pager: drop "wait for output to run less" hack

Commit 35ce862 (pager: Work around window resizing bug in
'less', 2007-01-24) causes git's pager sub-process to wait
to receive input after forking but before exec-ing the
pager. To handle this, run-command had to grow a "pre-exec
callback" feature. Unfortunately, this feature does not work
at all on Windows (where we do not fork), and interacts
poorly with run-command's parent notification system. Its
use should be discouraged.

The bug in less was fixed in version 406, which was released
in June 2007. It is probably safe at this point to remove
our workaround. That lets us rip out the preexec_cb feature
entirely.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

3 files changed, 0 insertions, 29 deletions

diff --git a/pager.c b/pager.c
index 4dcb08d967..c0b4387d96 100644
--- a/pager.c
+++ b/pager.c
@@ -11,21 +11,6 @@
  * something different on Windows.
  */
 
-#ifndef WIN32
-static void pager_preexec(void)
-{
-	/*
-	 * Work around bug in "less" by not starting it until we
-	 * have real input
-	 */
-	fd_set in;
-
-	FD_ZERO(&in);
-	FD_SET(0, &in);
-	select(1, &in, NULL, &in, NULL);
-}
-#endif
-
 static const char *pager_argv[] = { NULL, NULL };
 static struct child_process pager_process;
 
@@ -93,9 +78,6 @@ void setup_pager(void)
 		static const char *env[] = { "LESS=FRSX", NULL };
 		pager_process.env = env;
 	}
-#ifndef WIN32
-	pager_process.preexec_cb = pager_preexec;
-#endif
 	if (start_command(&pager_process))
 		return;
 
diff --git a/run-command.c b/run-command.c
index 606791dc67..dff28a7fcc 100644
--- a/run-command.c
+++ b/run-command.c
@@ -394,16 +394,6 @@ fail_pipe:
 					unsetenv(*cmd->env);
 			}
 		}
-		if (cmd->preexec_cb) {
-			/*
-			 * We cannot predict what the pre-exec callback does.
-			 * Forgo parent notification.
-			 */
-			close(child_notifier);
-			child_notifier = -1;
-
-			cmd->preexec_cb();
-		}
 		if (cmd->git_cmd) {
 			execv_git_cmd(cmd->argv);
 		} else if (cmd->use_shell) {
diff --git a/run-command.h b/run-command.h
index 44f7d2bd42..850c638f19 100644
--- a/run-command.h
+++ b/run-command.h
@@ -39,7 +39,6 @@ struct child_process {
 	unsigned stdout_to_stderr:1;
 	unsigned use_shell:1;
 	unsigned clean_on_exit:1;
-	void (*preexec_cb)(void);
 };
 
 int start_command(struct child_process *);