xfs_attr.h

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/*
 * Copyright (c) 2000,2002-2003,2005 Silicon Graphics, Inc.
 * All Rights Reserved.
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License as
 * published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it would be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write the Free Software Foundation,
 * Inc.,  51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
 */
#ifndef __XFS_ATTR_H__
#define __XFS_ATTR_H__

struct xfs_inode;
struct xfs_da_args;
struct xfs_attr_list_context;

/*
 * Large attribute lists are structured around Btrees where all the data
 * elements are in the leaf nodes.  Attribute names are hashed into an int,
 * then that int is used as the index into the Btree.  Since the hashval
 * of an attribute name may not be unique, we may have duplicate keys.
 * The internal links in the Btree are logical block offsets into the file.
 *
 * Small attribute lists use a different format and are packed as tightly
 * as possible so as to fit into the literal area of the inode.
 */

/*========================================================================
 * External interfaces
 *========================================================================*/


#define ATTR_DONTFOLLOW 0x0001  /* -- unused, from IRIX -- */
#define ATTR_ROOT   0x0002  /* use attrs in root (trusted) namespace */
#define ATTR_TRUST  0x0004  /* -- unused, from IRIX -- */
#define ATTR_SECURE 0x0008  /* use attrs in security namespace */
#define ATTR_CREATE 0x0010  /* pure create: fail if attr already exists */
#define ATTR_REPLACE    0x0020  /* pure set: fail if attr does not exist */

#define ATTR_KERNOTIME  0x1000  /* [kernel] don't update inode timestamps */
#define ATTR_KERNOVAL   0x2000  /* [kernel] get attr size only, not value */

#define XFS_ATTR_FLAGS \
    { ATTR_DONTFOLLOW,  "DONTFOLLOW" }, \
    { ATTR_ROOT,        "ROOT" }, \
    { ATTR_TRUST,       "TRUST" }, \
    { ATTR_SECURE,      "SECURE" }, \
    { ATTR_CREATE,      "CREATE" }, \
    { ATTR_REPLACE,     "REPLACE" }, \
    { ATTR_KERNOTIME,   "KERNOTIME" }, \
    { ATTR_KERNOVAL,    "KERNOVAL" }

/*
 * The maximum size (into the kernel or returned from the kernel) of an
 * attribute value or the buffer used for an attr_list() call.  Larger
 * sizes will result in an ERANGE return code.
 */
#define ATTR_MAX_VALUELEN   (64*1024)   /* max length of a value */

/*
 * Define how lists of attribute names are returned to the user from
 * the attr_list() call.  A large, 32bit aligned, buffer is passed in
 * along with its size.  We put an array of offsets at the top that each
 * reference an attrlist_ent_t and pack the attrlist_ent_t's at the bottom.
 */
typedef struct attrlist {
    __s32   al_count;   /* number of entries in attrlist */
    __s32   al_more;    /* T/F: more attrs (do call again) */
    __s32   al_offset[1];   /* byte offsets of attrs [var-sized] */
} attrlist_t;

/*
 * Show the interesting info about one attribute.  This is what the
 * al_offset[i] entry points to.
 */
typedef struct attrlist_ent {   /* data from attr_list() */
    __u32   a_valuelen; /* number bytes in value of attr */
    char    a_name[1];  /* attr name (NULL terminated) */
} attrlist_ent_t;

/*
 * Given a pointer to the (char*) buffer containing the attr_list() result,
 * and an index, return a pointer to the indicated attribute in the buffer.
 */
#define ATTR_ENTRY(buffer, index)       \
    ((attrlist_ent_t *)         \
     &((char *)buffer)[ ((attrlist_t *)(buffer))->al_offset[index] ])

/*
 * Kernel-internal version of the attrlist cursor.
 */
typedef struct attrlist_cursor_kern {
    __u32   hashval;    /* hash value of next entry to add */
    __u32   blkno;      /* block containing entry (suggestion) */
    __u32   offset;     /* offset in list of equal-hashvals */
    __u16   pad1;       /* padding to match user-level */
    __u8    pad2;       /* padding to match user-level */
    __u8    initted;    /* T/F: cursor has been initialized */
} attrlist_cursor_kern_t;


/*========================================================================
 * Structure used to pass context around among the routines.
 *========================================================================*/


typedef int (*put_listent_func_t)(struct xfs_attr_list_context *, int,
                  unsigned char *, int, int, unsigned char *);

typedef struct xfs_attr_list_context {
    struct xfs_inode        *dp;        /* inode */
    struct attrlist_cursor_kern *cursor;    /* position in list */
    char                *alist;     /* output buffer */
    int             seen_enough;    /* T/F: seen enough of list? */
    ssize_t             count;      /* num used entries */
    int             dupcnt;     /* count dup hashvals seen */
    int             bufsize;    /* total buffer size */
    int             firstu;     /* first used byte in buffer */
    int             flags;      /* from VOP call */
    int             resynch;    /* T/F: resynch with cursor */
    int             put_value;  /* T/F: need value for listent */
    put_listent_func_t      put_listent;    /* list output fmt function */
    int             index;      /* index into output buffer */
} xfs_attr_list_context_t;


/*========================================================================
 * Function prototypes for the kernel.
 *========================================================================*/

/*
 * Overall external interface routines.
 */
int xfs_attr_inactive(struct xfs_inode *dp);
int xfs_attr_rmtval_get(struct xfs_da_args *args);
int xfs_attr_list_int(struct xfs_attr_list_context *);

#endif  /* __XFS_ATTR_H__ */