Get gdbserver to relinquish control of the terminal

[Richard Sandiford <richard@codesourcery.com>]

This patch fixes the problem described here:

    http://www.cygwin.com/ml/gdb/2003-08/msg00037.html

namely, gdbserver does not hand back control of the terminal to
the original foreground group.  This is usually harmless on shells
with job control, as the shell will claim the terminal back itself,
but it causes shells like busybox's msh to exit.

Tested on m68k-uclinux.  OK to install?

Richard


gdb/gdbserver/
	* server.c (terminal_fd): New variable.
	(old_foreground_pgrp): Likewise.
	(restore_old_foreground_pgrp): New function.
	(start_inferior): Record the terminal file descriptor in terminal_fd
	and its original foreground group in old_foreground_pgrp.  Register
	restore_old_foreground_pgrp with atexit().

Index: gdb/gdbserver/server.c
===================================================================
RCS file: /cvs/src/src/gdb/gdbserver/server.c,v
retrieving revision 1.38
diff -u -p -r1.38 server.c
--- gdb/gdbserver/server.c	27 Jul 2006 00:06:12 -0000	1.38
+++ gdb/gdbserver/server.c	2 Aug 2006 14:43:15 -0000
@@ -45,6 +45,22 @@ jmp_buf toplevel;
 
 unsigned long signal_pid;
 
+#ifdef SIGTTOU
+/* A file descriptor for the controlling terminal.  */
+int terminal_fd;
+
+/* TERMINAL_FD's original foreground group.  */
+pid_t old_foreground_pgrp;
+
+/* Hand back terminal ownership to the original foreground group.  */
+
+static void
+restore_old_foreground_pgrp (void)
+{
+  tcsetpgrp (terminal_fd, old_foreground_pgrp);
+}
+#endif
+
 static int
 start_inferior (char *argv[], char *statusptr)
 {
@@ -62,7 +78,10 @@ start_inferior (char *argv[], char *stat
 #ifdef SIGTTOU
   signal (SIGTTOU, SIG_IGN);
   signal (SIGTTIN, SIG_IGN);
-  tcsetpgrp (fileno (stderr), signal_pid);
+  terminal_fd = fileno (stderr);
+  old_foreground_pgrp = tcgetpgrp (terminal_fd);
+  tcsetpgrp (terminal_fd, signal_pid);
+  atexit (restore_old_foreground_pgrp);
 #endif
 
   /* Wait till we are at 1st instruction in program, return signal number.  */