1 files changed, 178 insertions, 0 deletions
diff --git a/crates/cargo-util/src/read2.rs b/crates/cargo-util/src/read2.rs
new file mode 100644
index 0000000..742dc1d
--- /dev/null
+++ b/crates/cargo-util/src/read2.rs
@@ -0,0 +1,178 @@
+pub use self::imp::read2;
+
+#[cfg(unix)]
+mod imp {
+    use std::io;
+    use std::io::prelude::*;
+    use std::mem;
+    use std::os::unix::prelude::*;
+    use std::process::{ChildStderr, ChildStdout};
+
+    pub fn read2(
+        mut out_pipe: ChildStdout,
+        mut err_pipe: ChildStderr,
+        data: &mut dyn FnMut(bool, &mut Vec<u8>, bool),
+    ) -> io::Result<()> {
+        unsafe {
+            libc::fcntl(out_pipe.as_raw_fd(), libc::F_SETFL, libc::O_NONBLOCK);
+            libc::fcntl(err_pipe.as_raw_fd(), libc::F_SETFL, libc::O_NONBLOCK);
+        }
+
+        let mut out_done = false;
+        let mut err_done = false;
+        let mut out = Vec::new();
+        let mut err = Vec::new();
+
+        let mut fds: [libc::pollfd; 2] = unsafe { mem::zeroed() };
+        fds[0].fd = out_pipe.as_raw_fd();
+        fds[0].events = libc::POLLIN;
+        fds[1].fd = err_pipe.as_raw_fd();
+        fds[1].events = libc::POLLIN;
+        let mut nfds = 2;
+        let mut errfd = 1;
+
+        while nfds > 0 {
+            // wait for either pipe to become readable using `select`
+            let r = unsafe { libc::poll(fds.as_mut_ptr(), nfds, -1) };
+            if r == -1 {
+                let err = io::Error::last_os_error();
+                if err.kind() == io::ErrorKind::Interrupted {
+                    continue;
+                }
+                return Err(err);
+            }
+
+            // Read as much as we can from each pipe, ignoring EWOULDBLOCK or
+            // EAGAIN. If we hit EOF, then this will happen because the underlying
+            // reader will return Ok(0), in which case we'll see `Ok` ourselves. In
+            // this case we flip the other fd back into blocking mode and read
+            // whatever's leftover on that file descriptor.
+            let handle = |res: io::Result<_>| match res {
+                Ok(_) => Ok(true),
+                Err(e) => {
+                    if e.kind() == io::ErrorKind::WouldBlock {
+                        Ok(false)
+                    } else {
+                        Err(e)
+                    }
+                }
+            };
+            if !err_done && fds[errfd].revents != 0 && handle(err_pipe.read_to_end(&mut err))? {
+                err_done = true;
+                nfds -= 1;
+            }
+            data(false, &mut err, err_done);
+            if !out_done && fds[0].revents != 0 && handle(out_pipe.read_to_end(&mut out))? {
+                out_done = true;
+                fds[0].fd = err_pipe.as_raw_fd();
+                errfd = 0;
+                nfds -= 1;
+            }
+            data(true, &mut out, out_done);
+        }
+        Ok(())
+    }
+}
+
+#[cfg(windows)]
+mod imp {
+    use std::io;
+    use std::os::windows::prelude::*;
+    use std::process::{ChildStderr, ChildStdout};
+    use std::slice;
+
+    use miow::iocp::{CompletionPort, CompletionStatus};
+    use miow::pipe::NamedPipe;
+    use miow::Overlapped;
+    use windows_sys::Win32::Foundation::ERROR_BROKEN_PIPE;
+
+    struct Pipe<'a> {
+        dst: &'a mut Vec<u8>,
+        overlapped: Overlapped,
+        pipe: NamedPipe,
+        done: bool,
+    }
+
+    pub fn read2(
+        out_pipe: ChildStdout,
+        err_pipe: ChildStderr,
+        data: &mut dyn FnMut(bool, &mut Vec<u8>, bool),
+    ) -> io::Result<()> {
+        let mut out = Vec::new();
+        let mut err = Vec::new();
+
+        let port = CompletionPort::new(1)?;
+        port.add_handle(0, &out_pipe)?;
+        port.add_handle(1, &err_pipe)?;
+
+        unsafe {
+            let mut out_pipe = Pipe::new(out_pipe, &mut out);
+            let mut err_pipe = Pipe::new(err_pipe, &mut err);
+
+            out_pipe.read()?;
+            err_pipe.read()?;
+
+            let mut status = [CompletionStatus::zero(), CompletionStatus::zero()];
+
+            while !out_pipe.done || !err_pipe.done {
+                for status in port.get_many(&mut status, None)? {
+                    if status.token() == 0 {
+                        out_pipe.complete(status);
+                        data(true, out_pipe.dst, out_pipe.done);
+                        out_pipe.read()?;
+                    } else {
+                        err_pipe.complete(status);
+                        data(false, err_pipe.dst, err_pipe.done);
+                        err_pipe.read()?;
+                    }
+                }
+            }
+
+            Ok(())
+        }
+    }
+
+    impl<'a> Pipe<'a> {
+        unsafe fn new<P: IntoRawHandle>(p: P, dst: &'a mut Vec<u8>) -> Pipe<'a> {
+            Pipe {
+                dst,
+                pipe: NamedPipe::from_raw_handle(p.into_raw_handle()),
+                overlapped: Overlapped::zero(),
+                done: false,
+            }
+        }
+
+        unsafe fn read(&mut self) -> io::Result<()> {
+            let dst = slice_to_end(self.dst);
+            match self.pipe.read_overlapped(dst, self.overlapped.raw()) {
+                Ok(_) => Ok(()),
+                Err(e) => {
+                    if e.raw_os_error() == Some(ERROR_BROKEN_PIPE as i32) {
+                        self.done = true;
+                        Ok(())
+                    } else {
+                        Err(e)
+                    }
+                }
+            }
+        }
+
+        unsafe fn complete(&mut self, status: &CompletionStatus) {
+            let prev = self.dst.len();
+            self.dst.set_len(prev + status.bytes_transferred() as usize);
+            if status.bytes_transferred() == 0 {
+                self.done = true;
+            }
+        }
+    }
+
+    unsafe fn slice_to_end(v: &mut Vec<u8>) -> &mut [u8] {
+        if v.capacity() == 0 {
+            v.reserve(16);
+        }
+        if v.capacity() == v.len() {
+            v.reserve(1);
+        }
+        slice::from_raw_parts_mut(v.as_mut_ptr().add(v.len()), v.capacity() - v.len())
+    }
+}