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1.1 ! root 1: /* ! 2: * Copyright (c) 2000 Apple Computer, Inc. All rights reserved. ! 3: * ! 4: * @APPLE_LICENSE_HEADER_START@ ! 5: * ! 6: * The contents of this file constitute Original Code as defined in and ! 7: * are subject to the Apple Public Source License Version 1.1 (the ! 8: * "License"). You may not use this file except in compliance with the ! 9: * License. Please obtain a copy of the License at ! 10: * http://www.apple.com/publicsource and read it before using this file. ! 11: * ! 12: * This Original Code and all software distributed under the License are ! 13: * distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY KIND, EITHER ! 14: * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES, ! 15: * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY, ! 16: * FITNESS FOR A PARTICULAR PURPOSE OR NON-INFRINGEMENT. Please see the ! 17: * License for the specific language governing rights and limitations ! 18: * under the License. ! 19: * ! 20: * @APPLE_LICENSE_HEADER_END@ ! 21: */ ! 22: #ifndef _MACHO_LOADER_H_ ! 23: #define _MACHO_LOADER_H_ ! 24: ! 25: /* ! 26: * This file describes the format of mach object files. ! 27: */ ! 28: ! 29: /* ! 30: * <mach/machine.h> is needed here for the cpu_type_t and cpu_subtype_t types ! 31: * and contains the constants for the possible values of these types. ! 32: */ ! 33: #include <mach/machine.h> ! 34: ! 35: /* ! 36: * <mach/vm_prot.h> is needed here for the vm_prot_t type and contains the ! 37: * constants that are or'ed together for the possible values of this type. ! 38: */ ! 39: #include <mach/vm_prot.h> ! 40: ! 41: /* ! 42: * <machine/thread_status.h> is expected to define the flavors of the thread ! 43: * states and the structures of those flavors for each machine. ! 44: */ ! 45: #include <mach/machine/thread_status.h> ! 46: ! 47: /* ! 48: * The mach header appears at the very beginning of the object file. ! 49: */ ! 50: struct mach_header { ! 51: unsigned long magic; /* mach magic number identifier */ ! 52: cpu_type_t cputype; /* cpu specifier */ ! 53: cpu_subtype_t cpusubtype; /* machine specifier */ ! 54: unsigned long filetype; /* type of file */ ! 55: unsigned long ncmds; /* number of load commands */ ! 56: unsigned long sizeofcmds; /* the size of all the load commands */ ! 57: unsigned long flags; /* flags */ ! 58: }; ! 59: ! 60: /* Constant for the magic field of the mach_header */ ! 61: #define MH_MAGIC 0xfeedface /* the mach magic number */ ! 62: #define MH_CIGAM NXSwapInt(MH_MAGIC) ! 63: ! 64: /* ! 65: * The layout of the file depends on the filetype. For all but the MH_OBJECT ! 66: * file type the segments are padded out and aligned on a segment alignment ! 67: * boundary for efficient demand pageing. The MH_EXECUTE, MH_FVMLIB, MH_DYLIB, ! 68: * MH_DYLINKER and MH_BUNDLE file types also have the headers included as part ! 69: * of their first segment. ! 70: * ! 71: * The file type MH_OBJECT is a compact format intended as output of the ! 72: * assembler and input (and possibly output) of the link editor (the .o ! 73: * format). All sections are in one unnamed segment with no segment padding. ! 74: * This format is used as an executable format when the file is so small the ! 75: * segment padding greatly increases it's size. ! 76: * ! 77: * The file type MH_PRELOAD is an executable format intended for things that ! 78: * not executed under the kernel (proms, stand alones, kernels, etc). The ! 79: * format can be executed under the kernel but may demand paged it and not ! 80: * preload it before execution. ! 81: * ! 82: * A core file is in MH_CORE format and can be any in an arbritray legal ! 83: * Mach-O file. ! 84: * ! 85: * Constants for the filetype field of the mach_header ! 86: */ ! 87: #define MH_OBJECT 0x1 /* relocatable object file */ ! 88: #define MH_EXECUTE 0x2 /* demand paged executable file */ ! 89: #define MH_FVMLIB 0x3 /* fixed VM shared library file */ ! 90: #define MH_CORE 0x4 /* core file */ ! 91: #define MH_PRELOAD 0x5 /* preloaded executable file */ ! 92: #define MH_DYLIB 0x6 /* dynamicly bound shared library file*/ ! 93: #define MH_DYLINKER 0x7 /* dynamic link editor */ ! 94: #define MH_BUNDLE 0x8 /* dynamicly bound bundle file */ ! 95: ! 96: /* Constants for the flags field of the mach_header */ ! 97: #define MH_NOUNDEFS 0x1 /* the object file has no undefined ! 98: references, can be executed */ ! 99: #define MH_INCRLINK 0x2 /* the object file is the output of an ! 100: incremental link against a base file ! 101: and can't be link edited again */ ! 102: #define MH_DYLDLINK 0x4 /* the object file is input for the ! 103: dynamic linker and can't be staticly ! 104: link edited again */ ! 105: #define MH_BINDATLOAD 0x8 /* the object file's undefined ! 106: references are bound by the dynamic ! 107: linker when loaded. */ ! 108: #define MH_PREBOUND 0x10 /* the file has it's dynamic undefined ! 109: references prebound. */ ! 110: ! 111: /* ! 112: * The load commands directly follow the mach_header. The total size of all ! 113: * of the commands is given by the sizeofcmds field in the mach_header. All ! 114: * load commands must have as their first two fields cmd and cmdsize. The cmd ! 115: * field is filled in with a constant for that command type. Each command type ! 116: * has a structure specifically for it. The cmdsize field is the size in bytes ! 117: * of the particular load command structure plus anything that follows it that ! 118: * is a part of the load command (i.e. section structures, strings, etc.). To ! 119: * advance to the next load command the cmdsize can be added to the offset or ! 120: * pointer of the current load command. The cmdsize MUST be a multiple of ! 121: * sizeof(long) (this is forever the maximum alignment of any load commands). ! 122: * The padded bytes must be zero. All tables in the object file must also ! 123: * follow these rules so the file can be memory mapped. Otherwise the pointers ! 124: * to these tables will not work well or at all on some machines. With all ! 125: * padding zeroed like objects will compare byte for byte. ! 126: */ ! 127: struct load_command { ! 128: unsigned long cmd; /* type of load command */ ! 129: unsigned long cmdsize; /* total size of command in bytes */ ! 130: }; ! 131: ! 132: /* Constants for the cmd field of all load commands, the type */ ! 133: #define LC_SEGMENT 0x1 /* segment of this file to be mapped */ ! 134: #define LC_SYMTAB 0x2 /* link-edit stab symbol table info */ ! 135: #define LC_SYMSEG 0x3 /* link-edit gdb symbol table info (obsolete) */ ! 136: #define LC_THREAD 0x4 /* thread */ ! 137: #define LC_UNIXTHREAD 0x5 /* unix thread (includes a stack) */ ! 138: #define LC_LOADFVMLIB 0x6 /* load a specified fixed VM shared library */ ! 139: #define LC_IDFVMLIB 0x7 /* fixed VM shared library identification */ ! 140: #define LC_IDENT 0x8 /* object identification info (obsolete) */ ! 141: #define LC_FVMFILE 0x9 /* fixed VM file inclusion (internal use) */ ! 142: #define LC_PREPAGE 0xa /* prepage command (internal use) */ ! 143: #define LC_DYSYMTAB 0xb /* dynamic link-edit symbol table info */ ! 144: #define LC_LOAD_DYLIB 0xc /* load a dynamicly linked shared library */ ! 145: #define LC_ID_DYLIB 0xd /* dynamicly linked shared lib identification */ ! 146: #define LC_LOAD_DYLINKER 0xe /* load a dynamic linker */ ! 147: #define LC_ID_DYLINKER 0xf /* dynamic linker identification */ ! 148: #define LC_PREBOUND_DYLIB 0x10 /* modules prebound for a dynamicly */ ! 149: /* linked shared library */ ! 150: ! 151: /* ! 152: * A variable length string in a load command is represented by an lc_str ! 153: * union. The strings are stored just after the load command structure and ! 154: * the offset is from the start of the load command structure. The size ! 155: * of the string is reflected in the cmdsize field of the load command. ! 156: * Once again any padded bytes to bring the cmdsize field to a multiple ! 157: * of sizeof(long) must be zero. ! 158: */ ! 159: union lc_str { ! 160: unsigned long offset; /* offset to the string */ ! 161: char *ptr; /* pointer to the string */ ! 162: }; ! 163: ! 164: /* ! 165: * The segment load command indicates that a part of this file is to be ! 166: * mapped into the task's address space. The size of this segment in memory, ! 167: * vmsize, maybe equal to or larger than the amount to map from this file, ! 168: * filesize. The file is mapped starting at fileoff to the beginning of ! 169: * the segment in memory, vmaddr. The rest of the memory of the segment, ! 170: * if any, is allocated zero fill on demand. The segment's maximum virtual ! 171: * memory protection and initial virtual memory protection are specified ! 172: * by the maxprot and initprot fields. If the segment has sections then the ! 173: * section structures directly follow the segment command and their size is ! 174: * reflected in cmdsize. ! 175: */ ! 176: struct segment_command { ! 177: unsigned long cmd; /* LC_SEGMENT */ ! 178: unsigned long cmdsize; /* includes sizeof section structs */ ! 179: char segname[16]; /* segment name */ ! 180: unsigned long vmaddr; /* memory address of this segment */ ! 181: unsigned long vmsize; /* memory size of this segment */ ! 182: unsigned long fileoff; /* file offset of this segment */ ! 183: unsigned long filesize; /* amount to map from the file */ ! 184: vm_prot_t maxprot; /* maximum VM protection */ ! 185: vm_prot_t initprot; /* initial VM protection */ ! 186: unsigned long nsects; /* number of sections in segment */ ! 187: unsigned long flags; /* flags */ ! 188: }; ! 189: ! 190: /* Constants for the flags field of the segment_command */ ! 191: #define SG_HIGHVM 0x1 /* the file contents for this segment is for ! 192: the high part of the VM space, the low part ! 193: is zero filled (for stacks in core files) */ ! 194: #define SG_FVMLIB 0x2 /* this segment is the VM that is allocated by ! 195: a fixed VM library, for overlap checking in ! 196: the link editor */ ! 197: #define SG_NORELOC 0x4 /* this segment has nothing that was relocated ! 198: in it and nothing relocated to it, that is ! 199: it maybe safely replaced without relocation*/ ! 200: ! 201: /* ! 202: * A segment is made up of zero or more sections. Non-MH_OBJECT files have ! 203: * all of their segments with the proper sections in each, and padded to the ! 204: * specified segment alignment when produced by the link editor. The first ! 205: * segment of a MH_EXECUTE and MH_FVMLIB format file contains the mach_header ! 206: * and load commands of the object file before it's first section. The zero ! 207: * fill sections are always last in their segment (in all formats). This ! 208: * allows the zeroed segment padding to be mapped into memory where zero fill ! 209: * sections might be. ! 210: * ! 211: * The MH_OBJECT format has all of it's sections in one segment for ! 212: * compactness. There is no padding to a specified segment boundary and the ! 213: * mach_header and load commands are not part of the segment. ! 214: * ! 215: * Sections with the same section name, sectname, going into the same segment, ! 216: * segname, are combined by the link editor. The resulting section is aligned ! 217: * to the maximum alignment of the combined sections and is the new section's ! 218: * alignment. The combined sections are aligned to their original alignment in ! 219: * the combined section. Any padded bytes to get the specified alignment are ! 220: * zeroed. ! 221: * ! 222: * The format of the relocation entries referenced by the reloff and nreloc ! 223: * fields of the section structure for mach object files is described in the ! 224: * header file <reloc.h>. ! 225: */ ! 226: struct section { ! 227: char sectname[16]; /* name of this section */ ! 228: char segname[16]; /* segment this section goes in */ ! 229: unsigned long addr; /* memory address of this section */ ! 230: unsigned long size; /* size in bytes of this section */ ! 231: unsigned long offset; /* file offset of this section */ ! 232: unsigned long align; /* section alignment (power of 2) */ ! 233: unsigned long reloff; /* file offset of relocation entries */ ! 234: unsigned long nreloc; /* number of relocation entries */ ! 235: unsigned long flags; /* flags (section type and attributes)*/ ! 236: unsigned long reserved1; /* reserved */ ! 237: unsigned long reserved2; /* reserved */ ! 238: }; ! 239: ! 240: /* ! 241: * The flags field of a section structure is separated into two parts a section ! 242: * type and section attributes. The section types are mutually exclusive (it ! 243: * can only have one type) but the section attributes are not (it may have more ! 244: * than one attribute). ! 245: */ ! 246: #define SECTION_TYPE 0x000000ff /* 256 section types */ ! 247: #define SECTION_ATTRIBUTES 0xffffff00 /* 24 section attributes */ ! 248: ! 249: /* Constants for the type of a section */ ! 250: #define S_REGULAR 0x0 /* regular section */ ! 251: #define S_ZEROFILL 0x1 /* zero fill on demand section */ ! 252: #define S_CSTRING_LITERALS 0x2 /* section with only literal C strings*/ ! 253: #define S_4BYTE_LITERALS 0x3 /* section with only 4 byte literals */ ! 254: #define S_8BYTE_LITERALS 0x4 /* section with only 8 byte literals */ ! 255: #define S_LITERAL_POINTERS 0x5 /* section with only pointers to */ ! 256: /* literals */ ! 257: /* ! 258: * For the two types of symbol pointers sections and the symbol stubs section ! 259: * they have indirect symbol table entries. For each of the entries in the ! 260: * section the indirect symbol table entries, in corresponding order in the ! 261: * indirect symbol table, start at the index stored in the reserved1 field ! 262: * of the section structure. Since the indirect symbol table entries ! 263: * correspond to the entries in the section the number of indirect symbol table ! 264: * entries is inferred from the size of the section divided by the size of the ! 265: * entries in the section. For symbol pointers sections the size of the entries ! 266: * in the section is 4 bytes and for symbol stubs sections the byte size of the ! 267: * stubs is stored in the reserved2 field of the section structure. ! 268: */ ! 269: #define S_NON_LAZY_SYMBOL_POINTERS 0x6 /* section with only non-lazy ! 270: symbol pointers */ ! 271: #define S_LAZY_SYMBOL_POINTERS 0x7 /* section with only lazy symbol ! 272: pointers */ ! 273: #define S_SYMBOL_STUBS 0x8 /* section with only symbol ! 274: stubs, byte size of stub in ! 275: the reserved2 field */ ! 276: #define S_MOD_INIT_FUNC_POINTERS 0x9 /* section with only function ! 277: pointers for initialization*/ ! 278: /* ! 279: * Constants for the section attributes part of the flags field of a section ! 280: * structure. ! 281: */ ! 282: #define SECTION_ATTRIBUTES_USR 0xff000000 /* User setable attributes */ ! 283: #define S_ATTR_PURE_INSTRUCTIONS 0x80000000 /* section contains only true ! 284: machine instructions */ ! 285: #define SECTION_ATTRIBUTES_SYS 0x00ffff00 /* system setable attributes */ ! 286: #define S_ATTR_SOME_INSTRUCTIONS 0x00000400 /* section contains some ! 287: machine instructions */ ! 288: #define S_ATTR_EXT_RELOC 0x00000200 /* section has external ! 289: relocation entries */ ! 290: #define S_ATTR_LOC_RELOC 0x00000100 /* section has local ! 291: relocation entries */ ! 292: ! 293: ! 294: /* ! 295: * The names of segments and sections in them are mostly meaningless to the ! 296: * link-editor. But there are few things to support traditional UNIX ! 297: * executables that require the link-editor and assembler to use some names ! 298: * agreed upon by convention. ! 299: * ! 300: * The initial protection of the "__TEXT" segment has write protection turned ! 301: * off (not writeable). ! 302: * ! 303: * The link-editor will allocate common symbols at the end of the "__common" ! 304: * section in the "__DATA" segment. It will create the section and segment ! 305: * if needed. ! 306: */ ! 307: ! 308: /* The currently known segment names and the section names in those segments */ ! 309: ! 310: #define SEG_PAGEZERO "__PAGEZERO" /* the pagezero segment which has no */ ! 311: /* protections and catches NULL */ ! 312: /* references for MH_EXECUTE files */ ! 313: ! 314: ! 315: #define SEG_TEXT "__TEXT" /* the tradition UNIX text segment */ ! 316: #define SECT_TEXT "__text" /* the real text part of the text */ ! 317: /* section no headers, and no padding */ ! 318: #define SECT_FVMLIB_INIT0 "__fvmlib_init0" /* the fvmlib initialization */ ! 319: /* section */ ! 320: #define SECT_FVMLIB_INIT1 "__fvmlib_init1" /* the section following the */ ! 321: /* fvmlib initialization */ ! 322: /* section */ ! 323: ! 324: #define SEG_DATA "__DATA" /* the tradition UNIX data segment */ ! 325: #define SECT_DATA "__data" /* the real initialized data section */ ! 326: /* no padding, no bss overlap */ ! 327: #define SECT_BSS "__bss" /* the real uninitialized data section*/ ! 328: /* no padding */ ! 329: #define SECT_COMMON "__common" /* the section common symbols are */ ! 330: /* allocated in by the link editor */ ! 331: ! 332: #define SEG_OBJC "__OBJC" /* objective-C runtime segment */ ! 333: #define SECT_OBJC_SYMBOLS "__symbol_table" /* symbol table */ ! 334: #define SECT_OBJC_MODULES "__module_info" /* module information */ ! 335: #define SECT_OBJC_STRINGS "__selector_strs" /* string table */ ! 336: #define SECT_OBJC_REFS "__selector_refs" /* string table */ ! 337: ! 338: #define SEG_ICON "__ICON" /* the NeXT icon segment */ ! 339: #define SECT_ICON_HEADER "__header" /* the icon headers */ ! 340: #define SECT_ICON_TIFF "__tiff" /* the icons in tiff format */ ! 341: ! 342: #define SEG_LINKEDIT "__LINKEDIT" /* the segment containing all structs */ ! 343: /* created and maintained by the link */ ! 344: /* editor. Created with -seglinkedit */ ! 345: /* option to ld(1) for MH_EXECUTE and */ ! 346: /* FVMLIB file types only */ ! 347: ! 348: #define SEG_UNIXSTACK "__UNIXSTACK" /* the unix stack segment */ ! 349: ! 350: /* ! 351: * Fixed virtual memory shared libraries are identified by two things. The ! 352: * target pathname (the name of the library as found for execution), and the ! 353: * minor version number. The address of where the headers are loaded is in ! 354: * header_addr. ! 355: */ ! 356: struct fvmlib { ! 357: union lc_str name; /* library's target pathname */ ! 358: unsigned long minor_version; /* library's minor version number */ ! 359: unsigned long header_addr; /* library's header address */ ! 360: }; ! 361: ! 362: /* ! 363: * A fixed virtual shared library (filetype == MH_FVMLIB in the mach header) ! 364: * contains a fvmlib_command (cmd == LC_IDFVMLIB) to identify the library. ! 365: * An object that uses a fixed virtual shared library also contains a ! 366: * fvmlib_command (cmd == LC_LOADFVMLIB) for each library it uses. ! 367: */ ! 368: struct fvmlib_command { ! 369: unsigned long cmd; /* LC_IDFVMLIB or LC_LOADFVMLIB */ ! 370: unsigned long cmdsize; /* includes pathname string */ ! 371: struct fvmlib fvmlib; /* the library identification */ ! 372: }; ! 373: ! 374: /* ! 375: * Dynamicly linked shared libraries are identified by two things. The ! 376: * pathname (the name of the library as found for execution), and the ! 377: * compatibility version number. The pathname must match and the compatibility ! 378: * number in the user of the library must be greater than or equal to the ! 379: * library being used. The time stamp is used to record the time a library was ! 380: * built and copied into user so it can be use to determined if the library used ! 381: * at runtime is exactly the same as used to built the program. ! 382: */ ! 383: struct dylib { ! 384: union lc_str name; /* library's path name */ ! 385: unsigned long timestamp; /* library's build time stamp */ ! 386: unsigned long current_version; /* library's current version number */ ! 387: unsigned long compatibility_version;/* library's compatibility vers number*/ ! 388: }; ! 389: ! 390: /* ! 391: * A dynamicly linked shared library (filetype == MH_DYLIB in the mach header) ! 392: * contains a dylib_command (cmd == LC_ID_DYLIB) to identify the library. ! 393: * An object that uses a dynamicly linked shared library also contains a ! 394: * dylib_command (cmd == LC_LOAD_DYLIB) for each library it uses. ! 395: */ ! 396: struct dylib_command { ! 397: unsigned long cmd; /* LC_ID_DYLIB or LC_LOAD_DYLIB */ ! 398: unsigned long cmdsize; /* includes pathname string */ ! 399: struct dylib dylib; /* the library identification */ ! 400: }; ! 401: ! 402: /* ! 403: * A program (filetype == MH_EXECUTE) or bundle (filetype == MH_BUNDLE) that is ! 404: * prebound to it's dynamic libraries has one of these for each library that ! 405: * the static linker used in prebinding. It contains a bit vector for the ! 406: * modules in the library. The bits indicate which modules are bound (1) and ! 407: * which are not (0) from the library. The bit for module 0 is the low bit ! 408: * of the first byte. So the bit for the Nth module is: ! 409: * (linked_modules[N/8] >> N%8) & 1 ! 410: */ ! 411: struct prebound_dylib_command { ! 412: unsigned long cmd; /* LC_PREBOUND_DYLIB */ ! 413: unsigned long cmdsize; /* includes strings */ ! 414: union lc_str name; /* library's path name */ ! 415: unsigned long nmodules; /* number of modules in library */ ! 416: union lc_str linked_modules; /* bit vector of linked modules */ ! 417: }; ! 418: ! 419: /* ! 420: * A program that uses a dynamic linker contains a dylinker_command to identify ! 421: * the name of the dynamic linker (LC_LOAD_DYLINKER). And a dynamic linker ! 422: * contains a dylinker_command to identify the dynamic linker (LC_ID_DYLINKER). ! 423: * A file can have at most one of these. ! 424: */ ! 425: struct dylinker_command { ! 426: unsigned long cmd; /* LC_ID_DYLINKER or LC_LOAD_DYLINKER */ ! 427: unsigned long cmdsize; /* includes pathname string */ ! 428: union lc_str name; /* dynamic linker's path name */ ! 429: }; ! 430: ! 431: /* ! 432: * Thread commands contain machine-specific data structures suitable for ! 433: * use in the thread state primitives. The machine specific data structures ! 434: * follow the struct thread_command as follows. ! 435: * Each flavor of machine specific data structure is preceded by an unsigned ! 436: * long constant for the flavor of that data structure, an unsigned long ! 437: * that is the count of longs of the size of the state data structure and then ! 438: * the state data structure follows. This triple may be repeated for many ! 439: * flavors. The constants for the flavors, counts and state data structure ! 440: * definitions are expected to be in the header file <machine/thread_status.h>. ! 441: * These machine specific data structures sizes must be multiples of ! 442: * sizeof(long). The cmdsize reflects the total size of the thread_command ! 443: * and all of the sizes of the constants for the flavors, counts and state ! 444: * data structures. ! 445: * ! 446: * For executable objects that are unix processes there will be one ! 447: * thread_command (cmd == LC_UNIXTHREAD) created for it by the link-editor. ! 448: * This is the same as a LC_THREAD, except that a stack is automatically ! 449: * created (based on the shell's limit for the stack size). Command arguments ! 450: * and environment variables are copied onto that stack. ! 451: */ ! 452: struct thread_command { ! 453: unsigned long cmd; /* LC_THREAD or LC_UNIXTHREAD */ ! 454: unsigned long cmdsize; /* total size of this command */ ! 455: /* unsigned long flavor flavor of thread state */ ! 456: /* unsigned long count count of longs in thread state */ ! 457: /* struct XXX_thread_state state thread state for this flavor */ ! 458: /* ... */ ! 459: }; ! 460: ! 461: /* ! 462: * The symtab_command contains the offsets and sizes of the link-edit 4.3BSD ! 463: * "stab" style symbol table information as described in the header files ! 464: * <nlist.h> and <stab.h>. ! 465: */ ! 466: struct symtab_command { ! 467: unsigned long cmd; /* LC_SYMTAB */ ! 468: unsigned long cmdsize; /* sizeof(struct symtab_command) */ ! 469: unsigned long symoff; /* symbol table offset */ ! 470: unsigned long nsyms; /* number of symbol table entries */ ! 471: unsigned long stroff; /* string table offset */ ! 472: unsigned long strsize; /* string table size in bytes */ ! 473: }; ! 474: ! 475: /* ! 476: * This is the second set of the symbolic information which is used to support ! 477: * the data structures for the dynamicly link editor. ! 478: * ! 479: * The original set of symbolic information in the symtab_command which contains ! 480: * the symbol and string tables must also be present when this load command is ! 481: * present. When this load command is present the symbol table is organized ! 482: * into three groups of symbols: ! 483: * local symbols (static and debugging symbols) - grouped by module ! 484: * defined external symbols - grouped by module (sorted by name if not lib) ! 485: * undefined external symbols (sorted by name) ! 486: * In this load command there are offsets and counts to each of the three groups ! 487: * of symbols. ! 488: * ! 489: * This load command contains a the offsets and sizes of the following new ! 490: * symbolic information tables: ! 491: * table of contents ! 492: * module table ! 493: * reference symbol table ! 494: * indirect symbol table ! 495: * The first three tables above (the table of contents, module table and ! 496: * reference symbol table) are only present if the file is a dynamicly linked ! 497: * shared library. For executable and object modules, which are files ! 498: * containing only one module, the information that would be in these three ! 499: * tables is determined as follows: ! 500: * table of contents - the defined external symbols are sorted by name ! 501: * module table - the file contains only one module so everything in the ! 502: * file is part of the module. ! 503: * reference symbol table - is the defined and undefined external symbols ! 504: * ! 505: * For dynamicly linked shared library files this load command also contains ! 506: * offsets and sizes to the pool of relocation entries for all sections ! 507: * separated into two groups: ! 508: * external relocation entries ! 509: * local relocation entries ! 510: * For executable and object modules the relocation entries continue to hang ! 511: * off the section structures. ! 512: */ ! 513: struct dysymtab_command { ! 514: unsigned long cmd; /* LC_DYSYMTAB */ ! 515: unsigned long cmdsize; /* sizeof(struct dysymtab_command) */ ! 516: ! 517: /* ! 518: * The symbols indicated by symoff and nsyms of the LC_SYMTAB load command ! 519: * are grouped into the following three groups: ! 520: * local symbols (further grouped by the module they are from) ! 521: * defined external symbols (further grouped by the module they are from) ! 522: * undefined symbols ! 523: * ! 524: * The local symbols are used only for debugging. The dynamic binding ! 525: * process may have to use them to indicate to the debugger the local ! 526: * symbols for a module that is being bound. ! 527: * ! 528: * The last two groups are used by the dynamic binding process to do the ! 529: * binding (indirectly through the module table and the reference symbol ! 530: * table when this is a dynamicly linked shared library file). ! 531: */ ! 532: unsigned long ilocalsym; /* index to local symbols */ ! 533: unsigned long nlocalsym; /* number of local symbols */ ! 534: ! 535: unsigned long iextdefsym; /* index to externally defined symbols */ ! 536: unsigned long nextdefsym; /* number of externally defined symbols */ ! 537: ! 538: unsigned long iundefsym; /* index to undefined symbols */ ! 539: unsigned long nundefsym; /* number of undefined symbols */ ! 540: ! 541: /* ! 542: * For the for the dynamic binding process to find which module a symbol ! 543: * is defined in the table of contents is used (analogous to the ranlib ! 544: * structure in an archive) which maps defined external symbols to modules ! 545: * they are defined in. This exists only in a dynamicly linked shared ! 546: * library file. For executable and object modules the defined external ! 547: * symbols are sorted by name and is use as the table of contents. ! 548: */ ! 549: unsigned long tocoff; /* file offset to table of contents */ ! 550: unsigned long ntoc; /* number of entries in table of contents */ ! 551: ! 552: /* ! 553: * To support dynamic binding of "modules" (whole object files) the symbol ! 554: * table must reflect the modules that the file was created from. This is ! 555: * done by having a module table that has indexes and counts into the merged ! 556: * tables for each module. The module structure that these two entries ! 557: * refer to is described below. This exists only in a dynamicly linked ! 558: * shared library file. For executable and object modules the file only ! 559: * contains one module so everything in the file belongs to the module. ! 560: */ ! 561: unsigned long modtaboff; /* file offset to module table */ ! 562: unsigned long nmodtab; /* number of module table entries */ ! 563: ! 564: /* ! 565: * To support dynamic module binding the module structure for each module ! 566: * indicates the external references (defined and undefined) each module ! 567: * makes. For each module there is an offset and a count into the ! 568: * reference symbol table for the symbols that the module references. ! 569: * This exists only in a dynamicly linked shared library file. For ! 570: * executable and object modules the defined external symbols and the ! 571: * undefined external symbols indicates the external references. ! 572: */ ! 573: unsigned long extrefsymoff; /* offset to referenced symbol table */ ! 574: unsigned long nextrefsyms; /* number of referenced symbol table entries */ ! 575: ! 576: /* ! 577: * The sections that contain "symbol pointers" and "routine stubs" have ! 578: * indexes and (implied counts based on the size of the section and fixed ! 579: * size of the entry) into the "indirect symbol" table for each pointer ! 580: * and stub. For every section of these two types the index into the ! 581: * indirect symbol table is stored in the section header in the field ! 582: * reserved1. An indirect symbol table entry is simply a 32bit index into ! 583: * the symbol table to the symbol that the pointer or stub is referring to. ! 584: * The indirect symbol table is ordered to match the entries in the section. ! 585: */ ! 586: unsigned long indirectsymoff; /* file offset to the indirect symbol table */ ! 587: unsigned long nindirectsyms; /* number of indirect symbol table entries */ ! 588: ! 589: /* ! 590: * To support relocating an individual module in a library file quickly the ! 591: * external relocation entries for each module in the library need to be ! 592: * accessed efficiently. Since the relocation entries can't be accessed ! 593: * through the section headers for a library file they are separated into ! 594: * groups of local and external entries further grouped by module. In this ! 595: * case the presents of this load command who's extreloff, nextrel, ! 596: * locreloff and nlocrel fields are non-zero indicates that the relocation ! 597: * entries of non-merged sections are not referenced through the section ! 598: * structures (and the reloff and nreloc fields in the section headers are ! 599: * set to zero). ! 600: * ! 601: * Since the relocation entries are not accessed through the section headers ! 602: * this requires the r_address field to be something other than a section ! 603: * offset to identify the item to be relocated. In this case r_address is ! 604: * set to the offset from the vmaddr of the first LC_SEGMENT command. ! 605: * ! 606: * The relocation entries are grouped by module and the module table ! 607: * entries have indexes and counts into them for the group of external ! 608: * relocation entries for that the module. ! 609: * ! 610: * For sections that are merged across modules there must not be any ! 611: * remaining external relocation entries for them (for merged sections ! 612: * remaining relocation entries must be local). ! 613: */ ! 614: unsigned long extreloff; /* offset to external relocation entries */ ! 615: unsigned long nextrel; /* number of external relocation entries */ ! 616: ! 617: /* ! 618: * All the local relocation entries are grouped together (they are not ! 619: * grouped by their module since they are only used if the object is moved ! 620: * from it staticly link edited address). ! 621: */ ! 622: unsigned long locreloff; /* offset to local relocation entries */ ! 623: unsigned long nlocrel; /* number of local relocation entries */ ! 624: ! 625: }; ! 626: ! 627: /* ! 628: * An indirect symbol table entry is simply a 32bit index into the symbol table ! 629: * to the symbol that the pointer or stub is refering to. Unless it is for a ! 630: * non-lazy symbol pointer section for a defined symbol which strip(1) as ! 631: * removed. In which case it has the value INDIRECT_SYMBOL_LOCAL. If the ! 632: * symbol was also absolute INDIRECT_SYMBOL_ABS is or'ed with that. ! 633: */ ! 634: #define INDIRECT_SYMBOL_LOCAL 0x80000000 ! 635: #define INDIRECT_SYMBOL_ABS 0x40000000 ! 636: ! 637: ! 638: /* a table of contents entry */ ! 639: struct dylib_table_of_contents { ! 640: unsigned long symbol_index; /* the defined external symbol ! 641: (index into the symbol table) */ ! 642: unsigned long module_index; /* index into the module table this symbol ! 643: is defined in */ ! 644: }; ! 645: ! 646: /* a module table entry */ ! 647: struct dylib_module { ! 648: unsigned long module_name; /* the module name (index into string table) */ ! 649: ! 650: unsigned long iextdefsym; /* index into externally defined symbols */ ! 651: unsigned long nextdefsym; /* number of externally defined symbols */ ! 652: unsigned long irefsym; /* index into reference symbol table */ ! 653: unsigned long nrefsym; /* number of reference symbol table entries */ ! 654: unsigned long ilocalsym; /* index into symbols for local symbols */ ! 655: unsigned long nlocalsym; /* number of local symbols */ ! 656: ! 657: unsigned long iextrel; /* index into external relocation entries */ ! 658: unsigned long nextrel; /* number of external relocation entries */ ! 659: ! 660: unsigned long iinit; /* index into the init section */ ! 661: unsigned long ninit; /* number of init section entries */ ! 662: ! 663: unsigned long /* for this module address of the start of */ ! 664: objc_module_info_addr; /* the (__OBJC,__module_info) section */ ! 665: unsigned long /* for this module size of */ ! 666: objc_module_info_size; /* the (__OBJC,__module_info) section */ ! 667: }; ! 668: ! 669: /* ! 670: * The entries in the reference symbol table are used when loading the module ! 671: * (both by the static and dynamic link editors) and if the module is unloaded ! 672: * or replaced. Therefore all external symbols (defined and undefined) are ! 673: * listed in the module's reference table. The flags describe the type of ! 674: * reference that is being made. The constants for the flags are defined in ! 675: * <mach-o/nlist.h> as they are also used for symbol table entries. ! 676: */ ! 677: struct dylib_reference { ! 678: unsigned long isym:24, /* index into the symbol table */ ! 679: flags:8; /* flags to indicate the type of reference */ ! 680: }; ! 681: ! 682: /* ! 683: * The symseg_command contains the offset and size of the GNU style ! 684: * symbol table information as described in the header file <symseg.h>. ! 685: * The symbol roots of the symbol segments must also be aligned properly ! 686: * in the file. So the requirement of keeping the offsets aligned to a ! 687: * multiple of a sizeof(long) translates to the length field of the symbol ! 688: * roots also being a multiple of a long. Also the padding must again be ! 689: * zeroed. (THIS IS OBSOLETE and no longer supported). ! 690: */ ! 691: struct symseg_command { ! 692: unsigned long cmd; /* LC_SYMSEG */ ! 693: unsigned long cmdsize; /* sizeof(struct symseg_command) */ ! 694: unsigned long offset; /* symbol segment offset */ ! 695: unsigned long size; /* symbol segment size in bytes */ ! 696: }; ! 697: ! 698: /* ! 699: * The ident_command contains a free format string table following the ! 700: * ident_command structure. The strings are null terminated and the size of ! 701: * the command is padded out with zero bytes to a multiple of sizeof(long). ! 702: * (THIS IS OBSOLETE and no longer supported). ! 703: */ ! 704: struct ident_command { ! 705: unsigned long cmd; /* LC_IDENT */ ! 706: unsigned long cmdsize; /* strings that follow this command */ ! 707: }; ! 708: ! 709: /* ! 710: * The fvmfile_command contains a reference to a file to be loaded at the ! 711: * specified virtual address. (Presently, this command is reserved for NeXT ! 712: * internal use. The kernel ignores this command when loading a program into ! 713: * memory). ! 714: */ ! 715: struct fvmfile_command { ! 716: unsigned long cmd; /* LC_FVMFILE */ ! 717: unsigned long cmdsize; /* includes pathname string */ ! 718: union lc_str name; /* files pathname */ ! 719: unsigned long header_addr; /* files virtual address */ ! 720: }; ! 721: ! 722: #endif /*_MACHO_LOADER_H_*/
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