support: Implement <support/descriptors.h> to track file descriptors

1 files changed, 198 insertions, 0 deletions

diff --git a/support/tst-support_descriptors.c b/support/tst-support_descriptors.c
new file mode 100644
index 0000000000..5e9e824bc3
--- /dev/null
+++ b/support/tst-support_descriptors.c
@@ -0,0 +1,198 @@
+/* Tests for monitoring file descriptor usage.
+   Copyright (C) 2018 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 <fcntl.h>
+#include <stdbool.h>
+#include <stdlib.h>
+#include <string.h>
+#include <support/capture_subprocess.h>
+#include <support/check.h>
+#include <support/descriptors.h>
+#include <support/support.h>
+#include <support/xunistd.h>
+
+/* This is the next free descriptor that the subprocess will pick.  */
+static int free_descriptor;
+
+static void
+subprocess_no_change (void *closure)
+{
+  struct support_descriptors *descrs = support_descriptors_list ();
+  int fd = xopen ("/dev/null", O_WRONLY, 0);
+  TEST_COMPARE (fd, free_descriptor);
+  xclose (fd);
+  support_descriptors_free (descrs);
+}
+
+static void
+subprocess_closed_descriptor (void *closure)
+{
+  int fd = xopen ("/dev/null", O_WRONLY, 0);
+  TEST_COMPARE (fd, free_descriptor);
+  struct support_descriptors *descrs = support_descriptors_list ();
+  xclose (fd);
+  support_descriptors_check (descrs); /* Will report failure.  */
+  puts ("EOT");
+  support_descriptors_free (descrs);
+}
+
+static void
+subprocess_opened_descriptor (void *closure)
+{
+  struct support_descriptors *descrs = support_descriptors_list ();
+  int fd = xopen ("/dev/null", O_WRONLY, 0);
+  TEST_COMPARE (fd, free_descriptor);
+  support_descriptors_check (descrs); /* Will report failure.  */
+  puts ("EOT");
+  support_descriptors_free (descrs);
+}
+
+static void
+subprocess_changed_descriptor (void *closure)
+{
+  int fd = xopen ("/dev/null", O_WRONLY, 0);
+  TEST_COMPARE (fd, free_descriptor);
+  struct support_descriptors *descrs = support_descriptors_list ();
+  xclose (fd);
+  TEST_COMPARE (xopen ("/dev", O_DIRECTORY | O_RDONLY, 0), fd);
+  support_descriptors_check (descrs); /* Will report failure.  */
+  puts ("EOT");
+  support_descriptors_free (descrs);
+}
+
+static void
+report_subprocess_output (const char *name,
+                          struct support_capture_subprocess *proc)
+{
+  printf ("info: BEGIN %s output\n"
+          "%s"
+          "info: END %s output\n",
+          name, proc->out.buffer, name);
+}
+
+/* Use an explicit flag to preserve failure status across
+   support_record_failure_reset calls.  */
+static bool good = true;
+
+static void
+test_run (void)
+{
+  struct support_capture_subprocess proc = support_capture_subprocess
+    (&subprocess_no_change, NULL);
+  support_capture_subprocess_check (&proc, "subprocess_no_change",
+                                    0, sc_allow_none);
+  support_capture_subprocess_free (&proc);
+
+  char *expected = xasprintf ("\nDifferences:\n"
+                              "error: descriptor %d was closed\n"
+                              "EOT\n",
+                              free_descriptor);
+  good = good && !support_record_failure_is_failed ();
+  proc = support_capture_subprocess (&subprocess_closed_descriptor, NULL);
+  good = good && support_record_failure_is_failed ();
+  support_record_failure_reset (); /* Discard the reported error.  */
+  report_subprocess_output ("subprocess_closed_descriptor", &proc);
+  TEST_VERIFY (strstr (proc.out.buffer, expected) != NULL);
+  support_capture_subprocess_check (&proc, "subprocess_closed_descriptor",
+                                    0, sc_allow_stdout);
+  support_capture_subprocess_free (&proc);
+  free (expected);
+
+  expected = xasprintf ("\nDifferences:\n"
+                        "error: descriptor %d was opened (\"/dev/null\")\n"
+                        "EOT\n",
+                        free_descriptor);
+  good = good && !support_record_failure_is_failed ();
+  proc = support_capture_subprocess (&subprocess_opened_descriptor, NULL);
+  good = good && support_record_failure_is_failed ();
+  support_record_failure_reset (); /* Discard the reported error.  */
+  report_subprocess_output ("subprocess_opened_descriptor", &proc);
+  TEST_VERIFY (strstr (proc.out.buffer, expected) != NULL);
+  support_capture_subprocess_check (&proc, "subprocess_opened_descriptor",
+                                    0, sc_allow_stdout);
+  support_capture_subprocess_free (&proc);
+  free (expected);
+
+  expected = xasprintf ("\nDifferences:\n"
+                        "error: descriptor %d changed from \"/dev/null\""
+                        " to \"/dev\"\n"
+                        "error: descriptor %d changed ino ",
+                        free_descriptor, free_descriptor);
+  good = good && !support_record_failure_is_failed ();
+  proc = support_capture_subprocess (&subprocess_changed_descriptor, NULL);
+  good = good && support_record_failure_is_failed ();
+  support_record_failure_reset (); /* Discard the reported error.  */
+  report_subprocess_output ("subprocess_changed_descriptor", &proc);
+  TEST_VERIFY (strstr (proc.out.buffer, expected) != NULL);
+  support_capture_subprocess_check (&proc, "subprocess_changed_descriptor",
+                                    0, sc_allow_stdout);
+  support_capture_subprocess_free (&proc);
+  free (expected);
+}
+
+static int
+do_test (void)
+{
+  puts ("info: initial descriptor set");
+  {
+    struct support_descriptors *descrs = support_descriptors_list ();
+    support_descriptors_dump (descrs, "info:  ", stdout);
+    support_descriptors_free (descrs);
+  }
+
+  free_descriptor = xopen ("/dev/null", O_WRONLY, 0);
+  puts ("info: descriptor set with additional free descriptor");
+  {
+    struct support_descriptors *descrs = support_descriptors_list ();
+    support_descriptors_dump (descrs, "info:  ", stdout);
+    support_descriptors_free (descrs);
+  }
+  TEST_VERIFY (free_descriptor >= 3);
+  xclose (free_descriptor);
+
+  /* Initial test run without a sentinel descriptor.  The presence of
+     such a descriptor exercises different conditions in the list
+     comparison in support_descriptors_check.  */
+  test_run ();
+
+  /* Allocate a sentinel descriptor at the end of the descriptor list,
+     after free_descriptor.  */
+  int sentinel_fd;
+  {
+    int fd = xopen ("/dev/full", O_WRONLY, 0);
+    TEST_COMPARE (fd, free_descriptor);
+    sentinel_fd = dup (fd);
+    TEST_VERIFY_EXIT (sentinel_fd > fd);
+    xclose (fd);
+  }
+  puts ("info: descriptor set with sentinel descriptor");
+  {
+    struct support_descriptors *descrs = support_descriptors_list ();
+    support_descriptors_dump (descrs, "info:  ", stdout);
+    support_descriptors_free (descrs);
+  }
+
+  /* Second test run with sentinel descriptor.  */
+  test_run ();
+
+  xclose (sentinel_fd);
+
+  return !good;
+}
+
+#include <support/test-driver.c>