Created
November 1, 2011 04:32
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Object dump using gobjdump on Mac OSX
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| 1. Write a hello hello world c | |
| main( ) | |
| { | |
| printf("Hello World\n"); | |
| } | |
| 2. Compile it: gcc hello.c | |
| Bonus: `gcc -Wall -save-temps hello.c -o hello` will give you extra stuff like: | |
| 1. temp file (.i), | |
| 2. intermediate file which has the machine code (.o) and | |
| 3. assembly instructions (.s) | |
| 3. gobjdump -p a.out (Install binutils if you don't have it, port install binutils) | |
| 4. The object dump. | |
| a.out: file format mach-o-x86-64 | |
| Mach-O header: | |
| magic : feedfacf | |
| cputype : 01000007 (x86_64) | |
| cpusubtype: 80000003 | |
| filetype : 00000002 (execute) | |
| ncmds : 0000000d (13) | |
| sizeofcmds: 00000620 | |
| flags : 00200085 (noundefs+dyldlink+twolevel+pie) | |
| reserved : 00000000 | |
| Load command segment_64: name: __PAGEZERO | |
| vmaddr: 0000000000000000 vmsize: 0000000100000000 | |
| fileoff: 0000000000000000 filesize: 0000000000000000 endoff: 0000000000000000 | |
| nsects: 0 flags: 0 | |
| Load command segment_64: name: __TEXT | |
| vmaddr: 0000000100000000 vmsize: 0000000000001000 | |
| fileoff: 0000000000000000 filesize: 0000000000001000 endoff: 0000000000001000 | |
| nsects: 6 flags: 0 | |
| Section: __text __TEXT (bfdname: .text) | |
| addr: 0000000100000ec0 size: 0000000000000060 offset: 0000000000000ec0 | |
| align: 4 nreloc: 0 reloff: 0000000000000000 | |
| flags: 80000400 (type: regular attr: some_instructions+pure_instructions) | |
| reserved1: 0x0 reserved2: 0x0 reserved3: 0x0 | |
| Section: __stubs __TEXT (bfdname: __TEXT.__stubs) | |
| addr: 0000000100000f20 size: 000000000000000c offset: 0000000000000f20 | |
| align: 1 nreloc: 0 reloff: 0000000000000000 | |
| flags: 80000408 (type: symbol_stubs attr: some_instructions+pure_instructions) | |
| first indirect sym: 0 (2 entries) stub size: 6 reserved3: 0x0 | |
| Section: __stub_helper __TEXT (bfdname: __TEXT.__stub_helper) | |
| addr: 0000000100000f2c size: 0000000000000024 offset: 0000000000000f2c | |
| align: 2 nreloc: 0 reloff: 0000000000000000 | |
| flags: 80000400 (type: regular attr: some_instructions+pure_instructions) | |
| reserved1: 0x0 reserved2: 0x0 reserved3: 0x0 | |
| Section: __cstring __TEXT (bfdname: .cstring) | |
| addr: 0000000100000f50 size: 000000000000000c offset: 0000000000000f50 | |
| align: 0 nreloc: 0 reloff: 0000000000000000 | |
| flags: 00000002 (type: cstring_literals attr: -) | |
| reserved1: 0x0 reserved2: 0x0 reserved3: 0x0 | |
| Section: __unwind_info __TEXT (bfdname: __TEXT.__unwind_info) | |
| addr: 0000000100000f5c size: 0000000000000050 offset: 0000000000000f5c | |
| align: 0 nreloc: 0 reloff: 0000000000000000 | |
| flags: 00000000 (type: regular attr: -) | |
| reserved1: 0x0 reserved2: 0x0 reserved3: 0x0 | |
| Section: __eh_frame __TEXT (bfdname: .eh_frame) | |
| addr: 0000000100000fb0 size: 0000000000000048 offset: 0000000000000fb0 | |
| align: 3 nreloc: 0 reloff: 0000000000000000 | |
| flags: 00000000 (type: regular attr: -) | |
| reserved1: 0x0 reserved2: 0x0 reserved3: 0x0 | |
| Load command segment_64: name: __DATA | |
| vmaddr: 0000000100001000 vmsize: 0000000000001000 | |
| fileoff: 0000000000001000 filesize: 0000000000001000 endoff: 0000000000002000 | |
| nsects: 4 flags: 0 | |
| Section: __program_vars __DATA (bfdname: __DATA.__program_vars) | |
| addr: 0000000100001000 size: 0000000000000028 offset: 0000000000001000 | |
| align: 4 nreloc: 0 reloff: 0000000000000000 | |
| flags: 00000000 (type: regular attr: -) | |
| reserved1: 0x0 reserved2: 0x0 reserved3: 0x0 | |
| Section: __nl_symbol_ptr __DATA (bfdname: .non_lazy_symbol_ptr) | |
| addr: 0000000100001028 size: 0000000000000010 offset: 0000000000001028 | |
| align: 3 nreloc: 0 reloff: 0000000000000000 | |
| flags: 00000006 (type: non_lazy_symbol_pointers attr: -) | |
| first indirect sym: 2 (2 entries) reserved2: 0x0 reserved3: 0x0 | |
| Section: __la_symbol_ptr __DATA (bfdname: .lazy_symbol_ptr) | |
| addr: 0000000100001038 size: 0000000000000010 offset: 0000000000001038 | |
| align: 3 nreloc: 0 reloff: 0000000000000000 | |
| flags: 00000007 (type: lazy_symbol_pointers attr: -) | |
| first indirect sym: 4 (2 entries) reserved2: 0x0 reserved3: 0x0 | |
| Section: __common __DATA (bfdname: __DATA.__common) | |
| addr: 0000000100001048 size: 0000000000000020 offset: 0000000000000000 | |
| align: 3 nreloc: 0 reloff: 0000000000000000 | |
| flags: 00000001 (type: zerofill attr: -) | |
| reserved1: 0x0 reserved2: 0x0 reserved3: 0x0 | |
| Load command segment_64: name: __LINKEDIT | |
| vmaddr: 0000000100002000 vmsize: 0000000000001000 | |
| fileoff: 0000000000002000 filesize: 00000000000001f0 endoff: 00000000000021f0 | |
| nsects: 0 flags: 0 | |
| Load command dyld_info: | |
| rebase: off: 0x00002000 size: 8 | |
| bind: off: 0x00002008 size: 24 | |
| weak bind: off: 0x00000000 size: 0 | |
| lazy bind: off: 0x00002020 size: 24 | |
| export: off: 0x00002038 size: 120 | |
| Load command symtab: | |
| symoff: 0x000020b8 nsyms: 11 (endoff: 0x00002168) | |
| stroff: 0x00002180 strsize: 112 (endoff: 0x000021f0) | |
| Load command dysymtab: | |
| local symbols: idx: 0 num: 1 (nxtidx: 1) | |
| external symbols: idx: 1 num: 7 (nxtidx: 8) | |
| undefined symbols: idx: 8 num: 3 (nxtidx: 11) | |
| table of content: off: 0x00000000 num: 0 (endoff: 0x00000000) | |
| module table: off: 0x00000000 num: 0 (endoff: 0x00000000) | |
| external reference table: off: 0x00000000 num: 0 (endoff: 0x00000000) | |
| indirect symbol table: off: 0x00002168 num: 6 (endoff: 0x00002180) | |
| external relocation table: off: 0x00000000 num: 0 (endoff: 0x00000000) | |
| local relocation table: off: 0x00000000 num: 0 (endoff: 0x00000000) | |
| indirect symbols: | |
| for section __TEXT.__stubs: | |
| 0000000100000f20 0: 0x00000008 _exit | |
| 0000000100000f26 1: 0x00000009 _puts | |
| for section __DATA.__nl_symbol_ptr: | |
| 0000000100001028 2: 0x40000000 ABSOLUTE | |
| 0000000100001030 3: 0x40000000 ABSOLUTE | |
| for section __DATA.__la_symbol_ptr: | |
| 0000000100001038 4: 0x00000008 _exit | |
| 0000000100001040 5: 0x00000009 _puts | |
| Load command load_dylinker: /usr/lib/dyld | |
| Load command uuid: 6e 36 a1 13 e1 4e 3e cc bc 81 b1 fa d9 6f d5 d3 | |
| Load command *UNKNOWN*: | |
| Load command unixthread: nflavours: 1 | |
| 0: flavour: 0x00000004 offset: 0x00000550 size: 0x000000a8 | |
| Load command load_dylib: /usr/lib/libSystem.B.dylib | |
| time stamp: 0x00000002 | |
| current version: 0x009f0100 | |
| comptibility version: 0x00010000 | |
| Load command *UNKNOWN*: | |
| Segments and Sections: | |
| #: Segment name Section name Address | |
| [Segment __PAGEZERO 0000000000000000-00000000ffffffff ---] | |
| [Segment __TEXT 0000000100000000-0000000100000fff r-x] | |
| 01: __TEXT __text 0000000100000ec0 0000000000000060 80000400 | |
| 02: __TEXT __stubs 0000000100000f20 000000000000000c 80000408 | |
| 03: __TEXT __stub_helper 0000000100000f2c 0000000000000024 80000400 | |
| 04: __TEXT __cstring 0000000100000f50 000000000000000c 00000002 | |
| 05: __TEXT __unwind_info 0000000100000f5c 0000000000000050 00000000 | |
| 06: __TEXT __eh_frame 0000000100000fb0 0000000000000048 00000000 | |
| [Segment __DATA 0000000100001000-0000000100001fff rw-] | |
| 07: __DATA __program_vars 0000000100001000 0000000000000028 00000000 | |
| 08: __DATA __nl_symbol_ptr 0000000100001028 0000000000000010 00000006 | |
| 09: __DATA __la_symbol_ptr 0000000100001038 0000000000000010 00000007 | |
| 10: __DATA __common 0000000100001048 0000000000000020 00000001 | |
| [Segment __LINKEDIT 0000000100002000-0000000100002fff r--] | |
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