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43951585e1
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>
113 lines
3.3 KiB
C
113 lines
3.3 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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/*
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File: linux/xattr.h
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Extended attributes handling.
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Copyright (C) 2001 by Andreas Gruenbacher <a.gruenbacher@computer.org>
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Copyright (c) 2001-2002 Silicon Graphics, Inc. All Rights Reserved.
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Copyright (c) 2004 Red Hat, Inc., James Morris <jmorris@redhat.com>
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*/
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#ifndef _LINUX_XATTR_H
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#define _LINUX_XATTR_H
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#include <linux/slab.h>
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#include <linux/types.h>
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#include <linux/spinlock.h>
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#include <uapi/linux/xattr.h>
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struct inode;
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struct dentry;
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/*
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* struct xattr_handler: When @name is set, match attributes with exactly that
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* name. When @prefix is set instead, match attributes with that prefix and
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* with a non-empty suffix.
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*/
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struct xattr_handler {
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const char *name;
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const char *prefix;
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int flags; /* fs private flags */
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bool (*list)(struct dentry *dentry);
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int (*get)(const struct xattr_handler *, struct dentry *dentry,
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struct inode *inode, const char *name, void *buffer,
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size_t size);
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int (*set)(const struct xattr_handler *, struct dentry *dentry,
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struct inode *inode, const char *name, const void *buffer,
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size_t size, int flags);
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};
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const char *xattr_full_name(const struct xattr_handler *, const char *);
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struct xattr {
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const char *name;
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void *value;
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size_t value_len;
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};
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ssize_t __vfs_getxattr(struct dentry *, struct inode *, const char *, void *, size_t);
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ssize_t vfs_getxattr(struct dentry *, const char *, void *, size_t);
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ssize_t vfs_listxattr(struct dentry *d, char *list, size_t size);
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int __vfs_setxattr(struct dentry *, struct inode *, const char *, const void *, size_t, int);
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int __vfs_setxattr_noperm(struct dentry *, const char *, const void *, size_t, int);
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int vfs_setxattr(struct dentry *, const char *, const void *, size_t, int);
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int __vfs_removexattr(struct dentry *, const char *);
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int vfs_removexattr(struct dentry *, const char *);
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ssize_t generic_listxattr(struct dentry *dentry, char *buffer, size_t buffer_size);
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ssize_t vfs_getxattr_alloc(struct dentry *dentry, const char *name,
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char **xattr_value, size_t size, gfp_t flags);
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static inline const char *xattr_prefix(const struct xattr_handler *handler)
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{
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return handler->prefix ?: handler->name;
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}
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struct simple_xattrs {
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struct list_head head;
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spinlock_t lock;
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};
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struct simple_xattr {
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struct list_head list;
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char *name;
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size_t size;
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char value[];
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};
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/*
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* initialize the simple_xattrs structure
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*/
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static inline void simple_xattrs_init(struct simple_xattrs *xattrs)
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{
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INIT_LIST_HEAD(&xattrs->head);
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spin_lock_init(&xattrs->lock);
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}
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/*
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* free all the xattrs
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*/
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static inline void simple_xattrs_free(struct simple_xattrs *xattrs)
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{
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struct simple_xattr *xattr, *node;
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list_for_each_entry_safe(xattr, node, &xattrs->head, list) {
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kfree(xattr->name);
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kfree(xattr);
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}
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}
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struct simple_xattr *simple_xattr_alloc(const void *value, size_t size);
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int simple_xattr_get(struct simple_xattrs *xattrs, const char *name,
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void *buffer, size_t size);
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int simple_xattr_set(struct simple_xattrs *xattrs, const char *name,
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const void *value, size_t size, int flags,
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ssize_t *removed_size);
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ssize_t simple_xattr_list(struct inode *inode, struct simple_xattrs *xattrs, char *buffer,
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size_t size);
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void simple_xattr_list_add(struct simple_xattrs *xattrs,
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struct simple_xattr *new_xattr);
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#endif /* _LINUX_XATTR_H */
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