isatty: revert to previous behaviour

This partially reverts commit 60808a4820b1714.

1 files changed, 19 insertions, 18 deletions

diff --git a/share/functions/isatty.fish b/share/functions/isatty.fish
index f49b3aa4..d4f2c43e 100644
--- a/share/functions/isatty.fish
+++ b/share/functions/isatty.fish
@@ -1,27 +1,28 @@
-function isatty -d "Test if a file or file descriptor is a tty."
 
-# Use `command test` because `builtin test` doesn't open the regular fd's.
+function isatty -d "Tests if a file descriptor is a tty"
+	set -l fd 0
+	if count $argv >/dev/null
+		switch $argv[1]
 
-  switch "$argv"
+			case -h --h --he --hel --help
+				__fish_print_help isatty
+				return 0
 
-    case '-h*' '--h*'
-      __fish_print_help isatty
+			case stdin
+				set fd 0
 
-    case ''
-      command test -c /dev/stdin
+			case stdout
+				set fd 1
 
-    case '*'
-      if test -e "$argv" # The eval here is needed for symlinks. Unsure why.
-        command test -c "$argv"; and eval tty 0>"$argv" >/dev/null
+			case stderr
+				set fd 2
 
-      else if test -e /dev/"$argv"
-         command test -c /dev/"$argv"; and tty 0>/dev/"$argv" >/dev/null
+			case '*'
+				set fd $argv[1]
 
-      else if test -e /dev/fd/"$argv"
-         command test -c /dev/fd/"$argv"; and tty 0>/dev/fd/"$argv" >/dev/null
+		end
+	end
+
+	eval "tty 0>&$fd >/dev/null"
 
-      else
-         return 1
-    end
-  end
 end