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 #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  */
  74 typedef 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  */
  84 typedef 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  */
 100 typedef 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
 115 /* Return 0 on success, or -errno; other state communicated via *context */
 116 typedef int (*put_listent_func_t)(struct xfs_attr_list_context *, int,
 117                               unsigned char *, int, int);
 118
 119 typedef struct xfs_attr_list_context {
 120         struct xfs_inode                *dp;            /* inode */
 121         struct attrlist_cursor_kern     *cursor;        /* position in list */
 122         char                            *alist;         /* output buffer */
 123         int                             seen_enough;    /* T/F: seen enough of list? */
 124         ssize_t                         count;          /* num used entries */
 125         int                             dupcnt;         /* count dup hashvals seen */
 126         int                             bufsize;        /* total buffer size */
 127         int                             firstu;         /* first used byte in buffer */
 128         int                             flags;          /* from VOP call */
 129         int                             resynch;        /* T/F: resynch with cursor */
 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  */
 142 int xfs_attr_inactive(struct xfs_inode *dp);
 143 int xfs_attr_list_int(struct xfs_attr_list_context *);
 144 int xfs_inode_hasattr(struct xfs_inode *ip);
 145 int xfs_attr_get(struct xfs_inode *ip, const unsigned char *name,
 146                  unsigned char *value, int *valuelenp, int flags);
 147 int xfs_attr_set(struct xfs_inode *dp, const unsigned char *name,
 148                  unsigned char *value, int valuelen, int flags);
 149 int xfs_attr_remove(struct xfs_inode *dp, const unsigned char *name, int flags);
 150 int xfs_attr_list(struct xfs_inode *dp, char *buffer, int bufsize,
 151                   int flags, struct attrlist_cursor_kern *cursor);
 152
 153
 154 #endif  /* __XFS_ATTR_H__ */