近来在学习osx和ios方面的东西，简单熟悉了下oc的语法后打算学习下osx和ios下的文件格式。
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struct mach_header {
    uint32_t magic;
    cpu_type_t cputype;
    cpu_subtype_t cpusubtype;
    uint32_t filetype;
    uint32_t ncmds;
    uint32_t sizeofcmds;
    uint32_t flags;
};

struct mach_header_64 {
    uint32_t magic;
    cpu_type_t cputype;
    cpu_subtype_t cpusubtype;
    uint32_t filetype;
    uint32_t ncmds;
    uint32_t sizeofcmds;
    uint32_t flags;
    uint32_t reserved;
};

#define MH_MAGIC 0xfeedface    /* the mach magic number */
#define MH_CIGAM 0xcefaedfe    /* NXSwapInt(MH_MAGIC) */

#define MH_MAGIC_64 0xfeedfacf /* the 64-bit mach magic number */
#define MH_CIGAM_64 0xcffaedfe /* NXSwapInt(MH_MAGIC_64) */

#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 */

struct load_command {
    uint32_t cmd;
    uint32_t cmdsize;
};

segment_command          LC_SEGMENT
segment_command_64       LC_SEGMENT_64
fvmlib_command           LC_IDFVMLIB or LC_LOADFVMLIB
dylib_command            LC_ID_DYLIB, LC_LOAD_{,WEAK_}DYLIB, LC_REEXPORT_DYLIB`
sub_framework_command    LC_SUB_FRAMEWORK
sub_client_command       LC_SUB_CLIENT`
sub_umbrella_command     LC_SUB_UMBRELLA
sub_library_command      LC_SUB_LIBRARY
prebound_dylib_command   LC_PREBOUND_DYLIB
dylinker_command         LC_ID_DYLINKER, LC_LOAD_DYLINKER orLC_DYLD_ENVIRONMENT
thread_command           LC_THREAD or  LC_UNIXTHREAD
routines_command         LC_ROUTINES
symtab_command           LC_SYMTAB
dysymtab_command         LC_DYSYMTAB
twolevel_hints_command   LC_TWOLEVEL_HINTS
prebind_cksum_command    LC_PREBIND_CKSUM
uuid_command             LC_UUID
rpath_command            LC_RPATH
linkedit_data_command    LC_CODE_SIGNATURE,LC_SEGMENT_SPLIT_INFO,LC_FUNCTION_STARTS,  LC_DATA_IN_CODE, LC_DYLIB_CODE_SIGN_DRS or LC_LINKER_OPTIMIZATION_HINT.
encryption_info_command  LC_ENCRYPTION_INFO
version_min_command      LC_VERSION_MIN_MACOSX or LC_VERSION_MIN_IPHONEOS LC_VERSION_MIN_WATCHOS
dyld_info_command        LC_DYLD_INFO or LC_DYLD_INFO_ONLY
linker_option_command    LC_LINKER_OPTION
symseg_command           LC_SYMSEG
ident_command            LC_IDENT
fvmfile_command          LC_FVMFILE
entry_point_command      LC_MAIN
source_version_command   LC_SOURCE_VERSION

struct section {
    char sectname[16];
    char segname[16];
    uint32_t addr;
    uint32_t size;
    uint32_t offset;
    uint32_t align;
    uint32_t reloff;
    uint32_t nreloc;
    uint32_t flags;
    uint32_t reserved1;
    uint32_t reserved2;
};

struct section_64 {
    char sectname[16];
    char segname[16];
    uint64_t addr;
    uint64_t size;
    uint32_t offset;
    uint32_t align;
    uint32_t reloff;
    uint32_t nreloc;
    uint32_t flags;
    uint32_t reserved1;
    uint32_t reserved2;
    uint32_t reserved3;
};

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