unshare: new command

New utility allows to run process with separate mount, UTC, IPC or
network namespaces.

[kzak@redhat.com: - some cosmetic changes in usage() and err() usage
                  - move "if BUILD_UNSHARE" to separate place in Makefile.am
                  - add unshare to .gitignore]

Signed-off-by: Mikhail Gusarov <dottedmag@dottedmag.net>
Signed-off-by: Karel Zak <kzak@redhat.com>

1 files changed, 119 insertions, 0 deletions

diff --git a/sys-utils/unshare.c b/sys-utils/unshare.c
new file mode 100644
index 000000000..df75d1776
--- /dev/null
+++ b/sys-utils/unshare.c
@@ -0,0 +1,119 @@
+/*
+ * unshare(1) - command-line interface for unshare(2)
+ *
+ * Copyright (C) 2009 Mikhail Gusarov <dottedmag@dottedmag.net>
+ *
+ * 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 2, 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, write to the Free Software Foundation, Inc.,
+ * 675 Mass Ave, Cambridge, MA 02139, USA.
+ */
+
+#include <err.h>
+#include <errno.h>
+#include <getopt.h>
+#include <sched.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+
+#include "nls.h"
+
+#ifndef CLONE_NEWSNS
+# define CLONE_NEWNS 0x00020000
+#endif
+#ifndef CLONE_NEWUTS
+# define CLONE_NEWUTS 0x04000000
+#endif
+#ifndef CLONE_NEWIPC
+# define CLONE_NEWIPC 0x08000000
+#endif
+#ifndef CLONE_NEWNET
+# define CLONE_NEWNET 0x40000000
+#endif
+
+#ifndef HAVE_UNSHARE
+# include <sys/syscall.h>
+
+static int unshare(int flags)
+{
+	return syscall(SYS_unshare, flags);
+}
+#endif
+
+static void usage(int status)
+{
+	FILE *out = status == EXIT_SUCCESS ? stdout : stderr;
+
+	fprintf(out, _("Usage: %s [options] <program> [args...]\n"),
+		program_invocation_short_name);
+
+	fputs(_("Run program with some namespaces unshared from parent\n\n"
+		"  -h, --help        usage information (this)\n"
+		"  -m, --mount       unshare mounts namespace\n"
+		"  -u, --uts         unshare UTS namespace (hostname etc)\n"
+		"  -i, --ipc         unshare System V IPC namespace\n"
+		"  -n, --net         unshare network namespace\n"), out);
+
+	fprintf(out, _("\nFor more information see unshare(1).\n"));
+	exit(status);
+}
+
+int main(int argc, char *argv[])
+{
+	struct option longopts[] = {
+		{ "help", no_argument, 0, 'h' },
+		{ "mount", no_argument, 0, 'm' },
+		{ "uts", no_argument, 0, 'u' },
+		{ "ipc", no_argument, 0, 'i' },
+		{ "net", no_argument, 0, 'n' },
+	};
+
+	int unshare_flags = 0;
+
+	int c;
+
+	setlocale(LC_MESSAGES, "");
+	bindtextdomain(PACKAGE, LOCALEDIR);
+	textdomain(PACKAGE);
+
+	while((c = getopt_long(argc, argv, "hmuin", longopts, NULL)) != -1) {
+		switch(c) {
+		case 'h':
+			usage(EXIT_SUCCESS);
+		case 'm':
+			unshare_flags |= CLONE_NEWNS;
+			break;
+		case 'u':
+			unshare_flags |= CLONE_NEWUTS;
+			break;
+		case 'i':
+			unshare_flags |= CLONE_NEWIPC;
+			break;
+		case 'n':
+			unshare_flags |= CLONE_NEWNET;
+			break;
+		default:
+			usage(EXIT_FAILURE);
+		}
+	}
+
+	if(optind >= argc)
+		usage(EXIT_FAILURE);
+
+	if(-1 == unshare(unshare_flags))
+		err(EXIT_FAILURE, _("unshare failed"));
+
+	execvp(argv[optind], argv + optind);
+
+	err(EXIT_FAILURE, _("exec %s failed"), argv[optind]);
+}