emacs plugin tweak to open buffer from stdin (#5126)

plugins/emacs/emacsclient.sh

@@ -1,5 +1,7 @@
 #!/bin/sh
 
+function _emacsfun
+{
     # get list of available X windows.
     x=`emacsclient --alternate-editor '' --eval '(x-display-list)' 2>/dev/null`
 
@@ -10,3 +12,16 @@ else
         # prevent creating another X frame if there is at least one present.
         emacsclient --alternate-editor "" "$@"
     fi
+}
+
+
+# adopted from https://github.com/davidshepherd7/emacs-read-stdin/blob/master/emacs-read-stdin.sh
+# If the second argument is - then write stdin to a tempfile and open the
+# tempfile. (first argument will be `--no-wait` passed in by the plugin.zsh)
+if [[ $# -ge 2 ]] && [[ "$2" == - ]]; then
+    tempfile="$(mktemp emacs-stdin-$USER.XXXXXXX --tmpdir)"
+    cat - > "$tempfile"
+    _emacsfun --no-wait $tempfile
+else
+    _emacsfun "$@"
+fi