Add test asserting stdlib uses O_CLOEXEC

Author: mqudsi

src/tests/mod.rs

@@ -18,6 +18,7 @@ mod parser;
 mod reader;
 mod redirection;
 mod screen;
+mod std;
 mod string_escape;
 mod threads;
 mod tokenizer;

src/tests/std.rs

@@ -0,0 +1,16 @@
+//! This module contains tests that assert the functionality and behavior of the rust standard
+//! library, to ensure we can safely use its abstractions to perform low-level operations.
+
+use std::fs::File;
+use std::os::fd::AsRawFd;
+
+#[test]
+fn test_fd_cloexec() {
+    // Just open a file. Any file.
+    let file = File::create("test_file_for_fd_cloexec").unwrap();
+    let fd = file.as_raw_fd();
+    unsafe {
+        assert_eq!(libc::fcntl(fd, libc::F_GETFD) & libc::FD_CLOEXEC, libc::FD_CLOEXEC);
+    }
+    let _  = std::fs::remove_file("test_file_for_fd_cloexec");
+}