1 files changed, 152 insertions, 0 deletions
diff --git a/io/tst-closefrom.c b/io/tst-closefrom.c
new file mode 100644
index 0000000000..d4c187073c
--- /dev/null
+++ b/io/tst-closefrom.c
@@ -0,0 +1,152 @@
+/* Smoke test for the closefrom.
+   Copyright (C) 2021 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
+   <https://www.gnu.org/licenses/>.  */
+
+#include <errno.h>
+#include <fcntl.h>
+#include <sys/resource.h>
+#include <unistd.h>
+
+#include <support/check.h>
+#include <support/descriptors.h>
+#include <support/xunistd.h>
+
+#include <array_length.h>
+
+#define NFDS 100
+
+static int
+open_multiple_temp_files (void)
+{
+  /* Check if the temporary file descriptor has no no gaps.  */
+  int lowfd = xopen ("/dev/null", O_RDONLY, 0600);
+  for (int i = 1; i <= NFDS; i++)
+    TEST_COMPARE (xopen ("/dev/null", O_RDONLY, 0600), lowfd + i);
+  return lowfd;
+}
+
+static int
+closefrom_test (void)
+{
+  struct support_descriptors *descrs = support_descriptors_list ();
+
+  int lowfd = open_multiple_temp_files ();
+
+  const int maximum_fd = lowfd + NFDS;
+  const int half_fd = lowfd + NFDS / 2;
+  const int gap = maximum_fd / 4;
+
+  /* Close half of the descriptors and check result.  */
+  closefrom (half_fd);
+
+  for (int i = half_fd; i <= maximum_fd; i++)
+    {
+      TEST_COMPARE (fcntl (i, F_GETFL), -1);
+      TEST_COMPARE (errno, EBADF);
+    }
+  for (int i = 0; i < half_fd; i++)
+    TEST_VERIFY (fcntl (i, F_GETFL) > -1);
+
+  /* Create some gaps, close up to a threshold, and check result.  */
+  xclose (lowfd + 35);
+  xclose (lowfd + 38);
+  xclose (lowfd + 42);
+  xclose (lowfd + 46);
+
+  /* Close half of the descriptors and check result.  */
+  closefrom (gap);
+  for (int i = gap + 1; i < maximum_fd; i++)
+    {
+      TEST_COMPARE (fcntl (i, F_GETFL), -1);
+      TEST_COMPARE (errno, EBADF);
+    }
+  for (int i = 0; i < gap; i++)
+    TEST_VERIFY (fcntl (i, F_GETFL) > -1);
+
+  /* Close the remmaining but the last one.  */
+  closefrom (lowfd + 1);
+  for (int i = lowfd + 1; i <= maximum_fd; i++)
+    {
+      TEST_COMPARE (fcntl (i, F_GETFL), -1);
+      TEST_COMPARE (errno, EBADF);
+    }
+  TEST_VERIFY (fcntl (lowfd, F_GETFL) > -1);
+
+  /* Close the last one.  */
+  closefrom (lowfd);
+  TEST_COMPARE (fcntl (lowfd, F_GETFL), -1);
+  TEST_COMPARE (errno, EBADF);
+
+  /* Double check by check the /proc.  */
+  support_descriptors_check (descrs);
+  support_descriptors_free (descrs);
+
+  return 0;
+}
+
+/* Check if closefrom works even when no new file descriptors can be
+   created.  */
+static int
+closefrom_test_file_desc_limit (void)
+{
+  int max_fd = NFDS;
+  {
+    struct rlimit rl;
+    if (getrlimit (RLIMIT_NOFILE, &rl) == -1)
+      FAIL_EXIT1 ("getrlimit (RLIMIT_NOFILE): %m");
+
+    max_fd = (rl.rlim_cur < max_fd ? rl.rlim_cur : max_fd);
+    rl.rlim_cur = max_fd;
+
+    if (setrlimit (RLIMIT_NOFILE, &rl) == 1)
+      FAIL_EXIT1 ("setrlimit (RLIMIT_NOFILE): %m");
+  }
+
+  /* Exhauste the file descriptor limit.  */
+  int lowfd = xopen ("/dev/null", O_RDONLY, 0600);
+  for (;;)
+    {
+      int fd = open ("/dev/null", O_RDONLY, 0600);
+      if (fd == -1)
+	{
+	  if (errno != EMFILE)
+	    FAIL_EXIT1 ("open: %m");
+	  break;
+	}
+      TEST_VERIFY_EXIT (fd < max_fd);
+    }
+
+  closefrom (lowfd);
+  for (int i = lowfd; i < NFDS; i++)
+    {
+      TEST_COMPARE (fcntl (i, F_GETFL), -1);
+      TEST_COMPARE (errno, EBADF);
+    }
+
+  return 0;
+}
+
+static int
+do_test (void)
+{
+  closefrom_test ();
+  closefrom_test_file_desc_limit ();
+
+  return 0;
+}
+
+#include <support/test-driver.c>