/* This is a cut-down version of loader.h from cctools-895,
shrunk to eliminate aspects unwanted in libdwarf and to avoid
#include entirely. All tab characters replaced with 4 spaces
so various things no line up as they used to.
Comment reformatting for line length may have left
some original comments hard to follow.
cctools-895 in its original form
is available from https://opensource.apple.com/
see Developer Tools version 8.2.1. cctools-895/include/loader.h
and cctools-1009.3/cctools/include/mach-o/loader.h */
/*
* 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
#ifdef __cplusplus
extern "C" {
#endif /* __cplusplus */
#if 0 /* Not used here. DavidA. September 2018 */
#include changed to #xnclude so casual readers will not
be confused.
/*
* This file describes the format of mach object files.
*/
#xnclude <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.
*/
#xnclude <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.
*/
#xnclude <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.
*/
#xnclude <mach/machine/thread_status.h>
#xnclude <architecture/byte_order.h>
#endif /* 0 */
#ifndef TYP
#define TYP(n,l) char (n)[(l)]
#endif /* TYP */
/* This is Apple internal naming for Universal Binaries
and is not 'Inclusive Terminology" !! */
#define FAT_MAGIC 0xcafebabe
#define FAT_CIGAM 0xbebafeca
#define FAT_MAGIC_64 0xcafebabf
#define FAT_CIGAM_64 0xbfbafeca
struct fat_header {
TYP(magic,4); /* FAT_MAGIC or FAT_MAGIC_64 */
TYP(nfat_arch,4); /* number of structs that follow */
};
struct fat_arch {
TYP(cputype ,4); /* cpu specifier (int) */
TYP(cpusubtype,4); /* machine specifier (int) */
TYP(offset,4); /* file offset to this object file */
TYP(size,4); /* size of this object file */
TYP(align,4); /* alignment as a power of 2 */
};
struct fat_arch_64 {
TYP(cputype,4); /* cpu specifier (int) */
TYP(cpusubtype,4); /* machine specifier (int) */
TYP(offset,8); /* file offset to this object file */
TYP(size,8); /* size of this object file */
TYP(align,4); /* alignment as a power of 2 */
TYP(reserved,4); /* reserved */
};
/*
* The 32-bit mach header appears at the very
* beginning of the object file for
* 32-bit architectures.
*/
struct mach_header {
TYP(magic,4); /* mach magic number identifier */
TYP(cputype,4); /* cpu specifier */
TYP(cpusubtype,4); /* machine specifier */
TYP(filetype,4); /* type of file */
TYP(ncmds,4); /* number of load commands */
TYP(sizeofcmds,4); /* the size of all the load commands */
TYP(flags,4); /* flags */
};
/* Constant for the magic field of the
mach_header (32-bit architectures)
MH_MAGIC MH_MAGIC_64 appear in big-endian objects
MH_CIGAM MH_CIGAM_64 appear in little-endian objects */
#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 {
TYP(magic,4); /* mach magic number identifier */
TYP(cputype,4); /* cpu specifier */
TYP(cpusubtype,4); /* machine specifier */
TYP(filetype,4); /* type of file */
TYP(ncmds,4); /* number of load commands */
TYP(sizeofcmds,4); /* the size of all the load commands */
TYP(flags,4); /* flags */
TYP(reserved,4); /* 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 paging.
* 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
* in any 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
definitions 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. */
#define MH_APP_EXTENSION_SAFE 0x02000000
/* The code was linked for use in an
application extension. */
/*
* 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 {
TYP(cmd,4); /* type of load command */
TYP(cmdsize,4); /* 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 */
#define LC_MAIN (0x28|LC_REQ_DYLD)
/* replacement for LC_UNIXTHREAD */
#define LC_DATA_IN_CODE 0x29
/* table of non-instructions in __text */
#define LC_SOURCE_VERSION 0x2A
/* source version used to build binary */
#define LC_DYLIB_CODE_SIGN_DRS 0x2B
/* Code signing DRs copied from linked dylibs */
#define LC_ENCRYPTION_INFO_64 0x2C
/* 64-bit encrypted segment information */
#define LC_LINKER_OPTION 0x2D
/* linker options in MH_OBJECT files */
#define LC_LINKER_OPTIMIZATION_HINT 0x2E
/* optimization hints in MH_OBJECT files */
#define LC_VERSION_MIN_TVOS 0x2F
/* build for AppleTV min OS version */
#define LC_VERSION_MIN_WATCHOS 0x30
/* build for Watch min OS version */
#define LC_NOTE 0x31
/* arbitrary data included within a Mach-O file */
#define LC_BUILD_VERSION 0x32
/* build for platform min OS version */
#define LC_DYLD_EXPORTS_TRIE (0x33 | LC_REQ_DYLD)
/* used with linkedit_data_command, payload is trie */
#define LC_DYLD_CHAINED_FIXUPS (0x34 | LC_REQ_DYLD)
/* used with linkedit_data_command */
#define LC_FILESET_ENTRY (0x35 | LC_REQ_DYLD)
/* used with fileset_entry_command */
#define LC_ATOM_INFO 0x36
/* used with linkedit_data_command */
/*
* 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 {
TYP(offset,4); /* 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 */
TYP(cmd,4); /* LC_SEGMENT */
TYP(cmdsize,4); /* includes sizeof section structs */
char segname[16]; /* segment name */
TYP(vmaddr,4); /* memory address of this segment */
TYP(vmsize,4); /* memory size of this segment */
TYP(fileoff,4); /* file offset of this segment */
TYP(filesize,4); /* amount to map from the file */
TYP(maxprot,4); /* maximum VM protection */
TYP(initprot,4); /* initial VM protection */
TYP(nsects,4); /* number of sections in segment */
TYP(flags,4); /* 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 */
TYP(cmd,4); /* LC_SEGMENT_64 */
TYP(cmdsize,4); /* includes sizeof section_64 structs */
char segname[16]; /* segment name */
TYP(vmaddr,8); /* memory address of this segment */
TYP(vmsize,8); /* memory size of this segment */
TYP(fileoff,8); /* file offset of this segment */
TYP(filesize,8); /* amount to map from the file */
TYP(maxprot,4); /* maximum VM protection */
TYP(initprot,4); /* initial VM protection */
TYP(nsects,4); /* number of sections in segment */
TYP(flags,4); /* 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 */
TYP(addr,4); /* memory address of this section */
TYP(size,4); /* size in bytes of this section */
TYP(offset,4); /* file offset of this section */
TYP(align,4); /* section alignment (power of 2) */
TYP(reloff,4); /* file offset of relocation entries */
TYP(nreloc,4); /* number of relocation entries */
TYP(flags,4); /* flags (section type and attributes)*/
TYP(reserved1,4); /* reserved (for offset or index) */
TYP(reserved2,4); /* 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 */
TYP(addr,8); /* memory address of this section */
TYP(size,8); /* size in bytes of this section */
TYP(offset,4); /* file offset of this section */
TYP(align,4); /* section alignment (power of 2) */
TYP(reloff,4); /* file offset of relocation entries */
TYP(nreloc,4); /* number of relocation entries */
TYP(flags,4); /* flags (section type and attributes)*/
TYP(reserved1,4); /* reserved (for offset or index) */
TYP(reserved2,4); /* reserved (for count or sizeof) */
TYP(reserved3,4); /* 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 */
TYP(minor_version,4); /* library's minor version number */
TYP(header_addr,4); /* 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 {
TYP(cmd,4); /* LC_IDFVMLIB or LC_LOADFVMLIB */
TYP(cmdsize,4); /* 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 */
TYP(timestamp,4); /* library's build time stamp */
TYP(current_version,4); /* library's current version number */
TYP(compatibility_version,4);
/* 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 {
TYP(cmd,4); /* LC_ID_DYLIB, LC_LOAD_{,WEAK_}DYLIB,
LC_REEXPORT_DYLIB */
TYP(cmdsize,4); /* 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 {
TYP(cmd,4); /* LC_SUB_FRAMEWORK */
TYP(cmdsize,4); /* 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 {
TYP(cmd,4); /* LC_SUB_CLIENT */
TYP(cmdsize,4); /* 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 {
TYP(cmd,4); /* LC_SUB_UMBRELLA */
TYP(cmdsize,4); /* 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 {
TYP(cmd,4); /* LC_SUB_LIBRARY */
TYP(cmdsize,4); /* 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 {
TYP(cmd,4); /* LC_PREBOUND_DYLIB */
TYP(cmdsize,4); /* includes strings */
union lc_str name; /* library's path name */
TYP(nmodules,4); /* 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 {
TYP(cmd,4); /* LC_ID_DYLINKER, LC_LOAD_DYLINKER or
LC_DYLD_ENVIRONMENT */
TYP(cmdsize,4); /* 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 {
TYP(cmd,4); /* LC_THREAD or LC_UNIXTHREAD */
TYP(cmdsize,4); /* 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 */
TYP(cmd,4); /* LC_ROUTINES */
TYP(cmdsize,4); /* total size of this command */
TYP(init_address,4); /* address of initialization routine */
TYP(init_module,4); /* index into the module table that */
/* the init routine is defined in */
TYP(reserved1,4);
TYP(reserved2,4);
TYP(reserved3,4);
TYP(reserved4,4);
TYP(reserved5,4);
TYP(reserved6,4);
};
/*
* The 64-bit routines command. Same use as above.
*/
struct routines_command_64 { /* for 64-bit architectures */
TYP(cmd,4); /* LC_ROUTINES_64 */
TYP(cmdsize,4); /* total size of this command */
TYP(init_address,8); /* address of initialization routine */
TYP(init_module,8); /* index into the module table that */
/* the init routine is defined in */
TYP(reserved1,8);
TYP(reserved2,8);
TYP(reserved3,8);
TYP(reserved4,8);
TYP(reserved5,8);
TYP(reserved6,8);
};
/*
* 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 {
TYP(cmd,4); /* LC_SYMTAB */
TYP(cmdsize,4); /* sizeof(struct symtab_command) */
TYP(symoff,4); /* symbol table offset */
TYP(nsyms,4); /* number of symbol table entries */
TYP(stroff,4); /* string table offset */
TYP(strsize,4); /* 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 {
TYP(cmd,4); /* LC_DYSYMTAB */
TYP(cmdsize,4); /* 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).
*/
TYP(ilocalsym,4); /* index to local symbols */
TYP(nlocalsym,4); /* number of local symbols */
TYP(iextdefsym,4); /* index to externally defined symbols */
TYP(nextdefsym,4); /* number of externally defined symbols */
TYP(iundefsym,4); /* index to undefined symbols */
TYP(nundefsym,4); /* 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.
*/
TYP(tocoff,4); /* file offset to table of contents */
TYP(ntoc,4); /* 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.
*/
TYP(modtaboff,4); /* file offset to module table */
TYP(nmodtab,4); /* 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.
*/
TYP(extrefsymoff,4); /* offset to referenced symbol table */
TYP(nextrefsyms,4);/* 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.
*/
TYP(indirectsymoff,4);
/* file offset to the indirect symbol table */
TYP(nindirectsyms,4);
/* 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).
*/
TYP(extreloff,4); /* offset to external relocation entries */
TYP(nextrel,4); /* 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).
*/
TYP(locreloff,4); /* offset to local relocation entries */
TYP(nlocrel,4); /* 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
* referring to. Unless it is for a * non-lazy symbol pointer
* section for a defined symbol which strip(1) has
* 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 {
TYP(symbol_index,4); /* the defined external symbol
(index into the symbol table) */
TYP(module_index,4); /* index into the module table this symbol
is defined in */
};
/* a module table entry */
struct dylib_module {
/* the module name (index into string table) */
TYP(module_name,4);
TYP(iextdefsym,4); /* index into externally defined symbols */
TYP(nextdefsym,4); /* number of externally defined symbols */
TYP(irefsym,4); /* index into reference symbol table */
TYP(nrefsym,4); /* number of reference symbol table entries */
TYP(ilocalsym,4); /* index into symbols for local symbols */
TYP(nlocalsym,4); /* number of local symbols */
TYP(iextrel,4); /* index into external relocation entries */
TYP(nextrel,4); /* number of external relocation entries */
TYP(iinit_iterm,4); /* low 16 bits are the index into the init
section, high 16 bits are the index into
the term section */
TYP(ninit_nterm,4); /* low 16 bits are the number of init section
entries, high 16 bits are the number of
term section entries */
/* for this module address of the start of */
/* the (__OBJC,__module_info) section */
TYP(objc_module_info_addr,4);
/* for this module size of */
/* the (__OBJC,__module_info) section */
TYP(objc_module_info_size,4);
};
/* a 64-bit module table entry */
struct dylib_module_64 {
/* the module name (index into string table) */
TYP(module_name,4);
TYP(iextdefsym,4); /* index into externally defined symbols */
TYP(nextdefsym,4); /* number of externally defined symbols */
TYP(irefsym,4); /* index into reference symbol table */
TYP(nrefsym,4); /* number of reference symbol table entries */
TYP(ilocalsym,4); /* index into symbols for local symbols */
TYP(nlocalsym,4); /* number of local symbols */
TYP(iextrel,4); /* index into external relocation entries */
TYP(nextrel,4); /* number of external relocation entries */
TYP(iinit_iterm,4); /* low 16 bits are the index into the init
section, high 16 bits are the index into
the term section */
TYP(ninit_nterm,4); /* low 16 bits are the number of init section
entries, high 16 bits are the number of
term section entries */
TYP(objc_module_info_size,4); /* for this module size of */
/* the (__OBJC,__module_info) section */
TYP(objc_module_info_addr,8);
/* for this module address of the start of */
/* 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.
*/
#if 0 /* dwarf readers not using this */
struct dylib_reference {
UNUSED uint32_t isym:24, /* index into the symbol table */
UNUSED flags:8; /* flags to indicate the type of reference */
};
#endif /* 0 */
/*
* The twolevel_hints_command contains the
* offset and number of hints in the
* two-level namespace lookup hints table.
*/
struct twolevel_hints_command {
TYP(cmd,4); /* LC_TWOLEVEL_HINTS */
TYP(cmdsize,4); /* sizeof(struct twolevel_hints_command) */
TYP(offset,4); /* offset to the hint table */
TYP(nhints,4); /* 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.
*/
#if 0
/* Not used by dwarf readers. */
struct twolevel_hint {
UNUSED uint32_t
isub_image:8, /* index into the sub images */
itoc:24; /* index into the table of contents */
};
#endif
/*
* 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 {
TYP(cmd,4); /* LC_PREBIND_CKSUM */
TYP(cmdsize,4); /* sizeof(struct prebind_cksum_command) */
TYP(cksum,4); /* 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 {
TYP(cmd,4); /* LC_UUID */
TYP(cmdsize,4); /* sizeof(struct uuid_command) */
unsigned char 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 {
TYP(cmd,4); /* LC_RPATH */
TYP(cmdsize,4); /* 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 {
TYP(cmd,4); /* LC_CODE_SIGNATURE, LC_SEGMENT_SPLIT_INFO,
LC_FUNCTION_STARTS, LC_DATA_IN_CODE,
LC_DYLIB_CODE_SIGN_DRS or
LC_LINKER_OPTIMIZATION_HINT. */
TYP(cmdsize,4); /* sizeof(struct linkedit_data_command) */
TYP(dataoff,4); /* file offset of data in __LINKEDIT segment */
TYP(datasize,4); /* 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 {
TYP(cmd,4); /* LC_ENCRYPTION_INFO */
TYP(cmdsize,4); /* sizeof(struct encryption_info_command) */
TYP(cryptoff,4); /* file offset of encrypted range */
TYP(cryptsize,4); /* file size of encrypted range */
TYP(cryptid,4); /* which encryption system,
0 means not-encrypted yet */
};
/*
* The encryption_info_command_64 contains
* the file offset and size of an
* of an encrypted segment (for use in x86_64 targets).
*/
struct encryption_info_command_64 {
TYP(cmd,4); /* LC_ENCRYPTION_INFO_64 */
TYP(cmdsize,4); /* sizeof(struct encryption_info_command_64) */
TYP(cryptoff,4); /* file offset of encrypted range */
TYP(cryptsize,4); /* file size of encrypted range */
TYP(cryptid,4); /* which encryption system,
0 means not-encrypted yet */
TYP(pad,4); /* padding to make this struct's size a multiple
of 8 bytes */
};
/*
* The version_min_command contains the min OS version on which this
* binary was built to run.
*/
struct version_min_command {
TYP(cmd,4); /* LC_VERSION_MIN_MACOSX or
LC_VERSION_MIN_IPHONEOS or
LC_VERSION_MIN_WATCHOS or
LC_VERSION_MIN_TVOS */
TYP(cmdsize,4); /* sizeof(struct min_version_command) */
TYP(version,4); /* X.Y.Z is encoded in nibbles xxxx.yy.zz */
TYP(sdk,4); /* X.Y.Z is encoded in nibbles xxxx.yy.zz */
};
/*
* 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 {
TYP(cmd,4); /* LC_DYLD_INFO or LC_DYLD_INFO_ONLY */
TYP(cmdsize,4); /* 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.
*/
TYP(rebase_off,4); /* file offset to rebase info */
TYP(rebase_size,4); /* 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.
*/
TYP(bind_off,4); /* file offset to binding info */
TYP(bind_size,4); /* 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.
*/
TYP(weak_bind_off,4); /* file offset to weak binding info */
TYP(weak_bind_size,4); /* 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.
*/
TYP(lazy_bind_off,4); /* file offset to lazy binding info */
TYP(lazy_bind_size,4); /* 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.
* If the flags is EXPORT_SYMBOL_FLAGS_STUB_AND_RESOLVER,
* then following
* the flags is two uleb128s: the stub offset and
* the resolver offset.
* The stub is used by non-lazy pointers. The resolver is used
* by lazy pointers and must be called to get
* the actual address to use.
*
* 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.
*
*/
TYP(export_off,4); /* file offset to lazy binding info */
TYP(export_size,4); /* 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 linker_option_command contains linker
* options embedded in object files.
*/
struct linker_option_command {
TYP(cmd,4); /* LC_LINKER_OPTION only used in MH_OBJECT filetypes*/
TYP(cmdsize,4);
TYP(count,4); /* number of strings */
/* concatenation of zero terminated UTF8 strings.
Zero filled at end to align */
};
/*
* 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 {
TYP(cmd,4); /* LC_SYMSEG */
TYP(cmdsize,4); /* sizeof(struct symseg_command) */
TYP(offset,4); /* symbol segment offset */
TYP(size,4); /* 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 {
TYP(cmd,4); /* LC_IDENT */
TYP(cmdsize,4); /* 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 {
TYP(cmd,4); /* LC_FVMFILE */
TYP(cmdsize,4); /* includes pathname string */
union lc_str name; /* files pathname */
TYP(header_addr,4); /* files virtual address */
};
/*
* The entry_point_command is a replacement for thread_command.
* It is used for main executables to specify the
* location (file offset)
* of main(). If -stack_size was used at link time, the stacksize
* field will contain the stack size need for the main thread.
*/
struct entry_point_command {
TYP(cmd,4); /* LC_MAIN only used in MH_EXECUTE filetypes */
TYP(cmdsize,4); /* 24 */
TYP(entryoff,8); /* file (__TEXT) offset of main() */
TYP(stacksize,8); /* if not zero, initial stack size */
};
/*
* The source_version_command is an optional load command containing
* the version of the sources used to build the binary.
*/
struct source_version_command {
TYP(cmd,4); /* LC_SOURCE_VERSION */
TYP(cmdsize,4); /* 16 */
TYP(version,8); /* A.B.C.D.E packed as a24.b10.c10.d10.e10 */
};
/*
* The LC_DATA_IN_CODE load commands uses a linkedit_data_command
* to point to an array of data_in_code_entry entries. Each entry
* describes a range of data in a code section.
*/
struct data_in_code_entry {
TYP(offset,4); /* from mach_header to start of data range*/
TYP(length,2); /* number of bytes in data range */
TYP(kind,2); /* a DICE_KIND_* value */
};
#define DICE_KIND_DATA 0x0001
#define DICE_KIND_JUMP_TABLE8 0x0002
#define DICE_KIND_JUMP_TABLE16 0x0003
#define DICE_KIND_JUMP_TABLE32 0x0004
#define DICE_KIND_ABS_JUMP_TABLE32 0x0005
/*
* 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;
};
#ifdef __cplusplus
}
#endif /* __cplusplus */
#endif /* MACHO_LOADER_H */