1 /* 2 * Copyright (c) 1999-2010 Apple Inc. All Rights Reserved. 3 * 4 * @APPLE_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. Please obtain a copy of the License at 10 * http://www.opensource.apple.com/apsl/ and read it before using this 11 * file. 12 * 13 * The Original Code and all software distributed under the License are 14 * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER 15 * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES, 16 * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY, 17 * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT. 18 * Please see the License for the specific language governing rights and 19 * limitations under the License. 20 * 21 * @APPLE_LICENSE_HEADER_END@ 22 */ 23 #ifndef _MACHO_LOADER_H_ 24 #define _MACHO_LOADER_H_ 25 26 /* 27 * This file describes the format of mach object files. 28 */ 29 #include <stdint.h> 30 31 /* 32 * <mach/machine.h> is needed here for the cpu_type_t and cpu_subtype_t types 33 * and contains the constants for the possible values of these types. 34 */ 35 #include <mach/machine.h> 36 37 /* 38 * <mach/vm_prot.h> is needed here for the vm_prot_t type and contains the 39 * constants that are or'ed together for the possible values of this type. 40 */ 41 #include <mach/vm_prot.h> 42 43 /* 44 * <machine/thread_status.h> is expected to define the flavors of the thread 45 * states and the structures of those flavors for each machine. 46 */ 47 #include <mach/machine/thread_status.h> 48 #include <architecture/byte_order.h> 49 50 /* 51 * The 32-bit mach header appears at the very beginning of the object file for 52 * 32-bit architectures. 53 */ 54 struct mach_header { 55 uint32_t magic; /* mach magic number identifier */ 56 cpu_type_t cputype; /* cpu specifier */ 57 cpu_subtype_t cpusubtype; /* machine specifier */ 58 uint32_t filetype; /* type of file */ 59 uint32_t ncmds; /* number of load commands */ 60 uint32_t sizeofcmds; /* the size of all the load commands */ 61 uint32_t flags; /* flags */ 62 }; 63 64 /* Constant for the magic field of the mach_header (32-bit architectures) */ 65 #define MH_MAGIC 0xfeedface /* the mach magic number */ 66 #define MH_CIGAM 0xcefaedfe /* NXSwapInt(MH_MAGIC) */ 67 68 /* 69 * The 64-bit mach header appears at the very beginning of object files for 70 * 64-bit architectures. 71 */ 72 struct mach_header_64 { 73 uint32_t magic; /* mach magic number identifier */ 74 cpu_type_t cputype; /* cpu specifier */ 75 cpu_subtype_t cpusubtype; /* machine specifier */ 76 uint32_t filetype; /* type of file */ 77 uint32_t ncmds; /* number of load commands */ 78 uint32_t sizeofcmds; /* the size of all the load commands */ 79 uint32_t flags; /* flags */ 80 uint32_t reserved; /* reserved */ 81 }; 82 83 /* Constant for the magic field of the mach_header_64 (64-bit architectures) */ 84 #define MH_MAGIC_64 0xfeedfacf /* the 64-bit mach magic number */ 85 #define MH_CIGAM_64 0xcffaedfe /* NXSwapInt(MH_MAGIC_64) */ 86 87 /* 88 * The layout of the file depends on the filetype. For all but the MH_OBJECT 89 * file type the segments are padded out and aligned on a segment alignment 90 * boundary for efficient demand pageing. The MH_EXECUTE, MH_FVMLIB, MH_DYLIB, 91 * MH_DYLINKER and MH_BUNDLE file types also have the headers included as part 92 * of their first segment. 93 * 94 * The file type MH_OBJECT is a compact format intended as output of the 95 * assembler and input (and possibly output) of the link editor (the .o 96 * format). All sections are in one unnamed segment with no segment padding. 97 * This format is used as an executable format when the file is so small the 98 * segment padding greatly increases its size. 99 * 100 * The file type MH_PRELOAD is an executable format intended for things that 101 * are not executed under the kernel (proms, stand alones, kernels, etc). The 102 * format can be executed under the kernel but may demand paged it and not 103 * preload it before execution. 104 * 105 * A core file is in MH_CORE format and can be any in an arbritray legal 106 * Mach-O file. 107 * 108 * Constants for the filetype field of the mach_header 109 */ 110 #define MH_OBJECT 0x1 /* relocatable object file */ 111 #define MH_EXECUTE 0x2 /* demand paged executable file */ 112 #define MH_FVMLIB 0x3 /* fixed VM shared library file */ 113 #define MH_CORE 0x4 /* core file */ 114 #define MH_PRELOAD 0x5 /* preloaded executable file */ 115 #define MH_DYLIB 0x6 /* dynamically bound shared library */ 116 #define MH_DYLINKER 0x7 /* dynamic link editor */ 117 #define MH_BUNDLE 0x8 /* dynamically bound bundle file */ 118 #define MH_DYLIB_STUB 0x9 /* shared library stub for static */ 119 /* linking only, no section contents */ 120 #define MH_DSYM 0xa /* companion file with only debug */ 121 /* sections */ 122 #define MH_KEXT_BUNDLE 0xb /* x86_64 kexts */ 123 124 /* Constants for the flags field of the mach_header */ 125 #define MH_NOUNDEFS 0x1 /* the object file has no undefined 126 references */ 127 #define MH_INCRLINK 0x2 /* the object file is the output of an 128 incremental link against a base file 129 and can't be link edited again */ 130 #define MH_DYLDLINK 0x4 /* the object file is input for the 131 dynamic linker and can't be staticly 132 link edited again */ 133 #define MH_BINDATLOAD 0x8 /* the object file's undefined 134 references are bound by the dynamic 135 linker when loaded. */ 136 #define MH_PREBOUND 0x10 /* the file has its dynamic undefined 137 references prebound. */ 138 #define MH_SPLIT_SEGS 0x20 /* the file has its read-only and 139 read-write segments split */ 140 #define MH_LAZY_INIT 0x40 /* the shared library init routine is 141 to be run lazily via catching memory 142 faults to its writeable segments 143 (obsolete) */ 144 #define MH_TWOLEVEL 0x80 /* the image is using two-level name 145 space bindings */ 146 #define MH_FORCE_FLAT 0x100 /* the executable is forcing all images 147 to use flat name space bindings */ 148 #define MH_NOMULTIDEFS 0x200 /* this umbrella guarantees no multiple 149 defintions of symbols in its 150 sub-images so the two-level namespace 151 hints can always be used. */ 152 #define MH_NOFIXPREBINDING 0x400 /* do not have dyld notify the 153 prebinding agent about this 154 executable */ 155 #define MH_PREBINDABLE 0x800 /* the binary is not prebound but can 156 have its prebinding redone. only used 157 when MH_PREBOUND is not set. */ 158 #define MH_ALLMODSBOUND 0x1000 /* indicates that this binary binds to 159 all two-level namespace modules of 160 its dependent libraries. only used 161 when MH_PREBINDABLE and MH_TWOLEVEL 162 are both set. */ 163 #define MH_SUBSECTIONS_VIA_SYMBOLS 0x2000/* safe to divide up the sections into 164 sub-sections via symbols for dead 165 code stripping */ 166 #define MH_CANONICAL 0x4000 /* the binary has been canonicalized 167 via the unprebind operation */ 168 #define MH_WEAK_DEFINES 0x8000 /* the final linked image contains 169 external weak symbols */ 170 #define MH_BINDS_TO_WEAK 0x10000 /* the final linked image uses 171 weak symbols */ 172 173 #define MH_ALLOW_STACK_EXECUTION 0x20000/* When this bit is set, all stacks 174 in the task will be given stack 175 execution privilege. Only used in 176 MH_EXECUTE filetypes. */ 177 #define MH_ROOT_SAFE 0x40000 /* When this bit is set, the binary 178 declares it is safe for use in 179 processes with uid zero */ 180 181 #define MH_SETUID_SAFE 0x80000 /* When this bit is set, the binary 182 declares it is safe for use in 183 processes when issetugid() is true */ 184 185 #define MH_NO_REEXPORTED_DYLIBS 0x100000 /* When this bit is set on a dylib, 186 the static linker does not need to 187 examine dependent dylibs to see 188 if any are re-exported */ 189 #define MH_PIE 0x200000 /* When this bit is set, the OS will 190 load the main executable at a 191 random address. Only used in 192 MH_EXECUTE filetypes. */ 193 #define MH_DEAD_STRIPPABLE_DYLIB 0x400000 /* Only for use on dylibs. When 194 linking against a dylib that 195 has this bit set, the static linker 196 will automatically not create a 197 LC_LOAD_DYLIB load command to the 198 dylib if no symbols are being 199 referenced from the dylib. */ 200 #define MH_HAS_TLV_DESCRIPTORS 0x800000 /* Contains a section of type 201 S_THREAD_LOCAL_VARIABLES */ 202 203 #define MH_NO_HEAP_EXECUTION 0x1000000 /* When this bit is set, the OS will 204 run the main executable with 205 a non-executable heap even on 206 platforms (e.g. i386) that don't 207 require it. Only used in MH_EXECUTE 208 filetypes. */ 209 210 #define MH_APP_EXTENSION_SAFE 0x02000000 /* The code was linked for use in an 211 application extension. */ 212 213 #define MH_NLIST_OUTOFSYNC_WITH_DYLDINFO 0x04000000 /* The external symbols 214 listed in the nlist symbol table do 215 not include all the symbols listed in 216 the dyld info. */ 217 218 #define MH_SIM_SUPPORT 0x08000000 /* Allow LC_MIN_VERSION_MACOS and 219 LC_BUILD_VERSION load commands with 220 the platforms macOS, macCatalyst, 221 iOSSimulator, tvOSSimulator and 222 watchOSSimulator. */ 223 224 #define MH_DYLIB_IN_CACHE 0x80000000 /* Only for use on dylibs. When this bit 225 is set, the dylib is part of the dyld 226 shared cache, rather than loose in 227 the filesystem. */ 228 229 /* 230 * The load commands directly follow the mach_header. The total size of all 231 * of the commands is given by the sizeofcmds field in the mach_header. All 232 * load commands must have as their first two fields cmd and cmdsize. The cmd 233 * field is filled in with a constant for that command type. Each command type 234 * has a structure specifically for it. The cmdsize field is the size in bytes 235 * of the particular load command structure plus anything that follows it that 236 * is a part of the load command (i.e. section structures, strings, etc.). To 237 * advance to the next load command the cmdsize can be added to the offset or 238 * pointer of the current load command. The cmdsize for 32-bit architectures 239 * MUST be a multiple of 4 bytes and for 64-bit architectures MUST be a multiple 240 * of 8 bytes (these are forever the maximum alignment of any load commands). 241 * The padded bytes must be zero. All tables in the object file must also 242 * follow these rules so the file can be memory mapped. Otherwise the pointers 243 * to these tables will not work well or at all on some machines. With all 244 * padding zeroed like objects will compare byte for byte. 245 */ 246 struct load_command { 247 uint32_t cmd; /* type of load command */ 248 uint32_t cmdsize; /* total size of command in bytes */ 249 }; 250 251 /* 252 * After MacOS X 10.1 when a new load command is added that is required to be 253 * understood by the dynamic linker for the image to execute properly the 254 * LC_REQ_DYLD bit will be or'ed into the load command constant. If the dynamic 255 * linker sees such a load command it it does not understand will issue a 256 * "unknown load command required for execution" error and refuse to use the 257 * image. Other load commands without this bit that are not understood will 258 * simply be ignored. 259 */ 260 #define LC_REQ_DYLD 0x80000000 261 262 /* Constants for the cmd field of all load commands, the type */ 263 #define LC_SEGMENT 0x1 /* segment of this file to be mapped */ 264 #define LC_SYMTAB 0x2 /* link-edit stab symbol table info */ 265 #define LC_SYMSEG 0x3 /* link-edit gdb symbol table info (obsolete) */ 266 #define LC_THREAD 0x4 /* thread */ 267 #define LC_UNIXTHREAD 0x5 /* unix thread (includes a stack) */ 268 #define LC_LOADFVMLIB 0x6 /* load a specified fixed VM shared library */ 269 #define LC_IDFVMLIB 0x7 /* fixed VM shared library identification */ 270 #define LC_IDENT 0x8 /* object identification info (obsolete) */ 271 #define LC_FVMFILE 0x9 /* fixed VM file inclusion (internal use) */ 272 #define LC_PREPAGE 0xa /* prepage command (internal use) */ 273 #define LC_DYSYMTAB 0xb /* dynamic link-edit symbol table info */ 274 #define LC_LOAD_DYLIB 0xc /* load a dynamically linked shared library */ 275 #define LC_ID_DYLIB 0xd /* dynamically linked shared lib ident */ 276 #define LC_LOAD_DYLINKER 0xe /* load a dynamic linker */ 277 #define LC_ID_DYLINKER 0xf /* dynamic linker identification */ 278 #define LC_PREBOUND_DYLIB 0x10 /* modules prebound for a dynamically */ 279 /* linked shared library */ 280 #define LC_ROUTINES 0x11 /* image routines */ 281 #define LC_SUB_FRAMEWORK 0x12 /* sub framework */ 282 #define LC_SUB_UMBRELLA 0x13 /* sub umbrella */ 283 #define LC_SUB_CLIENT 0x14 /* sub client */ 284 #define LC_SUB_LIBRARY 0x15 /* sub library */ 285 #define LC_TWOLEVEL_HINTS 0x16 /* two-level namespace lookup hints */ 286 #define LC_PREBIND_CKSUM 0x17 /* prebind checksum */ 287 288 /* 289 * load a dynamically linked shared library that is allowed to be missing 290 * (all symbols are weak imported). 291 */ 292 #define LC_LOAD_WEAK_DYLIB (0x18 | LC_REQ_DYLD) 293 294 #define LC_SEGMENT_64 0x19 /* 64-bit segment of this file to be 295 mapped */ 296 #define LC_ROUTINES_64 0x1a /* 64-bit image routines */ 297 #define LC_UUID 0x1b /* the uuid */ 298 #define LC_RPATH (0x1c | LC_REQ_DYLD) /* runpath additions */ 299 #define LC_CODE_SIGNATURE 0x1d /* local of code signature */ 300 #define LC_SEGMENT_SPLIT_INFO 0x1e /* local of info to split segments */ 301 #define LC_REEXPORT_DYLIB (0x1f | LC_REQ_DYLD) /* load and re-export dylib */ 302 #define LC_LAZY_LOAD_DYLIB 0x20 /* delay load of dylib until first use */ 303 #define LC_ENCRYPTION_INFO 0x21 /* encrypted segment information */ 304 #define LC_DYLD_INFO 0x22 /* compressed dyld information */ 305 #define LC_DYLD_INFO_ONLY (0x22|LC_REQ_DYLD) /* compressed dyld information only */ 306 #define LC_LOAD_UPWARD_DYLIB (0x23 | LC_REQ_DYLD) /* load upward dylib */ 307 #define LC_VERSION_MIN_MACOSX 0x24 /* build for MacOSX min OS version */ 308 #define LC_VERSION_MIN_IPHONEOS 0x25 /* build for iPhoneOS min OS version */ 309 #define LC_FUNCTION_STARTS 0x26 /* compressed table of function start addresses */ 310 #define LC_DYLD_ENVIRONMENT 0x27 /* string for dyld to treat 311 like environment variable */ 312 #define LC_MAIN (0x28|LC_REQ_DYLD) /* replacement for LC_UNIXTHREAD */ 313 #define LC_DATA_IN_CODE 0x29 /* table of non-instructions in __text */ 314 #define LC_SOURCE_VERSION 0x2A /* source version used to build binary */ 315 #define LC_DYLIB_CODE_SIGN_DRS 0x2B /* Code signing DRs copied from linked dylibs */ 316 #define LC_ENCRYPTION_INFO_64 0x2C /* 64-bit encrypted segment information */ 317 #define LC_LINKER_OPTION 0x2D /* linker options in MH_OBJECT files */ 318 #define LC_LINKER_OPTIMIZATION_HINT 0x2E /* optimization hints in MH_OBJECT files */ 319 #define LC_VERSION_MIN_TVOS 0x2F /* build for AppleTV min OS version */ 320 #define LC_VERSION_MIN_WATCHOS 0x30 /* build for Watch min OS version */ 321 #define LC_NOTE 0x31 /* arbitrary data included within a Mach-O file */ 322 #define LC_BUILD_VERSION 0x32 /* build for platform min OS version */ 323 #define LC_DYLD_EXPORTS_TRIE (0x33 | LC_REQ_DYLD) /* used with linkedit_data_command, payload is trie */ 324 #define LC_DYLD_CHAINED_FIXUPS (0x34 | LC_REQ_DYLD) /* used with linkedit_data_command */ 325 326 /* 327 * A variable length string in a load command is represented by an lc_str 328 * union. The strings are stored just after the load command structure and 329 * the offset is from the start of the load command structure. The size 330 * of the string is reflected in the cmdsize field of the load command. 331 * Once again any padded bytes to bring the cmdsize field to a multiple 332 * of 4 bytes must be zero. 333 */ 334 union lc_str { 335 uint32_t offset; /* offset to the string */ 336 #ifndef __LP64__ 337 char *ptr; /* pointer to the string */ 338 #endif 339 }; 340 341 /* 342 * The segment load command indicates that a part of this file is to be 343 * mapped into the task's address space. The size of this segment in memory, 344 * vmsize, maybe equal to or larger than the amount to map from this file, 345 * filesize. The file is mapped starting at fileoff to the beginning of 346 * the segment in memory, vmaddr. The rest of the memory of the segment, 347 * if any, is allocated zero fill on demand. The segment's maximum virtual 348 * memory protection and initial virtual memory protection are specified 349 * by the maxprot and initprot fields. If the segment has sections then the 350 * section structures directly follow the segment command and their size is 351 * reflected in cmdsize. 352 */ 353 struct segment_command { /* for 32-bit architectures */ 354 uint32_t cmd; /* LC_SEGMENT */ 355 uint32_t cmdsize; /* includes sizeof section structs */ 356 char segname[16]; /* segment name */ 357 uint32_t vmaddr; /* memory address of this segment */ 358 uint32_t vmsize; /* memory size of this segment */ 359 uint32_t fileoff; /* file offset of this segment */ 360 uint32_t filesize; /* amount to map from the file */ 361 vm_prot_t maxprot; /* maximum VM protection */ 362 vm_prot_t initprot; /* initial VM protection */ 363 uint32_t nsects; /* number of sections in segment */ 364 uint32_t flags; /* flags */ 365 }; 366 367 /* 368 * The 64-bit segment load command indicates that a part of this file is to be 369 * mapped into a 64-bit task's address space. If the 64-bit segment has 370 * sections then section_64 structures directly follow the 64-bit segment 371 * command and their size is reflected in cmdsize. 372 */ 373 struct segment_command_64 { /* for 64-bit architectures */ 374 uint32_t cmd; /* LC_SEGMENT_64 */ 375 uint32_t cmdsize; /* includes sizeof section_64 structs */ 376 char segname[16]; /* segment name */ 377 uint64_t vmaddr; /* memory address of this segment */ 378 uint64_t vmsize; /* memory size of this segment */ 379 uint64_t fileoff; /* file offset of this segment */ 380 uint64_t filesize; /* amount to map from the file */ 381 vm_prot_t maxprot; /* maximum VM protection */ 382 vm_prot_t initprot; /* initial VM protection */ 383 uint32_t nsects; /* number of sections in segment */ 384 uint32_t flags; /* flags */ 385 }; 386 387 /* Constants for the flags field of the segment_command */ 388 #define SG_HIGHVM 0x1 /* the file contents for this segment is for 389 the high part of the VM space, the low part 390 is zero filled (for stacks in core files) */ 391 #define SG_FVMLIB 0x2 /* this segment is the VM that is allocated by 392 a fixed VM library, for overlap checking in 393 the link editor */ 394 #define SG_NORELOC 0x4 /* this segment has nothing that was relocated 395 in it and nothing relocated to it, that is 396 it maybe safely replaced without relocation*/ 397 #define SG_PROTECTED_VERSION_1 0x8 /* This segment is protected. If the 398 segment starts at file offset 0, the 399 first page of the segment is not 400 protected. All other pages of the 401 segment are protected. */ 402 #define SG_READ_ONLY 0x10 /* This segment is made read-only after fixups */ 403 404 405 406 /* 407 * A segment is made up of zero or more sections. Non-MH_OBJECT files have 408 * all of their segments with the proper sections in each, and padded to the 409 * specified segment alignment when produced by the link editor. The first 410 * segment of a MH_EXECUTE and MH_FVMLIB format file contains the mach_header 411 * and load commands of the object file before its first section. The zero 412 * fill sections are always last in their segment (in all formats). This 413 * allows the zeroed segment padding to be mapped into memory where zero fill 414 * sections might be. The gigabyte zero fill sections, those with the section 415 * type S_GB_ZEROFILL, can only be in a segment with sections of this type. 416 * These segments are then placed after all other segments. 417 * 418 * The MH_OBJECT format has all of its sections in one segment for 419 * compactness. There is no padding to a specified segment boundary and the 420 * mach_header and load commands are not part of the segment. 421 * 422 * Sections with the same section name, sectname, going into the same segment, 423 * segname, are combined by the link editor. The resulting section is aligned 424 * to the maximum alignment of the combined sections and is the new section's 425 * alignment. The combined sections are aligned to their original alignment in 426 * the combined section. Any padded bytes to get the specified alignment are 427 * zeroed. 428 * 429 * The format of the relocation entries referenced by the reloff and nreloc 430 * fields of the section structure for mach object files is described in the 431 * header file <reloc.h>. 432 */ 433 struct section { /* for 32-bit architectures */ 434 char sectname[16]; /* name of this section */ 435 char segname[16]; /* segment this section goes in */ 436 uint32_t addr; /* memory address of this section */ 437 uint32_t size; /* size in bytes of this section */ 438 uint32_t offset; /* file offset of this section */ 439 uint32_t align; /* section alignment (power of 2) */ 440 uint32_t reloff; /* file offset of relocation entries */ 441 uint32_t nreloc; /* number of relocation entries */ 442 uint32_t flags; /* flags (section type and attributes)*/ 443 uint32_t reserved1; /* reserved (for offset or index) */ 444 uint32_t reserved2; /* reserved (for count or sizeof) */ 445 }; 446 447 struct section_64 { /* for 64-bit architectures */ 448 char sectname[16]; /* name of this section */ 449 char segname[16]; /* segment this section goes in */ 450 uint64_t addr; /* memory address of this section */ 451 uint64_t size; /* size in bytes of this section */ 452 uint32_t offset; /* file offset of this section */ 453 uint32_t align; /* section alignment (power of 2) */ 454 uint32_t reloff; /* file offset of relocation entries */ 455 uint32_t nreloc; /* number of relocation entries */ 456 uint32_t flags; /* flags (section type and attributes)*/ 457 uint32_t reserved1; /* reserved (for offset or index) */ 458 uint32_t reserved2; /* reserved (for count or sizeof) */ 459 uint32_t reserved3; /* reserved */ 460 }; 461 462 /* 463 * The flags field of a section structure is separated into two parts a section 464 * type and section attributes. The section types are mutually exclusive (it 465 * can only have one type) but the section attributes are not (it may have more 466 * than one attribute). 467 */ 468 #define SECTION_TYPE 0x000000ff /* 256 section types */ 469 #define SECTION_ATTRIBUTES 0xffffff00 /* 24 section attributes */ 470 471 /* Constants for the type of a section */ 472 #define S_REGULAR 0x0 /* regular section */ 473 #define S_ZEROFILL 0x1 /* zero fill on demand section */ 474 #define S_CSTRING_LITERALS 0x2 /* section with only literal C strings*/ 475 #define S_4BYTE_LITERALS 0x3 /* section with only 4 byte literals */ 476 #define S_8BYTE_LITERALS 0x4 /* section with only 8 byte literals */ 477 #define S_LITERAL_POINTERS 0x5 /* section with only pointers to */ 478 /* literals */ 479 /* 480 * For the two types of symbol pointers sections and the symbol stubs section 481 * they have indirect symbol table entries. For each of the entries in the 482 * section the indirect symbol table entries, in corresponding order in the 483 * indirect symbol table, start at the index stored in the reserved1 field 484 * of the section structure. Since the indirect symbol table entries 485 * correspond to the entries in the section the number of indirect symbol table 486 * entries is inferred from the size of the section divided by the size of the 487 * entries in the section. For symbol pointers sections the size of the entries 488 * in the section is 4 bytes and for symbol stubs sections the byte size of the 489 * stubs is stored in the reserved2 field of the section structure. 490 */ 491 #define S_NON_LAZY_SYMBOL_POINTERS 0x6 /* section with only non-lazy 492 symbol pointers */ 493 #define S_LAZY_SYMBOL_POINTERS 0x7 /* section with only lazy symbol 494 pointers */ 495 #define S_SYMBOL_STUBS 0x8 /* section with only symbol 496 stubs, byte size of stub in 497 the reserved2 field */ 498 #define S_MOD_INIT_FUNC_POINTERS 0x9 /* section with only function 499 pointers for initialization*/ 500 #define S_MOD_TERM_FUNC_POINTERS 0xa /* section with only function 501 pointers for termination */ 502 #define S_COALESCED 0xb /* section contains symbols that 503 are to be coalesced */ 504 #define S_GB_ZEROFILL 0xc /* zero fill on demand section 505 (that can be larger than 4 506 gigabytes) */ 507 #define S_INTERPOSING 0xd /* section with only pairs of 508 function pointers for 509 interposing */ 510 #define S_16BYTE_LITERALS 0xe /* section with only 16 byte 511 literals */ 512 #define S_DTRACE_DOF 0xf /* section contains 513 DTrace Object Format */ 514 #define S_LAZY_DYLIB_SYMBOL_POINTERS 0x10 /* section with only lazy 515 symbol pointers to lazy 516 loaded dylibs */ 517 /* 518 * Section types to support thread local variables 519 */ 520 #define S_THREAD_LOCAL_REGULAR 0x11 /* template of initial 521 values for TLVs */ 522 #define S_THREAD_LOCAL_ZEROFILL 0x12 /* template of initial 523 values for TLVs */ 524 #define S_THREAD_LOCAL_VARIABLES 0x13 /* TLV descriptors */ 525 #define S_THREAD_LOCAL_VARIABLE_POINTERS 0x14 /* pointers to TLV 526 descriptors */ 527 #define S_THREAD_LOCAL_INIT_FUNCTION_POINTERS 0x15 /* functions to call 528 to initialize TLV 529 values */ 530 #define S_INIT_FUNC_OFFSETS 0x16 /* 32-bit offsets to 531 initializers */ 532 533 /* 534 * Constants for the section attributes part of the flags field of a section 535 * structure. 536 */ 537 #define SECTION_ATTRIBUTES_USR 0xff000000 /* User setable attributes */ 538 #define S_ATTR_PURE_INSTRUCTIONS 0x80000000 /* section contains only true 539 machine instructions */ 540 #define S_ATTR_NO_TOC 0x40000000 /* section contains coalesced 541 symbols that are not to be 542 in a ranlib table of 543 contents */ 544 #define S_ATTR_STRIP_STATIC_SYMS 0x20000000 /* ok to strip static symbols 545 in this section in files 546 with the MH_DYLDLINK flag */ 547 #define S_ATTR_NO_DEAD_STRIP 0x10000000 /* no dead stripping */ 548 #define S_ATTR_LIVE_SUPPORT 0x08000000 /* blocks are live if they 549 reference live blocks */ 550 #define S_ATTR_SELF_MODIFYING_CODE 0x04000000 /* Used with i386 code stubs 551 written on by dyld */ 552 /* 553 * If a segment contains any sections marked with S_ATTR_DEBUG then all 554 * sections in that segment must have this attribute. No section other than 555 * a section marked with this attribute may reference the contents of this 556 * section. A section with this attribute may contain no symbols and must have 557 * a section type S_REGULAR. The static linker will not copy section contents 558 * from sections with this attribute into its output file. These sections 559 * generally contain DWARF debugging info. 560 */ 561 #define S_ATTR_DEBUG 0x02000000 /* a debug section */ 562 #define SECTION_ATTRIBUTES_SYS 0x00ffff00 /* system setable attributes */ 563 #define S_ATTR_SOME_INSTRUCTIONS 0x00000400 /* section contains some 564 machine instructions */ 565 #define S_ATTR_EXT_RELOC 0x00000200 /* section has external 566 relocation entries */ 567 #define S_ATTR_LOC_RELOC 0x00000100 /* section has local 568 relocation entries */ 569 570 571 /* 572 * The names of segments and sections in them are mostly meaningless to the 573 * link-editor. But there are few things to support traditional UNIX 574 * executables that require the link-editor and assembler to use some names 575 * agreed upon by convention. 576 * 577 * The initial protection of the "__TEXT" segment has write protection turned 578 * off (not writeable). 579 * 580 * The link-editor will allocate common symbols at the end of the "__common" 581 * section in the "__DATA" segment. It will create the section and segment 582 * if needed. 583 */ 584 585 /* The currently known segment names and the section names in those segments */ 586 587 #define SEG_PAGEZERO "__PAGEZERO" /* the pagezero segment which has no */ 588 /* protections and catches NULL */ 589 /* references for MH_EXECUTE files */ 590 591 592 #define SEG_TEXT "__TEXT" /* the tradition UNIX text segment */ 593 #define SECT_TEXT "__text" /* the real text part of the text */ 594 /* section no headers, and no padding */ 595 #define SECT_FVMLIB_INIT0 "__fvmlib_init0" /* the fvmlib initialization */ 596 /* section */ 597 #define SECT_FVMLIB_INIT1 "__fvmlib_init1" /* the section following the */ 598 /* fvmlib initialization */ 599 /* section */ 600 601 #define SEG_DATA "__DATA" /* the tradition UNIX data segment */ 602 #define SECT_DATA "__data" /* the real initialized data section */ 603 /* no padding, no bss overlap */ 604 #define SECT_BSS "__bss" /* the real uninitialized data section*/ 605 /* no padding */ 606 #define SECT_COMMON "__common" /* the section common symbols are */ 607 /* allocated in by the link editor */ 608 609 #define SEG_OBJC "__OBJC" /* objective-C runtime segment */ 610 #define SECT_OBJC_SYMBOLS "__symbol_table" /* symbol table */ 611 #define SECT_OBJC_MODULES "__module_info" /* module information */ 612 #define SECT_OBJC_STRINGS "__selector_strs" /* string table */ 613 #define SECT_OBJC_REFS "__selector_refs" /* string table */ 614 615 #define SEG_ICON "__ICON" /* the icon segment */ 616 #define SECT_ICON_HEADER "__header" /* the icon headers */ 617 #define SECT_ICON_TIFF "__tiff" /* the icons in tiff format */ 618 619 #define SEG_LINKEDIT "__LINKEDIT" /* the segment containing all structs */ 620 /* created and maintained by the link */ 621 /* editor. Created with -seglinkedit */ 622 /* option to ld(1) for MH_EXECUTE and */ 623 /* FVMLIB file types only */ 624 625 #define SEG_UNIXSTACK "__UNIXSTACK" /* the unix stack segment */ 626 627 #define SEG_IMPORT "__IMPORT" /* the segment for the self (dyld) */ 628 /* modifing code stubs that has read, */ 629 /* write and execute permissions */ 630 631 /* 632 * Fixed virtual memory shared libraries are identified by two things. The 633 * target pathname (the name of the library as found for execution), and the 634 * minor version number. The address of where the headers are loaded is in 635 * header_addr. (THIS IS OBSOLETE and no longer supported). 636 */ 637 struct fvmlib { 638 union lc_str name; /* library's target pathname */ 639 uint32_t minor_version; /* library's minor version number */ 640 uint32_t header_addr; /* library's header address */ 641 }; 642 643 /* 644 * A fixed virtual shared library (filetype == MH_FVMLIB in the mach header) 645 * contains a fvmlib_command (cmd == LC_IDFVMLIB) to identify the library. 646 * An object that uses a fixed virtual shared library also contains a 647 * fvmlib_command (cmd == LC_LOADFVMLIB) for each library it uses. 648 * (THIS IS OBSOLETE and no longer supported). 649 */ 650 struct fvmlib_command { 651 uint32_t cmd; /* LC_IDFVMLIB or LC_LOADFVMLIB */ 652 uint32_t cmdsize; /* includes pathname string */ 653 struct fvmlib fvmlib; /* the library identification */ 654 }; 655 656 /* 657 * Dynamicly linked shared libraries are identified by two things. The 658 * pathname (the name of the library as found for execution), and the 659 * compatibility version number. The pathname must match and the compatibility 660 * number in the user of the library must be greater than or equal to the 661 * library being used. The time stamp is used to record the time a library was 662 * built and copied into user so it can be use to determined if the library used 663 * at runtime is exactly the same as used to built the program. 664 */ 665 struct dylib { 666 union lc_str name; /* library's path name */ 667 uint32_t timestamp; /* library's build time stamp */ 668 uint32_t current_version; /* library's current version number */ 669 uint32_t compatibility_version; /* library's compatibility vers number*/ 670 }; 671 672 /* 673 * A dynamically linked shared library (filetype == MH_DYLIB in the mach header) 674 * contains a dylib_command (cmd == LC_ID_DYLIB) to identify the library. 675 * An object that uses a dynamically linked shared library also contains a 676 * dylib_command (cmd == LC_LOAD_DYLIB, LC_LOAD_WEAK_DYLIB, or 677 * LC_REEXPORT_DYLIB) for each library it uses. 678 */ 679 struct dylib_command { 680 uint32_t cmd; /* LC_ID_DYLIB, LC_LOAD_{,WEAK_}DYLIB, 681 LC_REEXPORT_DYLIB */ 682 uint32_t cmdsize; /* includes pathname string */ 683 struct dylib dylib; /* the library identification */ 684 }; 685 686 /* 687 * A dynamically linked shared library may be a subframework of an umbrella 688 * framework. If so it will be linked with "-umbrella umbrella_name" where 689 * Where "umbrella_name" is the name of the umbrella framework. A subframework 690 * can only be linked against by its umbrella framework or other subframeworks 691 * that are part of the same umbrella framework. Otherwise the static link 692 * editor produces an error and states to link against the umbrella framework. 693 * The name of the umbrella framework for subframeworks is recorded in the 694 * following structure. 695 */ 696 struct sub_framework_command { 697 uint32_t cmd; /* LC_SUB_FRAMEWORK */ 698 uint32_t cmdsize; /* includes umbrella string */ 699 union lc_str umbrella; /* the umbrella framework name */ 700 }; 701 702 /* 703 * For dynamically linked shared libraries that are subframework of an umbrella 704 * framework they can allow clients other than the umbrella framework or other 705 * subframeworks in the same umbrella framework. To do this the subframework 706 * is built with "-allowable_client client_name" and an LC_SUB_CLIENT load 707 * command is created for each -allowable_client flag. The client_name is 708 * usually a framework name. It can also be a name used for bundles clients 709 * where the bundle is built with "-client_name client_name". 710 */ 711 struct sub_client_command { 712 uint32_t cmd; /* LC_SUB_CLIENT */ 713 uint32_t cmdsize; /* includes client string */ 714 union lc_str client; /* the client name */ 715 }; 716 717 /* 718 * A dynamically linked shared library may be a sub_umbrella of an umbrella 719 * framework. If so it will be linked with "-sub_umbrella umbrella_name" where 720 * Where "umbrella_name" is the name of the sub_umbrella framework. When 721 * staticly linking when -twolevel_namespace is in effect a twolevel namespace 722 * umbrella framework will only cause its subframeworks and those frameworks 723 * listed as sub_umbrella frameworks to be implicited linked in. Any other 724 * dependent dynamic libraries will not be linked it when -twolevel_namespace 725 * is in effect. The primary library recorded by the static linker when 726 * resolving a symbol in these libraries will be the umbrella framework. 727 * Zero or more sub_umbrella frameworks may be use by an umbrella framework. 728 * The name of a sub_umbrella framework is recorded in the following structure. 729 */ 730 struct sub_umbrella_command { 731 uint32_t cmd; /* LC_SUB_UMBRELLA */ 732 uint32_t cmdsize; /* includes sub_umbrella string */ 733 union lc_str sub_umbrella; /* the sub_umbrella framework name */ 734 }; 735 736 /* 737 * A dynamically linked shared library may be a sub_library of another shared 738 * library. If so it will be linked with "-sub_library library_name" where 739 * Where "library_name" is the name of the sub_library shared library. When 740 * staticly linking when -twolevel_namespace is in effect a twolevel namespace 741 * shared library will only cause its subframeworks and those frameworks 742 * listed as sub_umbrella frameworks and libraries listed as sub_libraries to 743 * be implicited linked in. Any other dependent dynamic libraries will not be 744 * linked it when -twolevel_namespace is in effect. The primary library 745 * recorded by the static linker when resolving a symbol in these libraries 746 * will be the umbrella framework (or dynamic library). Zero or more sub_library 747 * shared libraries may be use by an umbrella framework or (or dynamic library). 748 * The name of a sub_library framework is recorded in the following structure. 749 * For example /usr/lib/libobjc_profile.A.dylib would be recorded as "libobjc". 750 */ 751 struct sub_library_command { 752 uint32_t cmd; /* LC_SUB_LIBRARY */ 753 uint32_t cmdsize; /* includes sub_library string */ 754 union lc_str sub_library; /* the sub_library name */ 755 }; 756 757 /* 758 * A program (filetype == MH_EXECUTE) that is 759 * prebound to its dynamic libraries has one of these for each library that 760 * the static linker used in prebinding. It contains a bit vector for the 761 * modules in the library. The bits indicate which modules are bound (1) and 762 * which are not (0) from the library. The bit for module 0 is the low bit 763 * of the first byte. So the bit for the Nth module is: 764 * (linked_modules[N/8] >> N%8) & 1 765 */ 766 struct prebound_dylib_command { 767 uint32_t cmd; /* LC_PREBOUND_DYLIB */ 768 uint32_t cmdsize; /* includes strings */ 769 union lc_str name; /* library's path name */ 770 uint32_t nmodules; /* number of modules in library */ 771 union lc_str linked_modules; /* bit vector of linked modules */ 772 }; 773 774 /* 775 * A program that uses a dynamic linker contains a dylinker_command to identify 776 * the name of the dynamic linker (LC_LOAD_DYLINKER). And a dynamic linker 777 * contains a dylinker_command to identify the dynamic linker (LC_ID_DYLINKER). 778 * A file can have at most one of these. 779 * This struct is also used for the LC_DYLD_ENVIRONMENT load command and 780 * contains string for dyld to treat like environment variable. 781 */ 782 struct dylinker_command { 783 uint32_t cmd; /* LC_ID_DYLINKER, LC_LOAD_DYLINKER or 784 LC_DYLD_ENVIRONMENT */ 785 uint32_t cmdsize; /* includes pathname string */ 786 union lc_str name; /* dynamic linker's path name */ 787 }; 788 789 /* 790 * Thread commands contain machine-specific data structures suitable for 791 * use in the thread state primitives. The machine specific data structures 792 * follow the struct thread_command as follows. 793 * Each flavor of machine specific data structure is preceded by an uint32_t 794 * constant for the flavor of that data structure, an uint32_t that is the 795 * count of uint32_t's of the size of the state data structure and then 796 * the state data structure follows. This triple may be repeated for many 797 * flavors. The constants for the flavors, counts and state data structure 798 * definitions are expected to be in the header file <machine/thread_status.h>. 799 * These machine specific data structures sizes must be multiples of 800 * 4 bytes. The cmdsize reflects the total size of the thread_command 801 * and all of the sizes of the constants for the flavors, counts and state 802 * data structures. 803 * 804 * For executable objects that are unix processes there will be one 805 * thread_command (cmd == LC_UNIXTHREAD) created for it by the link-editor. 806 * This is the same as a LC_THREAD, except that a stack is automatically 807 * created (based on the shell's limit for the stack size). Command arguments 808 * and environment variables are copied onto that stack. 809 */ 810 struct thread_command { 811 uint32_t cmd; /* LC_THREAD or LC_UNIXTHREAD */ 812 uint32_t cmdsize; /* total size of this command */ 813 /* uint32_t flavor flavor of thread state */ 814 /* uint32_t count count of uint32_t's in thread state */ 815 /* struct XXX_thread_state state thread state for this flavor */ 816 /* ... */ 817 }; 818 819 /* 820 * The routines command contains the address of the dynamic shared library 821 * initialization routine and an index into the module table for the module 822 * that defines the routine. Before any modules are used from the library the 823 * dynamic linker fully binds the module that defines the initialization routine 824 * and then calls it. This gets called before any module initialization 825 * routines (used for C++ static constructors) in the library. 826 */ 827 struct routines_command { /* for 32-bit architectures */ 828 uint32_t cmd; /* LC_ROUTINES */ 829 uint32_t cmdsize; /* total size of this command */ 830 uint32_t init_address; /* address of initialization routine */ 831 uint32_t init_module; /* index into the module table that */ 832 /* the init routine is defined in */ 833 uint32_t reserved1; 834 uint32_t reserved2; 835 uint32_t reserved3; 836 uint32_t reserved4; 837 uint32_t reserved5; 838 uint32_t reserved6; 839 }; 840 841 /* 842 * The 64-bit routines command. Same use as above. 843 */ 844 struct routines_command_64 { /* for 64-bit architectures */ 845 uint32_t cmd; /* LC_ROUTINES_64 */ 846 uint32_t cmdsize; /* total size of this command */ 847 uint64_t init_address; /* address of initialization routine */ 848 uint64_t init_module; /* index into the module table that */ 849 /* the init routine is defined in */ 850 uint64_t reserved1; 851 uint64_t reserved2; 852 uint64_t reserved3; 853 uint64_t reserved4; 854 uint64_t reserved5; 855 uint64_t reserved6; 856 }; 857 858 /* 859 * The symtab_command contains the offsets and sizes of the link-edit 4.3BSD 860 * "stab" style symbol table information as described in the header files 861 * <nlist.h> and <stab.h>. 862 */ 863 struct symtab_command { 864 uint32_t cmd; /* LC_SYMTAB */ 865 uint32_t cmdsize; /* sizeof(struct symtab_command) */ 866 uint32_t symoff; /* symbol table offset */ 867 uint32_t nsyms; /* number of symbol table entries */ 868 uint32_t stroff; /* string table offset */ 869 uint32_t strsize; /* string table size in bytes */ 870 }; 871 872 /* 873 * This is the second set of the symbolic information which is used to support 874 * the data structures for the dynamically link editor. 875 * 876 * The original set of symbolic information in the symtab_command which contains 877 * the symbol and string tables must also be present when this load command is 878 * present. When this load command is present the symbol table is organized 879 * into three groups of symbols: 880 * local symbols (static and debugging symbols) - grouped by module 881 * defined external symbols - grouped by module (sorted by name if not lib) 882 * undefined external symbols (sorted by name if MH_BINDATLOAD is not set, 883 * and in order the were seen by the static 884 * linker if MH_BINDATLOAD is set) 885 * In this load command there are offsets and counts to each of the three groups 886 * of symbols. 887 * 888 * This load command contains a the offsets and sizes of the following new 889 * symbolic information tables: 890 * table of contents 891 * module table 892 * reference symbol table 893 * indirect symbol table 894 * The first three tables above (the table of contents, module table and 895 * reference symbol table) are only present if the file is a dynamically linked 896 * shared library. For executable and object modules, which are files 897 * containing only one module, the information that would be in these three 898 * tables is determined as follows: 899 * table of contents - the defined external symbols are sorted by name 900 * module table - the file contains only one module so everything in the 901 * file is part of the module. 902 * reference symbol table - is the defined and undefined external symbols 903 * 904 * For dynamically linked shared library files this load command also contains 905 * offsets and sizes to the pool of relocation entries for all sections 906 * separated into two groups: 907 * external relocation entries 908 * local relocation entries 909 * For executable and object modules the relocation entries continue to hang 910 * off the section structures. 911 */ 912 struct dysymtab_command { 913 uint32_t cmd; /* LC_DYSYMTAB */ 914 uint32_t cmdsize; /* sizeof(struct dysymtab_command) */ 915 916 /* 917 * The symbols indicated by symoff and nsyms of the LC_SYMTAB load command 918 * are grouped into the following three groups: 919 * local symbols (further grouped by the module they are from) 920 * defined external symbols (further grouped by the module they are from) 921 * undefined symbols 922 * 923 * The local symbols are used only for debugging. The dynamic binding 924 * process may have to use them to indicate to the debugger the local 925 * symbols for a module that is being bound. 926 * 927 * The last two groups are used by the dynamic binding process to do the 928 * binding (indirectly through the module table and the reference symbol 929 * table when this is a dynamically linked shared library file). 930 */ 931 uint32_t ilocalsym; /* index to local symbols */ 932 uint32_t nlocalsym; /* number of local symbols */ 933 934 uint32_t iextdefsym;/* index to externally defined symbols */ 935 uint32_t nextdefsym;/* number of externally defined symbols */ 936 937 uint32_t iundefsym; /* index to undefined symbols */ 938 uint32_t nundefsym; /* number of undefined symbols */ 939 940 /* 941 * For the for the dynamic binding process to find which module a symbol 942 * is defined in the table of contents is used (analogous to the ranlib 943 * structure in an archive) which maps defined external symbols to modules 944 * they are defined in. This exists only in a dynamically linked shared 945 * library file. For executable and object modules the defined external 946 * symbols are sorted by name and is use as the table of contents. 947 */ 948 uint32_t tocoff; /* file offset to table of contents */ 949 uint32_t ntoc; /* number of entries in table of contents */ 950 951 /* 952 * To support dynamic binding of "modules" (whole object files) the symbol 953 * table must reflect the modules that the file was created from. This is 954 * done by having a module table that has indexes and counts into the merged 955 * tables for each module. The module structure that these two entries 956 * refer to is described below. This exists only in a dynamically linked 957 * shared library file. For executable and object modules the file only 958 * contains one module so everything in the file belongs to the module. 959 */ 960 uint32_t modtaboff; /* file offset to module table */ 961 uint32_t nmodtab; /* number of module table entries */ 962 963 /* 964 * To support dynamic module binding the module structure for each module 965 * indicates the external references (defined and undefined) each module 966 * makes. For each module there is an offset and a count into the 967 * reference symbol table for the symbols that the module references. 968 * This exists only in a dynamically linked shared library file. For 969 * executable and object modules the defined external symbols and the 970 * undefined external symbols indicates the external references. 971 */ 972 uint32_t extrefsymoff; /* offset to referenced symbol table */ 973 uint32_t nextrefsyms; /* number of referenced symbol table entries */ 974 975 /* 976 * The sections that contain "symbol pointers" and "routine stubs" have 977 * indexes and (implied counts based on the size of the section and fixed 978 * size of the entry) into the "indirect symbol" table for each pointer 979 * and stub. For every section of these two types the index into the 980 * indirect symbol table is stored in the section header in the field 981 * reserved1. An indirect symbol table entry is simply a 32bit index into 982 * the symbol table to the symbol that the pointer or stub is referring to. 983 * The indirect symbol table is ordered to match the entries in the section. 984 */ 985 uint32_t indirectsymoff; /* file offset to the indirect symbol table */ 986 uint32_t nindirectsyms; /* number of indirect symbol table entries */ 987 988 /* 989 * To support relocating an individual module in a library file quickly the 990 * external relocation entries for each module in the library need to be 991 * accessed efficiently. Since the relocation entries can't be accessed 992 * through the section headers for a library file they are separated into 993 * groups of local and external entries further grouped by module. In this 994 * case the presents of this load command who's extreloff, nextrel, 995 * locreloff and nlocrel fields are non-zero indicates that the relocation 996 * entries of non-merged sections are not referenced through the section 997 * structures (and the reloff and nreloc fields in the section headers are 998 * set to zero). 999 * 1000 * Since the relocation entries are not accessed through the section headers 1001 * this requires the r_address field to be something other than a section 1002 * offset to identify the item to be relocated. In this case r_address is 1003 * set to the offset from the vmaddr of the first LC_SEGMENT command. 1004 * For MH_SPLIT_SEGS images r_address is set to the the offset from the 1005 * vmaddr of the first read-write LC_SEGMENT command. 1006 * 1007 * The relocation entries are grouped by module and the module table 1008 * entries have indexes and counts into them for the group of external 1009 * relocation entries for that the module. 1010 * 1011 * For sections that are merged across modules there must not be any 1012 * remaining external relocation entries for them (for merged sections 1013 * remaining relocation entries must be local). 1014 */ 1015 uint32_t extreloff; /* offset to external relocation entries */ 1016 uint32_t nextrel; /* number of external relocation entries */ 1017 1018 /* 1019 * All the local relocation entries are grouped together (they are not 1020 * grouped by their module since they are only used if the object is moved 1021 * from it staticly link edited address). 1022 */ 1023 uint32_t locreloff; /* offset to local relocation entries */ 1024 uint32_t nlocrel; /* number of local relocation entries */ 1025 1026 }; 1027 1028 /* 1029 * An indirect symbol table entry is simply a 32bit index into the symbol table 1030 * to the symbol that the pointer or stub is refering to. Unless it is for a 1031 * non-lazy symbol pointer section for a defined symbol which strip(1) as 1032 * removed. In which case it has the value INDIRECT_SYMBOL_LOCAL. If the 1033 * symbol was also absolute INDIRECT_SYMBOL_ABS is or'ed with that. 1034 */ 1035 #define INDIRECT_SYMBOL_LOCAL 0x80000000 1036 #define INDIRECT_SYMBOL_ABS 0x40000000 1037 1038 1039 /* a table of contents entry */ 1040 struct dylib_table_of_contents { 1041 uint32_t symbol_index; /* the defined external symbol 1042 (index into the symbol table) */ 1043 uint32_t module_index; /* index into the module table this symbol 1044 is defined in */ 1045 }; 1046 1047 /* a module table entry */ 1048 struct dylib_module { 1049 uint32_t module_name; /* the module name (index into string table) */ 1050 1051 uint32_t iextdefsym; /* index into externally defined symbols */ 1052 uint32_t nextdefsym; /* number of externally defined symbols */ 1053 uint32_t irefsym; /* index into reference symbol table */ 1054 uint32_t nrefsym; /* number of reference symbol table entries */ 1055 uint32_t ilocalsym; /* index into symbols for local symbols */ 1056 uint32_t nlocalsym; /* number of local symbols */ 1057 1058 uint32_t iextrel; /* index into external relocation entries */ 1059 uint32_t nextrel; /* number of external relocation entries */ 1060 1061 uint32_t iinit_iterm; /* low 16 bits are the index into the init 1062 section, high 16 bits are the index into 1063 the term section */ 1064 uint32_t ninit_nterm; /* low 16 bits are the number of init section 1065 entries, high 16 bits are the number of 1066 term section entries */ 1067 1068 uint32_t /* for this module address of the start of */ 1069 objc_module_info_addr; /* the (__OBJC,__module_info) section */ 1070 uint32_t /* for this module size of */ 1071 objc_module_info_size; /* the (__OBJC,__module_info) section */ 1072 }; 1073 1074 /* a 64-bit module table entry */ 1075 struct dylib_module_64 { 1076 uint32_t module_name; /* the module name (index into string table) */ 1077 1078 uint32_t iextdefsym; /* index into externally defined symbols */ 1079 uint32_t nextdefsym; /* number of externally defined symbols */ 1080 uint32_t irefsym; /* index into reference symbol table */ 1081 uint32_t nrefsym; /* number of reference symbol table entries */ 1082 uint32_t ilocalsym; /* index into symbols for local symbols */ 1083 uint32_t nlocalsym; /* number of local symbols */ 1084 1085 uint32_t iextrel; /* index into external relocation entries */ 1086 uint32_t nextrel; /* number of external relocation entries */ 1087 1088 uint32_t iinit_iterm; /* low 16 bits are the index into the init 1089 section, high 16 bits are the index into 1090 the term section */ 1091 uint32_t ninit_nterm; /* low 16 bits are the number of init section 1092 entries, high 16 bits are the number of 1093 term section entries */ 1094 1095 uint32_t /* for this module size of */ 1096 objc_module_info_size; /* the (__OBJC,__module_info) section */ 1097 uint64_t /* for this module address of the start of */ 1098 objc_module_info_addr; /* the (__OBJC,__module_info) section */ 1099 }; 1100 1101 /* 1102 * The entries in the reference symbol table are used when loading the module 1103 * (both by the static and dynamic link editors) and if the module is unloaded 1104 * or replaced. Therefore all external symbols (defined and undefined) are 1105 * listed in the module's reference table. The flags describe the type of 1106 * reference that is being made. The constants for the flags are defined in 1107 * <mach-o/nlist.h> as they are also used for symbol table entries. 1108 */ 1109 struct dylib_reference { 1110 uint32_t isym:24, /* index into the symbol table */ 1111 flags:8; /* flags to indicate the type of reference */ 1112 }; 1113 1114 /* 1115 * The twolevel_hints_command contains the offset and number of hints in the 1116 * two-level namespace lookup hints table. 1117 */ 1118 struct twolevel_hints_command { 1119 uint32_t cmd; /* LC_TWOLEVEL_HINTS */ 1120 uint32_t cmdsize; /* sizeof(struct twolevel_hints_command) */ 1121 uint32_t offset; /* offset to the hint table */ 1122 uint32_t nhints; /* number of hints in the hint table */ 1123 }; 1124 1125 /* 1126 * The entries in the two-level namespace lookup hints table are twolevel_hint 1127 * structs. These provide hints to the dynamic link editor where to start 1128 * looking for an undefined symbol in a two-level namespace image. The 1129 * isub_image field is an index into the sub-images (sub-frameworks and 1130 * sub-umbrellas list) that made up the two-level image that the undefined 1131 * symbol was found in when it was built by the static link editor. If 1132 * isub-image is 0 the the symbol is expected to be defined in library and not 1133 * in the sub-images. If isub-image is non-zero it is an index into the array 1134 * of sub-images for the umbrella with the first index in the sub-images being 1135 * 1. The array of sub-images is the ordered list of sub-images of the umbrella 1136 * that would be searched for a symbol that has the umbrella recorded as its 1137 * primary library. The table of contents index is an index into the 1138 * library's table of contents. This is used as the starting point of the 1139 * binary search or a directed linear search. 1140 */ 1141 struct twolevel_hint { 1142 uint32_t 1143 isub_image:8, /* index into the sub images */ 1144 itoc:24; /* index into the table of contents */ 1145 }; 1146 1147 /* 1148 * The prebind_cksum_command contains the value of the original check sum for 1149 * prebound files or zero. When a prebound file is first created or modified 1150 * for other than updating its prebinding information the value of the check sum 1151 * is set to zero. When the file has it prebinding re-done and if the value of 1152 * the check sum is zero the original check sum is calculated and stored in 1153 * cksum field of this load command in the output file. If when the prebinding 1154 * is re-done and the cksum field is non-zero it is left unchanged from the 1155 * input file. 1156 */ 1157 struct prebind_cksum_command { 1158 uint32_t cmd; /* LC_PREBIND_CKSUM */ 1159 uint32_t cmdsize; /* sizeof(struct prebind_cksum_command) */ 1160 uint32_t cksum; /* the check sum or zero */ 1161 }; 1162 1163 /* 1164 * The uuid load command contains a single 128-bit unique random number that 1165 * identifies an object produced by the static link editor. 1166 */ 1167 struct uuid_command { 1168 uint32_t cmd; /* LC_UUID */ 1169 uint32_t cmdsize; /* sizeof(struct uuid_command) */ 1170 uint8_t uuid[16]; /* the 128-bit uuid */ 1171 }; 1172 1173 /* 1174 * The rpath_command contains a path which at runtime should be added to 1175 * the current run path used to find @rpath prefixed dylibs. 1176 */ 1177 struct rpath_command { 1178 uint32_t cmd; /* LC_RPATH */ 1179 uint32_t cmdsize; /* includes string */ 1180 union lc_str path; /* path to add to run path */ 1181 }; 1182 1183 /* 1184 * The linkedit_data_command contains the offsets and sizes of a blob 1185 * of data in the __LINKEDIT segment. 1186 */ 1187 struct linkedit_data_command { 1188 uint32_t cmd; /* LC_CODE_SIGNATURE, LC_SEGMENT_SPLIT_INFO, 1189 LC_FUNCTION_STARTS, LC_DATA_IN_CODE, 1190 LC_DYLIB_CODE_SIGN_DRS, 1191 LC_LINKER_OPTIMIZATION_HINT, 1192 LC_DYLD_EXPORTS_TRIE, or 1193 LC_DYLD_CHAINED_FIXUPS. */ 1194 uint32_t cmdsize; /* sizeof(struct linkedit_data_command) */ 1195 uint32_t dataoff; /* file offset of data in __LINKEDIT segment */ 1196 uint32_t datasize; /* file size of data in __LINKEDIT segment */ 1197 }; 1198 1199 /* 1200 * The encryption_info_command contains the file offset and size of an 1201 * of an encrypted segment. 1202 */ 1203 struct encryption_info_command { 1204 uint32_t cmd; /* LC_ENCRYPTION_INFO */ 1205 uint32_t cmdsize; /* sizeof(struct encryption_info_command) */ 1206 uint32_t cryptoff; /* file offset of encrypted range */ 1207 uint32_t cryptsize; /* file size of encrypted range */ 1208 uint32_t cryptid; /* which enryption system, 1209 0 means not-encrypted yet */ 1210 }; 1211 1212 /* 1213 * The encryption_info_command_64 contains the file offset and size of an 1214 * of an encrypted segment (for use in x86_64 targets). 1215 */ 1216 struct encryption_info_command_64 { 1217 uint32_t cmd; /* LC_ENCRYPTION_INFO_64 */ 1218 uint32_t cmdsize; /* sizeof(struct encryption_info_command_64) */ 1219 uint32_t cryptoff; /* file offset of encrypted range */ 1220 uint32_t cryptsize; /* file size of encrypted range */ 1221 uint32_t cryptid; /* which enryption system, 1222 0 means not-encrypted yet */ 1223 uint32_t pad; /* padding to make this struct's size a multiple 1224 of 8 bytes */ 1225 }; 1226 1227 /* 1228 * The version_min_command contains the min OS version on which this 1229 * binary was built to run. 1230 */ 1231 struct version_min_command { 1232 uint32_t cmd; /* LC_VERSION_MIN_MACOSX or 1233 LC_VERSION_MIN_IPHONEOS or 1234 LC_VERSION_MIN_WATCHOS or 1235 LC_VERSION_MIN_TVOS */ 1236 uint32_t cmdsize; /* sizeof(struct min_version_command) */ 1237 uint32_t version; /* X.Y.Z is encoded in nibbles xxxx.yy.zz */ 1238 uint32_t sdk; /* X.Y.Z is encoded in nibbles xxxx.yy.zz */ 1239 }; 1240 1241 /* 1242 * The build_version_command contains the min OS version on which this 1243 * binary was built to run for its platform. The list of known platforms and 1244 * tool values following it. 1245 */ 1246 struct build_version_command { 1247 uint32_t cmd; /* LC_BUILD_VERSION */ 1248 uint32_t cmdsize; /* sizeof(struct build_version_command) plus */ 1249 /* ntools * sizeof(struct build_tool_version) */ 1250 uint32_t platform; /* platform */ 1251 uint32_t minos; /* X.Y.Z is encoded in nibbles xxxx.yy.zz */ 1252 uint32_t sdk; /* X.Y.Z is encoded in nibbles xxxx.yy.zz */ 1253 uint32_t ntools; /* number of tool entries following this */ 1254 }; 1255 1256 struct build_tool_version { 1257 uint32_t tool; /* enum for the tool */ 1258 uint32_t version; /* version number of the tool */ 1259 }; 1260 1261 /* Known values for the platform field above. */ 1262 #define PLATFORM_MACOS 1 1263 #define PLATFORM_IOS 2 1264 #define PLATFORM_TVOS 3 1265 #define PLATFORM_WATCHOS 4 1266 #define PLATFORM_BRIDGEOS 5 1267 #define PLATFORM_MACCATALYST 6 1268 #if (!defined(PLATFORM_MACCATALYST)) 1269 #define PLATFORM_MACCATALYST 6 1270 #endif 1271 #define PLATFORM_IOSSIMULATOR 7 1272 #define PLATFORM_TVOSSIMULATOR 8 1273 #define PLATFORM_WATCHOSSIMULATOR 9 1274 #define PLATFORM_DRIVERKIT 10 1275 1276 /* Known values for the tool field above. */ 1277 #define TOOL_CLANG 1 1278 #define TOOL_SWIFT 2 1279 #define TOOL_LD 3 1280 1281 /* 1282 * The dyld_info_command contains the file offsets and sizes of 1283 * the new compressed form of the information dyld needs to 1284 * load the image. This information is used by dyld on Mac OS X 1285 * 10.6 and later. All information pointed to by this command 1286 * is encoded using byte streams, so no endian swapping is needed 1287 * to interpret it. 1288 */ 1289 struct dyld_info_command { 1290 uint32_t cmd; /* LC_DYLD_INFO or LC_DYLD_INFO_ONLY */ 1291 uint32_t cmdsize; /* sizeof(struct dyld_info_command) */ 1292 1293 /* 1294 * Dyld rebases an image whenever dyld loads it at an address different 1295 * from its preferred address. The rebase information is a stream 1296 * of byte sized opcodes whose symbolic names start with REBASE_OPCODE_. 1297 * Conceptually the rebase information is a table of tuples: 1298 * <seg-index, seg-offset, type> 1299 * The opcodes are a compressed way to encode the table by only 1300 * encoding when a column changes. In addition simple patterns 1301 * like "every n'th offset for m times" can be encoded in a few 1302 * bytes. 1303 */ 1304 uint32_t rebase_off; /* file offset to rebase info */ 1305 uint32_t rebase_size; /* size of rebase info */ 1306 1307 /* 1308 * Dyld binds an image during the loading process, if the image 1309 * requires any pointers to be initialized to symbols in other images. 1310 * The bind information is a stream of byte sized 1311 * opcodes whose symbolic names start with BIND_OPCODE_. 1312 * Conceptually the bind information is a table of tuples: 1313 * <seg-index, seg-offset, type, symbol-library-ordinal, symbol-name, addend> 1314 * The opcodes are a compressed way to encode the table by only 1315 * encoding when a column changes. In addition simple patterns 1316 * like for runs of pointers initialzed to the same value can be 1317 * encoded in a few bytes. 1318 */ 1319 uint32_t bind_off; /* file offset to binding info */ 1320 uint32_t bind_size; /* size of binding info */ 1321 1322 /* 1323 * Some C++ programs require dyld to unique symbols so that all 1324 * images in the process use the same copy of some code/data. 1325 * This step is done after binding. The content of the weak_bind 1326 * info is an opcode stream like the bind_info. But it is sorted 1327 * alphabetically by symbol name. This enable dyld to walk 1328 * all images with weak binding information in order and look 1329 * for collisions. If there are no collisions, dyld does 1330 * no updating. That means that some fixups are also encoded 1331 * in the bind_info. For instance, all calls to "operator new" 1332 * are first bound to libstdc++.dylib using the information 1333 * in bind_info. Then if some image overrides operator new 1334 * that is detected when the weak_bind information is processed 1335 * and the call to operator new is then rebound. 1336 */ 1337 uint32_t weak_bind_off; /* file offset to weak binding info */ 1338 uint32_t weak_bind_size; /* size of weak binding info */ 1339 1340 /* 1341 * Some uses of external symbols do not need to be bound immediately. 1342 * Instead they can be lazily bound on first use. The lazy_bind 1343 * are contains a stream of BIND opcodes to bind all lazy symbols. 1344 * Normal use is that dyld ignores the lazy_bind section when 1345 * loading an image. Instead the static linker arranged for the 1346 * lazy pointer to initially point to a helper function which 1347 * pushes the offset into the lazy_bind area for the symbol 1348 * needing to be bound, then jumps to dyld which simply adds 1349 * the offset to lazy_bind_off to get the information on what 1350 * to bind. 1351 */ 1352 uint32_t lazy_bind_off; /* file offset to lazy binding info */ 1353 uint32_t lazy_bind_size; /* size of lazy binding infs */ 1354 1355 /* 1356 * The symbols exported by a dylib are encoded in a trie. This 1357 * is a compact representation that factors out common prefixes. 1358 * It also reduces LINKEDIT pages in RAM because it encodes all 1359 * information (name, address, flags) in one small, contiguous range. 1360 * The export area is a stream of nodes. The first node sequentially 1361 * is the start node for the trie. 1362 * 1363 * Nodes for a symbol start with a uleb128 that is the length of 1364 * the exported symbol information for the string so far. 1365 * If there is no exported symbol, the node starts with a zero byte. 1366 * If there is exported info, it follows the length. 1367 * 1368 * First is a uleb128 containing flags. Normally, it is followed by 1369 * a uleb128 encoded offset which is location of the content named 1370 * by the symbol from the mach_header for the image. If the flags 1371 * is EXPORT_SYMBOL_FLAGS_REEXPORT, then following the flags is 1372 * a uleb128 encoded library ordinal, then a zero terminated 1373 * UTF8 string. If the string is zero length, then the symbol 1374 * is re-export from the specified dylib with the same name. 1375 * If the flags is EXPORT_SYMBOL_FLAGS_STUB_AND_RESOLVER, then following 1376 * the flags is two uleb128s: the stub offset and the resolver offset. 1377 * The stub is used by non-lazy pointers. The resolver is used 1378 * by lazy pointers and must be called to get the actual address to use. 1379 * 1380 * After the optional exported symbol information is a byte of 1381 * how many edges (0-255) that this node has leaving it, 1382 * followed by each edge. 1383 * Each edge is a zero terminated UTF8 of the addition chars 1384 * in the symbol, followed by a uleb128 offset for the node that 1385 * edge points to. 1386 * 1387 */ 1388 uint32_t export_off; /* file offset to lazy binding info */ 1389 uint32_t export_size; /* size of lazy binding infs */ 1390 }; 1391 1392 /* 1393 * The following are used to encode rebasing information 1394 */ 1395 #define REBASE_TYPE_POINTER 1 1396 #define REBASE_TYPE_TEXT_ABSOLUTE32 2 1397 #define REBASE_TYPE_TEXT_PCREL32 3 1398 1399 #define REBASE_OPCODE_MASK 0xF0 1400 #define REBASE_IMMEDIATE_MASK 0x0F 1401 #define REBASE_OPCODE_DONE 0x00 1402 #define REBASE_OPCODE_SET_TYPE_IMM 0x10 1403 #define REBASE_OPCODE_SET_SEGMENT_AND_OFFSET_ULEB 0x20 1404 #define REBASE_OPCODE_ADD_ADDR_ULEB 0x30 1405 #define REBASE_OPCODE_ADD_ADDR_IMM_SCALED 0x40 1406 #define REBASE_OPCODE_DO_REBASE_IMM_TIMES 0x50 1407 #define REBASE_OPCODE_DO_REBASE_ULEB_TIMES 0x60 1408 #define REBASE_OPCODE_DO_REBASE_ADD_ADDR_ULEB 0x70 1409 #define REBASE_OPCODE_DO_REBASE_ULEB_TIMES_SKIPPING_ULEB 0x80 1410 1411 1412 /* 1413 * The following are used to encode binding information 1414 */ 1415 #define BIND_TYPE_POINTER 1 1416 #define BIND_TYPE_TEXT_ABSOLUTE32 2 1417 #define BIND_TYPE_TEXT_PCREL32 3 1418 1419 #define BIND_SPECIAL_DYLIB_SELF 0 1420 #define BIND_SPECIAL_DYLIB_MAIN_EXECUTABLE -1 1421 #define BIND_SPECIAL_DYLIB_FLAT_LOOKUP -2 1422 #define BIND_SPECIAL_DYLIB_WEAK_LOOKUP -3 1423 1424 #define BIND_SYMBOL_FLAGS_WEAK_IMPORT 0x1 1425 #define BIND_SYMBOL_FLAGS_NON_WEAK_DEFINITION 0x8 1426 1427 #define BIND_OPCODE_MASK 0xF0 1428 #define BIND_IMMEDIATE_MASK 0x0F 1429 #define BIND_OPCODE_DONE 0x00 1430 #define BIND_OPCODE_SET_DYLIB_ORDINAL_IMM 0x10 1431 #define BIND_OPCODE_SET_DYLIB_ORDINAL_ULEB 0x20 1432 #define BIND_OPCODE_SET_DYLIB_SPECIAL_IMM 0x30 1433 #define BIND_OPCODE_SET_SYMBOL_TRAILING_FLAGS_IMM 0x40 1434 #define BIND_OPCODE_SET_TYPE_IMM 0x50 1435 #define BIND_OPCODE_SET_ADDEND_SLEB 0x60 1436 #define BIND_OPCODE_SET_SEGMENT_AND_OFFSET_ULEB 0x70 1437 #define BIND_OPCODE_ADD_ADDR_ULEB 0x80 1438 #define BIND_OPCODE_DO_BIND 0x90 1439 #define BIND_OPCODE_DO_BIND_ADD_ADDR_ULEB 0xA0 1440 #define BIND_OPCODE_DO_BIND_ADD_ADDR_IMM_SCALED 0xB0 1441 #define BIND_OPCODE_DO_BIND_ULEB_TIMES_SKIPPING_ULEB 0xC0 1442 #define BIND_OPCODE_THREADED 0xD0 1443 #define BIND_SUBOPCODE_THREADED_SET_BIND_ORDINAL_TABLE_SIZE_ULEB 0x00 1444 #define BIND_SUBOPCODE_THREADED_APPLY 0x01 1445 1446 1447 /* 1448 * The following are used on the flags byte of a terminal node 1449 * in the export information. 1450 */ 1451 #define EXPORT_SYMBOL_FLAGS_KIND_MASK 0x03 1452 #define EXPORT_SYMBOL_FLAGS_KIND_REGULAR 0x00 1453 #define EXPORT_SYMBOL_FLAGS_KIND_THREAD_LOCAL 0x01 1454 #define EXPORT_SYMBOL_FLAGS_KIND_ABSOLUTE 0x02 1455 #define EXPORT_SYMBOL_FLAGS_WEAK_DEFINITION 0x04 1456 #define EXPORT_SYMBOL_FLAGS_REEXPORT 0x08 1457 #define EXPORT_SYMBOL_FLAGS_STUB_AND_RESOLVER 0x10 1458 1459 /* 1460 * The linker_option_command contains linker options embedded in object files. 1461 */ 1462 struct linker_option_command { 1463 uint32_t cmd; /* LC_LINKER_OPTION only used in MH_OBJECT filetypes */ 1464 uint32_t cmdsize; 1465 uint32_t count; /* number of strings */ 1466 /* concatenation of zero terminated UTF8 strings. 1467 Zero filled at end to align */ 1468 }; 1469 1470 /* 1471 * The symseg_command contains the offset and size of the GNU style 1472 * symbol table information as described in the header file <symseg.h>. 1473 * The symbol roots of the symbol segments must also be aligned properly 1474 * in the file. So the requirement of keeping the offsets aligned to a 1475 * multiple of a 4 bytes translates to the length field of the symbol 1476 * roots also being a multiple of a long. Also the padding must again be 1477 * zeroed. (THIS IS OBSOLETE and no longer supported). 1478 */ 1479 struct symseg_command { 1480 uint32_t cmd; /* LC_SYMSEG */ 1481 uint32_t cmdsize; /* sizeof(struct symseg_command) */ 1482 uint32_t offset; /* symbol segment offset */ 1483 uint32_t size; /* symbol segment size in bytes */ 1484 }; 1485 1486 /* 1487 * The ident_command contains a free format string table following the 1488 * ident_command structure. The strings are null terminated and the size of 1489 * the command is padded out with zero bytes to a multiple of 4 bytes/ 1490 * (THIS IS OBSOLETE and no longer supported). 1491 */ 1492 struct ident_command { 1493 uint32_t cmd; /* LC_IDENT */ 1494 uint32_t cmdsize; /* strings that follow this command */ 1495 }; 1496 1497 /* 1498 * The fvmfile_command contains a reference to a file to be loaded at the 1499 * specified virtual address. (Presently, this command is reserved for 1500 * internal use. The kernel ignores this command when loading a program into 1501 * memory). 1502 */ 1503 struct fvmfile_command { 1504 uint32_t cmd; /* LC_FVMFILE */ 1505 uint32_t cmdsize; /* includes pathname string */ 1506 union lc_str name; /* files pathname */ 1507 uint32_t header_addr; /* files virtual address */ 1508 }; 1509 1510 1511 /* 1512 * The entry_point_command is a replacement for thread_command. 1513 * It is used for main executables to specify the location (file offset) 1514 * of main(). If -stack_size was used at link time, the stacksize 1515 * field will contain the stack size need for the main thread. 1516 */ 1517 struct entry_point_command { 1518 uint32_t cmd; /* LC_MAIN only used in MH_EXECUTE filetypes */ 1519 uint32_t cmdsize; /* 24 */ 1520 uint64_t entryoff; /* file (__TEXT) offset of main() */ 1521 uint64_t stacksize;/* if not zero, initial stack size */ 1522 }; 1523 1524 1525 /* 1526 * The source_version_command is an optional load command containing 1527 * the version of the sources used to build the binary. 1528 */ 1529 struct source_version_command { 1530 uint32_t cmd; /* LC_SOURCE_VERSION */ 1531 uint32_t cmdsize; /* 16 */ 1532 uint64_t version; /* A.B.C.D.E packed as a24.b10.c10.d10.e10 */ 1533 }; 1534 1535 1536 /* 1537 * The LC_DATA_IN_CODE load commands uses a linkedit_data_command 1538 * to point to an array of data_in_code_entry entries. Each entry 1539 * describes a range of data in a code section. 1540 */ 1541 struct data_in_code_entry { 1542 uint32_t offset; /* from mach_header to start of data range*/ 1543 uint16_t length; /* number of bytes in data range */ 1544 uint16_t kind; /* a DICE_KIND_* value */ 1545 }; 1546 #define DICE_KIND_DATA 0x0001 1547 #define DICE_KIND_JUMP_TABLE8 0x0002 1548 #define DICE_KIND_JUMP_TABLE16 0x0003 1549 #define DICE_KIND_JUMP_TABLE32 0x0004 1550 #define DICE_KIND_ABS_JUMP_TABLE32 0x0005 1551 1552 1553 1554 /* 1555 * Sections of type S_THREAD_LOCAL_VARIABLES contain an array 1556 * of tlv_descriptor structures. 1557 */ 1558 struct tlv_descriptor 1559 { 1560 void* (*thunk)(struct tlv_descriptor*); 1561 unsigned long key; 1562 unsigned long offset; 1563 }; 1564 1565 /* 1566 * LC_NOTE commands describe a region of arbitrary data included in a Mach-O 1567 * file. Its initial use is to record extra data in MH_CORE files. 1568 */ 1569 struct note_command { 1570 uint32_t cmd; /* LC_NOTE */ 1571 uint32_t cmdsize; /* sizeof(struct note_command) */ 1572 char data_owner[16]; /* owner name for this LC_NOTE */ 1573 uint64_t offset; /* file offset of this data */ 1574 uint64_t size; /* length of data region */ 1575 }; 1576 1577 #endif /* _MACHO_LOADER_H_ */