Introduce nat/linux-namespaces.[ch]

This commit introduces new shared files nat/linux-namespaces.[ch]
containing code to support Linux namespaces that will be used by
both GDB and gdbserver.

gdb/ChangeLog:

	* configure.ac (AC_CHECK_FUNCS): Add setns.
	* config.in: Regenerate.
	* configure: Likewise.
	* nat/linux-namespaces.h: New file.
	* nat/linux-namespaces.c: Likewise.
	* Makefile.in (HFILES_NO_SRCDIR): Add nat/linux-namespaces.h.
	(linux-namespaces.o): New rule.
	* config/aarch64/linux.mh (NATDEPFILES): Add linux-namespaces.o.
	* config/alpha/alpha-linux.mh (NATDEPFILES): Likewise.
	* config/arm/linux.mh (NATDEPFILES): Likewise.
	* config/i386/linux.mh (NATDEPFILES): Likewise.
	* config/i386/linux64.mh (NATDEPFILES): Likewise.
	* config/ia64/linux.mh (NATDEPFILES): Likewise.
	* config/m32r/linux.mh (NATDEPFILES): Likewise.
	* config/m68k/linux.mh (NATDEPFILES): Likewise.
	* config/mips/linux.mh (NATDEPFILES): Likewise.
	* config/pa/linux.mh (NATDEPFILES): Likewise.
	* config/powerpc/linux.mh (NATDEPFILES): Likewise.
	* config/powerpc/ppc64-linux.mh (NATDEPFILES): Likewise.
	* config/powerpc/spu-linux.mh (NATDEPFILES): Likewise.
	* config/s390/linux.mh (NATDEPFILES): Likewise.
	* config/sparc/linux.mh (NATDEPFILES): Likewise.
	* config/sparc/linux64.mh (NATDEPFILES): Likewise.
	* config/tilegx/linux.mh (NATDEPFILES): Likewise.
	* config/xtensa/linux.mh (NATDEPFILES): Likewise.

gdb/gdbserver/ChangeLog:

	* configure.ac (AC_CHECK_FUNCS): Add setns.
	* config.in: Regenerate.
	* configure: Likewise.
	* Makefile.in (SFILES): Add nat/linux-namespaces.c.
	(linux-namespaces.o): New rule.
	* configure.srv (srv_linux_obj): Add linux-namespaces.o.

1 files changed, 76 insertions, 0 deletions

diff --git a/gdb/nat/linux-namespaces.h b/gdb/nat/linux-namespaces.h
new file mode 100644
index 0000000..f9adc07
--- /dev/null
+++ b/gdb/nat/linux-namespaces.h
@@ -0,0 +1,76 @@
+/* Linux namespaces(7) support.
+
+   Copyright (C) 2015 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 LINUX_NAMESPACES_H
+#define LINUX_NAMESPACES_H
+
+/* Set to nonzero to enable debugging of Linux namespaces code.  */
+
+extern int debug_linux_namespaces;
+
+/* Enumeration of Linux namespace types.  */
+
+enum linux_ns_type
+  {
+    /* IPC namespace: System V IPC, POSIX message queues.  */
+    LINUX_NS_IPC,
+
+    /* Mount namespace: mount points.  */
+    LINUX_NS_MNT,
+
+    /* Network namespace: network devices, stacks, ports, etc.  */
+    LINUX_NS_NET,
+
+    /* PID namespace: process IDs.  */
+    LINUX_NS_PID,
+
+    /* User namespace: user and group IDs.  */
+    LINUX_NS_USER,
+
+    /* UTS namespace: hostname and NIS domain name.  */
+    LINUX_NS_UTS,
+
+    /* Number of Linux namespaces.  */
+    NUM_LINUX_NS_TYPES
+  };
+
+/* Return nonzero if process PID has the same TYPE namespace as the
+   calling process, or if the kernel does not support TYPE namespaces
+   (in which case there is only one TYPE namespace).  Return zero if
+   the kernel supports TYPE namespaces and the two processes have
+   different TYPE namespaces.  */
+
+extern int linux_ns_same (pid_t pid, enum linux_ns_type type);
+
+/* Like gdb_open_cloexec, but in the mount namespace of process
+   PID.  */
+
+extern int linux_mntns_open_cloexec (pid_t pid, const char *filename,
+				     int flags, mode_t mode);
+
+/* Like unlink(2), but in the mount namespace of process PID.  */
+
+extern int linux_mntns_unlink (pid_t pid, const char *filename);
+
+/* Like readlink(2), but in the mount namespace of process PID.  */
+
+extern ssize_t linux_mntns_readlink (pid_t pid, const char *filename,
+				     char *buf, size_t bufsiz);
+
+#endif /* LINUX_NAMESPACES_H */