linux-stable/fs/jfs/jfs_xattr.h
Gustavo A. R. Silva 7aba5dcc23 jfs: Replace zero-length array with flexible-array member
The current codebase makes use of the zero-length array language
extension to the C90 standard, but the preferred mechanism to declare
variable-length types such as these ones is a flexible array member[1][2],
introduced in C99:

struct foo {
        int stuff;
        struct boo array[];
};

By making use of the mechanism above, we will get a compiler warning
in case the flexible array does not occur last in the structure, which
will help us prevent some kind of undefined behavior bugs from being
inadvertently introduced[3] to the codebase from now on.

Also, notice that, dynamic memory allocations won't be affected by
this change:

"Flexible array members have incomplete type, and so the sizeof operator
may not be applied. As a quirk of the original implementation of
zero-length arrays, sizeof evaluates to zero."[1]

This issue was found with the help of Coccinelle.

[1] https://gcc.gnu.org/onlinedocs/gcc/Zero-Length.html
[2] https://github.com/KSPP/linux/issues/21
[3] commit 7649773293 ("cxgb3/l2t: Fix undefined behaviour")

Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
Signed-off-by: Dave Kleikamp <dave.kleikamp@oracle.com>
2020-03-09 15:18:51 -05:00

62 lines
1.8 KiB
C

/* SPDX-License-Identifier: GPL-2.0-or-later */
/*
* Copyright (C) International Business Machines Corp., 2000-2002
*/
#ifndef H_JFS_XATTR
#define H_JFS_XATTR
#include <linux/xattr.h>
/*
* jfs_ea_list describe the on-disk format of the extended attributes.
* I know the null-terminator is redundant since namelen is stored, but
* I am maintaining compatibility with OS/2 where possible.
*/
struct jfs_ea {
u8 flag; /* Unused? */
u8 namelen; /* Length of name */
__le16 valuelen; /* Length of value */
char name[]; /* Attribute name (includes null-terminator) */
}; /* Value immediately follows name */
struct jfs_ea_list {
__le32 size; /* overall size */
struct jfs_ea ea[]; /* Variable length list */
};
/* Macros for defining maxiumum number of bytes supported for EAs */
#define MAXEASIZE 65535
#define MAXEALISTSIZE MAXEASIZE
/*
* some macros for dealing with variable length EA lists.
*/
#define EA_SIZE(ea) \
(sizeof (struct jfs_ea) + (ea)->namelen + 1 + \
le16_to_cpu((ea)->valuelen))
#define NEXT_EA(ea) ((struct jfs_ea *) (((char *) (ea)) + (EA_SIZE (ea))))
#define FIRST_EA(ealist) ((ealist)->ea)
#define EALIST_SIZE(ealist) le32_to_cpu((ealist)->size)
#define END_EALIST(ealist) \
((struct jfs_ea *) (((char *) (ealist)) + EALIST_SIZE(ealist)))
extern int __jfs_setxattr(tid_t, struct inode *, const char *, const void *,
size_t, int);
extern ssize_t __jfs_getxattr(struct inode *, const char *, void *, size_t);
extern ssize_t jfs_listxattr(struct dentry *, char *, size_t);
extern const struct xattr_handler *jfs_xattr_handlers[];
#ifdef CONFIG_JFS_SECURITY
extern int jfs_init_security(tid_t, struct inode *, struct inode *,
const struct qstr *);
#else
static inline int jfs_init_security(tid_t tid, struct inode *inode,
struct inode *dir, const struct qstr *qstr)
{
return 0;
}
#endif
#endif /* H_JFS_XATTR */