linux/fs/xfs/xfs_attr.h
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   1/*
   2 * Copyright (c) 2000,2002-2003,2005 Silicon Graphics, Inc.
   3 * All Rights Reserved.
   4 *
   5 * This program is free software; you can redistribute it and/or
   6 * modify it under the terms of the GNU General Public License as
   7 * published by the Free Software Foundation.
   8 *
   9 * This program is distributed in the hope that it would be useful,
  10 * but WITHOUT ANY WARRANTY; without even the implied warranty of
  11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12 * GNU General Public License for more details.
  13 *
  14 * You should have received a copy of the GNU General Public License
  15 * along with this program; if not, write the Free Software Foundation,
  16 * Inc.,  51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
  17 */
  18#ifndef __XFS_ATTR_H__
  19#define __XFS_ATTR_H__
  20
  21struct xfs_inode;
  22struct xfs_da_args;
  23struct xfs_attr_list_context;
  24
  25/*
  26 * Large attribute lists are structured around Btrees where all the data
  27 * elements are in the leaf nodes.  Attribute names are hashed into an int,
  28 * then that int is used as the index into the Btree.  Since the hashval
  29 * of an attribute name may not be unique, we may have duplicate keys.
  30 * The internal links in the Btree are logical block offsets into the file.
  31 *
  32 * Small attribute lists use a different format and are packed as tightly
  33 * as possible so as to fit into the literal area of the inode.
  34 */
  35
  36/*========================================================================
  37 * External interfaces
  38 *========================================================================*/
  39
  40
  41#define ATTR_DONTFOLLOW 0x0001  /* -- unused, from IRIX -- */
  42#define ATTR_ROOT       0x0002  /* use attrs in root (trusted) namespace */
  43#define ATTR_TRUST      0x0004  /* -- unused, from IRIX -- */
  44#define ATTR_SECURE     0x0008  /* use attrs in security namespace */
  45#define ATTR_CREATE     0x0010  /* pure create: fail if attr already exists */
  46#define ATTR_REPLACE    0x0020  /* pure set: fail if attr does not exist */
  47
  48#define ATTR_KERNOTIME  0x1000  /* [kernel] don't update inode timestamps */
  49#define ATTR_KERNOVAL   0x2000  /* [kernel] get attr size only, not value */
  50
  51#define XFS_ATTR_FLAGS \
  52        { ATTR_DONTFOLLOW,      "DONTFOLLOW" }, \
  53        { ATTR_ROOT,            "ROOT" }, \
  54        { ATTR_TRUST,           "TRUST" }, \
  55        { ATTR_SECURE,          "SECURE" }, \
  56        { ATTR_CREATE,          "CREATE" }, \
  57        { ATTR_REPLACE,         "REPLACE" }, \
  58        { ATTR_KERNOTIME,       "KERNOTIME" }, \
  59        { ATTR_KERNOVAL,        "KERNOVAL" }
  60
  61/*
  62 * The maximum size (into the kernel or returned from the kernel) of an
  63 * attribute value or the buffer used for an attr_list() call.  Larger
  64 * sizes will result in an ERANGE return code.
  65 */
  66#define ATTR_MAX_VALUELEN       (64*1024)       /* max length of a value */
  67
  68/*
  69 * Define how lists of attribute names are returned to the user from
  70 * the attr_list() call.  A large, 32bit aligned, buffer is passed in
  71 * along with its size.  We put an array of offsets at the top that each
  72 * reference an attrlist_ent_t and pack the attrlist_ent_t's at the bottom.
  73 */
  74typedef struct attrlist {
  75        __s32   al_count;       /* number of entries in attrlist */
  76        __s32   al_more;        /* T/F: more attrs (do call again) */
  77        __s32   al_offset[1];   /* byte offsets of attrs [var-sized] */
  78} attrlist_t;
  79
  80/*
  81 * Show the interesting info about one attribute.  This is what the
  82 * al_offset[i] entry points to.
  83 */
  84typedef struct attrlist_ent {   /* data from attr_list() */
  85        __u32   a_valuelen;     /* number bytes in value of attr */
  86        char    a_name[1];      /* attr name (NULL terminated) */
  87} attrlist_ent_t;
  88
  89/*
  90 * Given a pointer to the (char*) buffer containing the attr_list() result,
  91 * and an index, return a pointer to the indicated attribute in the buffer.
  92 */
  93#define ATTR_ENTRY(buffer, index)               \
  94        ((attrlist_ent_t *)                     \
  95         &((char *)buffer)[ ((attrlist_t *)(buffer))->al_offset[index] ])
  96
  97/*
  98 * Kernel-internal version of the attrlist cursor.
  99 */
 100typedef struct attrlist_cursor_kern {
 101        __u32   hashval;        /* hash value of next entry to add */
 102        __u32   blkno;          /* block containing entry (suggestion) */
 103        __u32   offset;         /* offset in list of equal-hashvals */
 104        __u16   pad1;           /* padding to match user-level */
 105        __u8    pad2;           /* padding to match user-level */
 106        __u8    initted;        /* T/F: cursor has been initialized */
 107} attrlist_cursor_kern_t;
 108
 109
 110/*========================================================================
 111 * Structure used to pass context around among the routines.
 112 *========================================================================*/
 113
 114
 115typedef int (*put_listent_func_t)(struct xfs_attr_list_context *, int,
 116                              unsigned char *, int, int, unsigned char *);
 117
 118typedef struct xfs_attr_list_context {
 119        struct xfs_inode                *dp;            /* inode */
 120        struct attrlist_cursor_kern     *cursor;        /* position in list */
 121        char                            *alist;         /* output buffer */
 122        int                             seen_enough;    /* T/F: seen enough of list? */
 123        ssize_t                         count;          /* num used entries */
 124        int                             dupcnt;         /* count dup hashvals seen */
 125        int                             bufsize;        /* total buffer size */
 126        int                             firstu;         /* first used byte in buffer */
 127        int                             flags;          /* from VOP call */
 128        int                             resynch;        /* T/F: resynch with cursor */
 129        int                             put_value;      /* T/F: need value for listent */
 130        put_listent_func_t              put_listent;    /* list output fmt function */
 131        int                             index;          /* index into output buffer */
 132} xfs_attr_list_context_t;
 133
 134
 135/*========================================================================
 136 * Function prototypes for the kernel.
 137 *========================================================================*/
 138
 139/*
 140 * Overall external interface routines.
 141 */
 142int xfs_attr_inactive(struct xfs_inode *dp);
 143int xfs_attr_list_int(struct xfs_attr_list_context *);
 144
 145#endif  /* __XFS_ATTR_H__ */
 146
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