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50b1203d8c
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>
Reviewed-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
171 lines
5.2 KiB
C
171 lines
5.2 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/*
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* fs/f2fs/xattr.h
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*
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* Copyright (c) 2012 Samsung Electronics Co., Ltd.
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* http://www.samsung.com/
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*
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* Portions of this code from linux/fs/ext2/xattr.h
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*
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* On-disk format of extended attributes for the ext2 filesystem.
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*
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* (C) 2001 Andreas Gruenbacher, <a.gruenbacher@computer.org>
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*/
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#ifndef __F2FS_XATTR_H__
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#define __F2FS_XATTR_H__
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#include <linux/init.h>
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#include <linux/xattr.h>
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/* Magic value in attribute blocks */
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#define F2FS_XATTR_MAGIC 0xF2F52011
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/* Maximum number of references to one attribute block */
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#define F2FS_XATTR_REFCOUNT_MAX 1024
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/* Name indexes */
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#define F2FS_SYSTEM_ADVISE_NAME "system.advise"
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#define F2FS_XATTR_INDEX_USER 1
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#define F2FS_XATTR_INDEX_POSIX_ACL_ACCESS 2
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#define F2FS_XATTR_INDEX_POSIX_ACL_DEFAULT 3
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#define F2FS_XATTR_INDEX_TRUSTED 4
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#define F2FS_XATTR_INDEX_LUSTRE 5
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#define F2FS_XATTR_INDEX_SECURITY 6
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#define F2FS_XATTR_INDEX_ADVISE 7
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/* Should be same as EXT4_XATTR_INDEX_ENCRYPTION */
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#define F2FS_XATTR_INDEX_ENCRYPTION 9
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#define F2FS_XATTR_INDEX_VERITY 11
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#define F2FS_XATTR_NAME_ENCRYPTION_CONTEXT "c"
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#define F2FS_XATTR_NAME_VERITY "v"
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struct f2fs_xattr_header {
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__le32 h_magic; /* magic number for identification */
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__le32 h_refcount; /* reference count */
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__u32 h_reserved[4]; /* zero right now */
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};
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struct f2fs_xattr_entry {
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__u8 e_name_index;
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__u8 e_name_len;
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__le16 e_value_size; /* size of attribute value */
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char e_name[]; /* attribute name */
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};
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#define XATTR_HDR(ptr) ((struct f2fs_xattr_header *)(ptr))
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#define XATTR_ENTRY(ptr) ((struct f2fs_xattr_entry *)(ptr))
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#define XATTR_FIRST_ENTRY(ptr) (XATTR_ENTRY(XATTR_HDR(ptr) + 1))
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#define XATTR_ROUND (3)
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#define XATTR_ALIGN(size) (((size) + XATTR_ROUND) & ~XATTR_ROUND)
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#define ENTRY_SIZE(entry) (XATTR_ALIGN(sizeof(struct f2fs_xattr_entry) + \
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(entry)->e_name_len + le16_to_cpu((entry)->e_value_size)))
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#define XATTR_NEXT_ENTRY(entry) ((struct f2fs_xattr_entry *)((char *)(entry) +\
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ENTRY_SIZE(entry)))
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#define IS_XATTR_LAST_ENTRY(entry) (*(__u32 *)(entry) == 0)
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#define list_for_each_xattr(entry, addr) \
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for (entry = XATTR_FIRST_ENTRY(addr);\
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!IS_XATTR_LAST_ENTRY(entry);\
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entry = XATTR_NEXT_ENTRY(entry))
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#define VALID_XATTR_BLOCK_SIZE (PAGE_SIZE - sizeof(struct node_footer))
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#define XATTR_PADDING_SIZE (sizeof(__u32))
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#define XATTR_SIZE(i) ((F2FS_I(i)->i_xattr_nid ? \
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VALID_XATTR_BLOCK_SIZE : 0) + \
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(inline_xattr_size(i)))
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#define MIN_OFFSET(i) XATTR_ALIGN(inline_xattr_size(i) + \
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VALID_XATTR_BLOCK_SIZE)
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#define MAX_VALUE_LEN(i) (MIN_OFFSET(i) - \
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sizeof(struct f2fs_xattr_header) - \
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sizeof(struct f2fs_xattr_entry))
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#define MAX_INLINE_XATTR_SIZE \
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(DEF_ADDRS_PER_INODE - \
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F2FS_TOTAL_EXTRA_ATTR_SIZE / sizeof(__le32) - \
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DEF_INLINE_RESERVED_SIZE - \
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MIN_INLINE_DENTRY_SIZE / sizeof(__le32))
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/*
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* On-disk structure of f2fs_xattr
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* We use inline xattrs space + 1 block for xattr.
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*
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* +--------------------+
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* | f2fs_xattr_header |
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* | |
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* +--------------------+
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* | f2fs_xattr_entry |
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* | .e_name_index = 1 |
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* | .e_name_len = 3 |
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* | .e_value_size = 14 |
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* | .e_name = "foo" |
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* | "value_of_xattr" |<- value_offs = e_name + e_name_len
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* +--------------------+
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* | f2fs_xattr_entry |
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* | .e_name_index = 4 |
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* | .e_name = "bar" |
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* +--------------------+
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* | |
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* | Free |
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* | |
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* +--------------------+<- MIN_OFFSET
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* | node_footer |
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* | (nid, ino, offset) |
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* +--------------------+
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*
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**/
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#ifdef CONFIG_F2FS_FS_XATTR
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extern const struct xattr_handler f2fs_xattr_user_handler;
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extern const struct xattr_handler f2fs_xattr_trusted_handler;
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extern const struct xattr_handler f2fs_xattr_advise_handler;
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extern const struct xattr_handler f2fs_xattr_security_handler;
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extern const struct xattr_handler *f2fs_xattr_handlers[];
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extern int f2fs_setxattr(struct inode *, int, const char *,
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const void *, size_t, struct page *, int);
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extern int f2fs_getxattr(struct inode *, int, const char *, void *,
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size_t, struct page *);
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extern ssize_t f2fs_listxattr(struct dentry *, char *, size_t);
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extern int f2fs_init_xattr_caches(struct f2fs_sb_info *);
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extern void f2fs_destroy_xattr_caches(struct f2fs_sb_info *);
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#else
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#define f2fs_xattr_handlers NULL
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static inline int f2fs_setxattr(struct inode *inode, int index,
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const char *name, const void *value, size_t size,
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struct page *page, int flags)
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{
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return -EOPNOTSUPP;
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}
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static inline int f2fs_getxattr(struct inode *inode, int index,
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const char *name, void *buffer,
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size_t buffer_size, struct page *dpage)
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{
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return -EOPNOTSUPP;
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}
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static inline ssize_t f2fs_listxattr(struct dentry *dentry, char *buffer,
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size_t buffer_size)
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{
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return -EOPNOTSUPP;
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}
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static int f2fs_init_xattr_caches(struct f2fs_sb_info *sbi) { return 0; }
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static void f2fs_destroy_xattr_caches(struct f2fs_sb_info *sbi) { }
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#endif
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#ifdef CONFIG_F2FS_FS_SECURITY
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extern int f2fs_init_security(struct inode *, struct inode *,
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const struct qstr *, struct page *);
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#else
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static inline int f2fs_init_security(struct inode *inode, struct inode *dir,
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const struct qstr *qstr, struct page *ipage)
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{
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return 0;
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}
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#endif
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#endif /* __F2FS_XATTR_H__ */
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