bsd/sys/decmpfs.h

   1 /*
   2  * Copyright (c) 2008 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 #ifndef _SYS_DECMPFS_H_
  29 #define _SYS_DECMPFS_H_ 1
  30
  31 #define MAX_DECMPFS_XATTR_SIZE 3802
  32
  33 /*
  34  NOTE:  decmpfs can only be used by thread-safe filesystems
  35  */
  36
  37 #define DECMPFS_MAGIC 0x636d7066 /* cmpf */
  38
  39 #define DECMPFS_XATTR_NAME "com.apple.decmpfs" /* extended attribute to use for decmpfs */
  40
  41 typedef struct __attribute__((packed)) {
  42     /* this structure represents the xattr on disk; the fields below are little-endian */
  43     uint32_t compression_magic;
  44     uint32_t compression_type;     /* see the enum below */
  45     uint64_t uncompressed_size;
  46     unsigned char attr_bytes[0];   /* the bytes of the attribute after the header */
  47 } decmpfs_disk_header;
  48
  49 typedef struct __attribute__((packed)) {
  50     /* this structure represents the xattr in memory; the fields below are host-endian */
  51     uint32_t attr_size;
  52     uint32_t compression_magic;
  53     uint32_t compression_type;
  54     uint64_t uncompressed_size;
  55     unsigned char attr_bytes[0];   /* the bytes of the attribute after the header */
  56 } decmpfs_header;
  57
  58 /* compression_type values */
  59 enum {
  60     CMP_Type1       = 1, /* uncompressed data in xattr */
  61
  62     /* additional types defined in AppleFSCompression project */
  63
  64     CMP_MAX         = 255
  65 };
  66
  67 typedef struct {
  68     void *buf;
  69     user_ssize_t size;
  70 } decmpfs_vector;
  71
  72 #if KERNEL
  73
  74 #include <kern/locks.h>
  75
  76 #if defined(__i386__) || defined(__x86_64__)
  77 #define DECMPFS_SUPPORTS_SWAP64 1
  78 /* otherwise, no OSCompareAndSwap64, so use a mutex */
  79 #endif
  80
  81 typedef struct decmpfs_cnode {
  82         uint8_t cmp_state;
  83         uint8_t cmp_minimal_xattr;       /* if non-zero, this file's com.apple.decmpfs xattr contained only the minimal decmpfs_disk_header */
  84         uint32_t cmp_type;
  85         uint32_t lockcount;
  86         void    *lockowner;              /* cnode's lock owner (if a thread is currently holding an exclusive lock) */
  87     uint64_t uncompressed_size __attribute__((aligned(8)));
  88     lck_rw_t compressed_data_lock;
  89 #if !DECMPFS_SUPPORTS_SWAP64
  90     /* we need a lock since we can't atomically fetch/set 64 bits */
  91     lck_mtx_t uncompressed_size_mtx;
  92 #endif /* !DECMPFS_SUPPORTS_SWAP64 */
  93 } decmpfs_cnode;
  94
  95 /* return values from decmpfs_file_is_compressed */
  96 enum {
  97     FILE_TYPE_UNKNOWN      = 0,
  98     FILE_IS_NOT_COMPRESSED = 1,
  99     FILE_IS_COMPRESSED     = 2,
 100     FILE_IS_CONVERTING     = 3  /* file is converting from compressed to decompressed */
 101 };
 102
 103 /* vfs entrypoints */
 104 extern vfs_context_t decmpfs_ctx;
 105
 106 /* client filesystem entrypoints */
 107 void decmpfs_init(void);
 108 void decmpfs_cnode_init(decmpfs_cnode *cp);
 109 void decmpfs_cnode_destroy(decmpfs_cnode *cp);
 110
 111 int decmpfs_hides_rsrc(vfs_context_t ctx, decmpfs_cnode *cp);
 112 int decmpfs_hides_xattr(vfs_context_t ctx, decmpfs_cnode *cp, const char *xattr);
 113
 114 boolean_t decmpfs_trylock_compressed_data(decmpfs_cnode *cp, int exclusive);
 115 void decmpfs_lock_compressed_data(decmpfs_cnode *cp, int exclusive);
 116 void decmpfs_unlock_compressed_data(decmpfs_cnode *cp, int exclusive);
 117
 118 uint32_t decmpfs_cnode_get_vnode_state(decmpfs_cnode *cp);
 119 void decmpfs_cnode_set_vnode_state(decmpfs_cnode *cp, uint32_t state, int skiplock);
 120 uint64_t decmpfs_cnode_get_vnode_cached_size(decmpfs_cnode *cp);
 121
 122 int decmpfs_file_is_compressed(vnode_t vp, decmpfs_cnode *cp);
 123 errno_t decmpfs_validate_compressed_file(vnode_t vp, decmpfs_cnode *cp);
 124 int decmpfs_decompress_file(vnode_t vp, decmpfs_cnode *cp, off_t toSize, int truncate_okay, int skiplock);  /* if toSize == -1, decompress the entire file */
 125 int decmpfs_free_compressed_data(vnode_t vp, decmpfs_cnode *cp);
 126 int decmpfs_update_attributes(vnode_t vp, struct vnode_attr *vap);
 127 /* the following two routines will set *is_compressed to 0 if the file was converted from compressed to decompressed before data could be fetched from the decompressor */
 128 errno_t decmpfs_pagein_compressed(struct vnop_pagein_args *ap, int *is_compressed, decmpfs_cnode *cp);
 129 errno_t decmpfs_read_compressed(struct vnop_read_args *ap, int *is_compressed, decmpfs_cnode *cp);
 130
 131 /* types shared between the kernel and kexts */
 132 typedef int (*decmpfs_validate_compressed_file_func)(vnode_t vp, vfs_context_t ctx, decmpfs_header *hdr);
 133 typedef void (*decmpfs_adjust_fetch_region_func)(vnode_t vp, vfs_context_t ctx, decmpfs_header *hdr, off_t *offset, user_ssize_t *size);
 134 typedef int (*decmpfs_fetch_uncompressed_data_func)(vnode_t vp, vfs_context_t ctx, decmpfs_header *hdr, off_t offset, user_ssize_t size, int nvec, decmpfs_vector *vec, uint64_t *bytes_read);
 135 typedef int (*decmpfs_free_compressed_data_func)(vnode_t vp, vfs_context_t ctx, decmpfs_header *hdr);
 136
 137 #define DECMPFS_REGISTRATION_VERSION 1
 138 typedef struct {
 139     int                                   decmpfs_registration;
 140     decmpfs_validate_compressed_file_func validate;
 141     decmpfs_adjust_fetch_region_func      adjust_fetch;
 142     decmpfs_fetch_uncompressed_data_func  fetch;
 143     decmpfs_free_compressed_data_func     free_data;
 144 } decmpfs_registration;
 145
 146 /* hooks for kexts to call */
 147 errno_t register_decmpfs_decompressor(uint32_t compression_type, decmpfs_registration *registration);
 148 errno_t unregister_decmpfs_decompressor(uint32_t compression_type, decmpfs_registration *registration);
 149
 150 #endif /* KERNEL */
 151
 152 #endif /* _SYS_DECMPFS_H_ */