Linux: Add getdents64 system call

No 32-bit system call wrapper is added because the interface
is problematic because it cannot deal with 64-bit inode numbers
and 64-bit directory hashes.

A future commit will deprecate the undocumented getdirentries
and getdirentries64 functions.

Reviewed-by: Carlos O'Donell <carlos@redhat.com>

1 files changed, 113 insertions, 0 deletions

diff --git a/sysdeps/unix/sysv/linux/tst-getdents64.c b/sysdeps/unix/sysv/linux/tst-getdents64.c
new file mode 100644
index 0000000000..c1f7721221
--- /dev/null
+++ b/sysdeps/unix/sysv/linux/tst-getdents64.c
@@ -0,0 +1,113 @@
+/* Test for reading directories with getdents64.
+   Copyright (C) 2019 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 <dirent.h>
+#include <errno.h>
+#include <fcntl.h>
+#include <stdbool.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <support/check.h>
+#include <support/support.h>
+#include <support/xunistd.h>
+#include <unistd.h>
+
+static int
+do_test (void)
+{
+  /* The test compares the iteration order with readdir64.  */
+  DIR *reference = opendir (".");
+  TEST_VERIFY_EXIT (reference != NULL);
+
+  int fd = xopen (".", O_RDONLY | O_DIRECTORY, 0);
+  TEST_VERIFY (fd >= 0);
+
+  /* Perform two passes, with a rewind operating between passes.  */
+  for (int pass = 0; pass < 2; ++pass)
+    {
+      /* Check that we need to fill the buffer multiple times.  */
+      int read_count = 0;
+
+      while (true)
+        {
+          /* Simple way to make sure that the memcpy below does not read
+             non-existing data.  */
+          struct
+          {
+            char buffer[1024];
+            struct dirent64 pad;
+          } data;
+
+          ssize_t ret = getdents64 (fd, &data.buffer, sizeof (data.buffer));
+          if (ret < 0)
+            FAIL_EXIT1 ("getdents64: %m");
+          if (ret == 0)
+            break;
+          ++read_count;
+
+          char *current = data.buffer;
+          char *end = data.buffer + ret;
+          while (current != end)
+            {
+              struct dirent64 entry;
+              memcpy (&entry, current, sizeof (entry));
+              /* Truncate overlong strings.  */
+              entry.d_name[sizeof (entry.d_name) - 1] = '\0';
+              TEST_VERIFY (strlen (entry.d_name) < sizeof (entry.d_name) - 1);
+
+              errno = 0;
+              struct dirent64 *refentry = readdir64 (reference);
+              if (refentry == NULL && errno == 0)
+                FAIL_EXIT1 ("readdir64 failed too early, at: %s",
+                            entry.d_name);
+              else if (refentry == NULL)
+                FAIL_EXIT1 ("readdir64: %m");
+
+              TEST_COMPARE_STRING (entry.d_name, refentry->d_name);
+              TEST_COMPARE (entry.d_ino, refentry->d_ino);
+              TEST_COMPARE (entry.d_off, refentry->d_off);
+              TEST_COMPARE (entry.d_type, refentry->d_type);
+
+              /* Offset zero is reserved for the first entry.  */
+              TEST_VERIFY (entry.d_off != 0);
+
+              TEST_VERIFY_EXIT (entry.d_reclen <= end - current);
+              current += entry.d_reclen;
+            }
+        }
+
+      /* We expect to have reached the end of the stream.  */
+      errno = 0;
+      TEST_VERIFY (readdir64 (reference) == NULL);
+      TEST_COMPARE (errno, 0);
+
+      /* direntries_read has been called more than once.  */
+      TEST_VERIFY (read_count > 0);
+
+      /* Rewind both directory streams.  */
+      xlseek (fd, 0, SEEK_SET);
+      rewinddir (reference);
+    }
+
+  xclose (fd);
+  closedir (reference);
+  return 0;
+}
+
+#include <support/test-driver.c>