Revert "syscall: use Ctty before fd shuffle"

This reverts commit 103b5b66921b351f8db4fc6e83bf147b1a0d7580.

Reason for revert: Breaks valid existing programs.

Updates #29458

Change-Id: I7ace4ae404cf2a8b0e15e646663c50115f74b758
Reviewed-on: https://go-review.googlesource.com/c/go/+/183939
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Greg Thelen <gthelen@google.com>
Reviewed-by: Ian Lance Taylor <iant@golang.org>

1 files changed, 21 insertions, 21 deletions

diff --git a/src/syscall/exec_libc.go b/src/syscall/exec_libc.go
index 11cd2bb9f3..0133139000 100644
--- a/src/syscall/exec_libc.go
+++ b/src/syscall/exec_libc.go
@@ -180,27 +180,6 @@ func forkAndExecInChild(argv0 *byte, argv, envv []*byte, chroot, dir *byte, attr
 		}
 	}
 
-	// Detach fd 0 from tty
-	if sys.Noctty {
-		err1 = ioctl(0, uintptr(TIOCNOTTY), 0)
-		if err1 != 0 {
-			goto childerror
-		}
-	}
-
-	// Set the controlling TTY to Ctty
-	if sys.Setctty {
-		// On AIX, TIOCSCTTY is undefined
-		if TIOCSCTTY == 0 {
-			err1 = ENOSYS
-			goto childerror
-		}
-		err1 = ioctl(uintptr(sys.Ctty), uintptr(TIOCSCTTY), 0)
-		if err1 != 0 {
-			goto childerror
-		}
-	}
-
 	// Pass 1: look for fd[i] < i and move those up above len(fd)
 	// so that pass 2 won't stomp on an fd it needs later.
 	if pipe < nextfd {
@@ -261,6 +240,27 @@ func forkAndExecInChild(argv0 *byte, argv, envv []*byte, chroot, dir *byte, attr
 		close(uintptr(i))
 	}
 
+	// Detach fd 0 from tty
+	if sys.Noctty {
+		err1 = ioctl(0, uintptr(TIOCNOTTY), 0)
+		if err1 != 0 {
+			goto childerror
+		}
+	}
+
+	// Set the controlling TTY to Ctty
+	if sys.Setctty {
+		// On AIX, TIOCSCTTY is undefined
+		if TIOCSCTTY == 0 {
+			err1 = ENOSYS
+			goto childerror
+		}
+		err1 = ioctl(uintptr(sys.Ctty), uintptr(TIOCSCTTY), 0)
+		if err1 != 0 {
+			goto childerror
+		}
+	}
+
 	// Time to exec.
 	err1 = execve(
 		uintptr(unsafe.Pointer(argv0)),