Set CLOEXEC with fcntl, Apple does not have pipe2

Author: saethlin

cargo-miri/bin.rs

@@ -280,11 +280,21 @@ fn exec_with_pipe(mut cmd: Command, input: &[u8]) {
         use std::process::Stdio;
 
         let mut fds: [libc::c_int; 2] = [0, 0];
-        // We need to set close-on-exec, otherwise our pipe isn't readable after exec
         // SAFETY: fds is an array of 2 libc::c_int
-        let res = unsafe { libc::pipe2(fds.as_mut_ptr(), libc::O_CLOEXEC) };
-        if res != 0 {
-            panic!("failed to create a pipe");
+        let res = unsafe { libc::pipe(fds.as_mut_ptr()) };
+        assert_eq!(res, 0, "failed to create pipe");
+
+        // We need to set close-on-exec, otherwise our pipe isn't readable after exec
+        // SAFETY: fcntl has no preconditions
+        unsafe {
+            for fd in &fds {
+                let res = libc::fcntl(
+                    *fd,
+                    libc::F_SETFD,
+                    libc::fcntl(*fd, libc::F_GETFD) | libc::FD_CLOEXEC,
+                );
+                assert_eq!(res, 0, "failed to set close-on-exec for pipe");
+            }
         }
 
         // SAFETY: Both elements of fds are open file descriptors, because pipe2 returned 0