init: fix pipe FILETABLE desync — use libc::pipe2 instead of raw syscall

create_pipe() used raw syscall::openat/syscall::dup which allocate kernel
fds WITHOUT registering in relibc FILETABLE. Later FILETABLE-managed
syscalls (Command::spawn -> relibc pipe2) reserve the same fd numbers,
causing EEXIST in kernel insert_file.

Replace with libc::pipe2 which goes through relibc FILETABLE-aware path.

init/src/service.rs

@@ -37,25 +37,13 @@ pub enum ServiceType {
 }
 
 fn create_pipe() -> io::Result<(File, OwnedFd)> {
-    let ns_fd = libredox::call::getns()
-        .map_err(|e| io::Error::from_raw_os_error(e.errno()))?;
-
-    let rd_fd = syscall::openat(
-        ns_fd,
-        "/scheme/pipe",
-        syscall::flag::O_RDONLY | syscall::flag::O_CLOEXEC,
-        0,
-    )
-    .map_err(|e| io::Error::from_raw_os_error(e.errno))?;
-
-    let wr_raw = syscall::dup(rd_fd, b"write")
-        .map_err(|e| {
-            let _ = syscall::close(rd_fd);
-            io::Error::from_raw_os_error(e.errno)
-        })?;
-
-    let wr = unsafe { OwnedFd::from_raw_fd(wr_raw as i32) };
-    let rd = unsafe { File::from_raw_fd(rd_fd as i32) };
+    let mut fds = [0i32; 2];
+    let res = unsafe { libc::pipe2(fds.as_mut_ptr(), libc::O_CLOEXEC) };
+    if res != 0 {
+        return Err(io::Error::last_os_error());
+    }
+    let rd = unsafe { File::from_raw_fd(fds[0]) };
+    let wr = unsafe { OwnedFd::from_raw_fd(fds[1]) };
     Ok((rd, wr))
 }