Replace syscall::pipe2 with pipe scheme.

src/platform/redox/extra.rs

@@ -2,6 +2,8 @@ use core::{ptr, slice};
 
 use crate::platform::{sys::e, types::*};
 
+use syscall::{error::*, F_SETFD, F_SETFL};
+
 #[no_mangle]
 pub unsafe extern "C" fn redox_fpath(fd: c_int, buf: *mut c_void, count: size_t) -> ssize_t {
     e(syscall::fpath(
@@ -48,4 +50,24 @@ pub unsafe extern "C" fn redox_physunmap(virtual_address: *mut c_void) -> c_int
     e(syscall::physunmap(virtual_address as usize)) as c_int
 }
 
+pub fn pipe2(fds: &mut [c_int], flags: usize) -> syscall::error::Result<()> {
+    let fds =
+        <&mut [c_int; 2]>::try_from(fds).expect("expected Pal pipe2 to have validated pipe2 array");
+
+    let mut read_fd = FdGuard::new(syscall::open("pipe:", flags)?);
+    let mut write_fd = FdGuard::new(syscall::dup(*read_fd, b"write")?);
+    syscall::fcntl(*write_fd, F_SETFL, flags)?;
+    syscall::fcntl(*write_fd, F_SETFD, flags)?;
+
+    *fds = [
+        c_int::try_from(*read_fd).map_err(|_| Error::new(EMFILE))?,
+        c_int::try_from(*write_fd).map_err(|_| Error::new(EMFILE))?,
+    ];
+
+    read_fd.take();
+    write_fd.take();
+
+    Ok(())
+}
+
 pub use redox_exec::{create_set_addr_space_buf, FdGuard};