Move parts of inferior job control to common/

This commit moves a few bits responsible for dealing with inferior job
control from GDB to common/, which makes them available to gdbserver.
This is necessary for the upcoming patches that will share
fork_inferior et al between GDB and gdbserver.

We move some parts of gdb/terminal.h to gdb/common/common-terminal.h,
especifically the code that checks terminal features and that are used
to set job_control accordingly.

After sharing parts of gdb/terminal.h, we also to share the two
functions on gdb/inflow.c that are going to be needed by the
fork_inferior rework.  They are 'gdb_setpgid' and the new
'have_job_control'.  I've also taken the opportunity to give a more
meaningful name to "inflow.c" on common/.  Now it is called
"job-control.c" (thanks Pedro for the suggestion).

gdb/ChangeLog:
2017-06-07  Sergio Durigan Junior  <sergiodj@redhat.com>

	* Makefile.in (SFILES): Add "common/job-control.c".
	(HFILES_NO_SRCDIR): Add "common/job-control.h".
	(COMMON_OBS): Add "job-control.o".
	* common/job-control.c: New file, with contents from
	"gdb/inflow.c".
	* common/job-control.h: New file, with contents from "terminal.h".
	* fork-child.c: Include "job-control.h".
	* inflow.c: Include "job-control.h".
	(gdb_setpgid): Move to "common/common-inflow.c".
	(_initialize_inflow): Move setting of "job_control" to
	"handle_job_control".
	* terminal.h (job_control): Moved to "common/common-terminal.h".
	(gdb_setpgid): Likewise.
	* top.c: Include "job_control.h".
	* utils.c: Likewise.
	(job_control): Moved to "job-control.c".

gdb/gdbserver/ChangeLog:
2017-06-07  Sergio Durigan Junior  <sergiodj@redhat.com>

	* Makefile.in (SFILE): Add "common/job-control.c".
	(OBS): Add "job-control.o".

2 files changed, 131 insertions, 0 deletions

diff --git a/gdb/common/job-control.c b/gdb/common/job-control.c
new file mode 100644
index 0000000..d76bc57
--- /dev/null
+++ b/gdb/common/job-control.c
@@ -0,0 +1,93 @@
+/* Job control and terminal related functions, for GDB and gdbserver
+   when running under Unix.
+
+   Copyright (C) 1986-2017 Free Software Foundation, Inc.
+
+   This file is part of GDB.
+
+   This program is free software; you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 3 of the License, or
+   (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
+
+#include "common-defs.h"
+#include "job-control.h"
+#include "gdb_termios.h"
+
+/* Nonzero if we have job control.  */
+int job_control;
+
+/* Set the process group ID of the inferior.
+
+   Just using job_control only does part of it because setpgid or
+   setpgrp might not exist on a system without job control.
+
+   For a more clean implementation, in libiberty, put a setpgid which merely
+   calls setpgrp and a setpgrp which does nothing (any system with job control
+   will have one or the other).  */
+
+int
+gdb_setpgid ()
+{
+  int retval = 0;
+
+  if (job_control)
+    {
+#if defined (HAVE_TERMIOS) || defined (TIOCGPGRP)
+#ifdef HAVE_SETPGID
+      /* The call setpgid (0, 0) is supposed to work and mean the same
+         thing as this, but on Ultrix 4.2A it fails with EPERM (and
+         setpgid (getpid (), getpid ()) succeeds).  */
+      retval = setpgid (getpid (), getpid ());
+#else
+#ifdef HAVE_SETPGRP
+#ifdef SETPGRP_VOID
+      retval = setpgrp ();
+#else
+      retval = setpgrp (getpid (), getpid ());
+#endif
+#endif /* HAVE_SETPGRP */
+#endif /* HAVE_SETPGID */
+#endif /* defined (HAVE_TERMIOS) || defined (TIOCGPGRP) */
+    }
+
+  return retval;
+}
+
+/* See common/common-terminal.h.  */
+
+void
+have_job_control ()
+{
+  /* OK, figure out whether we have job control.  If neither termios nor
+     sgtty (i.e. termio or go32), leave job_control 0.  */
+#if defined (HAVE_TERMIOS)
+  /* Do all systems with termios have the POSIX way of identifying job
+     control?  I hope so.  */
+#ifdef _POSIX_JOB_CONTROL
+  job_control = 1;
+#else
+#ifdef _SC_JOB_CONTROL
+  job_control = sysconf (_SC_JOB_CONTROL);
+#else
+  job_control = 0;		/* Have to assume the worst.  */
+#endif /* _SC_JOB_CONTROL */
+#endif /* _POSIX_JOB_CONTROL */
+#endif /* HAVE_TERMIOS */
+
+#ifdef HAVE_SGTTY
+#ifdef TIOCGPGRP
+  job_control = 1;
+#else
+  job_control = 0;
+#endif /* TIOCGPGRP */
+#endif /* sgtty */
+}
diff --git a/gdb/common/job-control.h b/gdb/common/job-control.h
new file mode 100644
index 0000000..9e284aa
--- /dev/null
+++ b/gdb/common/job-control.h
@@ -0,0 +1,38 @@
+/* Job control and terminal related functions, for GDB and gdbserver
+   when running under Unix.
+
+   Copyright (C) 1986-2017 Free Software Foundation, Inc.
+
+   This file is part of GDB.
+
+   This program is free software; you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 3 of the License, or
+   (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
+
+#ifndef JOB_CONTROL_H
+#define JOB_CONTROL_H
+
+/* Do we have job control?  Can be assumed to always be the same
+   within a given run of GDB.  Use in gdb/inflow.c and
+   common/common-inflow.c.  */
+extern int job_control;
+
+/* Set the process group of the caller to its own pid, or do nothing
+   if we lack job control.  */
+extern int gdb_setpgid ();
+
+/* Determine whether we have job control, and set variable JOB_CONTROL
+   accordingly.  This function must be called before any use of
+   JOB_CONTROL.  */
+extern void have_job_control ();
+
+#endif /* ! JOB_CONTROL_H */