Re: [RFA] Fix GDB's handling of the inferior controlling terminal.

[Thiago Jung Bauermann <bauerman at br dot ibm dot com>]

On Wed, 2008-03-12 at 08:39 -0400, Daniel Jacobowitz wrote:
> On Mon, Mar 10, 2008 at 02:41:56PM -0300, Thiago Jung Bauermann wrote:
> This is OK, thanks.
> 
> > +  ret = setsid();
> 
> Space there before paren.

Thanks! Committed with the change. Attached is the final patch.
-- 
[]'s
Thiago Jung Bauermann
Software Engineer
IBM Linux Technology Center

2008-03-10  Thiago Jung Bauermann  <bauerman.ibm.com>

	* configure.ac (AC_CHECK_FUNCS): Add check for setsid.
	* config.in, configure: Regenerate.
	* fork-child.c (fork_inferior): Call create_tty_session.
	* inflow.c (new_tty): Set controlling terminal with TIOCSCTTY.
	(create_tty_session): New function.
	* terminal.h: Declare create_tty_session.

=== modified file 'gdb/config.in'
Index: gdb/config.in
===================================================================
--- gdb/config.in.orig	2008-01-08 17:36:25.000000000 -0200
+++ gdb/config.in	2008-03-12 11:05:33.000000000 -0300
@@ -278,6 +278,9 @@
 /* Define to 1 if you have the `setpgrp' function. */
 #undef HAVE_SETPGRP
 
+/* Define to 1 if you have the `setsid' function. */
+#undef HAVE_SETSID
+
 /* Define to 1 if you have the <sgtty.h> header file. */
 #undef HAVE_SGTTY_H
 
Index: gdb/configure
===================================================================
--- gdb/configure.orig	2008-03-12 11:04:38.000000000 -0300
+++ gdb/configure	2008-03-12 11:05:34.000000000 -0300
@@ -18503,7 +18503,8 @@ done
 
 
 
-for ac_func in setpgid setpgrp
+
+for ac_func in setpgid setpgrp setsid
 do
 as_ac_var=`echo "ac_cv_func_$ac_func" | $as_tr_sh`
 echo "$as_me:$LINENO: checking for $ac_func" >&5
Index: gdb/configure.ac
===================================================================
--- gdb/configure.ac.orig	2008-03-12 11:04:38.000000000 -0300
+++ gdb/configure.ac	2008-03-12 11:05:34.000000000 -0300
@@ -603,7 +603,7 @@ AC_CHECK_FUNCS(getuid getgid)
 AC_CHECK_FUNCS(poll)
 AC_CHECK_FUNCS(pread64)
 AC_CHECK_FUNCS(sbrk)
-AC_CHECK_FUNCS(setpgid setpgrp)
+AC_CHECK_FUNCS(setpgid setpgrp setsid)
 AC_CHECK_FUNCS(sigaction sigprocmask sigsetmask)
 AC_CHECK_FUNCS(socketpair)
 AC_CHECK_FUNCS(syscall)
Index: gdb/fork-child.c
===================================================================
--- gdb/fork-child.c.orig	2008-03-12 11:04:38.000000000 -0300
+++ gdb/fork-child.c	2008-03-12 11:05:34.000000000 -0300
@@ -303,10 +303,16 @@ fork_inferior (char *exec_file_arg, char
       if (debug_fork)
 	sleep (debug_fork);
 
-      /* Run inferior in a separate process group.  */
-      debug_setpgrp = gdb_setpgid ();
-      if (debug_setpgrp == -1)
-	perror ("setpgrp failed in child");
+      /* Create a new session for the inferior process, if necessary.
+         It will also place the inferior in a separate process group.  */
+      if (create_tty_session () <= 0)
+	{
+	  /* No session was created, but we still want to run the inferior
+	     in a separate process group.  */
+	  debug_setpgrp = gdb_setpgid ();
+	  if (debug_setpgrp == -1)
+	    perror ("setpgrp failed in child");
+	}
 
       /* Ask the tty subsystem to switch to the one we specified
          earlier (or to share the current terminal, if none was
Index: gdb/inflow.c
===================================================================
--- gdb/inflow.c.orig	2008-01-03 19:27:04.000000000 -0200
+++ gdb/inflow.c	2008-03-12 11:08:55.000000000 -0300
@@ -557,6 +557,16 @@ new_tty (void)
       close (2);
       dup (tty);
     }
+
+#ifdef TIOCSCTTY
+  /* Make tty our new controlling terminal.  */
+  if (ioctl (tty, TIOCSCTTY, 0) == -1)
+    /* Mention GDB in warning because it will appear in the inferior's
+       terminal instead of GDB's.  */
+    warning ("GDB: Failed to set controlling terminal: %s",
+	     safe_strerror (errno));
+#endif
+
   if (tty > 2)
     close (tty);
 #endif /* !go32 && !win32 */
@@ -683,6 +693,33 @@ clear_sigio_trap (void)
 #endif /* No SIGIO.  */
 
 
+/* Create a new session if the inferior will run in a different tty.
+   A session is UNIX's way of grouping processes that share a controlling
+   terminal, so a new one is needed if the inferior terminal will be
+   different from GDB's.
+
+   Returns the session id of the new session, 0 if no session was created
+   or -1 if an error occurred.  */
+pid_t
+create_tty_session (void)
+{
+#ifdef HAVE_SETSID
+  pid_t ret;
+
+  if (!job_control || inferior_thisrun_terminal == 0)
+    return 0;
+
+  ret = setsid ();
+  if (ret == -1)
+    warning ("Failed to create new terminal session: setsid: %s",
+	     safe_strerror (errno));
+
+  return ret;
+#else
+  return 0;
+#endif /* HAVE_SETSID */
+}
+
 /* This is here because this is where we figure out whether we (probably)
    have job control.  Just using job_control only does part of it because
    setpgid or setpgrp might not exist on a system without job control.
Index: gdb/terminal.h
===================================================================
--- gdb/terminal.h.orig	2008-01-03 19:27:07.000000000 -0200
+++ gdb/terminal.h	2008-03-12 11:05:34.000000000 -0300
@@ -82,6 +82,8 @@ extern void new_tty (void);
    a given run of GDB.  In inflow.c.  */
 extern int job_control;
 
+extern int create_tty_session (void);
+
 /* Set the process group of the caller to its own pid, or do nothing if
    we lack job control.  */
 extern int gdb_setpgid (void);