successfully (status code {}).",
+                            cmd, program, status
+                    ),
+                ))
+            }
+        }
+        Ok(None) => Ok(None),
+        Err(e) => Err(Error::new(
+            ErrorKind::ToolExecError,
+            format!(
+                "Failed to wait on spawned child process, command {:?} with args {:?}: {}.",
+                cmd, program, e
+            ),
+        )),
+    }
+}