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 <stdbool.h>
  32 #include <sys/kdebug.h>
  33 #include <sys/kernel_types.h>
  34 #include <sys/vnode.h>
  35
  36 /*
  37  * Please switch on @DECMPFS_ENABLE_KDEBUG_TRACES to enable tracepoints.
  38  * Tracepoints are compiled out by default to eliminate any overhead due to
  39  * kernel tracing.
  40  *
  41  * #define DECMPFS_ENABLE_KDEBUG_TRACES 1
  42  */
  43 #if DECMPFS_ENABLE_KDEBUG_TRACES
  44 #define DECMPFS_EMIT_TRACE_ENTRY(D, ...)\
  45         KDBG_FILTERED((D) | DBG_FUNC_START, ## __VA_ARGS__)
  46 #define DECMPFS_EMIT_TRACE_RETURN(D, ...)\
  47         KDBG_FILTERED((D) | DBG_FUNC_END, ##__VA_ARGS__)
  48 #else
  49 #define DECMPFS_EMIT_TRACE_ENTRY(D, ...) do {} while (0)
  50 #define DECMPFS_EMIT_TRACE_RETURN(D, ...) do {} while (0)
  51 #endif /* DECMPFS_ENABLE_KDEBUG_TRACES */
  52
  53 /*
  54  * KERNEL_DEBUG related definitions for decmpfs.
  55  *
  56  * Please NOTE: The Class DBG_FSYSTEM = 3, and Subclass DBG_DECMP = 0x12, so
  57  * these debug codes are of the form 0x0312nnnn.
  58  */
  59 #define DECMPDBG_CODE(code)  FSDBG_CODE(DBG_DECMP, code)
  60
  61 enum {
  62     DECMPDBG_DECOMPRESS_FILE            = DECMPDBG_CODE(0), /* 0x03120000 */
  63     DECMPDBG_FETCH_COMPRESSED_HEADER    = DECMPDBG_CODE(1), /* 0x03120004 */
  64     DECMPDBG_FETCH_UNCOMPRESSED_DATA    = DECMPDBG_CODE(2), /* 0x03120008 */
  65     DECMPDBG_FREE_COMPRESSED_DATA       = DECMPDBG_CODE(4), /* 0x03120010 */
  66     DECMPDBG_FILE_IS_COMPRESSED         = DECMPDBG_CODE(5), /* 0x03120014 */
  67 };
  68
  69 #define MAX_DECMPFS_XATTR_SIZE 3802
  70
  71 /*
  72  NOTE:  decmpfs can only be used by thread-safe filesystems
  73  */
  74
  75 #define DECMPFS_MAGIC 0x636d7066 /* cmpf */
  76
  77 #define DECMPFS_XATTR_NAME "com.apple.decmpfs" /* extended attribute to use for decmpfs */
  78
  79 typedef struct __attribute__((packed)) {
  80     /* this structure represents the xattr on disk; the fields below are little-endian */
  81     uint32_t compression_magic;
  82     uint32_t compression_type;     /* see the enum below */
  83     uint64_t uncompressed_size;
  84     unsigned char attr_bytes[0];   /* the bytes of the attribute after the header */
  85 } decmpfs_disk_header;
  86
  87 typedef struct __attribute__((packed)) {
  88     /* this structure represents the xattr in memory; the fields below are host-endian */
  89     uint32_t attr_size;
  90     uint32_t compression_magic;
  91     uint32_t compression_type;
  92     uint64_t uncompressed_size;
  93     unsigned char attr_bytes[0];   /* the bytes of the attribute after the header */
  94 } decmpfs_header;
  95
  96 /* compression_type values */
  97 enum {
  98     CMP_Type1       = 1, /* uncompressed data in xattr */
  99
 100     /* additional types defined in AppleFSCompression project */
 101
 102     CMP_MAX         = 255 /* Highest compression_type supported */
 103 };
 104
 105 typedef struct {
 106     void *buf;
 107     user_ssize_t size;
 108 } decmpfs_vector;
 109
 110 #ifdef KERNEL
 111
 112 #ifdef XNU_KERNEL_PRIVATE
 113
 114 #include <kern/locks.h>
 115
 116 struct decmpfs_cnode {
 117     uint8_t cmp_state;
 118     uint8_t cmp_minimal_xattr;       /* if non-zero, this file's com.apple.decmpfs xattr contained only the minimal decmpfs_disk_header */
 119     uint32_t cmp_type;
 120     uint32_t lockcount;
 121     void    *lockowner;              /* cnode's lock owner (if a thread is currently holding an exclusive lock) */
 122     uint64_t uncompressed_size __attribute__((aligned(8)));
 123     uint64_t decompression_flags;
 124     lck_rw_t compressed_data_lock;
 125 };
 126
 127 #endif // XNU_KERNEL_PRIVATE
 128
 129 typedef struct decmpfs_cnode decmpfs_cnode;
 130
 131 /* return values from decmpfs_file_is_compressed */
 132 enum {
 133     FILE_TYPE_UNKNOWN      = 0,
 134     FILE_IS_NOT_COMPRESSED = 1,
 135     FILE_IS_COMPRESSED     = 2,
 136     FILE_IS_CONVERTING     = 3  /* file is converting from compressed to decompressed */
 137 };
 138
 139 /* vfs entrypoints */
 140 extern vfs_context_t decmpfs_ctx;
 141
 142 /* client filesystem entrypoints */
 143 void decmpfs_init(void);
 144 decmpfs_cnode *decmpfs_cnode_alloc(void);
 145 void decmpfs_cnode_free(decmpfs_cnode *dp);
 146 void decmpfs_cnode_init(decmpfs_cnode *cp);
 147 void decmpfs_cnode_destroy(decmpfs_cnode *cp);
 148
 149 int decmpfs_hides_rsrc(vfs_context_t ctx, decmpfs_cnode *cp);
 150 int decmpfs_hides_xattr(vfs_context_t ctx, decmpfs_cnode *cp, const char *xattr);
 151
 152 bool decmpfs_trylock_compressed_data(decmpfs_cnode *cp, int exclusive);
 153 void decmpfs_lock_compressed_data(decmpfs_cnode *cp, int exclusive);
 154 void decmpfs_unlock_compressed_data(decmpfs_cnode *cp, int exclusive);
 155
 156 uint32_t decmpfs_cnode_get_vnode_state(decmpfs_cnode *cp);
 157 void decmpfs_cnode_set_vnode_state(decmpfs_cnode *cp, uint32_t state, int skiplock);
 158 uint64_t decmpfs_cnode_get_vnode_cached_size(decmpfs_cnode *cp);
 159 uint32_t decmpfs_cnode_cmp_type(decmpfs_cnode *cp);
 160
 161 int decmpfs_file_is_compressed(vnode_t vp, decmpfs_cnode *cp);
 162 errno_t decmpfs_validate_compressed_file(vnode_t vp, decmpfs_cnode *cp);
 163 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 */
 164 int decmpfs_free_compressed_data(vnode_t vp, decmpfs_cnode *cp);
 165 int decmpfs_update_attributes(vnode_t vp, struct vnode_attr *vap);
 166 /* 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 */
 167 errno_t decmpfs_pagein_compressed(struct vnop_pagein_args *ap, int *is_compressed, decmpfs_cnode *cp);
 168 errno_t decmpfs_read_compressed(struct vnop_read_args *ap, int *is_compressed, decmpfs_cnode *cp);
 169
 170 /* types shared between the kernel and kexts */
 171 typedef int (*decmpfs_validate_compressed_file_func)(vnode_t vp, vfs_context_t ctx, decmpfs_header *hdr);
 172 typedef void (*decmpfs_adjust_fetch_region_func)(vnode_t vp, vfs_context_t ctx, decmpfs_header *hdr, off_t *offset, user_ssize_t *size);
 173 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);
 174 typedef int (*decmpfs_free_compressed_data_func)(vnode_t vp, vfs_context_t ctx, decmpfs_header *hdr);
 175 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
 176
 177 enum {
 178     DECMPFS_FLAGS_FORCE_FLUSH_ON_DECOMPRESS = 1 << 0,
 179 };
 180
 181 /* Versions that are supported for binary compatibility */
 182 #define DECMPFS_REGISTRATION_VERSION_V1 1
 183 #define DECMPFS_REGISTRATION_VERSION_V3 3
 184
 185 #define DECMPFS_REGISTRATION_VERSION (DECMPFS_REGISTRATION_VERSION_V3)
 186
 187 typedef struct {
 188     int                                   decmpfs_registration;
 189     decmpfs_validate_compressed_file_func validate;
 190     decmpfs_adjust_fetch_region_func      adjust_fetch;
 191     decmpfs_fetch_uncompressed_data_func  fetch;
 192     decmpfs_free_compressed_data_func     free_data;
 193     decmpfs_get_decompression_flags_func  get_flags;
 194 } decmpfs_registration;
 195
 196 /* hooks for kexts to call */
 197 errno_t register_decmpfs_decompressor(uint32_t compression_type, const decmpfs_registration *registration);
 198 errno_t unregister_decmpfs_decompressor(uint32_t compression_type, decmpfs_registration *registration);
 199
 200 #endif /* KERNEL */
 201
 202 #endif /* _SYS_DECMPFS_H_ */