support: Introduce new subdirectory for test infrastructure

The new test driver in <support/test-driver.c> has feature parity with
the old one.  The main difference is that its hooking mechanism is
based on functions and function pointers instead of macros.  This
commit also implements a new environment variable, TEST_COREDUMPS,
which disables the code which disables coredumps (that is, it enables
them if the invocation environment has not disabled them).

<test-skeleton.c> defines wrapper functions so that it is possible to
use existing macros with the new-style hook functionality.

This commit changes only a few test cases to the new test driver, to
make sure that it works as expected.

support/temp_file.c

@@ -0,0 +1,125 @@
+/* Temporary file handling for tests.
+   Copyright (C) 1998-2016 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/>.  */
+
+/* This is required to get an mkstemp which can create large files on
+   some 32-bit platforms. */
+#define _FILE_OFFSET_BITS 64
+
+#include <support/temp_file.h>
+#include <support/temp_file-internal.h>
+#include <support/support.h>
+
+#include <paths.h>
+#include <search.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+/* List of temporary files.  */
+static struct temp_name_list
+{
+  struct qelem q;
+  char *name;
+} *temp_name_list;
+
+/* Location of the temporary files.  Set by the test skeleton via
+   support_set_test_dir.  The string is not be freed.  */
+static const char *test_dir = _PATH_TMP;
+
+void
+add_temp_file (const char *name)
+{
+  struct temp_name_list *newp
+    = (struct temp_name_list *) xcalloc (sizeof (*newp), 1);
+  char *newname = strdup (name);
+  if (newname != NULL)
+    {
+      newp->name = newname;
+      if (temp_name_list == NULL)
+	temp_name_list = (struct temp_name_list *) &newp->q;
+      else
+	insque (newp, temp_name_list);
+    }
+  else
+    free (newp);
+}
+
+int
+create_temp_file (const char *base, char **filename)
+{
+  char *fname;
+  int fd;
+
+  fname = (char *) xmalloc (strlen (test_dir) + 1 + strlen (base)
+			    + sizeof ("XXXXXX"));
+  strcpy (stpcpy (stpcpy (stpcpy (fname, test_dir), "/"), base), "XXXXXX");
+
+  fd = mkstemp (fname);
+  if (fd == -1)
+    {
+      printf ("cannot open temporary file '%s': %m\n", fname);
+      free (fname);
+      return -1;
+    }
+
+  add_temp_file (fname);
+  if (filename != NULL)
+    *filename = fname;
+  else
+    free (fname);
+
+  return fd;
+}
+
+/* Helper functions called by the test skeleton follow.  */
+
+void
+support_set_test_dir (const char *path)
+{
+  test_dir = path;
+}
+
+void
+support_delete_temp_files (void)
+{
+  while (temp_name_list != NULL)
+    {
+      remove (temp_name_list->name);
+      free (temp_name_list->name);
+
+      struct temp_name_list *next
+	= (struct temp_name_list *) temp_name_list->q.q_forw;
+      free (temp_name_list);
+      temp_name_list = next;
+    }
+}
+
+void
+support_print_temp_files (FILE *f)
+{
+  if (temp_name_list != NULL)
+    {
+      struct temp_name_list *n;
+      fprintf (f, "temp_files=(\n");
+      for (n = temp_name_list;
+           n != NULL;
+           n = (struct temp_name_list *) n->q.q_forw)
+        fprintf (f, "  '%s'\n", n->name);
+      fprintf (f, ")\n");
+    }
+}