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 /*
  80  * This single field is to be interpreted differently depending on the
  81  * corresponding item type.
  82  * For regular files: it is a 64bits-encoded logical size
  83  * For directories: it is a 64bits-encoded number of children (ie st_nlink - 2)
  84  * For packages: it is 40bits encoded size and 24bits number of children at root
  85  */
  86 typedef struct __attribute__((packed)) {
  87         uint64_t  value;
  88 } decmpfs_raw_item_size;
  89
  90 #define DECMPFS_PKG_SIZE_MASK           0x000000ffffffffffULL
  91 #define DECMPFS_PKG_COUNT_MASK          0xffffff
  92 #define DECMPFS_PKG_CHLD_COUNT_SHIFT    40
  93
  94 #define DECMPFS_PKG_SIZE(x)             ((x).value & DECMPFS_PKG_SIZE_MASK)
  95 #define DECMPFS_PKG_CHLD_COUNT(x)       ((uint32_t)(((x).value >> DECMPFS_PKG_CHLD_COUNT_SHIFT) & DECMPFS_PKG_COUNT_MASK))
  96 #define DECMPFS_PKG_VALUE_FROM_SIZE_COUNT(size, count) \
  97         (((size) & DECMPFS_PKG_SIZE_MASK) | ((uint64_t)(count) << DECMPFS_PKG_CHLD_COUNT_SHIFT))
  98
  99 /* Dataless file or directory */
 100 #define DATALESS_CMPFS_TYPE     0x80000001
 101
 102 /* Dataless package, with number of root children and total size encoded on disk */
 103 #define DATALESS_PKG_CMPFS_TYPE 0x80000002
 104
 105
 106 static inline bool
 107 decmpfs_type_is_dataless(uint32_t cmp_type)
 108 {
 109         return cmp_type == DATALESS_CMPFS_TYPE || cmp_type == DATALESS_PKG_CMPFS_TYPE;
 110 }
 111
 112 typedef struct __attribute__((packed)) {
 113         /* this structure represents the xattr on disk; the fields below are little-endian */
 114         uint32_t compression_magic;
 115         uint32_t compression_type;   /* see the enum below */
 116         union {
 117                 uint64_t uncompressed_size;  /* compatility accessor */
 118                 decmpfs_raw_item_size _size;
 119         };
 120         unsigned char attr_bytes[0]; /* the bytes of the attribute after the header */
 121 } decmpfs_disk_header;
 122
 123 typedef struct __attribute__((packed)) {
 124         /* this structure represents the xattr in memory; the fields below are host-endian */
 125         uint32_t attr_size;
 126         uint32_t compression_magic;
 127         uint32_t compression_type;
 128         union {
 129                 /*
 130                  * although uncompressed_size remains available for backward-compatibility reasons
 131                  * the uncompressed size and nchildren should be accessed using the inline helpers
 132                  * below
 133                  */
 134                 uint64_t uncompressed_size;
 135                 decmpfs_raw_item_size _size;
 136         };
 137         unsigned char attr_bytes[0]; /* the bytes of the attribute after the header */
 138 } decmpfs_header;
 139
 140 static inline uint64_t
 141 decmpfs_get_uncompressed_size(const decmpfs_header *hdr)
 142 {
 143         if (hdr->compression_magic == DECMPFS_MAGIC && hdr->compression_type == DATALESS_PKG_CMPFS_TYPE) {
 144                 return DECMPFS_PKG_SIZE(hdr->_size);
 145         }
 146
 147         return hdr->uncompressed_size;
 148 }
 149
 150 static inline uint32_t
 151 decmpfs_get_directory_entries(const decmpfs_header *hdr)
 152 {
 153         if (hdr->compression_magic == DECMPFS_MAGIC && hdr->compression_type == DATALESS_PKG_CMPFS_TYPE) {
 154                 return DECMPFS_PKG_CHLD_COUNT(hdr->_size);
 155         }
 156
 157         return (uint32_t)hdr->uncompressed_size;
 158 }
 159
 160 /* compression_type values */
 161 enum {
 162         CMP_Type1       = 1,/* uncompressed data in xattr */
 163
 164         /* additional types defined in AppleFSCompression project */
 165
 166         CMP_MAX         = 255/* Highest compression_type supported */
 167 };
 168
 169 typedef struct {
 170         void *buf;
 171         user_ssize_t size;
 172 } decmpfs_vector;
 173
 174 #ifdef KERNEL
 175
 176 #ifdef XNU_KERNEL_PRIVATE
 177
 178 #include <kern/locks.h>
 179
 180 struct decmpfs_cnode {
 181         uint8_t cmp_state;
 182         uint8_t cmp_minimal_xattr;   /* if non-zero, this file's com.apple.decmpfs xattr contained only the minimal decmpfs_disk_header */
 183         uint32_t cmp_type;
 184         uint32_t lockcount;
 185         void    *lockowner;          /* cnode's lock owner (if a thread is currently holding an exclusive lock) */
 186         uint64_t uncompressed_size __attribute__((aligned(8)));
 187         uint64_t nchildren __attribute__((aligned(8))); /* for dataless directories (incl. packages) */
 188         uint64_t total_size __attribute__((aligned(8)));/* for dataless directories (incl. packages) */
 189         uint64_t decompression_flags;
 190         lck_rw_t compressed_data_lock;
 191 };
 192
 193 #endif // XNU_KERNEL_PRIVATE
 194
 195 typedef struct decmpfs_cnode decmpfs_cnode;
 196
 197 /* return values from decmpfs_file_is_compressed */
 198 enum {
 199         FILE_TYPE_UNKNOWN      = 0,
 200         FILE_IS_NOT_COMPRESSED = 1,
 201         FILE_IS_COMPRESSED     = 2,
 202         FILE_IS_CONVERTING     = 3/* file is converting from compressed to decompressed */
 203 };
 204
 205 /* vfs entrypoints */
 206 extern vfs_context_t decmpfs_ctx;
 207
 208 /* client filesystem entrypoints */
 209 void decmpfs_init(void);
 210 decmpfs_cnode *decmpfs_cnode_alloc(void);
 211 void decmpfs_cnode_free(decmpfs_cnode *dp);
 212 void decmpfs_cnode_init(decmpfs_cnode *cp);
 213 void decmpfs_cnode_destroy(decmpfs_cnode *cp);
 214
 215 int decmpfs_hides_rsrc(vfs_context_t ctx, decmpfs_cnode *cp);
 216 int decmpfs_hides_xattr(vfs_context_t ctx, decmpfs_cnode *cp, const char *xattr);
 217
 218 bool decmpfs_trylock_compressed_data(decmpfs_cnode *cp, int exclusive);
 219 void decmpfs_lock_compressed_data(decmpfs_cnode *cp, int exclusive);
 220 void decmpfs_unlock_compressed_data(decmpfs_cnode *cp, int exclusive);
 221
 222 uint32_t decmpfs_cnode_get_vnode_state(decmpfs_cnode *cp);
 223 void decmpfs_cnode_set_vnode_state(decmpfs_cnode *cp, uint32_t state, int skiplock);
 224 uint64_t decmpfs_cnode_get_vnode_cached_size(decmpfs_cnode *cp);
 225 uint64_t decmpfs_cnode_get_vnode_cached_nchildren(decmpfs_cnode *cp);
 226 uint64_t decmpfs_cnode_get_vnode_cached_total_size(decmpfs_cnode *cp);
 227 void decmpfs_cnode_set_vnode_cached_size(decmpfs_cnode *cp, uint64_t size);
 228 void decmpfs_cnode_set_vnode_cached_nchildren(decmpfs_cnode *cp, uint64_t nchildren);
 229 void decmpfs_cnode_set_vnode_cached_total_size(decmpfs_cnode *cp, uint64_t total_sz);
 230 uint32_t decmpfs_cnode_cmp_type(decmpfs_cnode *cp);
 231
 232 int decmpfs_file_is_compressed(vnode_t vp, decmpfs_cnode *cp);
 233 errno_t decmpfs_validate_compressed_file(vnode_t vp, decmpfs_cnode *cp);
 234 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 */
 235 int decmpfs_free_compressed_data(vnode_t vp, decmpfs_cnode *cp);
 236 int decmpfs_update_attributes(vnode_t vp, struct vnode_attr *vap);
 237 /* 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 */
 238 errno_t decmpfs_pagein_compressed(struct vnop_pagein_args *ap, int *is_compressed, decmpfs_cnode *cp);
 239 errno_t decmpfs_read_compressed(struct vnop_read_args *ap, int *is_compressed, decmpfs_cnode *cp);
 240
 241 /* types shared between the kernel and kexts */
 242 typedef int (*decmpfs_validate_compressed_file_func)(vnode_t vp, vfs_context_t ctx, decmpfs_header *hdr);
 243 typedef void (*decmpfs_adjust_fetch_region_func)(vnode_t vp, vfs_context_t ctx, decmpfs_header *hdr, off_t *offset, user_ssize_t *size);
 244 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);
 245 typedef int (*decmpfs_free_compressed_data_func)(vnode_t vp, vfs_context_t ctx, decmpfs_header *hdr);
 246 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
 247
 248 enum {
 249         DECMPFS_FLAGS_FORCE_FLUSH_ON_DECOMPRESS = 1 << 0,
 250 };
 251
 252 /* Versions that are supported for binary compatibility */
 253 #define DECMPFS_REGISTRATION_VERSION_V1 1
 254 #define DECMPFS_REGISTRATION_VERSION_V3 3
 255
 256 #define DECMPFS_REGISTRATION_VERSION (DECMPFS_REGISTRATION_VERSION_V3)
 257
 258 typedef struct {
 259         int                                   decmpfs_registration;
 260         decmpfs_validate_compressed_file_func validate;
 261         decmpfs_adjust_fetch_region_func      adjust_fetch;
 262         decmpfs_fetch_uncompressed_data_func  fetch;
 263         decmpfs_free_compressed_data_func     free_data;
 264         decmpfs_get_decompression_flags_func  get_flags;
 265 } decmpfs_registration;
 266
 267 /* hooks for kexts to call */
 268 errno_t register_decmpfs_decompressor(uint32_t compression_type, const decmpfs_registration *registration);
 269 errno_t unregister_decmpfs_decompressor(uint32_t compression_type, decmpfs_registration *registration);
 270
 271 #endif /* KERNEL */
 272
 273 #endif /* _SYS_DECMPFS_H_ */