Fix comment

Author: tiif

tests/pass-dep/libc/libc-fs-with-isolation.rs

@@ -53,7 +53,7 @@ fn test_socketpair_setfl_getfl() {
     let res = unsafe { libc::fcntl(fds[0], libc::F_GETFL) };
     assert_eq!(res, new_flag);
 
-    // Test unset flag
+    // Test if O_NONBLOCK flag can be unset.
     let res = unsafe { libc::fcntl(fds[0], libc::F_SETFL, 0) };
     assert_eq!(res, 0);
     let new_flag = libc::O_RDWR;
@@ -71,7 +71,7 @@ fn test_pipe_setfl_getfl() {
     let res = unsafe { libc::pipe(fds.as_mut_ptr()) };
     assert_eq!(res, 0);
 
-    // Test if both sides have O_RDWR.
+    // Both sides should either have O_RONLY or O_WRONLY.
     let res = unsafe { libc::fcntl(fds[0], libc::F_GETFL) };
     assert_eq!(res, libc::O_RDONLY);
     let res = unsafe { libc::fcntl(fds[1], libc::F_GETFL) };
@@ -86,7 +86,7 @@ fn test_pipe_setfl_getfl() {
     let res = unsafe { libc::fcntl(fds[0], libc::F_GETFL) };
     assert_eq!(res, new_flag);
 
-    // Test unset flag.
+    // Test if O_NONBLOCK flag can be unset.
     let res = unsafe { libc::fcntl(fds[0], libc::F_SETFL, 0) };
     assert_eq!(res, 0);
     let new_flag = libc::O_RDONLY;