launch_editor(): indicate that Git waits for user input

When a graphical GIT_EDITOR is spawned by a Git command that opens
and waits for user input (e.g. "git rebase -i"), then the editor window
might be obscured by other windows. The user may be left staring at the
original Git terminal window without even realizing that s/he needs to
interact with another window before Git can proceed. To this user Git
appears hanging.

Show a message in the original terminal and get rid of it when the
editor returns.

Signed-off-by: Junio C Hamano <gitster@pobox.com>
Signed-off-by: Lars Schneider <larsxschneider@gmail.com>

Author: gitster

editor.c

@@ -40,6 +40,35 @@ int launch_editor(const char *path, struct strbuf *buffer, const char *const *en
 		const char *args[] = { editor, real_path(path), NULL };
 		struct child_process p = CHILD_PROCESS_INIT;
 		int ret, sig;
+		static const char *close_notice = NULL;
+
+		if (isatty(2) && !close_notice) {
+			char *term = getenv("TERM");
+
+			if (term && strcmp(term, "dumb"))
+				/*
+				 * go back to the beginning and erase the
+				 * entire line if the terminal is capable
+				 * to do so, to avoid wasting the vertical
+				 * space.
+				 */
+				close_notice = "\r\033[K";
+			else if (term && strstr(term, "emacsclient"))
+				/*
+				 * `emacsclient` (or `emacsclientw` on Windows) already prints
+				 * ("Waiting for Emacs...") if a file is opened for editing.
+				 * Therefore, we don't need to print the editor launch info.
+				 */
+				;
+			else
+				/* otherwise, complete and waste the line */
+				close_notice = _("done.\n");
+		}
+
+		if (close_notice) {
+			fprintf(stderr, _("Launched editor. Waiting for your input... "));
+			fflush(stderr);
+		}
 
 		p.argv = args;
 		p.env = env;
@@ -53,11 +82,14 @@ int launch_editor(const char *path, struct strbuf *buffer, const char *const *en
 		sig = ret - 128;
 		sigchain_pop(SIGINT);
 		sigchain_pop(SIGQUIT);
+
 		if (sig == SIGINT || sig == SIGQUIT)
 			raise(sig);
 		if (ret)
 			return error("There was a problem with the editor '%s'.",
 					editor);
+		if (close_notice)
+			fputs(close_notice, stderr);
 	}
 
 	if (!buffer)