[v4,12/13] dirent: Add tst-rewinddir

  It verifies that rewinddir allows restarting the directory
iteration.
---
 dirent/Makefile        |   1 +
 dirent/tst-rewinddir.c | 207 +++++++++++++++++++++++++++++++++++++++++
 2 files changed, 208 insertions(+)
 create mode 100644 dirent/tst-rewinddir.c
  

Florian Weimer <fweimer@redhat.com> writes:
> It verifies that rewinddir allows restarting the directory
> iteration.

LGTM with the usual atomic/volatile question.
Reviewed-by: DJ Delorie <dj@redhat.com>

> diff --git a/dirent/Makefile b/dirent/Makefile
> +  tst-rewinddir \

Ok.

> diff --git a/dirent/tst-rewinddir.c b/dirent/tst-rewinddir.c
> new file mode 100644
> index 0000000000..1479766ebe
> --- /dev/null
> +++ b/dirent/tst-rewinddir.c
> @@ -0,0 +1,207 @@
> +/* Test for rewinddir, using FUSE.
> +   Copyright (C) 2024 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 <dirent.h>
> +#include <stdio.h>
> +#include <stdlib.h>
> +#include <support/check.h>
> +#include <support/fuse.h>
> +#include <support/readdir.h>
> +#include <support/support.h>
> +#include <support/xdirent.h>

Ok.

> +/* Return the file name at the indicated directory offset.  */
> +static char *
> +name_at_offset (unsigned int offset)
> +{
> +  if (offset <= 1)
> +    return xstrdup (".." + !offset); /* "." or "..".  */
> +  else
> +    /* Pad the name with a lot of zeros, so that the dirent buffer gets
> +       filled more quickly.  */
> +    return xasprintf ("file%0240u", offset);
> +}

Ok.

> +/* This many directory entries, including "." and "..".  */
> +enum { directory_entries = 200 };

Ok.

> +/* Add the directory entry at OFFSET to the stream D.  */
> +static uint64_t
> +add_directory_entry (struct support_fuse_dirstream *d, uint64_t offset)
> +{
> +  if (offset >= directory_entries)
> +    return 0;
> +
> +  char *name = name_at_offset (offset);
> +  uint64_t ino = 1000 + offset; /* Arbitrary value, distinct from 1.  */
> +  uint32_t type = DT_REG;
> +  if (offset <= 1)
> +    {
> +      type = DT_DIR;
> +      ino = 1;
> +    }
> +
> +  ++offset;
> +  bool added = support_fuse_dirstream_add (d, ino, offset, type, name);
> +  free (name);
> +  if (added)
> +    return offset;
> +  else
> +    return 0;
> +}

Ok.

> +/* Set to true if getdents64 should produce only one entry.  */
> +static bool one_entry_per_getdents64;

Ok but the usual atomics/volatile question.

> +static void
> +fuse_thread (struct support_fuse *f, void *closure)
> +{
> +  struct fuse_in_header *inh;
> +  while ((inh = support_fuse_next (f)) != NULL)
> +    {
> +      if (support_fuse_handle_mountpoint (f)
> +          || (inh->nodeid == 1 && support_fuse_handle_directory (f)))
> +        continue;
> +      switch (inh->opcode)
> +        {

Ok.

> +        case FUSE_READDIR:
> +          if (inh->nodeid == 1)
> +            {
> +              uint64_t offset = support_fuse_cast (READ, inh)->offset;
> +              struct support_fuse_dirstream *d
> +                = support_fuse_prepare_readdir (f);
> +              while (true)
> +                {
> +                  offset = add_directory_entry (d, offset);
> +                  if (offset == 0 || one_entry_per_getdents64)
> +                    break;
> +                }
> +              support_fuse_reply_prepared (f);
> +            }

Ok.

> +          else
> +            support_fuse_reply_error (f, EIO);
> +          break;
> +        default:
> +          FAIL ("unexpected event %s", support_fuse_opcode (inh->opcode));
> +          support_fuse_reply_error (f, EIO);
> +        }
> +    }
> +}

Ok.

> +/* Lists the entire directory from start to end.  */
> +static void
> +verify_directory (DIR *dir, enum support_readdir_op op)
> +{
> +  struct support_dirent e = { 0, };
> +
> +  TEST_VERIFY (support_readdir (dir, op, &e));
> +  TEST_COMPARE_STRING (e.d_name, ".");
> +  TEST_VERIFY (support_readdir (dir, op, &e));
> +  TEST_COMPARE_STRING (e.d_name, "..");
> +  for (int i = 2; i < directory_entries; ++i)
> +    {
> +      char *expected = name_at_offset (i);
> +      TEST_VERIFY (support_readdir (dir, op, &e));
> +      TEST_COMPARE_STRING (e.d_name, expected);
> +      free (expected);
> +    }
> +  TEST_VERIFY (!support_readdir (dir, op, &e));
> +  free (e.d_name);
> +}

Ok.

> +/* Run tests with rewinding after ENTRIES readdir calls.  */
> +static void
> +rewind_after (unsigned int rewind_at)
> +{
> +  for (enum support_readdir_op op = 0; op <= support_readdir_op_last (); ++op)
> +    {
> +      printf ("info: testing %s (rewind_at=%u)\n",
> +              support_readdir_function (op), rewind_at);
> +
> +      struct support_fuse *f = support_fuse_mount (fuse_thread, NULL);
> +      DIR *dir = xopendir (support_fuse_mountpoint (f));
> +      struct support_dirent e = { 0, };

Ok.

> +      switch (rewind_at)
> +        {
> +        case 0:
> +          break;
> +        case 1:
> +          TEST_VERIFY (support_readdir (dir, op, &e));
> +          TEST_COMPARE_STRING (e.d_name, ".");
> +          break;
> +        default:
> +          TEST_VERIFY (support_readdir (dir, op, &e));
> +          TEST_COMPARE_STRING (e.d_name, ".");
> +          TEST_VERIFY (support_readdir (dir, op, &e));
> +          TEST_COMPARE_STRING (e.d_name, "..");
> +          for (int i = 2; i < directory_entries; ++i)
> +            {
> +              if (i == rewind_at)
> +                break;
> +              char *expected = name_at_offset (i);
> +              TEST_VERIFY (support_readdir (dir, op, &e));
> +              TEST_COMPARE_STRING (e.d_name, expected);
> +              free (expected);
> +            }
> +          break;
> +        }

Ok.

> +      errno = 0;
> +      rewinddir (dir);
> +      TEST_COMPARE (errno, 0);
> +      verify_directory (dir, op);

Ok.

> +      free (e.d_name);
> +      xclosedir (dir);
> +      support_fuse_unmount (f);
> +    }
> +}

Ok.

> +static int
> +do_test (void)
> +{
> +  support_fuse_init ();
> +
> +  /* One pass without rewinding to verify that the generated directory
> +     content matches expectations.  */
> +  {
> +    struct support_fuse *f = support_fuse_mount (fuse_thread, NULL);
> +    DIR *dir = xopendir (support_fuse_mountpoint (f));
> +    verify_directory (dir, SUPPORT_READDIR64);
> +    xclosedir (dir);
> +    support_fuse_unmount (f);
> +  }

Ok.

> +  for (int do_unbuffered = 0; do_unbuffered < 2; ++do_unbuffered)
> +    {
> +      one_entry_per_getdents64 = do_unbuffered;
> +
> +      for (int i = 0; i < 20; ++i)
> +        rewind_after (i);
> +      rewind_after (50);
> +      rewind_after (100);
> +      rewind_after (150);
> +      rewind_after (180);
> +      rewind_after (199);
> +    }

Ok.

> +
> +  return 0;
> +}
> +
> +#include <support/test-driver.c>

Ok.
  

* DJ Delorie:

> Florian Weimer <fweimer@redhat.com> writes:
>> It verifies that rewinddir allows restarting the directory
>> iteration.
>
> LGTM with the usual atomic/volatile question.
> Reviewed-by: DJ Delorie <dj@redhat.com>

Thanks.  This one doesn't need _Atomic because the FUSE thread is
started anew for every subtest.

Florian