3 files changed, 104 insertions, 0 deletions

diff --git a/support/Makefile b/support/Makefile
index 423538d06a..1eba34b749 100644
--- a/support/Makefile
+++ b/support/Makefile
@@ -40,6 +40,7 @@ libsupport-routines = \
   support_can_chroot \
   support_capture_subprocess \
   support_capture_subprocess_check \
+  support_chroot \
   support_enter_network_namespace \
   support_format_address_family \
   support_format_addrinfo \
diff --git a/support/namespace.h b/support/namespace.h
index e1ccaa1ef0..859c2fda3f 100644
--- a/support/namespace.h
+++ b/support/namespace.h
@@ -60,6 +60,38 @@ bool support_in_uts_namespace (void);
    non-zero exit status.  */
 void support_isolate_in_subprocess (void (*callback) (void *), void *closure);
 
+/* Describe the setup of a chroot environment, for
+   support_chroot_create below.  */
+struct support_chroot_configuration
+{
+  /* File contents.  The files are not created if the field is
+     NULL.  */
+  const char *resolv_conf;
+};
+
+/* The result of the creation of a chroot.  */
+struct support_chroot
+{
+  /* Path information.  All these paths are relative to the parent
+     chroot.  */
+
+  /* Path to the chroot directory.  */
+  char *path_chroot;
+
+  /* Path to the /etc/resolv.conf file.  */
+  char *path_resolv_conf;
+};
+
+/* Create a chroot environment.  The returned data should be freed
+   using support_chroot_free below.  The files will be deleted when
+   the process exits.  This function does not enter the chroot.  */
+struct support_chroot *support_chroot_create
+  (struct support_chroot_configuration);
+
+/* Deallocate the chroot information created by
+   support_chroot_create.  */
+void support_chroot_free (struct support_chroot *);
+
 __END_DECLS
 
 #endif
diff --git a/support/support_chroot.c b/support/support_chroot.c
new file mode 100644
index 0000000000..c0807b313a
--- /dev/null
+++ b/support/support_chroot.c
@@ -0,0 +1,71 @@
+/* Setup a chroot environment for use within tests.
+   Copyright (C) 2017 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library 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
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#include <stdlib.h>
+#include <support/check.h>
+#include <support/namespace.h>
+#include <support/support.h>
+#include <support/temp_file.h>
+#include <support/test-driver.h>
+#include <support/xunistd.h>
+
+struct support_chroot *
+support_chroot_create (struct support_chroot_configuration conf)
+{
+  struct support_chroot *chroot = xmalloc (sizeof (*chroot));
+
+  chroot->path_chroot = xasprintf ("%s/tst-resolv-res_init-XXXXXX", test_dir);
+  if (mkdtemp (chroot->path_chroot) == NULL)
+    FAIL_EXIT1 ("mkdtemp (\"%s\"): %m", chroot->path_chroot);
+  add_temp_file (chroot->path_chroot);
+
+  /* Create the /etc directory in the chroot environment.  */
+  char *path_etc = xasprintf ("%s/etc", chroot->path_chroot);
+  xmkdir (path_etc, 0777);
+  add_temp_file (path_etc);
+
+  if (conf.resolv_conf != NULL)
+    {
+      /* Create an empty resolv.conf file.  */
+      chroot->path_resolv_conf = xasprintf ("%s/resolv.conf", path_etc);
+      add_temp_file (chroot->path_resolv_conf);
+      support_write_file_string (chroot->path_resolv_conf, conf.resolv_conf);
+    }
+  else
+    chroot->path_resolv_conf = NULL;
+
+  free (path_etc);
+
+  /* valgrind needs a temporary directory in the chroot.  */
+  {
+    char *path_tmp = xasprintf ("%s/tmp", chroot->path_chroot);
+    xmkdir (path_tmp, 0777);
+    add_temp_file (path_tmp);
+    free (path_tmp);
+  }
+
+  return chroot;
+}
+
+void
+support_chroot_free (struct support_chroot *chroot)
+{
+  free (chroot->path_chroot);
+  free (chroot->path_resolv_conf);
+  free (chroot);
+}