/*
  Copyright (c) 2013 Red Hat, Inc. <http://www.redhat.com>
  This file is part of GlusterFS.

  This file is licensed to you under your choice of the GNU Lesser
  General Public License, version 3 or any later version (LGPLv3 or
  later), or the GNU General Public License, version 2 (GPLv2), in all
  cases as published by the Free Software Foundation.
*/

#ifndef _GLUSTERFS_ACL_H
#define _GLUSTERFS_ACL_H

/* WARNING: Much if this code is restricted to Linux usage.
 *
 * It would be much cleaner to replace the code with something that is based on
 * libacl (or its libc implementation on *BSD).
 *
 * Initial work for replacing this Linux specific implementation has been
 * started as part of the "Improve POSIX ACLs" feature. Functionality for this
 * feature has been added to the end of this file.
 */

#include <stdint.h>
#include <sys/types.h> /* For uid_t */

#include "glusterfs/locking.h" /* For gf_lock_t in struct posix_acl_conf */

#define ACL_PROGRAM 100227
#define ACLV3_VERSION 3

#define POSIX_ACL_MINIMAL_ACE_COUNT 3

#define POSIX_ACL_READ (0x04)
#define POSIX_ACL_WRITE (0x02)
#define POSIX_ACL_EXECUTE (0x01)

#define POSIX_ACL_UNDEFINED_TAG (0x00)
#define POSIX_ACL_USER_OBJ (0x01)
#define POSIX_ACL_USER (0x02)
#define POSIX_ACL_GROUP_OBJ (0x04)
#define POSIX_ACL_GROUP (0x08)
#define POSIX_ACL_MASK (0x10)
#define POSIX_ACL_OTHER (0x20)

#define POSIX_ACL_UNDEFINED_ID (-1)

#define POSIX_ACL_XATTR_VERSION (0x02)

#define POSIX_ACL_ACCESS_XATTR "system.posix_acl_access"
#define POSIX_ACL_DEFAULT_XATTR "system.posix_acl_default"

struct posix_acl_xattr_entry {
    uint16_t tag;
    uint16_t perm;
    uint32_t id;
};

struct posix_acl_xattr_header {
    uint32_t version;
    struct posix_acl_xattr_entry entries[];
};

typedef struct posix_acl_xattr_entry posix_acl_xattr_entry;
typedef struct posix_acl_xattr_header posix_acl_xattr_header;

static inline size_t
posix_acl_xattr_size(unsigned int count)
{
    return (sizeof(posix_acl_xattr_header) +
            (count * sizeof(posix_acl_xattr_entry)));
}

static inline ssize_t
posix_acl_xattr_count(size_t size)
{
    if (size < sizeof(posix_acl_xattr_header))
        return (-1);
    size -= sizeof(posix_acl_xattr_header);
    if (size % sizeof(posix_acl_xattr_entry))
        return (-1);
    return (size / sizeof(posix_acl_xattr_entry));
}

struct posix_ace {
    uint16_t tag;
    uint16_t perm;
    uint32_t id;
};

struct posix_acl {
    int refcnt;
    int count;
    struct posix_ace entries[];
};

struct posix_acl_ctx {
    uid_t uid;
    gid_t gid;
    mode_t perm;
    glusterfs_fop_t fop;
    struct posix_acl *acl_access;
    struct posix_acl *acl_default;
};

struct posix_acl_conf {
    gf_lock_t acl_lock;
    uid_t super_uid;
    struct posix_acl *minimal_acl;
};

/* Above this comment, the legacy POSIX ACL support is kept until it is not
 * used anymore. Below you will find the more portable version to support POSIX
 * ACls based on the implementation of libacl (see sys/acl.h). */

/* virtual xattrs passed over RPC, not stored on disk */
#define GF_POSIX_ACL_ACCESS "glusterfs.posix.acl"
#define GF_POSIX_ACL_DEFAULT "glusterfs.posix.default_acl"
#define GF_POSIX_ACL_REQUEST(key)                                              \
    (!strncmp(key, GF_POSIX_ACL_ACCESS, SLEN(GF_POSIX_ACL_ACCESS)) ||          \
     !strncmp(key, GF_POSIX_ACL_DEFAULT, SLEN(GF_POSIX_ACL_DEFAULT)))

#ifdef HAVE_SYS_ACL_H /* only NetBSD does not support POSIX ACLs */

#include <sys/acl.h>

static inline const char *
gf_posix_acl_get_key(const acl_type_t type)
{
    char *acl_key = NULL;

    switch (type) {
        case ACL_TYPE_ACCESS:
            acl_key = GF_POSIX_ACL_ACCESS;
            break;
        case ACL_TYPE_DEFAULT:
            acl_key = GF_POSIX_ACL_DEFAULT;
            break;
        default:
            errno = EINVAL;
    }

    return acl_key;
}

static inline const acl_type_t
gf_posix_acl_get_type(const char *key)
{
    acl_type_t type = 0;

    if (!strncmp(key, GF_POSIX_ACL_ACCESS, SLEN(GF_POSIX_ACL_ACCESS)))
        type = ACL_TYPE_ACCESS;
    else if (!strncmp(key, GF_POSIX_ACL_DEFAULT, SLEN(GF_POSIX_ACL_DEFAULT)))
        type = ACL_TYPE_DEFAULT;
    else
        errno = EINVAL;

    return type;
}

#endif /* HAVE_SYS_ACL_H */
#endif /* _GLUSTERFS_ACL_H */