Rejigger the atty detection stuff.

src/atty.rs

@@ -0,0 +1,41 @@
+/*!
+This atty module contains functions for detecting whether ripgrep is being fed
+from (or to) a terminal. Windows and Unix do this differently, so implement
+both here.
+*/
+
+#[cfg(unix)]
+pub fn on_stdin() -> bool {
+    use libc;
+    0 < unsafe { libc::isatty(libc::STDIN_FILENO) }
+}
+
+#[cfg(unix)]
+pub fn on_stdout() -> bool {
+    use libc;
+    0 < unsafe { libc::isatty(libc::STDOUT_FILENO) }
+}
+
+#[cfg(windows)]
+pub fn on_stdin() -> bool {
+    use kernel32;
+    use winapi;
+
+    unsafe {
+        let fd = winapi::winbase::STD_INPUT_HANDLE;
+        let mut out = 0;
+        kernel32::GetConsoleMode(kernel32::GetStdHandle(fd), &mut out) != 0
+    }
+}
+
+#[cfg(windows)]
+pub fn on_stdout() -> bool {
+    use kernel32;
+    use winapi;
+
+    unsafe {
+        let fd = winapi::winbase::STD_OUTPUT_HANDLE;
+        let mut out = 0;
+        kernel32::GetConsoleMode(kernel32::GetStdHandle(fd), &mut out) != 0
+    }
+}