Linux: Rewrite __old_getdents64 [BZ #23497]

Commit 298d0e3129c0b5137f4989275b13fe30d0733c4d ("Consolidate Linux
getdents{64} implementation") broke the implementation because it does
not take into account struct offset differences.

The new implementation is close to the old one, before the
consolidation, but has been cleaned up slightly.

1 files changed, 111 insertions, 0 deletions

diff --git a/sysdeps/unix/sysv/linux/tst-readdir64-compat.c b/sysdeps/unix/sysv/linux/tst-readdir64-compat.c
new file mode 100644
index 0000000..43c4a84
--- /dev/null
+++ b/sysdeps/unix/sysv/linux/tst-readdir64-compat.c
@@ -0,0 +1,111 @@
+/* Test readdir64 compatibility symbol.
+   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 <dirent.h>
+#include <dlfcn.h>
+#include <errno.h>
+#include <shlib-compat.h>
+#include <stdbool.h>
+#include <stdio.h>
+#include <string.h>
+#include <support/check.h>
+
+/* Copied from <olddirent.h>.  */
+struct __old_dirent64
+  {
+    __ino_t d_ino;
+    __off64_t d_off;
+    unsigned short int d_reclen;
+    unsigned char d_type;
+    char d_name[256];
+  };
+
+typedef struct __old_dirent64 *(*compat_readdir64_type) (DIR *);
+
+#if TEST_COMPAT (libc, GLIBC_2_1, GLIBC_2_2)
+struct __old_dirent64 *compat_readdir64 (DIR *);
+compat_symbol_reference (libc, compat_readdir64, readdir64, GLIBC_2_1);
+#endif
+
+static int
+do_test (void)
+{
+#if TEST_COMPAT (libc, GLIBC_2_1, GLIBC_2_2)
+
+  /* Directory stream using the non-compat readdir64 symbol.  The test
+     checks against this.  */
+  DIR *dir_reference = opendir (".");
+  TEST_VERIFY_EXIT (dir_reference != NULL);
+  DIR *dir_test = opendir (".");
+  TEST_VERIFY_EXIT (dir_test != NULL);
+
+  /* This loop assumes that the enumeration order is consistent for
+     two different handles.  Nothing should write to the current
+     directory (in the source tree) while this test runs, so there
+     should not be any difference due to races.  */
+  size_t count = 0;
+  while (true)
+    {
+      errno = 0;
+      struct dirent64 *entry_reference = readdir64 (dir_reference);
+      if (entry_reference == NULL && errno != 0)
+        FAIL_EXIT1 ("readdir64 entry %zu: %m\n", count);
+      struct __old_dirent64 *entry_test = compat_readdir64 (dir_test);
+      if (entry_reference == NULL)
+        {
+          if (errno == EOVERFLOW)
+            {
+              TEST_VERIFY (entry_reference->d_ino
+                           != (__ino_t) entry_reference->d_ino);
+              printf ("info: inode number overflow at entry %zu\n", count);
+              break;
+            }
+          if (errno != 0)
+            FAIL_EXIT1 ("compat readdir64 entry %zu: %m\n", count);
+        }
+
+      /* Check that both streams end at the same time.  */
+      if (entry_reference == NULL)
+        {
+          TEST_VERIFY (entry_test == NULL);
+          break;
+        }
+      else
+        TEST_VERIFY_EXIT (entry_test != NULL);
+
+      /* Check that the entries are the same.  */
+      TEST_COMPARE_BLOB (entry_reference->d_name,
+                         strlen (entry_reference->d_name),
+                         entry_test->d_name, strlen (entry_test->d_name));
+      TEST_COMPARE (entry_reference->d_ino, entry_test->d_ino);
+      TEST_COMPARE (entry_reference->d_off, entry_test->d_off);
+      TEST_COMPARE (entry_reference->d_type, entry_test->d_type);
+      TEST_COMPARE (entry_reference->d_reclen, entry_test->d_reclen);
+
+      ++count;
+    }
+  printf ("info: %zu directory entries found\n", count);
+  TEST_VERIFY (count >= 3);     /* ".", "..", and some source files.  */
+
+  TEST_COMPARE (closedir (dir_test), 0);
+  TEST_COMPARE (closedir (dir_reference), 0);
+#endif
+  return 0;
+}
+
+#include <support/test-driver.c>