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Diffstat (limited to 'src/third_party/mac_headers/mach-o/loader.h')
| -rw-r--r-- | src/third_party/mac_headers/mach-o/loader.h | 1402 |
1 files changed, 1402 insertions, 0 deletions
diff --git a/src/third_party/mac_headers/mach-o/loader.h b/src/third_party/mac_headers/mach-o/loader.h new file mode 100644 index 00000000..ff18e29c --- /dev/null +++ b/src/third_party/mac_headers/mach-o/loader.h @@ -0,0 +1,1402 @@ +/* + * Copyright (c) 1999-2010 Apple Inc. All Rights Reserved. + * + * @APPLE_LICENSE_HEADER_START@ + * + * This file contains Original Code and/or Modifications of Original Code + * as defined in and that are subject to the Apple Public Source License + * Version 2.0 (the 'License'). You may not use this file except in + * compliance with the License. Please obtain a copy of the License at + * http://www.opensource.apple.com/apsl/ and read it before using this + * file. + * + * The Original Code and all software distributed under the License are + * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER + * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES, + * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY, + * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT. + * Please see the License for the specific language governing rights and + * limitations under the License. + * + * @APPLE_LICENSE_HEADER_END@ + */ +#ifndef _MACHO_LOADER_H_ +#define _MACHO_LOADER_H_ + +/* + * This file describes the format of mach object files. + */ +#include <stdint.h> + +/* + * <mach/machine.h> is needed here for the cpu_type_t and cpu_subtype_t types + * and contains the constants for the possible values of these types. + */ +#include <mach/machine.h> + +/* + * <mach/vm_prot.h> is needed here for the vm_prot_t type and contains the + * constants that are or'ed together for the possible values of this type. + */ +#include <mach/vm_prot.h> + +/* + * <machine/thread_status.h> is expected to define the flavors of the thread + * states and the structures of those flavors for each machine. + */ +#include <mach/machine/thread_status.h> +#include <architecture/byte_order.h> + +/* + * The 32-bit mach header appears at the very beginning of the object file for + * 32-bit architectures. + */ +struct mach_header { + uint32_t magic; /* mach magic number identifier */ + cpu_type_t cputype; /* cpu specifier */ + cpu_subtype_t cpusubtype; /* machine specifier */ + uint32_t filetype; /* type of file */ + uint32_t ncmds; /* number of load commands */ + uint32_t sizeofcmds; /* the size of all the load commands */ + uint32_t flags; /* flags */ +}; + +/* Constant for the magic field of the mach_header (32-bit architectures) */ +#define MH_MAGIC 0xfeedface /* the mach magic number */ +#define MH_CIGAM 0xcefaedfe /* NXSwapInt(MH_MAGIC) */ + +/* + * The 64-bit mach header appears at the very beginning of object files for + * 64-bit architectures. + */ +struct mach_header_64 { + uint32_t magic; /* mach magic number identifier */ + cpu_type_t cputype; /* cpu specifier */ + cpu_subtype_t cpusubtype; /* machine specifier */ + uint32_t filetype; /* type of file */ + uint32_t ncmds; /* number of load commands */ + uint32_t sizeofcmds; /* the size of all the load commands */ + uint32_t flags; /* flags */ + uint32_t reserved; /* reserved */ +}; + +/* Constant for the magic field of the mach_header_64 (64-bit architectures) */ +#define MH_MAGIC_64 0xfeedfacf /* the 64-bit mach magic number */ +#define MH_CIGAM_64 0xcffaedfe /* NXSwapInt(MH_MAGIC_64) */ + +/* + * The layout of the file depends on the filetype. For all but the MH_OBJECT + * file type the segments are padded out and aligned on a segment alignment + * boundary for efficient demand pageing. The MH_EXECUTE, MH_FVMLIB, MH_DYLIB, + * MH_DYLINKER and MH_BUNDLE file types also have the headers included as part + * of their first segment. + * + * The file type MH_OBJECT is a compact format intended as output of the + * assembler and input (and possibly output) of the link editor (the .o + * format). All sections are in one unnamed segment with no segment padding. + * This format is used as an executable format when the file is so small the + * segment padding greatly increases its size. + * + * The file type MH_PRELOAD is an executable format intended for things that + * are not executed under the kernel (proms, stand alones, kernels, etc). The + * format can be executed under the kernel but may demand paged it and not + * preload it before execution. + * + * A core file is in MH_CORE format and can be any in an arbritray legal + * Mach-O file. + * + * Constants for the filetype field of the mach_header + */ +#define MH_OBJECT 0x1 /* relocatable object file */ +#define MH_EXECUTE 0x2 /* demand paged executable file */ +#define MH_FVMLIB 0x3 /* fixed VM shared library file */ +#define MH_CORE 0x4 /* core file */ +#define MH_PRELOAD 0x5 /* preloaded executable file */ +#define MH_DYLIB 0x6 /* dynamically bound shared library */ +#define MH_DYLINKER 0x7 /* dynamic link editor */ +#define MH_BUNDLE 0x8 /* dynamically bound bundle file */ +#define MH_DYLIB_STUB 0x9 /* shared library stub for static */ + /* linking only, no section contents */ +#define MH_DSYM 0xa /* companion file with only debug */ + /* sections */ +#define MH_KEXT_BUNDLE 0xb /* x86_64 kexts */ + +/* Constants for the flags field of the mach_header */ +#define MH_NOUNDEFS 0x1 /* the object file has no undefined + references */ +#define MH_INCRLINK 0x2 /* the object file is the output of an + incremental link against a base file + and can't be link edited again */ +#define MH_DYLDLINK 0x4 /* the object file is input for the + dynamic linker and can't be staticly + link edited again */ +#define MH_BINDATLOAD 0x8 /* the object file's undefined + references are bound by the dynamic + linker when loaded. */ +#define MH_PREBOUND 0x10 /* the file has its dynamic undefined + references prebound. */ +#define MH_SPLIT_SEGS 0x20 /* the file has its read-only and + read-write segments split */ +#define MH_LAZY_INIT 0x40 /* the shared library init routine is + to be run lazily via catching memory + faults to its writeable segments + (obsolete) */ +#define MH_TWOLEVEL 0x80 /* the image is using two-level name + space bindings */ +#define MH_FORCE_FLAT 0x100 /* the executable is forcing all images + to use flat name space bindings */ +#define MH_NOMULTIDEFS 0x200 /* this umbrella guarantees no multiple + defintions of symbols in its + sub-images so the two-level namespace + hints can always be used. */ +#define MH_NOFIXPREBINDING 0x400 /* do not have dyld notify the + prebinding agent about this + executable */ +#define MH_PREBINDABLE 0x800 /* the binary is not prebound but can + have its prebinding redone. only used + when MH_PREBOUND is not set. */ +#define MH_ALLMODSBOUND 0x1000 /* indicates that this binary binds to + all two-level namespace modules of + its dependent libraries. only used + when MH_PREBINDABLE and MH_TWOLEVEL + are both set. */ +#define MH_SUBSECTIONS_VIA_SYMBOLS 0x2000/* safe to divide up the sections into + sub-sections via symbols for dead + code stripping */ +#define MH_CANONICAL 0x4000 /* the binary has been canonicalized + via the unprebind operation */ +#define MH_WEAK_DEFINES 0x8000 /* the final linked image contains + external weak symbols */ +#define MH_BINDS_TO_WEAK 0x10000 /* the final linked image uses + weak symbols */ + +#define MH_ALLOW_STACK_EXECUTION 0x20000/* When this bit is set, all stacks + in the task will be given stack + execution privilege. Only used in + MH_EXECUTE filetypes. */ +#define MH_ROOT_SAFE 0x40000 /* When this bit is set, the binary + declares it is safe for use in + processes with uid zero */ + +#define MH_SETUID_SAFE 0x80000 /* When this bit is set, the binary + declares it is safe for use in + processes when issetugid() is true */ + +#define MH_NO_REEXPORTED_DYLIBS 0x100000 /* When this bit is set on a dylib, + the static linker does not need to + examine dependent dylibs to see + if any are re-exported */ +#define MH_PIE 0x200000 /* When this bit is set, the OS will + load the main executable at a + random address. Only used in + MH_EXECUTE filetypes. */ +#define MH_DEAD_STRIPPABLE_DYLIB 0x400000 /* Only for use on dylibs. When + linking against a dylib that + has this bit set, the static linker + will automatically not create a + LC_LOAD_DYLIB load command to the + dylib if no symbols are being + referenced from the dylib. */ +#define MH_HAS_TLV_DESCRIPTORS 0x800000 /* Contains a section of type + S_THREAD_LOCAL_VARIABLES */ + +#define MH_NO_HEAP_EXECUTION 0x1000000 /* When this bit is set, the OS will + run the main executable with + a non-executable heap even on + platforms (e.g. i386) that don't + require it. Only used in MH_EXECUTE + filetypes. */ + +/* + * The load commands directly follow the mach_header. The total size of all + * of the commands is given by the sizeofcmds field in the mach_header. All + * load commands must have as their first two fields cmd and cmdsize. The cmd + * field is filled in with a constant for that command type. Each command type + * has a structure specifically for it. The cmdsize field is the size in bytes + * of the particular load command structure plus anything that follows it that + * is a part of the load command (i.e. section structures, strings, etc.). To + * advance to the next load command the cmdsize can be added to the offset or + * pointer of the current load command. The cmdsize for 32-bit architectures + * MUST be a multiple of 4 bytes and for 64-bit architectures MUST be a multiple + * of 8 bytes (these are forever the maximum alignment of any load commands). + * The padded bytes must be zero. All tables in the object file must also + * follow these rules so the file can be memory mapped. Otherwise the pointers + * to these tables will not work well or at all on some machines. With all + * padding zeroed like objects will compare byte for byte. + */ +struct load_command { + uint32_t cmd; /* type of load command */ + uint32_t cmdsize; /* total size of command in bytes */ +}; + +/* + * After MacOS X 10.1 when a new load command is added that is required to be + * understood by the dynamic linker for the image to execute properly the + * LC_REQ_DYLD bit will be or'ed into the load command constant. If the dynamic + * linker sees such a load command it it does not understand will issue a + * "unknown load command required for execution" error and refuse to use the + * image. Other load commands without this bit that are not understood will + * simply be ignored. + */ +#define LC_REQ_DYLD 0x80000000 + +/* Constants for the cmd field of all load commands, the type */ +#define LC_SEGMENT 0x1 /* segment of this file to be mapped */ +#define LC_SYMTAB 0x2 /* link-edit stab symbol table info */ +#define LC_SYMSEG 0x3 /* link-edit gdb symbol table info (obsolete) */ +#define LC_THREAD 0x4 /* thread */ +#define LC_UNIXTHREAD 0x5 /* unix thread (includes a stack) */ +#define LC_LOADFVMLIB 0x6 /* load a specified fixed VM shared library */ +#define LC_IDFVMLIB 0x7 /* fixed VM shared library identification */ +#define LC_IDENT 0x8 /* object identification info (obsolete) */ +#define LC_FVMFILE 0x9 /* fixed VM file inclusion (internal use) */ +#define LC_PREPAGE 0xa /* prepage command (internal use) */ +#define LC_DYSYMTAB 0xb /* dynamic link-edit symbol table info */ +#define LC_LOAD_DYLIB 0xc /* load a dynamically linked shared library */ +#define LC_ID_DYLIB 0xd /* dynamically linked shared lib ident */ +#define LC_LOAD_DYLINKER 0xe /* load a dynamic linker */ +#define LC_ID_DYLINKER 0xf /* dynamic linker identification */ +#define LC_PREBOUND_DYLIB 0x10 /* modules prebound for a dynamically */ + /* linked shared library */ +#define LC_ROUTINES 0x11 /* image routines */ +#define LC_SUB_FRAMEWORK 0x12 /* sub framework */ +#define LC_SUB_UMBRELLA 0x13 /* sub umbrella */ +#define LC_SUB_CLIENT 0x14 /* sub client */ +#define LC_SUB_LIBRARY 0x15 /* sub library */ +#define LC_TWOLEVEL_HINTS 0x16 /* two-level namespace lookup hints */ +#define LC_PREBIND_CKSUM 0x17 /* prebind checksum */ + +/* + * load a dynamically linked shared library that is allowed to be missing + * (all symbols are weak imported). + */ +#define LC_LOAD_WEAK_DYLIB (0x18 | LC_REQ_DYLD) + +#define LC_SEGMENT_64 0x19 /* 64-bit segment of this file to be + mapped */ +#define LC_ROUTINES_64 0x1a /* 64-bit image routines */ +#define LC_UUID 0x1b /* the uuid */ +#define LC_RPATH (0x1c | LC_REQ_DYLD) /* runpath additions */ +#define LC_CODE_SIGNATURE 0x1d /* local of code signature */ +#define LC_SEGMENT_SPLIT_INFO 0x1e /* local of info to split segments */ +#define LC_REEXPORT_DYLIB (0x1f | LC_REQ_DYLD) /* load and re-export dylib */ +#define LC_LAZY_LOAD_DYLIB 0x20 /* delay load of dylib until first use */ +#define LC_ENCRYPTION_INFO 0x21 /* encrypted segment information */ +#define LC_DYLD_INFO 0x22 /* compressed dyld information */ +#define LC_DYLD_INFO_ONLY (0x22|LC_REQ_DYLD) /* compressed dyld information only */ +#define LC_LOAD_UPWARD_DYLIB (0x23 | LC_REQ_DYLD) /* load upward dylib */ +#define LC_VERSION_MIN_MACOSX 0x24 /* build for MacOSX min OS version */ +#define LC_VERSION_MIN_IPHONEOS 0x25 /* build for iPhoneOS min OS version */ +#define LC_FUNCTION_STARTS 0x26 /* compressed table of function start addresses */ +#define LC_DYLD_ENVIRONMENT 0x27 /* string for dyld to treat + like environment variable */ + +/* + * A variable length string in a load command is represented by an lc_str + * union. The strings are stored just after the load command structure and + * the offset is from the start of the load command structure. The size + * of the string is reflected in the cmdsize field of the load command. + * Once again any padded bytes to bring the cmdsize field to a multiple + * of 4 bytes must be zero. + */ +union lc_str { + uint32_t offset; /* offset to the string */ +#ifndef __LP64__ + char *ptr; /* pointer to the string */ +#endif +}; + +/* + * The segment load command indicates that a part of this file is to be + * mapped into the task's address space. The size of this segment in memory, + * vmsize, maybe equal to or larger than the amount to map from this file, + * filesize. The file is mapped starting at fileoff to the beginning of + * the segment in memory, vmaddr. The rest of the memory of the segment, + * if any, is allocated zero fill on demand. The segment's maximum virtual + * memory protection and initial virtual memory protection are specified + * by the maxprot and initprot fields. If the segment has sections then the + * section structures directly follow the segment command and their size is + * reflected in cmdsize. + */ +struct segment_command { /* for 32-bit architectures */ + uint32_t cmd; /* LC_SEGMENT */ + uint32_t cmdsize; /* includes sizeof section structs */ + char segname[16]; /* segment name */ + uint32_t vmaddr; /* memory address of this segment */ + uint32_t vmsize; /* memory size of this segment */ + uint32_t fileoff; /* file offset of this segment */ + uint32_t filesize; /* amount to map from the file */ + vm_prot_t maxprot; /* maximum VM protection */ + vm_prot_t initprot; /* initial VM protection */ + uint32_t nsects; /* number of sections in segment */ + uint32_t flags; /* flags */ +}; + +/* + * The 64-bit segment load command indicates that a part of this file is to be + * mapped into a 64-bit task's address space. If the 64-bit segment has + * sections then section_64 structures directly follow the 64-bit segment + * command and their size is reflected in cmdsize. + */ +struct segment_command_64 { /* for 64-bit architectures */ + uint32_t cmd; /* LC_SEGMENT_64 */ + uint32_t cmdsize; /* includes sizeof section_64 structs */ + char segname[16]; /* segment name */ + uint64_t vmaddr; /* memory address of this segment */ + uint64_t vmsize; /* memory size of this segment */ + uint64_t fileoff; /* file offset of this segment */ + uint64_t filesize; /* amount to map from the file */ + vm_prot_t maxprot; /* maximum VM protection */ + vm_prot_t initprot; /* initial VM protection */ + uint32_t nsects; /* number of sections in segment */ + uint32_t flags; /* flags */ +}; + +/* Constants for the flags field of the segment_command */ +#define SG_HIGHVM 0x1 /* the file contents for this segment is for + the high part of the VM space, the low part + is zero filled (for stacks in core files) */ +#define SG_FVMLIB 0x2 /* this segment is the VM that is allocated by + a fixed VM library, for overlap checking in + the link editor */ +#define SG_NORELOC 0x4 /* this segment has nothing that was relocated + in it and nothing relocated to it, that is + it maybe safely replaced without relocation*/ +#define SG_PROTECTED_VERSION_1 0x8 /* This segment is protected. If the + segment starts at file offset 0, the + first page of the segment is not + protected. All other pages of the + segment are protected. */ + +/* + * A segment is made up of zero or more sections. Non-MH_OBJECT files have + * all of their segments with the proper sections in each, and padded to the + * specified segment alignment when produced by the link editor. The first + * segment of a MH_EXECUTE and MH_FVMLIB format file contains the mach_header + * and load commands of the object file before its first section. The zero + * fill sections are always last in their segment (in all formats). This + * allows the zeroed segment padding to be mapped into memory where zero fill + * sections might be. The gigabyte zero fill sections, those with the section + * type S_GB_ZEROFILL, can only be in a segment with sections of this type. + * These segments are then placed after all other segments. + * + * The MH_OBJECT format has all of its sections in one segment for + * compactness. There is no padding to a specified segment boundary and the + * mach_header and load commands are not part of the segment. + * + * Sections with the same section name, sectname, going into the same segment, + * segname, are combined by the link editor. The resulting section is aligned + * to the maximum alignment of the combined sections and is the new section's + * alignment. The combined sections are aligned to their original alignment in + * the combined section. Any padded bytes to get the specified alignment are + * zeroed. + * + * The format of the relocation entries referenced by the reloff and nreloc + * fields of the section structure for mach object files is described in the + * header file <reloc.h>. + */ +struct section { /* for 32-bit architectures */ + char sectname[16]; /* name of this section */ + char segname[16]; /* segment this section goes in */ + uint32_t addr; /* memory address of this section */ + uint32_t size; /* size in bytes of this section */ + uint32_t offset; /* file offset of this section */ + uint32_t align; /* section alignment (power of 2) */ + uint32_t reloff; /* file offset of relocation entries */ + uint32_t nreloc; /* number of relocation entries */ + uint32_t flags; /* flags (section type and attributes)*/ + uint32_t reserved1; /* reserved (for offset or index) */ + uint32_t reserved2; /* reserved (for count or sizeof) */ +}; + +struct section_64 { /* for 64-bit architectures */ + char sectname[16]; /* name of this section */ + char segname[16]; /* segment this section goes in */ + uint64_t addr; /* memory address of this section */ + uint64_t size; /* size in bytes of this section */ + uint32_t offset; /* file offset of this section */ + uint32_t align; /* section alignment (power of 2) */ + uint32_t reloff; /* file offset of relocation entries */ + uint32_t nreloc; /* number of relocation entries */ + uint32_t flags; /* flags (section type and attributes)*/ + uint32_t reserved1; /* reserved (for offset or index) */ + uint32_t reserved2; /* reserved (for count or sizeof) */ + uint32_t reserved3; /* reserved */ +}; + +/* + * The flags field of a section structure is separated into two parts a section + * type and section attributes. The section types are mutually exclusive (it + * can only have one type) but the section attributes are not (it may have more + * than one attribute). + */ +#define SECTION_TYPE 0x000000ff /* 256 section types */ +#define SECTION_ATTRIBUTES 0xffffff00 /* 24 section attributes */ + +/* Constants for the type of a section */ +#define S_REGULAR 0x0 /* regular section */ +#define S_ZEROFILL 0x1 /* zero fill on demand section */ +#define S_CSTRING_LITERALS 0x2 /* section with only literal C strings*/ +#define S_4BYTE_LITERALS 0x3 /* section with only 4 byte literals */ +#define S_8BYTE_LITERALS 0x4 /* section with only 8 byte literals */ +#define S_LITERAL_POINTERS 0x5 /* section with only pointers to */ + /* literals */ +/* + * For the two types of symbol pointers sections and the symbol stubs section + * they have indirect symbol table entries. For each of the entries in the + * section the indirect symbol table entries, in corresponding order in the + * indirect symbol table, start at the index stored in the reserved1 field + * of the section structure. Since the indirect symbol table entries + * correspond to the entries in the section the number of indirect symbol table + * entries is inferred from the size of the section divided by the size of the + * entries in the section. For symbol pointers sections the size of the entries + * in the section is 4 bytes and for symbol stubs sections the byte size of the + * stubs is stored in the reserved2 field of the section structure. + */ +#define S_NON_LAZY_SYMBOL_POINTERS 0x6 /* section with only non-lazy + symbol pointers */ +#define S_LAZY_SYMBOL_POINTERS 0x7 /* section with only lazy symbol + pointers */ +#define S_SYMBOL_STUBS 0x8 /* section with only symbol + stubs, byte size of stub in + the reserved2 field */ +#define S_MOD_INIT_FUNC_POINTERS 0x9 /* section with only function + pointers for initialization*/ +#define S_MOD_TERM_FUNC_POINTERS 0xa /* section with only function + pointers for termination */ +#define S_COALESCED 0xb /* section contains symbols that + are to be coalesced */ +#define S_GB_ZEROFILL 0xc /* zero fill on demand section + (that can be larger than 4 + gigabytes) */ +#define S_INTERPOSING 0xd /* section with only pairs of + function pointers for + interposing */ +#define S_16BYTE_LITERALS 0xe /* section with only 16 byte + literals */ +#define S_DTRACE_DOF 0xf /* section contains + DTrace Object Format */ +#define S_LAZY_DYLIB_SYMBOL_POINTERS 0x10 /* section with only lazy + symbol pointers to lazy + loaded dylibs */ +/* + * Section types to support thread local variables + */ +#define S_THREAD_LOCAL_REGULAR 0x11 /* template of initial + values for TLVs */ +#define S_THREAD_LOCAL_ZEROFILL 0x12 /* template of initial + values for TLVs */ +#define S_THREAD_LOCAL_VARIABLES 0x13 /* TLV descriptors */ +#define S_THREAD_LOCAL_VARIABLE_POINTERS 0x14 /* pointers to TLV + descriptors */ +#define S_THREAD_LOCAL_INIT_FUNCTION_POINTERS 0x15 /* functions to call + to initialize TLV + values */ + +/* + * Constants for the section attributes part of the flags field of a section + * structure. + */ +#define SECTION_ATTRIBUTES_USR 0xff000000 /* User setable attributes */ +#define S_ATTR_PURE_INSTRUCTIONS 0x80000000 /* section contains only true + machine instructions */ +#define S_ATTR_NO_TOC 0x40000000 /* section contains coalesced + symbols that are not to be + in a ranlib table of + contents */ +#define S_ATTR_STRIP_STATIC_SYMS 0x20000000 /* ok to strip static symbols + in this section in files + with the MH_DYLDLINK flag */ +#define S_ATTR_NO_DEAD_STRIP 0x10000000 /* no dead stripping */ +#define S_ATTR_LIVE_SUPPORT 0x08000000 /* blocks are live if they + reference live blocks */ +#define S_ATTR_SELF_MODIFYING_CODE 0x04000000 /* Used with i386 code stubs + written on by dyld */ +/* + * If a segment contains any sections marked with S_ATTR_DEBUG then all + * sections in that segment must have this attribute. No section other than + * a section marked with this attribute may reference the contents of this + * section. A section with this attribute may contain no symbols and must have + * a section type S_REGULAR. The static linker will not copy section contents + * from sections with this attribute into its output file. These sections + * generally contain DWARF debugging info. + */ +#define S_ATTR_DEBUG 0x02000000 /* a debug section */ +#define SECTION_ATTRIBUTES_SYS 0x00ffff00 /* system setable attributes */ +#define S_ATTR_SOME_INSTRUCTIONS 0x00000400 /* section contains some + machine instructions */ +#define S_ATTR_EXT_RELOC 0x00000200 /* section has external + relocation entries */ +#define S_ATTR_LOC_RELOC 0x00000100 /* section has local + relocation entries */ + + +/* + * The names of segments and sections in them are mostly meaningless to the + * link-editor. But there are few things to support traditional UNIX + * executables that require the link-editor and assembler to use some names + * agreed upon by convention. + * + * The initial protection of the "__TEXT" segment has write protection turned + * off (not writeable). + * + * The link-editor will allocate common symbols at the end of the "__common" + * section in the "__DATA" segment. It will create the section and segment + * if needed. + */ + +/* The currently known segment names and the section names in those segments */ + +#define SEG_PAGEZERO "__PAGEZERO" /* the pagezero segment which has no */ + /* protections and catches NULL */ + /* references for MH_EXECUTE files */ + + +#define SEG_TEXT "__TEXT" /* the tradition UNIX text segment */ +#define SECT_TEXT "__text" /* the real text part of the text */ + /* section no headers, and no padding */ +#define SECT_FVMLIB_INIT0 "__fvmlib_init0" /* the fvmlib initialization */ + /* section */ +#define SECT_FVMLIB_INIT1 "__fvmlib_init1" /* the section following the */ + /* fvmlib initialization */ + /* section */ + +#define SEG_DATA "__DATA" /* the tradition UNIX data segment */ +#define SECT_DATA "__data" /* the real initialized data section */ + /* no padding, no bss overlap */ +#define SECT_BSS "__bss" /* the real uninitialized data section*/ + /* no padding */ +#define SECT_COMMON "__common" /* the section common symbols are */ + /* allocated in by the link editor */ + +#define SEG_OBJC "__OBJC" /* objective-C runtime segment */ +#define SECT_OBJC_SYMBOLS "__symbol_table" /* symbol table */ +#define SECT_OBJC_MODULES "__module_info" /* module information */ +#define SECT_OBJC_STRINGS "__selector_strs" /* string table */ +#define SECT_OBJC_REFS "__selector_refs" /* string table */ + +#define SEG_ICON "__ICON" /* the icon segment */ +#define SECT_ICON_HEADER "__header" /* the icon headers */ +#define SECT_ICON_TIFF "__tiff" /* the icons in tiff format */ + +#define SEG_LINKEDIT "__LINKEDIT" /* the segment containing all structs */ + /* created and maintained by the link */ + /* editor. Created with -seglinkedit */ + /* option to ld(1) for MH_EXECUTE and */ + /* FVMLIB file types only */ + +#define SEG_UNIXSTACK "__UNIXSTACK" /* the unix stack segment */ + +#define SEG_IMPORT "__IMPORT" /* the segment for the self (dyld) */ + /* modifing code stubs that has read, */ + /* write and execute permissions */ + +/* + * Fixed virtual memory shared libraries are identified by two things. The + * target pathname (the name of the library as found for execution), and the + * minor version number. The address of where the headers are loaded is in + * header_addr. (THIS IS OBSOLETE and no longer supported). + */ +struct fvmlib { + union lc_str name; /* library's target pathname */ + uint32_t minor_version; /* library's minor version number */ + uint32_t header_addr; /* library's header address */ +}; + +/* + * A fixed virtual shared library (filetype == MH_FVMLIB in the mach header) + * contains a fvmlib_command (cmd == LC_IDFVMLIB) to identify the library. + * An object that uses a fixed virtual shared library also contains a + * fvmlib_command (cmd == LC_LOADFVMLIB) for each library it uses. + * (THIS IS OBSOLETE and no longer supported). + */ +struct fvmlib_command { + uint32_t cmd; /* LC_IDFVMLIB or LC_LOADFVMLIB */ + uint32_t cmdsize; /* includes pathname string */ + struct fvmlib fvmlib; /* the library identification */ +}; + +/* + * Dynamicly linked shared libraries are identified by two things. The + * pathname (the name of the library as found for execution), and the + * compatibility version number. The pathname must match and the compatibility + * number in the user of the library must be greater than or equal to the + * library being used. The time stamp is used to record the time a library was + * built and copied into user so it can be use to determined if the library used + * at runtime is exactly the same as used to built the program. + */ +struct dylib { + union lc_str name; /* library's path name */ + uint32_t timestamp; /* library's build time stamp */ + uint32_t current_version; /* library's current version number */ + uint32_t compatibility_version; /* library's compatibility vers number*/ +}; + +/* + * A dynamically linked shared library (filetype == MH_DYLIB in the mach header) + * contains a dylib_command (cmd == LC_ID_DYLIB) to identify the library. + * An object that uses a dynamically linked shared library also contains a + * dylib_command (cmd == LC_LOAD_DYLIB, LC_LOAD_WEAK_DYLIB, or + * LC_REEXPORT_DYLIB) for each library it uses. + */ +struct dylib_command { + uint32_t cmd; /* LC_ID_DYLIB, LC_LOAD_{,WEAK_}DYLIB, + LC_REEXPORT_DYLIB */ + uint32_t cmdsize; /* includes pathname string */ + struct dylib dylib; /* the library identification */ +}; + +/* + * A dynamically linked shared library may be a subframework of an umbrella + * framework. If so it will be linked with "-umbrella umbrella_name" where + * Where "umbrella_name" is the name of the umbrella framework. A subframework + * can only be linked against by its umbrella framework or other subframeworks + * that are part of the same umbrella framework. Otherwise the static link + * editor produces an error and states to link against the umbrella framework. + * The name of the umbrella framework for subframeworks is recorded in the + * following structure. + */ +struct sub_framework_command { + uint32_t cmd; /* LC_SUB_FRAMEWORK */ + uint32_t cmdsize; /* includes umbrella string */ + union lc_str umbrella; /* the umbrella framework name */ +}; + +/* + * For dynamically linked shared libraries that are subframework of an umbrella + * framework they can allow clients other than the umbrella framework or other + * subframeworks in the same umbrella framework. To do this the subframework + * is built with "-allowable_client client_name" and an LC_SUB_CLIENT load + * command is created for each -allowable_client flag. The client_name is + * usually a framework name. It can also be a name used for bundles clients + * where the bundle is built with "-client_name client_name". + */ +struct sub_client_command { + uint32_t cmd; /* LC_SUB_CLIENT */ + uint32_t cmdsize; /* includes client string */ + union lc_str client; /* the client name */ +}; + +/* + * A dynamically linked shared library may be a sub_umbrella of an umbrella + * framework. If so it will be linked with "-sub_umbrella umbrella_name" where + * Where "umbrella_name" is the name of the sub_umbrella framework. When + * staticly linking when -twolevel_namespace is in effect a twolevel namespace + * umbrella framework will only cause its subframeworks and those frameworks + * listed as sub_umbrella frameworks to be implicited linked in. Any other + * dependent dynamic libraries will not be linked it when -twolevel_namespace + * is in effect. The primary library recorded by the static linker when + * resolving a symbol in these libraries will be the umbrella framework. + * Zero or more sub_umbrella frameworks may be use by an umbrella framework. + * The name of a sub_umbrella framework is recorded in the following structure. + */ +struct sub_umbrella_command { + uint32_t cmd; /* LC_SUB_UMBRELLA */ + uint32_t cmdsize; /* includes sub_umbrella string */ + union lc_str sub_umbrella; /* the sub_umbrella framework name */ +}; + +/* + * A dynamically linked shared library may be a sub_library of another shared + * library. If so it will be linked with "-sub_library library_name" where + * Where "library_name" is the name of the sub_library shared library. When + * staticly linking when -twolevel_namespace is in effect a twolevel namespace + * shared library will only cause its subframeworks and those frameworks + * listed as sub_umbrella frameworks and libraries listed as sub_libraries to + * be implicited linked in. Any other dependent dynamic libraries will not be + * linked it when -twolevel_namespace is in effect. The primary library + * recorded by the static linker when resolving a symbol in these libraries + * will be the umbrella framework (or dynamic library). Zero or more sub_library + * shared libraries may be use by an umbrella framework or (or dynamic library). + * The name of a sub_library framework is recorded in the following structure. + * For example /usr/lib/libobjc_profile.A.dylib would be recorded as "libobjc". + */ +struct sub_library_command { + uint32_t cmd; /* LC_SUB_LIBRARY */ + uint32_t cmdsize; /* includes sub_library string */ + union lc_str sub_library; /* the sub_library name */ +}; + +/* + * A program (filetype == MH_EXECUTE) that is + * prebound to its dynamic libraries has one of these for each library that + * the static linker used in prebinding. It contains a bit vector for the + * modules in the library. The bits indicate which modules are bound (1) and + * which are not (0) from the library. The bit for module 0 is the low bit + * of the first byte. So the bit for the Nth module is: + * (linked_modules[N/8] >> N%8) & 1 + */ +struct prebound_dylib_command { + uint32_t cmd; /* LC_PREBOUND_DYLIB */ + uint32_t cmdsize; /* includes strings */ + union lc_str name; /* library's path name */ + uint32_t nmodules; /* number of modules in library */ + union lc_str linked_modules; /* bit vector of linked modules */ +}; + +/* + * A program that uses a dynamic linker contains a dylinker_command to identify + * the name of the dynamic linker (LC_LOAD_DYLINKER). And a dynamic linker + * contains a dylinker_command to identify the dynamic linker (LC_ID_DYLINKER). + * A file can have at most one of these. + * This struct is also used for the LC_DYLD_ENVIRONMENT load command and + * contains string for dyld to treat like environment variable. + */ +struct dylinker_command { + uint32_t cmd; /* LC_ID_DYLINKER, LC_LOAD_DYLINKER or + LC_DYLD_ENVIRONMENT */ + uint32_t cmdsize; /* includes pathname string */ + union lc_str name; /* dynamic linker's path name */ +}; + +/* + * Thread commands contain machine-specific data structures suitable for + * use in the thread state primitives. The machine specific data structures + * follow the struct thread_command as follows. + * Each flavor of machine specific data structure is preceded by an unsigned + * long constant for the flavor of that data structure, an uint32_t + * that is the count of longs of the size of the state data structure and then + * the state data structure follows. This triple may be repeated for many + * flavors. The constants for the flavors, counts and state data structure + * definitions are expected to be in the header file <machine/thread_status.h>. + * These machine specific data structures sizes must be multiples of + * 4 bytes The cmdsize reflects the total size of the thread_command + * and all of the sizes of the constants for the flavors, counts and state + * data structures. + * + * For executable objects that are unix processes there will be one + * thread_command (cmd == LC_UNIXTHREAD) created for it by the link-editor. + * This is the same as a LC_THREAD, except that a stack is automatically + * created (based on the shell's limit for the stack size). Command arguments + * and environment variables are copied onto that stack. + */ +struct thread_command { + uint32_t cmd; /* LC_THREAD or LC_UNIXTHREAD */ + uint32_t cmdsize; /* total size of this command */ + /* uint32_t flavor flavor of thread state */ + /* uint32_t count count of longs in thread state */ + /* struct XXX_thread_state state thread state for this flavor */ + /* ... */ +}; + +/* + * The routines command contains the address of the dynamic shared library + * initialization routine and an index into the module table for the module + * that defines the routine. Before any modules are used from the library the + * dynamic linker fully binds the module that defines the initialization routine + * and then calls it. This gets called before any module initialization + * routines (used for C++ static constructors) in the library. + */ +struct routines_command { /* for 32-bit architectures */ + uint32_t cmd; /* LC_ROUTINES */ + uint32_t cmdsize; /* total size of this command */ + uint32_t init_address; /* address of initialization routine */ + uint32_t init_module; /* index into the module table that */ + /* the init routine is defined in */ + uint32_t reserved1; + uint32_t reserved2; + uint32_t reserved3; + uint32_t reserved4; + uint32_t reserved5; + uint32_t reserved6; +}; + +/* + * The 64-bit routines command. Same use as above. + */ +struct routines_command_64 { /* for 64-bit architectures */ + uint32_t cmd; /* LC_ROUTINES_64 */ + uint32_t cmdsize; /* total size of this command */ + uint64_t init_address; /* address of initialization routine */ + uint64_t init_module; /* index into the module table that */ + /* the init routine is defined in */ + uint64_t reserved1; + uint64_t reserved2; + uint64_t reserved3; + uint64_t reserved4; + uint64_t reserved5; + uint64_t reserved6; +}; + +/* + * The symtab_command contains the offsets and sizes of the link-edit 4.3BSD + * "stab" style symbol table information as described in the header files + * <nlist.h> and <stab.h>. + */ +struct symtab_command { + uint32_t cmd; /* LC_SYMTAB */ + uint32_t cmdsize; /* sizeof(struct symtab_command) */ + uint32_t symoff; /* symbol table offset */ + uint32_t nsyms; /* number of symbol table entries */ + uint32_t stroff; /* string table offset */ + uint32_t strsize; /* string table size in bytes */ +}; + +/* + * This is the second set of the symbolic information which is used to support + * the data structures for the dynamically link editor. + * + * The original set of symbolic information in the symtab_command which contains + * the symbol and string tables must also be present when this load command is + * present. When this load command is present the symbol table is organized + * into three groups of symbols: + * local symbols (static and debugging symbols) - grouped by module + * defined external symbols - grouped by module (sorted by name if not lib) + * undefined external symbols (sorted by name if MH_BINDATLOAD is not set, + * and in order the were seen by the static + * linker if MH_BINDATLOAD is set) + * In this load command there are offsets and counts to each of the three groups + * of symbols. + * + * This load command contains a the offsets and sizes of the following new + * symbolic information tables: + * table of contents + * module table + * reference symbol table + * indirect symbol table + * The first three tables above (the table of contents, module table and + * reference symbol table) are only present if the file is a dynamically linked + * shared library. For executable and object modules, which are files + * containing only one module, the information that would be in these three + * tables is determined as follows: + * table of contents - the defined external symbols are sorted by name + * module table - the file contains only one module so everything in the + * file is part of the module. + * reference symbol table - is the defined and undefined external symbols + * + * For dynamically linked shared library files this load command also contains + * offsets and sizes to the pool of relocation entries for all sections + * separated into two groups: + * external relocation entries + * local relocation entries + * For executable and object modules the relocation entries continue to hang + * off the section structures. + */ +struct dysymtab_command { + uint32_t cmd; /* LC_DYSYMTAB */ + uint32_t cmdsize; /* sizeof(struct dysymtab_command) */ + + /* + * The symbols indicated by symoff and nsyms of the LC_SYMTAB load command + * are grouped into the following three groups: + * local symbols (further grouped by the module they are from) + * defined external symbols (further grouped by the module they are from) + * undefined symbols + * + * The local symbols are used only for debugging. The dynamic binding + * process may have to use them to indicate to the debugger the local + * symbols for a module that is being bound. + * + * The last two groups are used by the dynamic binding process to do the + * binding (indirectly through the module table and the reference symbol + * table when this is a dynamically linked shared library file). + */ + uint32_t ilocalsym; /* index to local symbols */ + uint32_t nlocalsym; /* number of local symbols */ + + uint32_t iextdefsym;/* index to externally defined symbols */ + uint32_t nextdefsym;/* number of externally defined symbols */ + + uint32_t iundefsym; /* index to undefined symbols */ + uint32_t nundefsym; /* number of undefined symbols */ + + /* + * For the for the dynamic binding process to find which module a symbol + * is defined in the table of contents is used (analogous to the ranlib + * structure in an archive) which maps defined external symbols to modules + * they are defined in. This exists only in a dynamically linked shared + * library file. For executable and object modules the defined external + * symbols are sorted by name and is use as the table of contents. + */ + uint32_t tocoff; /* file offset to table of contents */ + uint32_t ntoc; /* number of entries in table of contents */ + + /* + * To support dynamic binding of "modules" (whole object files) the symbol + * table must reflect the modules that the file was created from. This is + * done by having a module table that has indexes and counts into the merged + * tables for each module. The module structure that these two entries + * refer to is described below. This exists only in a dynamically linked + * shared library file. For executable and object modules the file only + * contains one module so everything in the file belongs to the module. + */ + uint32_t modtaboff; /* file offset to module table */ + uint32_t nmodtab; /* number of module table entries */ + + /* + * To support dynamic module binding the module structure for each module + * indicates the external references (defined and undefined) each module + * makes. For each module there is an offset and a count into the + * reference symbol table for the symbols that the module references. + * This exists only in a dynamically linked shared library file. For + * executable and object modules the defined external symbols and the + * undefined external symbols indicates the external references. + */ + uint32_t extrefsymoff; /* offset to referenced symbol table */ + uint32_t nextrefsyms; /* number of referenced symbol table entries */ + + /* + * The sections that contain "symbol pointers" and "routine stubs" have + * indexes and (implied counts based on the size of the section and fixed + * size of the entry) into the "indirect symbol" table for each pointer + * and stub. For every section of these two types the index into the + * indirect symbol table is stored in the section header in the field + * reserved1. An indirect symbol table entry is simply a 32bit index into + * the symbol table to the symbol that the pointer or stub is referring to. + * The indirect symbol table is ordered to match the entries in the section. + */ + uint32_t indirectsymoff; /* file offset to the indirect symbol table */ + uint32_t nindirectsyms; /* number of indirect symbol table entries */ + + /* + * To support relocating an individual module in a library file quickly the + * external relocation entries for each module in the library need to be + * accessed efficiently. Since the relocation entries can't be accessed + * through the section headers for a library file they are separated into + * groups of local and external entries further grouped by module. In this + * case the presents of this load command who's extreloff, nextrel, + * locreloff and nlocrel fields are non-zero indicates that the relocation + * entries of non-merged sections are not referenced through the section + * structures (and the reloff and nreloc fields in the section headers are + * set to zero). + * + * Since the relocation entries are not accessed through the section headers + * this requires the r_address field to be something other than a section + * offset to identify the item to be relocated. In this case r_address is + * set to the offset from the vmaddr of the first LC_SEGMENT command. + * For MH_SPLIT_SEGS images r_address is set to the the offset from the + * vmaddr of the first read-write LC_SEGMENT command. + * + * The relocation entries are grouped by module and the module table + * entries have indexes and counts into them for the group of external + * relocation entries for that the module. + * + * For sections that are merged across modules there must not be any + * remaining external relocation entries for them (for merged sections + * remaining relocation entries must be local). + */ + uint32_t extreloff; /* offset to external relocation entries */ + uint32_t nextrel; /* number of external relocation entries */ + + /* + * All the local relocation entries are grouped together (they are not + * grouped by their module since they are only used if the object is moved + * from it staticly link edited address). + */ + uint32_t locreloff; /* offset to local relocation entries */ + uint32_t nlocrel; /* number of local relocation entries */ + +}; + +/* + * An indirect symbol table entry is simply a 32bit index into the symbol table + * to the symbol that the pointer or stub is refering to. Unless it is for a + * non-lazy symbol pointer section for a defined symbol which strip(1) as + * removed. In which case it has the value INDIRECT_SYMBOL_LOCAL. If the + * symbol was also absolute INDIRECT_SYMBOL_ABS is or'ed with that. + */ +#define INDIRECT_SYMBOL_LOCAL 0x80000000 +#define INDIRECT_SYMBOL_ABS 0x40000000 + + +/* a table of contents entry */ +struct dylib_table_of_contents { + uint32_t symbol_index; /* the defined external symbol + (index into the symbol table) */ + uint32_t module_index; /* index into the module table this symbol + is defined in */ +}; + +/* a module table entry */ +struct dylib_module { + uint32_t module_name; /* the module name (index into string table) */ + + uint32_t iextdefsym; /* index into externally defined symbols */ + uint32_t nextdefsym; /* number of externally defined symbols */ + uint32_t irefsym; /* index into reference symbol table */ + uint32_t nrefsym; /* number of reference symbol table entries */ + uint32_t ilocalsym; /* index into symbols for local symbols */ + uint32_t nlocalsym; /* number of local symbols */ + + uint32_t iextrel; /* index into external relocation entries */ + uint32_t nextrel; /* number of external relocation entries */ + + uint32_t iinit_iterm; /* low 16 bits are the index into the init + section, high 16 bits are the index into + the term section */ + uint32_t ninit_nterm; /* low 16 bits are the number of init section + entries, high 16 bits are the number of + term section entries */ + + uint32_t /* for this module address of the start of */ + objc_module_info_addr; /* the (__OBJC,__module_info) section */ + uint32_t /* for this module size of */ + objc_module_info_size; /* the (__OBJC,__module_info) section */ +}; + +/* a 64-bit module table entry */ +struct dylib_module_64 { + uint32_t module_name; /* the module name (index into string table) */ + + uint32_t iextdefsym; /* index into externally defined symbols */ + uint32_t nextdefsym; /* number of externally defined symbols */ + uint32_t irefsym; /* index into reference symbol table */ + uint32_t nrefsym; /* number of reference symbol table entries */ + uint32_t ilocalsym; /* index into symbols for local symbols */ + uint32_t nlocalsym; /* number of local symbols */ + + uint32_t iextrel; /* index into external relocation entries */ + uint32_t nextrel; /* number of external relocation entries */ + + uint32_t iinit_iterm; /* low 16 bits are the index into the init + section, high 16 bits are the index into + the term section */ + uint32_t ninit_nterm; /* low 16 bits are the number of init section + entries, high 16 bits are the number of + term section entries */ + + uint32_t /* for this module size of */ + objc_module_info_size; /* the (__OBJC,__module_info) section */ + uint64_t /* for this module address of the start of */ + objc_module_info_addr; /* the (__OBJC,__module_info) section */ +}; + +/* + * The entries in the reference symbol table are used when loading the module + * (both by the static and dynamic link editors) and if the module is unloaded + * or replaced. Therefore all external symbols (defined and undefined) are + * listed in the module's reference table. The flags describe the type of + * reference that is being made. The constants for the flags are defined in + * <mach-o/nlist.h> as they are also used for symbol table entries. + */ +struct dylib_reference { + uint32_t isym:24, /* index into the symbol table */ + flags:8; /* flags to indicate the type of reference */ +}; + +/* + * The twolevel_hints_command contains the offset and number of hints in the + * two-level namespace lookup hints table. + */ +struct twolevel_hints_command { + uint32_t cmd; /* LC_TWOLEVEL_HINTS */ + uint32_t cmdsize; /* sizeof(struct twolevel_hints_command) */ + uint32_t offset; /* offset to the hint table */ + uint32_t nhints; /* number of hints in the hint table */ +}; + +/* + * The entries in the two-level namespace lookup hints table are twolevel_hint + * structs. These provide hints to the dynamic link editor where to start + * looking for an undefined symbol in a two-level namespace image. The + * isub_image field is an index into the sub-images (sub-frameworks and + * sub-umbrellas list) that made up the two-level image that the undefined + * symbol was found in when it was built by the static link editor. If + * isub-image is 0 the the symbol is expected to be defined in library and not + * in the sub-images. If isub-image is non-zero it is an index into the array + * of sub-images for the umbrella with the first index in the sub-images being + * 1. The array of sub-images is the ordered list of sub-images of the umbrella + * that would be searched for a symbol that has the umbrella recorded as its + * primary library. The table of contents index is an index into the + * library's table of contents. This is used as the starting point of the + * binary search or a directed linear search. + */ +struct twolevel_hint { + uint32_t + isub_image:8, /* index into the sub images */ + itoc:24; /* index into the table of contents */ +}; + +/* + * The prebind_cksum_command contains the value of the original check sum for + * prebound files or zero. When a prebound file is first created or modified + * for other than updating its prebinding information the value of the check sum + * is set to zero. When the file has it prebinding re-done and if the value of + * the check sum is zero the original check sum is calculated and stored in + * cksum field of this load command in the output file. If when the prebinding + * is re-done and the cksum field is non-zero it is left unchanged from the + * input file. + */ +struct prebind_cksum_command { + uint32_t cmd; /* LC_PREBIND_CKSUM */ + uint32_t cmdsize; /* sizeof(struct prebind_cksum_command) */ + uint32_t cksum; /* the check sum or zero */ +}; + +/* + * The uuid load command contains a single 128-bit unique random number that + * identifies an object produced by the static link editor. + */ +struct uuid_command { + uint32_t cmd; /* LC_UUID */ + uint32_t cmdsize; /* sizeof(struct uuid_command) */ + uint8_t uuid[16]; /* the 128-bit uuid */ +}; + +/* + * The rpath_command contains a path which at runtime should be added to + * the current run path used to find @rpath prefixed dylibs. + */ +struct rpath_command { + uint32_t cmd; /* LC_RPATH */ + uint32_t cmdsize; /* includes string */ + union lc_str path; /* path to add to run path */ +}; + +/* + * The linkedit_data_command contains the offsets and sizes of a blob + * of data in the __LINKEDIT segment. + */ +struct linkedit_data_command { + uint32_t cmd; /* LC_CODE_SIGNATURE, LC_SEGMENT_SPLIT_INFO, + or LC_FUNCTION_STARTS */ + uint32_t cmdsize; /* sizeof(struct linkedit_data_command) */ + uint32_t dataoff; /* file offset of data in __LINKEDIT segment */ + uint32_t datasize; /* file size of data in __LINKEDIT segment */ +}; + +/* + * The encryption_info_command contains the file offset and size of an + * of an encrypted segment. + */ +struct encryption_info_command { + uint32_t cmd; /* LC_ENCRYPTION_INFO */ + uint32_t cmdsize; /* sizeof(struct encryption_info_command) */ + uint32_t cryptoff; /* file offset of encrypted range */ + uint32_t cryptsize; /* file size of encrypted range */ + uint32_t cryptid; /* which enryption system, + 0 means not-encrypted yet */ +}; + +/* + * The version_min_command contains the min OS version on which this + * binary was built to run. + */ +struct version_min_command { + uint32_t cmd; /* LC_VERSION_MIN_MACOSX or + LC_VERSION_MIN_IPHONEOS */ + uint32_t cmdsize; /* sizeof(struct min_version_command) */ + uint32_t version; /* X.Y.Z is encoded in nibbles xxxx.yy.zz */ + uint32_t reserved; /* zero */ +}; + +/* + * The dyld_info_command contains the file offsets and sizes of + * the new compressed form of the information dyld needs to + * load the image. This information is used by dyld on Mac OS X + * 10.6 and later. All information pointed to by this command + * is encoded using byte streams, so no endian swapping is needed + * to interpret it. + */ +struct dyld_info_command { + uint32_t cmd; /* LC_DYLD_INFO or LC_DYLD_INFO_ONLY */ + uint32_t cmdsize; /* sizeof(struct dyld_info_command) */ + + /* + * Dyld rebases an image whenever dyld loads it at an address different + * from its preferred address. The rebase information is a stream + * of byte sized opcodes whose symbolic names start with REBASE_OPCODE_. + * Conceptually the rebase information is a table of tuples: + * <seg-index, seg-offset, type> + * The opcodes are a compressed way to encode the table by only + * encoding when a column changes. In addition simple patterns + * like "every n'th offset for m times" can be encoded in a few + * bytes. + */ + uint32_t rebase_off; /* file offset to rebase info */ + uint32_t rebase_size; /* size of rebase info */ + + /* + * Dyld binds an image during the loading process, if the image + * requires any pointers to be initialized to symbols in other images. + * The bind information is a stream of byte sized + * opcodes whose symbolic names start with BIND_OPCODE_. + * Conceptually the bind information is a table of tuples: + * <seg-index, seg-offset, type, symbol-library-ordinal, symbol-name, addend> + * The opcodes are a compressed way to encode the table by only + * encoding when a column changes. In addition simple patterns + * like for runs of pointers initialzed to the same value can be + * encoded in a few bytes. + */ + uint32_t bind_off; /* file offset to binding info */ + uint32_t bind_size; /* size of binding info */ + + /* + * Some C++ programs require dyld to unique symbols so that all + * images in the process use the same copy of some code/data. + * This step is done after binding. The content of the weak_bind + * info is an opcode stream like the bind_info. But it is sorted + * alphabetically by symbol name. This enable dyld to walk + * all images with weak binding information in order and look + * for collisions. If there are no collisions, dyld does + * no updating. That means that some fixups are also encoded + * in the bind_info. For instance, all calls to "operator new" + * are first bound to libstdc++.dylib using the information + * in bind_info. Then if some image overrides operator new + * that is detected when the weak_bind information is processed + * and the call to operator new is then rebound. + */ + uint32_t weak_bind_off; /* file offset to weak binding info */ + uint32_t weak_bind_size; /* size of weak binding info */ + + /* + * Some uses of external symbols do not need to be bound immediately. + * Instead they can be lazily bound on first use. The lazy_bind + * are contains a stream of BIND opcodes to bind all lazy symbols. + * Normal use is that dyld ignores the lazy_bind section when + * loading an image. Instead the static linker arranged for the + * lazy pointer to initially point to a helper function which + * pushes the offset into the lazy_bind area for the symbol + * needing to be bound, then jumps to dyld which simply adds + * the offset to lazy_bind_off to get the information on what + * to bind. + */ + uint32_t lazy_bind_off; /* file offset to lazy binding info */ + uint32_t lazy_bind_size; /* size of lazy binding infs */ + + /* + * The symbols exported by a dylib are encoded in a trie. This + * is a compact representation that factors out common prefixes. + * It also reduces LINKEDIT pages in RAM because it encodes all + * information (name, address, flags) in one small, contiguous range. + * The export area is a stream of nodes. The first node sequentially + * is the start node for the trie. + * + * Nodes for a symbol start with a uleb128 that is the length of + * the exported symbol information for the string so far. + * If there is no exported symbol, the node starts with a zero byte. + * If there is exported info, it follows the length. First is + * a uleb128 containing flags. Normally, it is followed by a + * uleb128 encoded offset which is location of the content named + * by the symbol from the mach_header for the image. If the flags + * is EXPORT_SYMBOL_FLAGS_REEXPORT, then following the flags is + * a uleb128 encoded library ordinal, then a zero terminated + * UTF8 string. If the string is zero length, then the symbol + * is re-export from the specified dylib with the same name. + * + * After the optional exported symbol information is a byte of + * how many edges (0-255) that this node has leaving it, + * followed by each edge. + * Each edge is a zero terminated UTF8 of the addition chars + * in the symbol, followed by a uleb128 offset for the node that + * edge points to. + * + */ + uint32_t export_off; /* file offset to lazy binding info */ + uint32_t export_size; /* size of lazy binding infs */ +}; + +/* + * The following are used to encode rebasing information + */ +#define REBASE_TYPE_POINTER 1 +#define REBASE_TYPE_TEXT_ABSOLUTE32 2 +#define REBASE_TYPE_TEXT_PCREL32 3 + +#define REBASE_OPCODE_MASK 0xF0 +#define REBASE_IMMEDIATE_MASK 0x0F +#define REBASE_OPCODE_DONE 0x00 +#define REBASE_OPCODE_SET_TYPE_IMM 0x10 +#define REBASE_OPCODE_SET_SEGMENT_AND_OFFSET_ULEB 0x20 +#define REBASE_OPCODE_ADD_ADDR_ULEB 0x30 +#define REBASE_OPCODE_ADD_ADDR_IMM_SCALED 0x40 +#define REBASE_OPCODE_DO_REBASE_IMM_TIMES 0x50 +#define REBASE_OPCODE_DO_REBASE_ULEB_TIMES 0x60 +#define REBASE_OPCODE_DO_REBASE_ADD_ADDR_ULEB 0x70 +#define REBASE_OPCODE_DO_REBASE_ULEB_TIMES_SKIPPING_ULEB 0x80 + + +/* + * The following are used to encode binding information + */ +#define BIND_TYPE_POINTER 1 +#define BIND_TYPE_TEXT_ABSOLUTE32 2 +#define BIND_TYPE_TEXT_PCREL32 3 + +#define BIND_SPECIAL_DYLIB_SELF 0 +#define BIND_SPECIAL_DYLIB_MAIN_EXECUTABLE -1 +#define BIND_SPECIAL_DYLIB_FLAT_LOOKUP -2 + +#define BIND_SYMBOL_FLAGS_WEAK_IMPORT 0x1 +#define BIND_SYMBOL_FLAGS_NON_WEAK_DEFINITION 0x8 + +#define BIND_OPCODE_MASK 0xF0 +#define BIND_IMMEDIATE_MASK 0x0F +#define BIND_OPCODE_DONE 0x00 +#define BIND_OPCODE_SET_DYLIB_ORDINAL_IMM 0x10 +#define BIND_OPCODE_SET_DYLIB_ORDINAL_ULEB 0x20 +#define BIND_OPCODE_SET_DYLIB_SPECIAL_IMM 0x30 +#define BIND_OPCODE_SET_SYMBOL_TRAILING_FLAGS_IMM 0x40 +#define BIND_OPCODE_SET_TYPE_IMM 0x50 +#define BIND_OPCODE_SET_ADDEND_SLEB 0x60 +#define BIND_OPCODE_SET_SEGMENT_AND_OFFSET_ULEB 0x70 +#define BIND_OPCODE_ADD_ADDR_ULEB 0x80 +#define BIND_OPCODE_DO_BIND 0x90 +#define BIND_OPCODE_DO_BIND_ADD_ADDR_ULEB 0xA0 +#define BIND_OPCODE_DO_BIND_ADD_ADDR_IMM_SCALED 0xB0 +#define BIND_OPCODE_DO_BIND_ULEB_TIMES_SKIPPING_ULEB 0xC0 + + +/* + * The following are used on the flags byte of a terminal node + * in the export information. + */ +#define EXPORT_SYMBOL_FLAGS_KIND_MASK 0x03 +#define EXPORT_SYMBOL_FLAGS_KIND_REGULAR 0x00 +#define EXPORT_SYMBOL_FLAGS_KIND_THREAD_LOCAL 0x01 +#define EXPORT_SYMBOL_FLAGS_WEAK_DEFINITION 0x04 +#define EXPORT_SYMBOL_FLAGS_REEXPORT 0x08 +#define EXPORT_SYMBOL_FLAGS_STUB_AND_RESOLVER 0x10 + +/* + * The symseg_command contains the offset and size of the GNU style + * symbol table information as described in the header file <symseg.h>. + * The symbol roots of the symbol segments must also be aligned properly + * in the file. So the requirement of keeping the offsets aligned to a + * multiple of a 4 bytes translates to the length field of the symbol + * roots also being a multiple of a long. Also the padding must again be + * zeroed. (THIS IS OBSOLETE and no longer supported). + */ +struct symseg_command { + uint32_t cmd; /* LC_SYMSEG */ + uint32_t cmdsize; /* sizeof(struct symseg_command) */ + uint32_t offset; /* symbol segment offset */ + uint32_t size; /* symbol segment size in bytes */ +}; + +/* + * The ident_command contains a free format string table following the + * ident_command structure. The strings are null terminated and the size of + * the command is padded out with zero bytes to a multiple of 4 bytes/ + * (THIS IS OBSOLETE and no longer supported). + */ +struct ident_command { + uint32_t cmd; /* LC_IDENT */ + uint32_t cmdsize; /* strings that follow this command */ +}; + +/* + * The fvmfile_command contains a reference to a file to be loaded at the + * specified virtual address. (Presently, this command is reserved for + * internal use. The kernel ignores this command when loading a program into + * memory). + */ +struct fvmfile_command { + uint32_t cmd; /* LC_FVMFILE */ + uint32_t cmdsize; /* includes pathname string */ + union lc_str name; /* files pathname */ + uint32_t header_addr; /* files virtual address */ +}; + +/* + * Sections of type S_THREAD_LOCAL_VARIABLES contain an array + * of tlv_descriptor structures. + */ +struct tlv_descriptor +{ + void* (*thunk)(struct tlv_descriptor*); + unsigned long key; + unsigned long offset; +}; + +#endif /* _MACHO_LOADER_H_ */ |