hpfs: replace one-element array with flexible-array member

There is a regular need in the kernel to provide a way to declare having
a dynamically sized set of trailing elements in a structure. Kernel code
should always use “flexible array members”[1] for these cases. The older
style of one-element or zero-length arrays should no longer be used[2].

Also, this helps with the ongoing efforts to enable -Warray-bounds by
fixing the following warning:

  CC [M]  fs/hpfs/dir.o
fs/hpfs/dir.c: In function `hpfs_readdir':
fs/hpfs/dir.c:163:41: warning: array subscript 1 is above array bounds of `u8[1]' {aka `unsigned char[1]'} [-Warray-bounds]
  163 |         || de ->name[0] != 1 || de->name[1] != 1))
      |                                 ~~~~~~~~^~~

[1] https://en.wikipedia.org/wiki/Flexible_array_member
[2] https://www.kernel.org/doc/html/v5.10/process/deprecated.html#zero-length-and-one-element-arrays

Link: https://github.com/KSPP/linux/issues/79
Link: https://github.com/KSPP/linux/issues/109
Link: https://lkml.kernel.org/r/20210326173510.GA81212@embeddedor
Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>
Cc: Mikulas Patocka <mikulas@artax.karlin.mff.cuni.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/fs/hpfs/hpfs.h b/fs/hpfs/hpfs.h
index 302f45101a9661c3a50dd12dc0130965eaf53c89..d92c4af3e1b43d164a1fc8d1e27bde8cce8e6166 100644 (file)
--- a/fs/hpfs/hpfs.h
+++ b/fs/hpfs/hpfs.h
@@ -356,7 +356,8 @@ struct hpfs_dirent {
   u8 no_of_acls;                       /* number of ACL's (low 3 bits) */
   u8 ix;                               /* code page index (of filename), see
                                           struct code_page_data */
-  u8 namelen, name[1];                 /* file name */
+  u8 namelen;                          /* file name length */
+  u8 name[];                           /* file name */
   /* dnode_secno down;   btree down pointer, if present,
                          follows name on next word boundary, or maybe it
                          precedes next dirent, which is on a word boundary. */