bsd/miscfs/mockfs/mockfs.h

   1 /*
   2  * Copyright (c) 2012 Apple Inc. All rights reserved.
   3  *
   4  * @APPLE_OSREFERENCE_LICENSE_HEADER_START@
   5  *
   6  * This file contains Original Code and/or Modifications of Original Code
   7  * as defined in and that are subject to the Apple Public Source License
   8  * Version 2.0 (the 'License'). You may not use this file except in
   9  * compliance with the License. The rights granted to you under the License
  10  * may not be used to create, or enable the creation or redistribution of,
  11  * unlawful or unlicensed copies of an Apple operating system, or to
  12  * circumvent, violate, or enable the circumvention or violation of, any
  13  * terms of an Apple operating system software license agreement.
  14  *
  15  * Please obtain a copy of the License at
  16  * http://www.opensource.apple.com/apsl/ and read it before using this file.
  17  *
  18  * The Original Code and all software distributed under the License are
  19  * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  20  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  21  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
  22  * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
  23  * Please see the License for the specific language governing rights and
  24  * limitations under the License.
  25  *
  26  * @APPLE_OSREFERENCE_LICENSE_HEADER_END@
  27  */
  28
  29 #ifndef MOCKFS_H
  30 #define MOCKFS_H
  31
  32 #if MOCKFS
  33
  34 #include <kern/locks.h>
  35 #include <miscfs/mockfs/mockfs_fsnode.h>
  36 #include <sys/kernel_types.h>
  37
  38 /*
  39  * mockfs is effectively a "fake" filesystem; the primary motivation for it being that we may have cases
  40  *   where our userspace needs are extremely simple/consistent and can provided by a single binary.  mockfs
  41  *   uses an in-memory tree to define the structure for an extremely simple filesystem, which makes the
  42  *   assumption that our root device is in fact a mach-o file, and provides a minimal filesystem to support
  43  *   this:  the root directory, a mountpoint for devfs (given that very basic userspace code may assume the
  44  *   existance of /dev/), and an executable representing the root device.
  45  *
  46  * The functionality supported by mockfs is minimal: it is read-only, and does not support user initiated IO,
  47  *   but it supports lookup (so it should be possible for the user to access /dev/).
  48  *
  49  * mockfs is primarily targeted towards memory-backed devices, and will (when possible) attempt to inform the
  50  *   VM that we are using a memory-backed device, so that we can eschew IO to the backing device completely,
  51  *   and avoid having an extra copy of the data in the UBC (as well as the overhead associated with creating
  52  *   that copy).
  53  *
  54  * For the moment, mockfs is not marked in vfs_conf.c as being threadsafe.
  55  */
  56
  57 struct mockfs_mount {
  58         lck_mtx_t       mockfs_mnt_mtx;         /* Mount-wide (and tree-wide) mutex */
  59         mockfs_fsnode_t mockfs_root;            /* Root of the node tree */
  60         boolean_t       mockfs_memory_backed;   /* Does the backing store reside in memory */
  61         boolean_t       mockfs_physical_memory; /* (valid if memory backed) */
  62         uint32_t        mockfs_memdev_base;     /* Base page of the backing store (valid if memory backed) */
  63         uint64_t        mockfs_memdev_size;     /* Size of the backing store (valid if memory backed) */
  64 };
  65
  66 typedef struct mockfs_mount * mockfs_mount_t;
  67
  68 #endif /* MOCKFS */
  69
  70 #endif /* MOCKFS_H */