[PATCH] linux: Split tst-ttyname

[Adhemerval Zanella <adhemerval.zanella@linaro.org>]

The tst-ttyname may fail in container environments while trying to
mount the procfs after the unshare (test do_in_chroot_2).  It is not
clear why exaclty kernel returns EPERM in this case, the container
does have CAP_SYS_CHROOT, SELinux/AppArmor is disabled, and there is
no seccomp filter.

To avoid always reporting the test as FAIL in such scenario, the
test that uses new namespaces is moved to a new one and the failure
on the mount command is now report as UNSUPPORTED.

Checked on x86_64-linux-gnu and aarch64-linux-gnu.
---
 sysdeps/unix/sysv/linux/Makefile              |   1 +
 sysdeps/unix/sysv/linux/tst-ttyname-common.c  | 416 ++++++++++++++
 .../unix/sysv/linux/tst-ttyname-namespace.c   | 147 +++++
 sysdeps/unix/sysv/linux/tst-ttyname.c         | 512 +-----------------
 4 files changed, 567 insertions(+), 509 deletions(-)
 create mode 100644 sysdeps/unix/sysv/linux/tst-ttyname-common.c
 create mode 100644 sysdeps/unix/sysv/linux/tst-ttyname-namespace.c

diff --git a/sysdeps/unix/sysv/linux/Makefile b/sysdeps/unix/sysv/linux/Makefile
index 594a5dc53e..61b9e4bef0 100644
--- a/sysdeps/unix/sysv/linux/Makefile
+++ b/sysdeps/unix/sysv/linux/Makefile
@@ -225,6 +225,7 @@ tests += \
   tst-tgkill \
   tst-timerfd \
   tst-ttyname \
+  tst-ttyname-namespace \
   # tests
 
 # process_madvise requires CAP_SYS_ADMIN.
diff --git a/sysdeps/unix/sysv/linux/tst-ttyname-common.c b/sysdeps/unix/sysv/linux/tst-ttyname-common.c
new file mode 100644
index 0000000000..3f6d8ee944
--- /dev/null
+++ b/sysdeps/unix/sysv/linux/tst-ttyname-common.c
@@ -0,0 +1,416 @@
+/* Common definitions for ttyname tests.
+   Copyright (C) 2017-2023 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; see the file COPYING.LIB.  If
+   not, see <https://www.gnu.org/licenses/>.  */
+
+#include <dirent.h>
+#include <errno.h>
+#include <fcntl.h>
+#include <limits.h>
+#include <stdbool.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/mount.h>
+#include <sys/resource.h>
+#include <sys/stat.h>
+#include <unistd.h>
+
+#include <support/check.h>
+#include <support/support.h>
+#include <support/temp_file.h>
+#include <support/test-driver.h>
+#include <support/xunistd.h>
+
+/* generic utilities */
+
+#define VERIFY(expr)                                                    \
+  do {                                                                  \
+    if (!(expr))                                                        \
+      {                                                                 \
+        printf ("error: %s:%d: %s: %m\n",                               \
+                __FILE__, __LINE__, #expr);                             \
+        exit (1);                                                       \
+      }                                                                 \
+  } while (0)
+
+static void
+touch (const char *path, mode_t mode)
+{
+  xclose (xopen (path, O_WRONLY|O_CREAT|O_NOCTTY, mode));
+}
+
+static size_t
+trim_prefix (char *str, size_t str_len, const char *prefix)
+{
+  size_t prefix_len = strlen (prefix);
+  if (str_len > prefix_len && memcmp (str, prefix, prefix_len) == 0)
+    {
+      memmove (str, str + prefix_len, str_len - prefix_len);
+      return str_len - prefix_len;
+    }
+  return str_len;
+}
+
+/* returns a pointer to static storage */
+static char *
+proc_fd_readlink (const char *linkname)
+{
+  static char target[PATH_MAX+1];
+  ssize_t target_len = readlink (linkname, target, PATH_MAX);
+  VERIFY (target_len > 0);
+  target_len = trim_prefix (target, target_len, "(unreachable)");
+  target[target_len] = '\0';
+  return target;
+}
+
+/* plain ttyname runner */
+
+struct result
+{
+  const char *name;
+  int err;
+};
+
+/* strings in result structure are in static storage */
+static struct result
+run_ttyname (int fd)
+{
+  struct result ret;
+  errno = 0;
+  ret.name = ttyname (fd);
+  ret.err = errno;
+  return ret;
+}
+
+static bool
+eq_ttyname (struct result actual, struct result expected)
+{
+  char *actual_name, *expected_name;
+
+  if ((actual.err == expected.err)
+      && (!actual.name == !expected.name)
+      && (actual.name ? strcmp (actual.name, expected.name) == 0 : true))
+    {
+      if (expected.name)
+        expected_name = xasprintf ("\"%s\"", expected.name);
+      else
+	expected_name = xstrdup ("NULL");
+
+      printf ("info:      ttyname: PASS {name=%s, errno=%d}\n",
+	      expected_name, expected.err);
+
+      free (expected_name);
+      return true;
+    }
+
+  if (actual.name)
+    actual_name = xasprintf ("\"%s\"", actual.name);
+  else
+    actual_name = xstrdup ("NULL");
+
+  if (expected.name)
+    expected_name = xasprintf ("\"%s\"", expected.name);
+  else
+    expected_name = xstrdup ("NULL");
+
+  printf ("error:     ttyname: actual {name=%s, errno=%d} != expected {name=%s, errno=%d}\n",
+	  actual_name, actual.err,
+	  expected_name, expected.err);
+
+  free (actual_name);
+  free (expected_name);
+  return false;
+}
+
+/* ttyname_r runner */
+
+struct result_r
+{
+  const char *name;
+  int ret;
+  int err;
+};
+
+/* strings in result structure are in static storage */
+static struct result_r
+run_ttyname_r (int fd)
+{
+  static char buf[TTY_NAME_MAX];
+
+  struct result_r ret;
+  errno = 0;
+  ret.ret = ttyname_r (fd, buf, TTY_NAME_MAX);
+  ret.err = errno;
+  if (ret.ret == 0)
+    ret.name = buf;
+  else
+    ret.name = NULL;
+  return ret;
+}
+
+static bool
+eq_ttyname_r (struct result_r actual, struct result_r expected)
+{
+  char *actual_name, *expected_name;
+
+  if ((actual.err == expected.err)
+      && (actual.ret == expected.ret)
+      && (!actual.name == !expected.name)
+      && (actual.name ? strcmp (actual.name, expected.name) == 0 : true))
+    {
+      if (expected.name)
+        expected_name = xasprintf ("\"%s\"", expected.name);
+      else
+        expected_name = xstrdup ("NULL");
+
+      printf ("info:      ttyname_r: PASS {name=%s, ret=%d, errno=%d}\n",
+              expected_name, expected.ret, expected.err);
+
+      free (expected_name);
+      return true;
+    }
+
+  if (actual.name)
+    actual_name = xasprintf ("\"%s\"", actual.name);
+  else
+    actual_name = xstrdup ("NULL");
+
+  if (expected.name)
+    expected_name = xasprintf ("\"%s\"", expected.name);
+  else
+    expected_name = xstrdup ("NULL");
+
+  printf ("error:     ttyname_r: actual {name=%s, ret=%d, errno=%d} != expected {name=%s, ret=%d, errno=%d}\n",
+	  actual_name, actual.ret, actual.err,
+	  expected_name, expected.ret, expected.err);
+
+  free (actual_name);
+  free (expected_name);
+  return false;
+}
+
+/* combined runner */
+
+static bool
+doit (int fd, const char *testname, struct result_r expected_r)
+{
+  struct result expected = {.name=expected_r.name, .err=expected_r.ret};
+  bool ret = true;
+
+  printf ("info:    testcase: %s\n", testname);
+
+  if (!eq_ttyname (run_ttyname (fd), expected))
+    ret = false;
+  if (!eq_ttyname_r (run_ttyname_r (fd), expected_r))
+    ret = false;
+
+  if (!ret)
+    support_record_failure ();
+
+  return ret;
+}
+
+/* chroot setup */
+
+static char *chrootdir;
+
+static void
+prepare (int argc, char **argv)
+{
+  chrootdir = xasprintf ("%s/tst-ttyname-XXXXXX", test_dir);
+  if (mkdtemp (chrootdir) == NULL)
+    FAIL_EXIT1 ("mkdtemp (\"%s\"): %m", chrootdir);
+  add_temp_file (chrootdir);
+}
+#define PREPARE prepare
+
+/* Adjust the file limit so that we have a chance to open PTY.  */
+static void
+adjust_file_limit (const char *pty)
+{
+  int number = -1;
+  if (sscanf (pty, "/dev/pts/%d", &number) != 1 || number < 0)
+    FAIL_EXIT1 ("invalid PTY name: \"%s\"", pty);
+
+  /* Add a few additional descriptors to cover standard I/O streams
+     etc.  */
+  rlim_t desired_limit = number + 10;
+
+  struct rlimit lim;
+  if (getrlimit (RLIMIT_NOFILE, &lim) != 0)
+    FAIL_EXIT1 ("getrlimit (RLIMIT_NOFILE): %m");
+  if (lim.rlim_cur < desired_limit)
+    {
+      printf ("info: adjusting RLIMIT_NOFILE from %llu to %llu\n",
+	      (unsigned long long int) lim.rlim_cur,
+	      (unsigned long long int) desired_limit);
+      lim.rlim_cur = desired_limit;
+      if (setrlimit (RLIMIT_NOFILE, &lim) != 0)
+	printf ("warning: setrlimit (RLIMIT_NOFILE) failed: %m\n");
+    }
+}
+
+/* main test */
+
+static int
+run_chroot_tests (const char *slavename, int slave)
+{
+  struct stat st;
+  bool ok = true;
+
+  /* There are 3 groups of tests here.  The first group fairly
+     generically does things known to mess up ttyname, and verifies
+     that ttyname copes correctly.  The remaining groups are
+     increasingly convoluted, as we target specific parts of ttyname
+     to try to confuse.  */
+
+  /* Basic tests that it doesn't get confused by multiple devpts
+     instances.  */
+  {
+    VERIFY (stat (slavename, &st) < 0); /* sanity check */
+    if (!doit (slave, "no conflict, no match",
+               (struct result_r){.name=NULL, .ret=ENODEV, .err=ENODEV}))
+      ok = false;
+    VERIFY (mount ("/console", "/dev/console", NULL, MS_BIND, NULL) == 0);
+    if (!doit (slave, "no conflict, console",
+               (struct result_r){.name="/dev/console", .ret=0, .err=0}))
+      ok = false;
+    VERIFY (umount ("/dev/console") == 0);
+
+    /* Keep creating PTYs until we we get a name collision.  */
+    while (true)
+      {
+	if (stat (slavename, &st) == 0)
+	  break;
+	if (posix_openpt (O_RDWR|O_NOCTTY|O_NONBLOCK) < 0)
+	  {
+	    if (errno == ENOSPC || errno == EMFILE || errno == ENFILE)
+	      FAIL_UNSUPPORTED ("cannot re-create PTY \"%s\" in chroot: %m"
+				" (consider increasing limits)", slavename);
+	    else
+	      FAIL_EXIT1 ("cannot re-create PTY \"%s\" chroot: %m", slavename);
+	  }
+      }
+
+    if (!doit (slave, "conflict, no match",
+               (struct result_r){.name=NULL, .ret=ENODEV, .err=ENODEV}))
+      ok = false;
+    VERIFY (mount ("/console", "/dev/console", NULL, MS_BIND, NULL) == 0);
+    if (!doit (slave, "conflict, console",
+               (struct result_r){.name="/dev/console", .ret=0, .err=0}))
+      ok = false;
+    VERIFY (umount ("/dev/console") == 0);
+  }
+
+  /* The first tests kinda assumed that they hit certain code-paths
+     based on assuming that the readlink target is 'slavename', but
+     that's not quite always true.  They're still a good preliminary
+     sanity check, so keep them, but let's add tests that make sure
+     that those code-paths are hit by doing a readlink ourself.  */
+  {
+    char *linkname = xasprintf ("/proc/self/fd/%d", slave);
+    char *target = proc_fd_readlink (linkname);
+    free (linkname);
+    /* Depending on how we set up the chroot, the kernel may or may not
+       trim the leading path to the target (it may give us "/6",
+       instead of "/dev/pts/6").  We test it both ways (do_in_chroot_1
+       and do_in_chroot_2).  This test group relies on the target
+       existing, so guarantee that it does exist by creating it if
+       necessary.  */
+    if (stat (target, &st) < 0)
+      {
+        VERIFY (errno == ENOENT);
+        touch (target, 0);
+      }
+
+    VERIFY (mount ("/console", "/dev/console", NULL, MS_BIND, NULL) == 0);
+    VERIFY (mount ("/console", target, NULL, MS_BIND, NULL) == 0);
+    if (!doit (slave, "with readlink target",
+               (struct result_r){.name=target, .ret=0, .err=0}))
+      ok = false;
+    VERIFY (umount (target) == 0);
+    VERIFY (umount ("/dev/console") == 0);
+
+    VERIFY (mount ("/console", "/dev/console", NULL, MS_BIND, NULL) == 0);
+    VERIFY (mount (slavename, target, NULL, MS_BIND, NULL) == 0);
+    if (!doit (slave, "with readlink trap; fallback",
+               (struct result_r){.name="/dev/console", .ret=0, .err=0}))
+      ok = false;
+    VERIFY (umount (target) == 0);
+    VERIFY (umount ("/dev/console") == 0);
+
+    VERIFY (mount (slavename, target, NULL, MS_BIND, NULL) == 0);
+    if (!doit (slave, "with readlink trap; no fallback",
+               (struct result_r){.name=NULL, .ret=ENODEV, .err=ENODEV}))
+      ok = false;
+    VERIFY (umount (target) == 0);
+  }
+
+  /* This test makes sure that everything still works OK if readdir
+     finds a pseudo-match before and/or after the actual match.  Now,
+     to do that, we need to control that readdir finds the
+     pseudo-matches before and after the actual match; and there's no
+     good way to control that order in absence of whitebox testing.
+     So, just create 3 files, then use opendir/readdir to see what
+     order they are in, and assign meaning based on that order, not by
+     name; assigning the first to be a pseudo-match, the second to be
+     the actual match, and the third to be a pseudo-match.  This
+     assumes that (on tmpfs) ordering within the directory is stable
+     in the absence of modification, which seems reasonably safe.  */
+  {
+    /* since we're testing the fallback search, disable the readlink
+       happy-path */
+    VERIFY (umount2 ("/proc", MNT_DETACH) == 0);
+
+    touch ("/dev/console1", 0);
+    touch ("/dev/console2", 0);
+    touch ("/dev/console3", 0);
+
+    char *c[3];
+    int ci = 0;
+    DIR *dirstream = opendir ("/dev");
+    VERIFY (dirstream != NULL);
+    struct dirent *d;
+    while ((d = readdir (dirstream)) != NULL && ci < 3)
+      {
+        if (strcmp (d->d_name, "console1")
+            && strcmp (d->d_name, "console2")
+            && strcmp (d->d_name, "console3") )
+          continue;
+        c[ci++] = xasprintf ("/dev/%s", d->d_name);
+      }
+    VERIFY (ci == 3);
+    VERIFY (closedir (dirstream) == 0);
+
+    VERIFY (mount (slavename, c[0], NULL, MS_BIND, NULL) == 0);
+    VERIFY (mount ("/console", c[1], NULL, MS_BIND, NULL) == 0);
+    VERIFY (mount (slavename, c[2], NULL, MS_BIND, NULL) == 0);
+    VERIFY (umount2 ("/dev/pts", MNT_DETACH) == 0);
+    if (!doit (slave, "with search-path trap",
+               (struct result_r){.name=c[1], .ret=0, .err=0}))
+      ok = false;
+    for (int i = 0; i < 3; i++)
+      {
+        VERIFY (umount (c[i]) == 0);
+        VERIFY (unlink (c[i]) == 0);
+        free (c[i]);
+      }
+  }
+
+  return ok ? 0 : 1;
+}
+
diff --git a/sysdeps/unix/sysv/linux/tst-ttyname-namespace.c b/sysdeps/unix/sysv/linux/tst-ttyname-namespace.c
new file mode 100644
index 0000000000..7b74258c10
--- /dev/null
+++ b/sysdeps/unix/sysv/linux/tst-ttyname-namespace.c
@@ -0,0 +1,147 @@
+/* Tests for ttyname/ttyname_r with namespaces.
+   Copyright (C) 2017-2023 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; see the file COPYING.LIB.  If
+   not, see <https://www.gnu.org/licenses/>.  */
+
+#include <sched.h>
+#include <sys/prctl.h>
+#include <sys/wait.h>
+
+#include <support/namespace.h>
+
+#include "tst-ttyname-common.c"
+
+static int
+do_in_chroot_2 (int (*cb)(const char *, int))
+{
+  printf ("info:  entering chroot 2\n");
+
+  int pid_pipe[2];
+  xpipe (pid_pipe);
+  int exit_pipe[2];
+  xpipe (exit_pipe);
+
+  /* Open the PTS that we'll be testing on.  */
+  int master;
+  char *slavename;
+  VERIFY ((master = posix_openpt (O_RDWR|O_NOCTTY|O_NONBLOCK)) >= 0);
+  VERIFY ((slavename = ptsname (master)));
+  VERIFY (unlockpt (master) == 0);
+  if (strncmp (slavename, "/dev/pts/", 9) != 0)
+    FAIL_UNSUPPORTED ("slave pseudo-terminal is not under /dev/pts/: %s",
+                      slavename);
+  adjust_file_limit (slavename);
+  /* wait until in a new mount ns to open the slave */
+
+  /* enable `wait`ing on grandchildren */
+  VERIFY (prctl (PR_SET_CHILD_SUBREAPER, 1) == 0);
+
+  pid_t pid = xfork (); /* outer child */
+  if (pid == 0)
+    {
+      xclose (master);
+      xclose (pid_pipe[0]);
+      xclose (exit_pipe[1]);
+
+      if (!support_enter_mount_namespace ())
+	FAIL_UNSUPPORTED ("could not enter new mount namespace");
+
+      int slave = xopen (slavename, O_RDWR, 0);
+      if (!doit (slave, "basic smoketest",
+                 (struct result_r){.name=slavename, .ret=0, .err=0}))
+        _exit (1);
+
+      VERIFY (mount ("tmpfs", chrootdir, "tmpfs", 0, "mode=755") == 0);
+      VERIFY (chdir (chrootdir) == 0);
+
+      xmkdir ("proc", 0755);
+      xmkdir ("dev", 0755);
+      xmkdir ("dev/pts", 0755);
+
+      VERIFY (mount ("devpts", "dev/pts", "devpts",
+                     MS_NOSUID|MS_NOEXEC,
+                     "newinstance,ptmxmode=0666,mode=620") == 0);
+      VERIFY (symlink ("pts/ptmx", "dev/ptmx") == 0);
+
+      touch ("console", 0);
+      touch ("dev/console", 0);
+      VERIFY (mount (slavename, "console", NULL, MS_BIND, NULL) == 0);
+
+      xchroot (".");
+
+      if (unshare (CLONE_NEWNS | CLONE_NEWPID) < 0)
+        FAIL_UNSUPPORTED ("could not enter new PID namespace");
+      pid = xfork (); /* inner child */
+      if (pid == 0)
+        {
+          xclose (pid_pipe[1]);
+
+          /* wait until the outer child has exited */
+          char c;
+          VERIFY (read (exit_pipe[0], &c, 1) == 0);
+          xclose (exit_pipe[0]);
+
+	  if (mount ("proc", "/proc", "proc",
+		     MS_NOSUID|MS_NOEXEC|MS_NODEV, NULL) != 0)
+	    {
+	      /* This happens if we're trying to create a nested container,
+		 like if the build is running under podman, and we lack
+		 priviledges.  */
+	      if (errno == EPERM)
+		_exit (EXIT_UNSUPPORTED);
+	      else
+		_exit (EXIT_FAILURE);
+	    }
+
+          char *linkname = xasprintf ("/proc/self/fd/%d", slave);
+          char *target = proc_fd_readlink (linkname);
+          VERIFY (strcmp (target, strrchr (slavename, '/')) == 0);
+          free (linkname);
+
+          _exit (cb (slavename, slave));
+        }
+
+      int status;
+      xwaitpid (pid, &status, 0);
+      _exit (WEXITSTATUS (status));
+    }
+  xclose (pid_pipe[1]);
+  xclose (exit_pipe[0]);
+  xclose (exit_pipe[1]);
+
+  /* wait for the outer child */
+  int status;
+  xwaitpid (pid, &status, 0);
+  VERIFY (WIFEXITED (status));
+  int ret = WEXITSTATUS (status);
+  if (ret != 0)
+    FAIL_UNSUPPORTED ("unable to mount /proc on inner child process");
+  xclose (master);
+
+  return 0;
+}
+
+static int
+do_test (void)
+{
+  support_become_root ();
+
+  do_in_chroot_2 (run_chroot_tests);
+
+  return 0;
+}
+
+#include <support/test-driver.c>
diff --git a/sysdeps/unix/sysv/linux/tst-ttyname.c b/sysdeps/unix/sysv/linux/tst-ttyname.c
index ef55665fbe..04601777d6 100644
--- a/sysdeps/unix/sysv/linux/tst-ttyname.c
+++ b/sysdeps/unix/sysv/linux/tst-ttyname.c
@@ -15,256 +15,12 @@
    License along with the GNU C Library; see the file COPYING.LIB.  If
    not, see <https://www.gnu.org/licenses/>.  */
 
-#include <dirent.h>
-#include <errno.h>
-#include <fcntl.h>
-#include <limits.h>
 #include <sched.h>
-#include <stdio.h>
-#include <stdlib.h>
-#include <string.h>
-#include <sys/mount.h>
 #include <sys/prctl.h>
-#include <sys/stat.h>
-#include <sys/wait.h>
-#include <sys/resource.h>
-#include <unistd.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>
 
-/* generic utilities */
-
-#define VERIFY(expr)                                                    \
-  do {                                                                  \
-    if (!(expr))                                                        \
-      {                                                                 \
-        printf ("error: %s:%d: %s: %m\n",                               \
-                __FILE__, __LINE__, #expr);                             \
-        exit (1);                                                       \
-      }                                                                 \
-  } while (0)
-
-static void
-touch (const char *path, mode_t mode)
-{
-  xclose (xopen (path, O_WRONLY|O_CREAT|O_NOCTTY, mode));
-}
-
-static size_t
-trim_prefix (char *str, size_t str_len, const char *prefix)
-{
-  size_t prefix_len = strlen (prefix);
-  if (str_len > prefix_len && memcmp (str, prefix, prefix_len) == 0)
-    {
-      memmove (str, str + prefix_len, str_len - prefix_len);
-      return str_len - prefix_len;
-    }
-  return str_len;
-}
-
-/* returns a pointer to static storage */
-static char *
-proc_fd_readlink (const char *linkname)
-{
-  static char target[PATH_MAX+1];
-  ssize_t target_len = readlink (linkname, target, PATH_MAX);
-  VERIFY (target_len > 0);
-  target_len = trim_prefix (target, target_len, "(unreachable)");
-  target[target_len] = '\0';
-  return target;
-}
-
-/* plain ttyname runner */
-
-struct result
-{
-  const char *name;
-  int err;
-};
-
-/* strings in result structure are in static storage */
-static struct result
-run_ttyname (int fd)
-{
-  struct result ret;
-  errno = 0;
-  ret.name = ttyname (fd);
-  ret.err = errno;
-  return ret;
-}
-
-static bool
-eq_ttyname (struct result actual, struct result expected)
-{
-  char *actual_name, *expected_name;
-
-  if ((actual.err == expected.err)
-      && (!actual.name == !expected.name)
-      && (actual.name ? strcmp (actual.name, expected.name) == 0 : true))
-    {
-      if (expected.name)
-        expected_name = xasprintf ("\"%s\"", expected.name);
-      else
-	expected_name = xstrdup ("NULL");
-
-      printf ("info:      ttyname: PASS {name=%s, errno=%d}\n",
-	      expected_name, expected.err);
-
-      free (expected_name);
-      return true;
-    }
-
-  if (actual.name)
-    actual_name = xasprintf ("\"%s\"", actual.name);
-  else
-    actual_name = xstrdup ("NULL");
-
-  if (expected.name)
-    expected_name = xasprintf ("\"%s\"", expected.name);
-  else
-    expected_name = xstrdup ("NULL");
-
-  printf ("error:     ttyname: actual {name=%s, errno=%d} != expected {name=%s, errno=%d}\n",
-	  actual_name, actual.err,
-	  expected_name, expected.err);
-
-  free (actual_name);
-  free (expected_name);
-  return false;
-}
-
-/* ttyname_r runner */
-
-struct result_r
-{
-  const char *name;
-  int ret;
-  int err;
-};
-
-/* strings in result structure are in static storage */
-static struct result_r
-run_ttyname_r (int fd)
-{
-  static char buf[TTY_NAME_MAX];
-
-  struct result_r ret;
-  errno = 0;
-  ret.ret = ttyname_r (fd, buf, TTY_NAME_MAX);
-  ret.err = errno;
-  if (ret.ret == 0)
-    ret.name = buf;
-  else
-    ret.name = NULL;
-  return ret;
-}
-
-static bool
-eq_ttyname_r (struct result_r actual, struct result_r expected)
-{
-  char *actual_name, *expected_name;
-
-  if ((actual.err == expected.err)
-      && (actual.ret == expected.ret)
-      && (!actual.name == !expected.name)
-      && (actual.name ? strcmp (actual.name, expected.name) == 0 : true))
-    {
-      if (expected.name)
-        expected_name = xasprintf ("\"%s\"", expected.name);
-      else
-        expected_name = xstrdup ("NULL");
-
-      printf ("info:      ttyname_r: PASS {name=%s, ret=%d, errno=%d}\n",
-              expected_name, expected.ret, expected.err);
-
-      free (expected_name);
-      return true;
-    }
-
-  if (actual.name)
-    actual_name = xasprintf ("\"%s\"", actual.name);
-  else
-    actual_name = xstrdup ("NULL");
-
-  if (expected.name)
-    expected_name = xasprintf ("\"%s\"", expected.name);
-  else
-    expected_name = xstrdup ("NULL");
-
-  printf ("error:     ttyname_r: actual {name=%s, ret=%d, errno=%d} != expected {name=%s, ret=%d, errno=%d}\n",
-	  actual_name, actual.ret, actual.err,
-	  expected_name, expected.ret, expected.err);
-
-  free (actual_name);
-  free (expected_name);
-  return false;
-}
-
-/* combined runner */
-
-static bool
-doit (int fd, const char *testname, struct result_r expected_r)
-{
-  struct result expected = {.name=expected_r.name, .err=expected_r.ret};
-  bool ret = true;
-
-  printf ("info:    testcase: %s\n", testname);
-
-  if (!eq_ttyname (run_ttyname (fd), expected))
-    ret = false;
-  if (!eq_ttyname_r (run_ttyname_r (fd), expected_r))
-    ret = false;
-
-  if (!ret)
-    support_record_failure ();
-
-  return ret;
-}
-
-/* chroot setup */
-
-static char *chrootdir;
-
-static void
-prepare (int argc, char **argv)
-{
-  chrootdir = xasprintf ("%s/tst-ttyname-XXXXXX", test_dir);
-  if (mkdtemp (chrootdir) == NULL)
-    FAIL_EXIT1 ("mkdtemp (\"%s\"): %m", chrootdir);
-  add_temp_file (chrootdir);
-}
-#define PREPARE prepare
-
-/* Adjust the file limit so that we have a chance to open PTY.  */
-static void
-adjust_file_limit (const char *pty)
-{
-  int number = -1;
-  if (sscanf (pty, "/dev/pts/%d", &number) != 1 || number < 0)
-    FAIL_EXIT1 ("invalid PTY name: \"%s\"", pty);
-
-  /* Add a few additional descriptors to cover standard I/O streams
-     etc.  */
-  rlim_t desired_limit = number + 10;
-
-  struct rlimit lim;
-  if (getrlimit (RLIMIT_NOFILE, &lim) != 0)
-    FAIL_EXIT1 ("getrlimit (RLIMIT_NOFILE): %m");
-  if (lim.rlim_cur < desired_limit)
-    {
-      printf ("info: adjusting RLIMIT_NOFILE from %llu to %llu\n",
-	      (unsigned long long int) lim.rlim_cur,
-	      (unsigned long long int) desired_limit);
-      lim.rlim_cur = desired_limit;
-      if (setrlimit (RLIMIT_NOFILE, &lim) != 0)
-	printf ("warning: setrlimit (RLIMIT_NOFILE) failed: %m\n");
-    }
-}
+#include "tst-ttyname-common.c"
 
 /* These chroot setup functions put the TTY at at "/console" (where it
    won't be found by ttyname), and create "/dev/console" as an
@@ -341,276 +97,14 @@ do_in_chroot_1 (int (*cb)(const char *, int))
   return WEXITSTATUS (status);
 }
 
-static int
-do_in_chroot_2 (int (*cb)(const char *, int))
-{
-  printf ("info:  entering chroot 2\n");
-
-  int pid_pipe[2];
-  xpipe (pid_pipe);
-  int exit_pipe[2];
-  xpipe (exit_pipe);
-
-  /* Open the PTS that we'll be testing on.  */
-  int master;
-  char *slavename;
-  VERIFY ((master = posix_openpt (O_RDWR|O_NOCTTY|O_NONBLOCK)) >= 0);
-  VERIFY ((slavename = ptsname (master)));
-  VERIFY (unlockpt (master) == 0);
-  if (strncmp (slavename, "/dev/pts/", 9) != 0)
-    FAIL_UNSUPPORTED ("slave pseudo-terminal is not under /dev/pts/: %s",
-                      slavename);
-  adjust_file_limit (slavename);
-  /* wait until in a new mount ns to open the slave */
-
-  /* enable `wait`ing on grandchildren */
-  VERIFY (prctl (PR_SET_CHILD_SUBREAPER, 1) == 0);
-
-  pid_t pid = xfork (); /* outer child */
-  if (pid == 0)
-    {
-      xclose (master);
-      xclose (pid_pipe[0]);
-      xclose (exit_pipe[1]);
-
-      if (!support_enter_mount_namespace ())
-	FAIL_UNSUPPORTED ("could not enter new mount namespace");
-
-      int slave = xopen (slavename, O_RDWR, 0);
-      if (!doit (slave, "basic smoketest",
-                 (struct result_r){.name=slavename, .ret=0, .err=0}))
-        _exit (1);
-
-      VERIFY (mount ("tmpfs", chrootdir, "tmpfs", 0, "mode=755") == 0);
-      VERIFY (chdir (chrootdir) == 0);
-
-      xmkdir ("proc", 0755);
-      xmkdir ("dev", 0755);
-      xmkdir ("dev/pts", 0755);
-
-      VERIFY (mount ("devpts", "dev/pts", "devpts",
-                     MS_NOSUID|MS_NOEXEC,
-                     "newinstance,ptmxmode=0666,mode=620") == 0);
-      VERIFY (symlink ("pts/ptmx", "dev/ptmx") == 0);
-
-      touch ("console", 0);
-      touch ("dev/console", 0);
-      VERIFY (mount (slavename, "console", NULL, MS_BIND, NULL) == 0);
-
-      xchroot (".");
-
-      if (unshare (CLONE_NEWNS | CLONE_NEWPID) < 0)
-        FAIL_UNSUPPORTED ("could not enter new PID namespace");
-      pid = xfork (); /* inner child */
-      if (pid == 0)
-        {
-          xclose (pid_pipe[1]);
-
-          /* wait until the outer child has exited */
-          char c;
-          VERIFY (read (exit_pipe[0], &c, 1) == 0);
-          xclose (exit_pipe[0]);
-
-          VERIFY (mount ("proc", "/proc", "proc",
-                         MS_NOSUID|MS_NOEXEC|MS_NODEV, NULL) == 0);
-
-          char *linkname = xasprintf ("/proc/self/fd/%d", slave);
-          char *target = proc_fd_readlink (linkname);
-          VERIFY (strcmp (target, strrchr (slavename, '/')) == 0);
-          free (linkname);
-
-          _exit (cb (slavename, slave));
-        }
-      xwrite (pid_pipe[1], &pid, sizeof pid);
-      _exit (0);
-    }
-  xclose (pid_pipe[1]);
-  xclose (exit_pipe[0]);
-  xclose (exit_pipe[1]);
-
-  /* wait for the outer child */
-  int status;
-  xwaitpid (pid, &status, 0);
-  VERIFY (WIFEXITED (status));
-  int ret = WEXITSTATUS (status);
-  if (ret != 0)
-    return ret;
-
-  /* set 'pid' to the inner child */
-  VERIFY (read (pid_pipe[0], &pid, sizeof pid) == sizeof pid);
-  xclose (pid_pipe[0]);
-
-  /* wait for the inner child */
-  xwaitpid (pid, &status, 0);
-  VERIFY (WIFEXITED (status));
-  xclose (master);
-  return WEXITSTATUS (status);
-}
-
-/* main test */
-
-static int
-run_chroot_tests (const char *slavename, int slave)
-{
-  struct stat st;
-  bool ok = true;
-
-  /* There are 3 groups of tests here.  The first group fairly
-     generically does things known to mess up ttyname, and verifies
-     that ttyname copes correctly.  The remaining groups are
-     increasingly convoluted, as we target specific parts of ttyname
-     to try to confuse.  */
-
-  /* Basic tests that it doesn't get confused by multiple devpts
-     instances.  */
-  {
-    VERIFY (stat (slavename, &st) < 0); /* sanity check */
-    if (!doit (slave, "no conflict, no match",
-               (struct result_r){.name=NULL, .ret=ENODEV, .err=ENODEV}))
-      ok = false;
-    VERIFY (mount ("/console", "/dev/console", NULL, MS_BIND, NULL) == 0);
-    if (!doit (slave, "no conflict, console",
-               (struct result_r){.name="/dev/console", .ret=0, .err=0}))
-      ok = false;
-    VERIFY (umount ("/dev/console") == 0);
-
-    /* Keep creating PTYs until we we get a name collision.  */
-    while (true)
-      {
-	if (stat (slavename, &st) == 0)
-	  break;
-	if (posix_openpt (O_RDWR|O_NOCTTY|O_NONBLOCK) < 0)
-	  {
-	    if (errno == ENOSPC || errno == EMFILE || errno == ENFILE)
-	      FAIL_UNSUPPORTED ("cannot re-create PTY \"%s\" in chroot: %m"
-				" (consider increasing limits)", slavename);
-	    else
-	      FAIL_EXIT1 ("cannot re-create PTY \"%s\" chroot: %m", slavename);
-	  }
-      }
-
-    if (!doit (slave, "conflict, no match",
-               (struct result_r){.name=NULL, .ret=ENODEV, .err=ENODEV}))
-      ok = false;
-    VERIFY (mount ("/console", "/dev/console", NULL, MS_BIND, NULL) == 0);
-    if (!doit (slave, "conflict, console",
-               (struct result_r){.name="/dev/console", .ret=0, .err=0}))
-      ok = false;
-    VERIFY (umount ("/dev/console") == 0);
-  }
-
-  /* The first tests kinda assumed that they hit certain code-paths
-     based on assuming that the readlink target is 'slavename', but
-     that's not quite always true.  They're still a good preliminary
-     sanity check, so keep them, but let's add tests that make sure
-     that those code-paths are hit by doing a readlink ourself.  */
-  {
-    char *linkname = xasprintf ("/proc/self/fd/%d", slave);
-    char *target = proc_fd_readlink (linkname);
-    free (linkname);
-    /* Depending on how we set up the chroot, the kernel may or may not
-       trim the leading path to the target (it may give us "/6",
-       instead of "/dev/pts/6").  We test it both ways (do_in_chroot_1
-       and do_in_chroot_2).  This test group relies on the target
-       existing, so guarantee that it does exist by creating it if
-       necessary.  */
-    if (stat (target, &st) < 0)
-      {
-        VERIFY (errno == ENOENT);
-        touch (target, 0);
-      }
-
-    VERIFY (mount ("/console", "/dev/console", NULL, MS_BIND, NULL) == 0);
-    VERIFY (mount ("/console", target, NULL, MS_BIND, NULL) == 0);
-    if (!doit (slave, "with readlink target",
-               (struct result_r){.name=target, .ret=0, .err=0}))
-      ok = false;
-    VERIFY (umount (target) == 0);
-    VERIFY (umount ("/dev/console") == 0);
-
-    VERIFY (mount ("/console", "/dev/console", NULL, MS_BIND, NULL) == 0);
-    VERIFY (mount (slavename, target, NULL, MS_BIND, NULL) == 0);
-    if (!doit (slave, "with readlink trap; fallback",
-               (struct result_r){.name="/dev/console", .ret=0, .err=0}))
-      ok = false;
-    VERIFY (umount (target) == 0);
-    VERIFY (umount ("/dev/console") == 0);
-
-    VERIFY (mount (slavename, target, NULL, MS_BIND, NULL) == 0);
-    if (!doit (slave, "with readlink trap; no fallback",
-               (struct result_r){.name=NULL, .ret=ENODEV, .err=ENODEV}))
-      ok = false;
-    VERIFY (umount (target) == 0);
-  }
-
-  /* This test makes sure that everything still works OK if readdir
-     finds a pseudo-match before and/or after the actual match.  Now,
-     to do that, we need to control that readdir finds the
-     pseudo-matches before and after the actual match; and there's no
-     good way to control that order in absence of whitebox testing.
-     So, just create 3 files, then use opendir/readdir to see what
-     order they are in, and assign meaning based on that order, not by
-     name; assigning the first to be a pseudo-match, the second to be
-     the actual match, and the third to be a pseudo-match.  This
-     assumes that (on tmpfs) ordering within the directory is stable
-     in the absence of modification, which seems reasonably safe.  */
-  {
-    /* since we're testing the fallback search, disable the readlink
-       happy-path */
-    VERIFY (umount2 ("/proc", MNT_DETACH) == 0);
-
-    touch ("/dev/console1", 0);
-    touch ("/dev/console2", 0);
-    touch ("/dev/console3", 0);
-
-    char *c[3];
-    int ci = 0;
-    DIR *dirstream = opendir ("/dev");
-    VERIFY (dirstream != NULL);
-    struct dirent *d;
-    while ((d = readdir (dirstream)) != NULL && ci < 3)
-      {
-        if (strcmp (d->d_name, "console1")
-            && strcmp (d->d_name, "console2")
-            && strcmp (d->d_name, "console3") )
-          continue;
-        c[ci++] = xasprintf ("/dev/%s", d->d_name);
-      }
-    VERIFY (ci == 3);
-    VERIFY (closedir (dirstream) == 0);
-
-    VERIFY (mount (slavename, c[0], NULL, MS_BIND, NULL) == 0);
-    VERIFY (mount ("/console", c[1], NULL, MS_BIND, NULL) == 0);
-    VERIFY (mount (slavename, c[2], NULL, MS_BIND, NULL) == 0);
-    VERIFY (umount2 ("/dev/pts", MNT_DETACH) == 0);
-    if (!doit (slave, "with search-path trap",
-               (struct result_r){.name=c[1], .ret=0, .err=0}))
-      ok = false;
-    for (int i = 0; i < 3; i++)
-      {
-        VERIFY (umount (c[i]) == 0);
-        VERIFY (unlink (c[i]) == 0);
-        free (c[i]);
-      }
-  }
-
-  return ok ? 0 : 1;
-}
-
 static int
 do_test (void)
 {
   support_become_root ();
 
-  int ret1 = do_in_chroot_1 (run_chroot_tests);
-  if (ret1 == EXIT_UNSUPPORTED)
-    return ret1;
-
-  int ret2 = do_in_chroot_2 (run_chroot_tests);
-  if (ret2 == EXIT_UNSUPPORTED)
-    return ret2;
+  do_in_chroot_1 (run_chroot_tests);
 
-  return  ret1 | ret2;
+  return 0;
 }
 
 #include <support/test-driver.c>
-- 
2.34.1