objdump

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objdump (part of the GNU Binutils) is a program for displaying various information about object files. For instance, it can be used as a disassembler to view executable in assembly form. It is part of the GNU Binutils for fine-grained control over executable and other binary data.

For example,

$ objdump -D -M intel file.bin | grep main.: -A20

This performs disassembly on the file «file.bin», with the assembly code shown in Intel syntax. We then redirect it to grep, which searches the main function and displays 20 lines of its code.

Example output:

  4004ed:	55                   	push   rbp
  4004ee:	48 89 e5             	mov    rbp,rsp
  4004f1:	c7 45 ec 00 00 00 00 	mov    DWORD PTR [rbp-0x14],0x0
  4004f8:	c7 45 f0 01 00 00 00 	mov    DWORD PTR [rbp-0x10],0x1
  4004ff:	c7 45 f4 02 00 00 00 	mov    DWORD PTR [rbp-0xc],0x2
  400506:	c7 45 f8 03 00 00 00 	mov    DWORD PTR [rbp-0x8],0x3
  40050d:	c7 45 fc 04 00 00 00 	mov    DWORD PTR [rbp-0x4],0x4
  400514:	c7 45 ec 00 00 00 00 	mov    DWORD PTR [rbp-0x14],0x0
  40051b:	eb 13                	jmp    400530 <main+0x43>
  40051d:	8b 05 15 0b 20 00    	mov    eax,DWORD PTR [rip+0x200b15]        # 601038 <globalA>
  400523:	83 e8 01             	sub    eax,0x1
  400526:	89 05 0c 0b 20 00    	mov    DWORD PTR [rip+0x200b0c],eax        # 601038 <globalA>
  40052c:	83 45 ec 01          	add    DWORD PTR [rbp-0x14],0x1
  400530:	8b 05 02 0b 20 00    	mov    eax,DWORD PTR [rip+0x200b02]        # 601038 <globalA>
  400536:	39 45 ec             	cmp    DWORD PTR [rbp-0x14],eax
  400539:	7c e2                	jl     40051d <main+0x30>
  40053b:	5d                   	pop    rbp
  40053c:	c3                   	ret    
  40053d:	0f 1f 00             	nop    DWORD PTR [rax]

objdump uses the BFD library to read the contents of object files.

Similar utilities are Borland TDUMP, Microsoft DUMPBIN, and (also included in the binutils package), readelf that can only read ELF files and it does not use the BFD library.

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