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