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Re: [Gcl-devel] Re: ACL2 Version 4.0


From: Camm Maguire
Subject: Re: [Gcl-devel] Re: ACL2 Version 4.0
Date: Tue, 27 Jul 2010 10:00:52 -0400
User-agent: Gnus/5.11 (Gnus v5.11) Emacs/22.2 (gnu/linux)

Thank you so much!  But after reviewing the below, it appears I now
need:

/usr/include/mach-o/nlist.h
/usr/include/nlist.h

Take care,

"George W. Dinolt" <address@hidden> writes:

> Camm:
> I have been a lurker on the list for several years.  Time for a small
> contribution.
>
> I tried the same test as Matt on a Snow Leopard MAC and got the same
> result.  I also have access to a Mac running Leopard.  I was able to
> compile gcl on that (after making sure that tcl/tk was not in the
> path). I checked the differences between Leopard and Snow Leopard with
> the files you suggested we look at, they are in /usr/include.
>
> The one that is different in Snow Leopard is "loader.h".  It is
> included below.
>
> Unfortunately, I am unable to make a machine available to you.  My
> machines are relatively hidden behind U.S. gov't firewalls.
>
> I hope this will be of some help.
>
> Regards,
> George Dinolt
> ----------------------------------------
> loader.h from Snow Leopard
> ----------------------------------------
> /*
>  * Copyright (c) 1999-2008 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_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_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. */
>
> /*
>  * 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 */
>
> /*
>  * 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 */
> /*
>  * 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.
>  */
> struct dylinker_command {
>     uint32_t    cmd;        /* LC_ID_DYLINKER or LC_LOAD_DYLINKER */
>     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 or
> LC_SEGMENT_SPLIT_INFO */
>     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 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 rebase 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 byte that is the length of
>      * the exported symbol information for the string so far.
>      * If there is no exported symbol, the byte is zero. If there
>      * is exported info, it follows the length byte.  The exported
>      * info normally consists of a flags and offset both encoded
>      * in uleb128.  The offset is location of the content named
>      * by the symbol.  It is the offset from the mach_header for
>      * the image.
>      *
>      * After the initial byte and 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 cstring 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_INDIRECT_DEFINITION            0x08
> #define EXPORT_SYMBOL_FLAGS_HAS_SPECIALIZATIONS            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 */
> };
>
> #endif /* _MACHO_LOADER_H_ */
>
>
> On 07/26/10 15:21, Camm Maguire wrote:
>> Greetings1
>>
>> Matt Kaufmann<address@hidden>  writes:
>>
>>    
>>> Hi, Camm --
>>>
>>> I'd be very happy to give you access to my laptop, which is the Intel
>>> box in question (which is running Mac OS 10.6.4, by the way).  But I
>>> don't know how to do it.  I think could create an account, but how do
>>>      
>> Well, this looks difficult.  It would be great if you could send me
>> these files:
>>
>> #include<mach-o/loader.h>
>> #include<mach-o/nlist.h>
>>
>> #include<mach/mach.h>
>>
>> Separately, if you are interested, I can send you a small patch that
>> steps around rsym_macosx all together.  Of course, if you are still on
>> vacation, please don't bother about this until you get home!  If there
>> is a machine at ut you could point me to, that of course would be
>> great, but if you'd have to ask David Ranger, perhaps I could just
>> email him myself.
>>
>> Last update, gcl can now run cross compiled for windows on Linux under
>> wine.  maxima just passed all its tests.  Checking acl2 ....  The idea
>> being to get one tree verified on both these seldom used machines (mac
>> and windows) and then finalize gcl 2.6.8.
>>
>> Take care,
>>
>>    
>>> -- Matt
>>>     From: Camm Maguire<address@hidden>
>>>     Date: Mon, 26 Jul 2010 11:07:47 -0400
>>>     X-SpamAssassin-Status: No, hits=0.2 required=5.0
>>>     X-UTCS-Spam-Status: No, hits=-180 required=165
>>>
>>>     Greetings!  Sigh.  I was afraid of this.  There are multiple versions
>>>     of mac os x out there which apparently differ in significant ways.
>>>     Not sure of the versioning system, but 10.4, 10.5, and 10.6 sound
>>>     familiar.  This code was well tested on the axiom intel mac box. Could
>>>     you please provide access to the box in question?
>>>
>>>     Take care,
>>>     --
>>>     Camm Maguire                                        address@hidden
>>>     
>>> ==========================================================================
>>>     "The earth is but one country, and mankind its citizens."  --  
>>> Baha'u'llah
>>>
>>>
>>>
>>>
>>>      
>>    
>
>
>
>

-- 
Camm Maguire                                        address@hidden
==========================================================================
"The earth is but one country, and mankind its citizens."  --  Baha'u'llah



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