libxfs/xfs_attr.h

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * Copyright (c) 2000,2002-2003,2005 Silicon Graphics, Inc.
   4  * All Rights Reserved.
   5  */
   6 #ifndef __XFS_ATTR_H__
   7 #define __XFS_ATTR_H__
   8
   9 struct xfs_inode;
  10 struct xfs_da_args;
  11 struct xfs_attr_list_context;
  12
  13 /*
  14  * Large attribute lists are structured around Btrees where all the data
  15  * elements are in the leaf nodes.  Attribute names are hashed into an int,
  16  * then that int is used as the index into the Btree.  Since the hashval
  17  * of an attribute name may not be unique, we may have duplicate keys.
  18  * The internal links in the Btree are logical block offsets into the file.
  19  *
  20  * Small attribute lists use a different format and are packed as tightly
  21  * as possible so as to fit into the literal area of the inode.
  22  */
  23
  24 /*========================================================================
  25  * External interfaces
  26  *========================================================================*/
  27
  28
  29 #define ATTR_DONTFOLLOW 0x0001  /* -- unused, from IRIX -- */
  30 #define ATTR_ROOT       0x0002  /* use attrs in root (trusted) namespace */
  31 #define ATTR_TRUST      0x0004  /* -- unused, from IRIX -- */
  32 #define ATTR_SECURE     0x0008  /* use attrs in security namespace */
  33 #define ATTR_CREATE     0x0010  /* pure create: fail if attr already exists */
  34 #define ATTR_REPLACE    0x0020  /* pure set: fail if attr does not exist */
  35
  36 #define ATTR_KERNOTIME  0x1000  /* [kernel] don't update inode timestamps */
  37 #define ATTR_KERNOVAL   0x2000  /* [kernel] get attr size only, not value */
  38
  39 #define ATTR_INCOMPLETE 0x4000  /* [kernel] return INCOMPLETE attr keys */
  40
  41 #define XFS_ATTR_FLAGS \
  42         { ATTR_DONTFOLLOW,      "DONTFOLLOW" }, \
  43         { ATTR_ROOT,            "ROOT" }, \
  44         { ATTR_TRUST,           "TRUST" }, \
  45         { ATTR_SECURE,          "SECURE" }, \
  46         { ATTR_CREATE,          "CREATE" }, \
  47         { ATTR_REPLACE,         "REPLACE" }, \
  48         { ATTR_KERNOTIME,       "KERNOTIME" }, \
  49         { ATTR_KERNOVAL,        "KERNOVAL" }, \
  50         { ATTR_INCOMPLETE,      "INCOMPLETE" }
  51
  52 /*
  53  * The maximum size (into the kernel or returned from the kernel) of an
  54  * attribute value or the buffer used for an attr_list() call.  Larger
  55  * sizes will result in an ERANGE return code.
  56  */
  57 #define ATTR_MAX_VALUELEN       (64*1024)       /* max length of a value */
  58
  59 /*
  60  * Define how lists of attribute names are returned to the user from
  61  * the attr_list() call.  A large, 32bit aligned, buffer is passed in
  62  * along with its size.  We put an array of offsets at the top that each
  63  * reference an attrlist_ent_t and pack the attrlist_ent_t's at the bottom.
  64  */
  65 typedef struct attrlist {
  66         __s32   al_count;       /* number of entries in attrlist */
  67         __s32   al_more;        /* T/F: more attrs (do call again) */
  68         __s32   al_offset[1];   /* byte offsets of attrs [var-sized] */
  69 } attrlist_t;
  70
  71 /*
  72  * Show the interesting info about one attribute.  This is what the
  73  * al_offset[i] entry points to.
  74  */
  75 typedef struct attrlist_ent {   /* data from attr_list() */
  76         __u32   a_valuelen;     /* number bytes in value of attr */
  77         char    a_name[1];      /* attr name (NULL terminated) */
  78 } attrlist_ent_t;
  79
  80 /*
  81  * Given a pointer to the (char*) buffer containing the attr_list() result,
  82  * and an index, return a pointer to the indicated attribute in the buffer.
  83  */
  84 #define ATTR_ENTRY(buffer, index)               \
  85         ((attrlist_ent_t *)                     \
  86          &((char *)buffer)[ ((attrlist_t *)(buffer))->al_offset[index] ])
  87
  88 /*
  89  * Kernel-internal version of the attrlist cursor.
  90  */
  91 typedef struct attrlist_cursor_kern {
  92         __u32   hashval;        /* hash value of next entry to add */
  93         __u32   blkno;          /* block containing entry (suggestion) */
  94         __u32   offset;         /* offset in list of equal-hashvals */
  95         __u16   pad1;           /* padding to match user-level */
  96         __u8    pad2;           /* padding to match user-level */
  97         __u8    initted;        /* T/F: cursor has been initialized */
  98 } attrlist_cursor_kern_t;
  99
 100
 101 /*========================================================================
 102  * Structure used to pass context around among the routines.
 103  *========================================================================*/
 104
 105
 106 /* void; state communicated via *context */
 107 typedef void (*put_listent_func_t)(struct xfs_attr_list_context *, int,
 108                               unsigned char *, int, int);
 109
 110 typedef struct xfs_attr_list_context {
 111         struct xfs_trans                *tp;
 112         struct xfs_inode                *dp;            /* inode */
 113         struct attrlist_cursor_kern     *cursor;        /* position in list */
 114         char                            *alist;         /* output buffer */
 115         int                             seen_enough;    /* T/F: seen enough of list? */
 116         ssize_t                         count;          /* num used entries */
 117         int                             dupcnt;         /* count dup hashvals seen */
 118         int                             bufsize;        /* total buffer size */
 119         int                             firstu;         /* first used byte in buffer */
 120         int                             flags;          /* from VOP call */
 121         int                             resynch;        /* T/F: resynch with cursor */
 122         put_listent_func_t              put_listent;    /* list output fmt function */
 123         int                             index;          /* index into output buffer */
 124 } xfs_attr_list_context_t;
 125
 126
 127 /*========================================================================
 128  * Function prototypes for the kernel.
 129  *========================================================================*/
 130
 131 /*
 132  * Overall external interface routines.
 133  */
 134 int xfs_attr_inactive(struct xfs_inode *dp);
 135 int xfs_attr_list_int_ilocked(struct xfs_attr_list_context *);
 136 int xfs_attr_list_int(struct xfs_attr_list_context *);
 137 int xfs_inode_hasattr(struct xfs_inode *ip);
 138 int xfs_attr_get_ilocked(struct xfs_inode *ip, struct xfs_da_args *args);
 139 int xfs_attr_get(struct xfs_inode *ip, const unsigned char *name,
 140                  unsigned char *value, int *valuelenp, int flags);
 141 int xfs_attr_set(struct xfs_inode *dp, const unsigned char *name,
 142                  unsigned char *value, int valuelen, int flags);
 143 int xfs_attr_set_args(struct xfs_da_args *args, struct xfs_buf **leaf_bp);
 144 int xfs_attr_remove(struct xfs_inode *dp, const unsigned char *name, int flags);
 145 int xfs_attr_remove_args(struct xfs_da_args *args);
 146 int xfs_attr_list(struct xfs_inode *dp, char *buffer, int bufsize,
 147                   int flags, struct attrlist_cursor_kern *cursor);
 148
 149
 150 #endif  /* __XFS_ATTR_H__ */