fs/xfs/xfs_attr.h

   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
  21 struct xfs_inode;
  22 struct xfs_da_args;
  23 struct 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 /*
  52  * The maximum size (into the kernel or returned from the kernel) of an
  53  * attribute value or the buffer used for an attr_list() call.  Larger
  54  * sizes will result in an ERANGE return code.
  55  */
  56 #define ATTR_MAX_VALUELEN       (64*1024)       /* max length of a value */
  57
  58 /*
  59  * Define how lists of attribute names are returned to the user from
  60  * the attr_list() call.  A large, 32bit aligned, buffer is passed in
  61  * along with its size.  We put an array of offsets at the top that each
  62  * reference an attrlist_ent_t and pack the attrlist_ent_t's at the bottom.
  63  */
  64 typedef struct attrlist {
  65         __s32   al_count;       /* number of entries in attrlist */
  66         __s32   al_more;        /* T/F: more attrs (do call again) */
  67         __s32   al_offset[1];   /* byte offsets of attrs [var-sized] */
  68 } attrlist_t;
  69
  70 /*
  71  * Show the interesting info about one attribute.  This is what the
  72  * al_offset[i] entry points to.
  73  */
  74 typedef struct attrlist_ent {   /* data from attr_list() */
  75         __u32   a_valuelen;     /* number bytes in value of attr */
  76         char    a_name[1];      /* attr name (NULL terminated) */
  77 } attrlist_ent_t;
  78
  79 /*
  80  * Given a pointer to the (char*) buffer containing the attr_list() result,
  81  * and an index, return a pointer to the indicated attribute in the buffer.
  82  */
  83 #define ATTR_ENTRY(buffer, index)               \
  84         ((attrlist_ent_t *)                     \
  85          &((char *)buffer)[ ((attrlist_t *)(buffer))->al_offset[index] ])
  86
  87 /*
  88  * Kernel-internal version of the attrlist cursor.
  89  */
  90 typedef struct attrlist_cursor_kern {
  91         __u32   hashval;        /* hash value of next entry to add */
  92         __u32   blkno;          /* block containing entry (suggestion) */
  93         __u32   offset;         /* offset in list of equal-hashvals */
  94         __u16   pad1;           /* padding to match user-level */
  95         __u8    pad2;           /* padding to match user-level */
  96         __u8    initted;        /* T/F: cursor has been initialized */
  97 } attrlist_cursor_kern_t;
  98
  99
 100 /*========================================================================
 101  * Structure used to pass context around among the routines.
 102  *========================================================================*/
 103
 104
 105 typedef int (*put_listent_func_t)(struct xfs_attr_list_context *, int,
 106                                       char *, int, int, char *);
 107
 108 typedef struct xfs_attr_list_context {
 109         struct xfs_inode                *dp;            /* inode */
 110         struct attrlist_cursor_kern     *cursor;        /* position in list */
 111         char                            *alist;         /* output buffer */
 112         int                             seen_enough;    /* T/F: seen enough of list? */
 113         ssize_t                         count;          /* num used entries */
 114         int                             dupcnt;         /* count dup hashvals seen */
 115         int                             bufsize;        /* total buffer size */
 116         int                             firstu;         /* first used byte in buffer */
 117         int                             flags;          /* from VOP call */
 118         int                             resynch;        /* T/F: resynch with cursor */
 119         int                             put_value;      /* T/F: need value for listent */
 120         put_listent_func_t              put_listent;    /* list output fmt function */
 121         int                             index;          /* index into output buffer */
 122 } xfs_attr_list_context_t;
 123
 124
 125 /*========================================================================
 126  * Function prototypes for the kernel.
 127  *========================================================================*/
 128
 129 /*
 130  * Overall external interface routines.
 131  */
 132 int xfs_attr_inactive(struct xfs_inode *dp);
 133 int xfs_attr_fetch(struct xfs_inode *, struct xfs_name *, char *, int *, int);
 134 int xfs_attr_rmtval_get(struct xfs_da_args *args);
 135 int xfs_attr_list_int(struct xfs_attr_list_context *);
 136
 137 #endif  /* __XFS_ATTR_H__ */