diff mbox series

Linux: Do not skip d_ino == 0 entries in readdir, readdir64 (bug 12165)

Message ID 87o7vbj1kz.fsf@oldenburg.str.redhat.com
State New
Headers show
Series Linux: Do not skip d_ino == 0 entries in readdir, readdir64 (bug 12165) | expand

Commit Message

Florian Weimer Sept. 19, 2022, 6:54 a.m. UTC 
POSIX does not say this value is special.  For example, old XFS file
systems may still use inode number zero.

Also update the comment regarding ENOENT.  Linux may return ENOENT
for some file systems.

Tested on i686-linux-gnu and x86_64-linux-gnu.

---
 sysdeps/unix/sysv/linux/readdir.c   |  57 +++++++----------
 sysdeps/unix/sysv/linux/readdir64.c | 120 +++++++++++++++---------------------
 2 files changed, 69 insertions(+), 108 deletions(-)


base-commit: 2ff6775ad341b10a08e3b27d6e1df1da637747c7

Comments

Andreas Schwab Sept. 19, 2022, 8:26 a.m. UTC | #1 
On Sep 19 2022, Florian Weimer via Libc-alpha wrote:

> -	  if (bytes <= 0)
> -	    {
> -	      /* On some systems getdents fails with ENOENT when the

Shouldn't that be "some file systems"?

> -		 open directory has been rmdir'd already.  POSIX.1
> -		 requires that we treat this condition like normal EOF.  */
> -	      if (bytes < 0 && errno == ENOENT)
> -		bytes = 0;
> -
> -	      /* Don't modifiy errno when reaching EOF.  */
> -	      if (bytes == 0)
> -		__set_errno (saved_errno);
> -	      dp = NULL;
> -	      break;
> -	    }
> -	  dirp->size = (size_t) bytes;
> -
> -	  /* Reset the offset into the buffer.  */
> -	  dirp->offset = 0;
> +	  /* Linux fails with ENOENT if IS_DEADDIR is true for the

What is IS_DEADDIR?
Florian Weimer Sept. 19, 2022, 8:30 a.m. UTC | #2 
* Andreas Schwab:

> On Sep 19 2022, Florian Weimer via Libc-alpha wrote:
>
>> -	  if (bytes <= 0)
>> -	    {
>> -	      /* On some systems getdents fails with ENOENT when the
>
> Shouldn't that be "some file systems"?
>
>> -		 open directory has been rmdir'd already.  POSIX.1
>> -		 requires that we treat this condition like normal EOF.  */
>> -	      if (bytes < 0 && errno == ENOENT)
>> -		bytes = 0;
>> -
>> -	      /* Don't modifiy errno when reaching EOF.  */
>> -	      if (bytes == 0)
>> -		__set_errno (saved_errno);
>> -	      dp = NULL;
>> -	      break;
>> -	    }
>> -	  dirp->size = (size_t) bytes;
>> -
>> -	  /* Reset the offset into the buffer.  */
>> -	  dirp->offset = 0;
>> +	  /* Linux fails with ENOENT if IS_DEADDIR is true for the
>
> What is IS_DEADDIR?

It's an internal Linux construct.  Isn't this clear from the context?

Thanks,
Florian
Andreas Schwab Sept. 19, 2022, 8:53 a.m. UTC | #3 
On Sep 19 2022, Florian Weimer wrote:

> * Andreas Schwab:
>
>> On Sep 19 2022, Florian Weimer via Libc-alpha wrote:
>>
>>> -	  if (bytes <= 0)
>>> -	    {
>>> -	      /* On some systems getdents fails with ENOENT when the
>>
>> Shouldn't that be "some file systems"?
>>
>>> -		 open directory has been rmdir'd already.  POSIX.1
>>> -		 requires that we treat this condition like normal EOF.  */
>>> -	      if (bytes < 0 && errno == ENOENT)
>>> -		bytes = 0;
>>> -
>>> -	      /* Don't modifiy errno when reaching EOF.  */
>>> -	      if (bytes == 0)
>>> -		__set_errno (saved_errno);
>>> -	      dp = NULL;
>>> -	      break;
>>> -	    }
>>> -	  dirp->size = (size_t) bytes;
>>> -
>>> -	  /* Reset the offset into the buffer.  */
>>> -	  dirp->offset = 0;
>>> +	  /* Linux fails with ENOENT if IS_DEADDIR is true for the
>>
>> What is IS_DEADDIR?
>
> It's an internal Linux construct.  Isn't this clear from the context?

I'd rather keep the original comment with the missing word added.  I
find it easier to understand without the reference to kernel internals.
Florian Weimer Sept. 19, 2022, 9:30 a.m. UTC | #4 
* Andreas Schwab:

> On Sep 19 2022, Florian Weimer wrote:
>
>> * Andreas Schwab:
>>
>>> On Sep 19 2022, Florian Weimer via Libc-alpha wrote:
>>>
>>>> -	  if (bytes <= 0)
>>>> -	    {
>>>> -	      /* On some systems getdents fails with ENOENT when the
>>>
>>> Shouldn't that be "some file systems"?
>>>
>>>> -		 open directory has been rmdir'd already.  POSIX.1
>>>> -		 requires that we treat this condition like normal EOF.  */
>>>> -	      if (bytes < 0 && errno == ENOENT)
>>>> -		bytes = 0;
>>>> -
>>>> -	      /* Don't modifiy errno when reaching EOF.  */
>>>> -	      if (bytes == 0)
>>>> -		__set_errno (saved_errno);
>>>> -	      dp = NULL;
>>>> -	      break;
>>>> -	    }
>>>> -	  dirp->size = (size_t) bytes;
>>>> -
>>>> -	  /* Reset the offset into the buffer.  */
>>>> -	  dirp->offset = 0;
>>>> +	  /* Linux fails with ENOENT if IS_DEADDIR is true for the
>>>
>>> What is IS_DEADDIR?
>>
>> It's an internal Linux construct.  Isn't this clear from the context?
>
> I'd rather keep the original comment with the missing word added.  I
> find it easier to understand without the reference to kernel internals.

What about this?

	  /* Linux may fail with ENOENT on some file systems if the
	     directory inode is marked as dead (deleted).  POSIX
	     treats this as a regular end-of-directory condition, so
	     do not set errno in that case, to indicate success.  */

Thanks,
Florian
Andreas Schwab Sept. 19, 2022, 9:58 a.m. UTC | #5 
On Sep 19 2022, Florian Weimer wrote:

> What about this?
>
> 	  /* Linux may fail with ENOENT on some file systems if the
> 	     directory inode is marked as dead (deleted).  POSIX
> 	     treats this as a regular end-of-directory condition, so
> 	     do not set errno in that case, to indicate success.  */

Ok.
diff mbox series

Patch

diff --git a/sysdeps/unix/sysv/linux/readdir.c b/sysdeps/unix/sysv/linux/readdir.c
index b480135164..15f0033f36 100644
--- a/sysdeps/unix/sysv/linux/readdir.c
+++ b/sysdeps/unix/sysv/linux/readdir.c
@@ -28,48 +28,33 @@  __readdir_unlocked (DIR *dirp)
   struct dirent *dp;
   int saved_errno = errno;
 
-  do
+  if (dirp->offset >= dirp->size)
     {
-      size_t reclen;
+      /* We've emptied out our buffer.  Refill it.  */
 
-      if (dirp->offset >= dirp->size)
+      size_t maxread = dirp->allocation;
+      ssize_t bytes;
+
+      bytes = __getdents (dirp->fd, dirp->data, maxread);
+      if (bytes <= 0)
 	{
-	  /* We've emptied out our buffer.  Refill it.  */
-
-	  size_t maxread = dirp->allocation;
-	  ssize_t bytes;
-
-	  bytes = __getdents (dirp->fd, dirp->data, maxread);
-	  if (bytes <= 0)
-	    {
-	      /* On some systems getdents fails with ENOENT when the
-		 open directory has been rmdir'd already.  POSIX.1
-		 requires that we treat this condition like normal EOF.  */
-	      if (bytes < 0 && errno == ENOENT)
-		bytes = 0;
-
-	      /* Don't modifiy errno when reaching EOF.  */
-	      if (bytes == 0)
-		__set_errno (saved_errno);
-	      dp = NULL;
-	      break;
-	    }
-	  dirp->size = (size_t) bytes;
-
-	  /* Reset the offset into the buffer.  */
-	  dirp->offset = 0;
+	  /* Linux fails with ENOENT if IS_DEADDIR is true for the
+	     directory inode.  POSIX treats this as a regular
+	     end-of-directory condition, so do not set errno in that
+	     case, to indicate success.  */
+	  if (bytes == 0 || errno == ENOENT)
+	    __set_errno (saved_errno);
+	  return NULL;
 	}
+      dirp->size = (size_t) bytes;
 
-      dp = (struct dirent *) &dirp->data[dirp->offset];
+      /* Reset the offset into the buffer.  */
+      dirp->offset = 0;
+    }
 
-      reclen = dp->d_reclen;
-
-      dirp->offset += reclen;
-
-      dirp->filepos = dp->d_off;
-
-      /* Skip deleted files.  */
-    } while (dp->d_ino == 0);
+  dp = (struct dirent *) &dirp->data[dirp->offset];
+  dirp->offset += dp->d_reclen;
+  dirp->filepos = dp->d_off;
 
   return dp;
 }
diff --git a/sysdeps/unix/sysv/linux/readdir64.c b/sysdeps/unix/sysv/linux/readdir64.c
index 52b11eb9d9..f56c3c0d8e 100644
--- a/sysdeps/unix/sysv/linux/readdir64.c
+++ b/sysdeps/unix/sysv/linux/readdir64.c
@@ -37,48 +37,36 @@  __readdir64 (DIR *dirp)
   __libc_lock_lock (dirp->lock);
 #endif
 
-  do
+  if (dirp->offset >= dirp->size)
     {
-      size_t reclen;
+      /* We've emptied out our buffer.  Refill it.  */
 
-      if (dirp->offset >= dirp->size)
+      size_t maxread = dirp->allocation;
+      ssize_t bytes;
+
+      bytes = __getdents64 (dirp->fd, dirp->data, maxread);
+      if (bytes <= 0)
 	{
-	  /* We've emptied out our buffer.  Refill it.  */
-
-	  size_t maxread = dirp->allocation;
-	  ssize_t bytes;
-
-	  bytes = __getdents64 (dirp->fd, dirp->data, maxread);
-	  if (bytes <= 0)
-	    {
-	      /* On some systems getdents fails with ENOENT when the
-		 open directory has been rmdir'd already.  POSIX.1
-		 requires that we treat this condition like normal EOF.  */
-	      if (bytes < 0 && errno == ENOENT)
-		bytes = 0;
-
-	      /* Don't modifiy errno when reaching EOF.  */
-	      if (bytes == 0)
-		__set_errno (saved_errno);
-	      dp = NULL;
-	      break;
-	    }
-	  dirp->size = (size_t) bytes;
-
-	  /* Reset the offset into the buffer.  */
-	  dirp->offset = 0;
+	  /* Linux fails with ENOENT if IS_DEADDIR is true for the
+	     directory inode.  POSIX treats this as a regular
+	     end-of-directory condition, so do not set errno in that
+	     case, to indicate success.  */
+	  if (bytes == 0 || errno == ENOENT)
+	    __set_errno (saved_errno);
+#if IS_IN (libc)
+	  __libc_lock_unlock (dirp->lock);
+#endif
+	  return NULL;
 	}
+      dirp->size = (size_t) bytes;
 
-      dp = (struct dirent64 *) &dirp->data[dirp->offset];
+      /* Reset the offset into the buffer.  */
+      dirp->offset = 0;
+    }
 
-      reclen = dp->d_reclen;
-
-      dirp->offset += reclen;
-
-      dirp->filepos = dp->d_off;
-
-      /* Skip deleted files.  */
-    } while (dp->d_ino == 0);
+  dp = (struct dirent64 *) &dirp->data[dirp->offset];
+  dirp->offset += dp->d_reclen;
+  dirp->filepos = dp->d_off;
 
 #if IS_IN (libc)
   __libc_lock_unlock (dirp->lock);
@@ -115,48 +103,36 @@  __old_readdir64 (DIR *dirp)
   __libc_lock_lock (dirp->lock);
 #endif
 
-  do
+  if (dirp->offset >= dirp->size)
     {
-      size_t reclen;
+      /* We've emptied out our buffer.  Refill it.  */
 
-      if (dirp->offset >= dirp->size)
+      size_t maxread = dirp->allocation;
+      ssize_t bytes;
+
+      bytes = __old_getdents64 (dirp->fd, dirp->data, maxread);
+      if (bytes <= 0)
 	{
-	  /* We've emptied out our buffer.  Refill it.  */
-
-	  size_t maxread = dirp->allocation;
-	  ssize_t bytes;
-
-	  bytes = __old_getdents64 (dirp->fd, dirp->data, maxread);
-	  if (bytes <= 0)
-	    {
-	      /* On some systems getdents fails with ENOENT when the
-		 open directory has been rmdir'd already.  POSIX.1
-		 requires that we treat this condition like normal EOF.  */
-	      if (bytes < 0 && errno == ENOENT)
-		bytes = 0;
-
-	      /* Don't modifiy errno when reaching EOF.  */
-	      if (bytes == 0)
-		__set_errno (saved_errno);
-	      dp = NULL;
-	      break;
-	    }
-	  dirp->size = (size_t) bytes;
-
-	  /* Reset the offset into the buffer.  */
-	  dirp->offset = 0;
+	  /* Linux fails with ENOENT if IS_DEADDIR is true for the
+	     directory inode.  POSIX treats this as a regular
+	     end-of-directory condition, so do not set errno in that
+	     case, to indicate success.  */
+	  if (bytes == 0 || errno == ENOENT)
+	    __set_errno (saved_errno);
+#if IS_IN (libc)
+	  __libc_lock_unlock (dirp->lock);
+#endif
+	  return NULL;
 	}
+      dirp->size = (size_t) bytes;
 
-      dp = (struct __old_dirent64 *) &dirp->data[dirp->offset];
+      /* Reset the offset into the buffer.  */
+      dirp->offset = 0;
+    }
 
-      reclen = dp->d_reclen;
-
-      dirp->offset += reclen;
-
-      dirp->filepos = dp->d_off;
-
-      /* Skip deleted files.  */
-    } while (dp->d_ino == 0);
+  dp = (struct __old_dirent64 *) &dirp->data[dirp->offset];
+  dirp->offset += dp->d_reclen;
+  dirp->filepos = dp->d_off;
 
 #if IS_IN (libc)
   __libc_lock_unlock (dirp->lock);