Open stdio without cloexec

src/main.rs

@@ -3,16 +3,23 @@
 extern crate syscall;
 
 use std::env;
-use std::fs::{File, OpenOptions, read_dir};
+use std::fs::{File, read_dir};
 use std::io::{Read, Error, Result};
-use std::os::unix::io::AsRawFd;
+use std::os::unix::io::{AsRawFd, FromRawFd};
 use std::path::Path;
 use std::process::Command;
+use syscall::flag::{O_RDONLY, O_WRONLY};
 
 fn switch_stdio(stdio: &str) -> Result<()> {
-    let stdin = OpenOptions::new().read(true).open(stdio)?;
-    let stdout = OpenOptions::new().write(true).open(stdio)?;
-    let stderr = OpenOptions::new().write(true).open(stdio)?;
+    let stdin = unsafe { File::from_raw_fd(
+        syscall::open(stdio, O_RDONLY).map_err(|err| Error::from_raw_os_error(err.errno))?
+    ) };
+    let stdout = unsafe { File::from_raw_fd(
+        syscall::open(stdio, O_WRONLY).map_err(|err| Error::from_raw_os_error(err.errno))?
+    ) };
+    let stderr = unsafe { File::from_raw_fd(
+        syscall::open(stdio, O_WRONLY).map_err(|err| Error::from_raw_os_error(err.errno))?
+    ) };
 
     syscall::dup2(stdin.as_raw_fd(), 0, &[]).map_err(|err| Error::from_raw_os_error(err.errno))?;
     syscall::dup2(stdout.as_raw_fd(), 1, &[]).map_err(|err| Error::from_raw_os_error(err.errno))?;