[Libguestfs] [PATCH] mllib: check the right out channel for tty

[Pino Toscano]

Make sure to check whether the given output channel is a tty before
sending ANSI terminal codes to it, instead of always check what stdout
is.
---
 mllib/common_utils.ml | 13 ++++++++-----
 1 file changed, 8 insertions(+), 5 deletions(-)

diff --git a/mllib/common_utils.ml b/mllib/common_utils.ml
index 9fcd8dd..83ebd3a 100644
--- a/mllib/common_utils.ml
+++ b/mllib/common_utils.ml
@@ -205,17 +205,20 @@ let rec combine3 xs ys zs =
   | x::xs, y::ys, z::zs -> (x, y, z) :: combine3 xs ys zs
   | _ -> invalid_arg "combine3"
 
+let istty chan =
+  Unix.isatty (Unix.descr_of_out_channel chan)
+
 (* ANSI terminal colours. *)
 let ansi_green ?(chan = stdout) () =
-  if Unix.isatty Unix.stdout then output_string chan "\x1b[0;32m"
+  if istty chan then output_string chan "\x1b[0;32m"
 let ansi_red ?(chan = stdout) () =
-  if Unix.isatty Unix.stdout then output_string chan "\x1b[1;31m"
+  if istty chan then output_string chan "\x1b[1;31m"
 let ansi_blue ?(chan = stdout) () =
-  if Unix.isatty Unix.stdout then output_string chan "\x1b[1;34m"
+  if istty chan then output_string chan "\x1b[1;34m"
 let ansi_magenta ?(chan = stdout) () =
-  if Unix.isatty Unix.stdout then output_string chan "\x1b[1;35m"
+  if istty chan then output_string chan "\x1b[1;35m"
 let ansi_restore ?(chan = stdout) () =
-  if Unix.isatty Unix.stdout then output_string chan "\x1b[0m"
+  if istty chan then output_string chan "\x1b[0m"
 
 (* Timestamped progress messages, used for ordinary messages when not
  * --quiet.
-- 
1.9.3