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 #include <sys/kernel_types.h>
  32 #include <stdbool.h>
  33 #include <sys/vnode.h>
  34
  35 #define MAX_DECMPFS_XATTR_SIZE 3802
  36
  37 /*
  38  NOTE:  decmpfs can only be used by thread-safe filesystems
  39  */
  40
  41 #define DECMPFS_MAGIC 0x636d7066 /* cmpf */
  42
  43 #define DECMPFS_XATTR_NAME "com.apple.decmpfs" /* extended attribute to use for decmpfs */
  44
  45 typedef struct __attribute__((packed)) {
  46     /* this structure represents the xattr on disk; the fields below are little-endian */
  47     uint32_t compression_magic;
  48     uint32_t compression_type;     /* see the enum below */
  49     uint64_t uncompressed_size;
  50     unsigned char attr_bytes[0];   /* the bytes of the attribute after the header */
  51 } decmpfs_disk_header;
  52
  53 typedef struct __attribute__((packed)) {
  54     /* this structure represents the xattr in memory; the fields below are host-endian */
  55     uint32_t attr_size;
  56     uint32_t compression_magic;
  57     uint32_t compression_type;
  58     uint64_t uncompressed_size;
  59     unsigned char attr_bytes[0];   /* the bytes of the attribute after the header */
  60 } decmpfs_header;
  61
  62 /* compression_type values */
  63 enum {
  64     CMP_Type1       = 1, /* uncompressed data in xattr */
  65
  66     /* additional types defined in AppleFSCompression project */
  67
  68     CMP_MAX         = 255 /* Highest compression_type supported */
  69 };
  70
  71 typedef struct {
  72     void *buf;
  73     user_ssize_t size;
  74 } decmpfs_vector;
  75
  76 #if KERNEL
  77
  78 #if XNU_KERNEL_PRIVATE
  79
  80 #include <kern/locks.h>
  81
  82 struct decmpfs_cnode {
  83     uint8_t cmp_state;
  84     uint8_t cmp_minimal_xattr;       /* if non-zero, this file's com.apple.decmpfs xattr contained only the minimal decmpfs_disk_header */
  85     uint32_t cmp_type;
  86     uint32_t lockcount;
  87     void    *lockowner;              /* cnode's lock owner (if a thread is currently holding an exclusive lock) */
  88     uint64_t uncompressed_size __attribute__((aligned(8)));
  89     uint64_t decompression_flags;
  90     lck_rw_t compressed_data_lock;
  91 };
  92
  93 #endif // XNU_KERNEL_PRIVATE
  94
  95 typedef struct decmpfs_cnode decmpfs_cnode;
  96
  97 /* return values from decmpfs_file_is_compressed */
  98 enum {
  99     FILE_TYPE_UNKNOWN      = 0,
 100     FILE_IS_NOT_COMPRESSED = 1,
 101     FILE_IS_COMPRESSED     = 2,
 102     FILE_IS_CONVERTING     = 3  /* file is converting from compressed to decompressed */
 103 };
 104
 105 /* vfs entrypoints */
 106 extern vfs_context_t decmpfs_ctx;
 107
 108 /* client filesystem entrypoints */
 109 void decmpfs_init(void);
 110 decmpfs_cnode *decmpfs_cnode_alloc(void);
 111 void decmpfs_cnode_free(decmpfs_cnode *dp);
 112 void decmpfs_cnode_init(decmpfs_cnode *cp);
 113 void decmpfs_cnode_destroy(decmpfs_cnode *cp);
 114
 115 int decmpfs_hides_rsrc(vfs_context_t ctx, decmpfs_cnode *cp);
 116 int decmpfs_hides_xattr(vfs_context_t ctx, decmpfs_cnode *cp, const char *xattr);
 117
 118 bool decmpfs_trylock_compressed_data(decmpfs_cnode *cp, int exclusive);
 119 void decmpfs_lock_compressed_data(decmpfs_cnode *cp, int exclusive);
 120 void decmpfs_unlock_compressed_data(decmpfs_cnode *cp, int exclusive);
 121
 122 uint32_t decmpfs_cnode_get_vnode_state(decmpfs_cnode *cp);
 123 void decmpfs_cnode_set_vnode_state(decmpfs_cnode *cp, uint32_t state, int skiplock);
 124 uint64_t decmpfs_cnode_get_vnode_cached_size(decmpfs_cnode *cp);
 125 uint32_t decmpfs_cnode_cmp_type(decmpfs_cnode *cp);
 126
 127 int decmpfs_file_is_compressed(vnode_t vp, decmpfs_cnode *cp);
 128 errno_t decmpfs_validate_compressed_file(vnode_t vp, decmpfs_cnode *cp);
 129 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 */
 130 int decmpfs_free_compressed_data(vnode_t vp, decmpfs_cnode *cp);
 131 int decmpfs_update_attributes(vnode_t vp, struct vnode_attr *vap);
 132 /* 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 */
 133 errno_t decmpfs_pagein_compressed(struct vnop_pagein_args *ap, int *is_compressed, decmpfs_cnode *cp);
 134 errno_t decmpfs_read_compressed(struct vnop_read_args *ap, int *is_compressed, decmpfs_cnode *cp);
 135
 136 /* types shared between the kernel and kexts */
 137 typedef int (*decmpfs_validate_compressed_file_func)(vnode_t vp, vfs_context_t ctx, decmpfs_header *hdr);
 138 typedef void (*decmpfs_adjust_fetch_region_func)(vnode_t vp, vfs_context_t ctx, decmpfs_header *hdr, off_t *offset, user_ssize_t *size);
 139 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);
 140 typedef int (*decmpfs_free_compressed_data_func)(vnode_t vp, vfs_context_t ctx, decmpfs_header *hdr);
 141 typedef uint64_t (*decmpfs_get_decompression_flags_func)(vnode_t vp, vfs_context_t ctx, decmpfs_header *hdr); // returns flags from the DECMPFS_FLAGS enumeration below
 142
 143 enum {
 144     DECMPFS_FLAGS_FORCE_FLUSH_ON_DECOMPRESS = 1 << 0,
 145 };
 146
 147 /* Versions that are supported for binary compatibility */
 148 #define DECMPFS_REGISTRATION_VERSION_V1 1
 149 #define DECMPFS_REGISTRATION_VERSION_V3 3
 150
 151 #define DECMPFS_REGISTRATION_VERSION (DECMPFS_REGISTRATION_VERSION_V3)
 152
 153 typedef struct {
 154     int                                   decmpfs_registration;
 155     decmpfs_validate_compressed_file_func validate;
 156     decmpfs_adjust_fetch_region_func      adjust_fetch;
 157     decmpfs_fetch_uncompressed_data_func  fetch;
 158     decmpfs_free_compressed_data_func     free_data;
 159     decmpfs_get_decompression_flags_func  get_flags;
 160 } decmpfs_registration;
 161
 162 /* hooks for kexts to call */
 163 errno_t register_decmpfs_decompressor(uint32_t compression_type, decmpfs_registration *registration);
 164 errno_t unregister_decmpfs_decompressor(uint32_t compression_type, decmpfs_registration *registration);
 165
 166 #endif /* KERNEL */
 167
 168 #endif /* _SYS_DECMPFS_H_ */