示例源代码
int main(){
fstream fs;
char* buf = new char[100];
fs.open("readme");
if(!fs.is_open())
cout<< "open file failed"<<endl;
fs.getline(buf, 100);
cout<< buf<<endl;
fs.close();
}objdump
如果是情况一，直接用地址dump出来。咱们回头看一下Backtrace信息：bdi_register+0xec/0x150，这里的0xec是偏移，而0x150是该函数的大小。用objdump默认可以获取整个vmlinux的代码，但是咱们其实只获取一部分，这个可以通过--start-address和--stop-address来指定。另外-d可以汇编代码，-S则可以并入源代码。
显示来自目标 <文件> 的信息。
至少必须给出以下选项之一：
-a, --archive-headers Display archive header information
-f, --file-headers Display the contents of the overall file header
-p, --private-headers Display object format specific file header contents
-P, --private=OPT,OPT... Display object format specific contents
-h, --[section-]headers Display the contents of the section headers
-x, --all-headers Display the contents of all headers
-d, --disassemble Display assembler contents of executable sections
-D, --disassemble-all Display assembler contents of all sections
-S, --source Intermix source code with disassembly 源代码和汇编代码混合显示
-s, --full-contents Display the full contents of all sections requested
-g, --debugging Display debug information in object file
-e, --debugging-tags Display debug information using ctags style
-G, --stabs Display (in raw form) any STABS info in the file
-W[lLiaprmfFsoRt] or
--dwarf[=rawline,=decodedline,=info,=abbrev,=pubnames,=aranges,=macro,=frames,
=frames-interp,=str,=loc,=Ranges,=pubtypes,
=gdb_index,=trace_info,=trace_abbrev,=trace_aranges,
=addr,=cu_index]
Display DWARF info in the file
-t, --syms Display the contents of the symbol table(s)
-T, --dynamic-syms Display the contents of the dynamic symbol table
-r, --reloc Display the relocation entries in the file
-R, --dynamic-reloc Display the dynamic relocation entries in the file
@<file> Read options from <file>
-v, --version Display this program's version number
-i, --info List object formats and architectures supported
-H, --help Display this informatio-C ：c++ 符号名逆向，可以显示出可读的C++符号名（最好的方式）
ll@ll-VirtualBox:~/mycode/c++/lession3$ objdump -SC a.out
0000000000400ca6 <main>:
400ca6: 55 push %rbp
400ca7: 48 89 e5 mov %rsp,%rbp
400caa: 53 push %rbx
400cab: 48 81 ec 38 02 00 00 sub $0x238,%rsp
400cb2: 64 48 8b 04 25 28 00 mov %fs:0x28,%rax
400cb9: 00 00
400cbb: 48 89 45 e8 mov %rax,-0x18(%rbp)
400cbf: 31 c0 xor %eax,%eax
400cc1: 48 8d 85 d0 fd ff ff lea -0x230(%rbp),%rax
400cc8: 48 89 c7 mov %rax,%rdi
400ccb: e8 50 fe ff ff callq 400b20 <std::basic_fstream<char, std::char_traits<char> >::basic_fstream()@plt>
400cd0: bf 64 00 00 00 mov $0x64,%edi
400cd5: e8 b6 fd ff ff callq 400a90 <operator new[](unsigned long)@plt>
400cda: 48 89 85 c8 fd ff ff mov %rax,-0x238(%rbp)
400ce1: be 10 00 00 00 mov $0x10,%esi
400ce6: bf 08 00 00 00 mov $0x8,%edi
400ceb: e8 3a 01 00 00 callq 400e2a <std::operator|(std::_Ios_Openmode, std::_Ios_Openmode)>
400cf0: 89 c2 mov %eax,%edx
400cf2: 48 8d 85 d0 fd ff ff lea -0x230(%rbp),%rax
400cf9: be c4 0e 40 00 mov $0x400ec4,%esi
400cfe: 48 89 c7 mov %rax,%rdi
400d01: e8 8a fe ff ff callq 400b90 <std::basic_fstream<char, std::char_traits<char> >::open(char const*, std::_Ios_Openmode)@plt>
400d06: 48 8d 85 d0 fd ff ff lea -0x230(%rbp),%rax
400d0d: 48 89 c7 mov %rax,%rdi
400d10: e8 3b fe ff ff callq 400b50 <std::basic_fstream<char, std::char_traits<char> >::is_open()@plt>
400d15: 83 f0 01 xor $0x1,%eax
400d18: 84 c0 test %al,%al
400d1a: 74 1c je 400d38 <main+0x92>
400d1c: be cb 0e 40 00 mov $0x400ecb,%esi
400d21: bf c0 20 60 00 mov $0x6020c0,%edi
400d26: e8 b5 fd ff ff callq 400ae0 <std::basic_ostream<char, std::char_traits<char> >& std::operator<< <std::char_traits<char> >(std::basic_ostream<char, std::char_traits<char> >&, char const*)@plt>
400d2b: be 60 0b 40 00 mov $0x400b60,%esi
400d30: 48 89 c7 mov %rax,%rdi
400d33: e8 08 fe ff ff callq 400b40 <std::ostream::operator<<(std::ostream& (*)(std::ostream&))@plt>
400d38: 48 8b 8d c8 fd ff ff mov -0x238(%rbp),%rcx
400d3f: 48 8d 85 d0 fd ff ff lea -0x230(%rbp),%rax
400d46: ba 64 00 00 00 mov $0x64,%edx
400d4b: 48 89 ce mov %rcx,%rsi
400d4e: 48 89 c7 mov %rax,%rdi
400d51: e8 aa fd ff ff callq 400b00 <std::istream::getline(char*, long)@plt>
400d56: 48 8b 85 c8 fd ff ff mov -0x238(%rbp),%rax
400d5d: 48 89 c6 mov %rax,%rsi
400d60: bf c0 20 60 00 mov $0x6020c0,%edi
400d65: e8 76 fd ff ff callq 400ae0 <std::basic_ostream<char, std::char_traits<char> >& std::operator<< <std::char_traits<char> >(std::basic_ostream<char, std::char_traits<char> >&, char const*)@plt>
400d6a: be 60 0b 40 00 mov $0x400b60,%esi
400d6f: 48 89 c7 mov %rax,%rdi
400d72: e8 c9 fd ff ff callq 400b40 <std::ostream::operator<<(std::ostream& (*)(std::ostream&))@plt>
400d77: 48 8d 85 d0 fd ff ff lea -0x230(%rbp),%rax
400d7e: 48 89 c7 mov %rax,%rdi
400d81: e8 6a fd ff ff callq 400af0 <std::basic_fstream<char, std::char_traits<char> >::close()@plt>
400d86: 48 8d 85 d0 fd ff ff lea -0x230(%rbp),%rax
400d8d: 48 89 c7 mov %rax,%rdi
400d90: e8 7b fd ff ff callq 400b10 <std::basic_fstream<char, std::char_traits<char> >::~basic_fstream()@plt>
400d95: b8 00 00 00 00 mov $0x0,%eax
400d9a: 48 8b 4d e8 mov -0x18(%rbp),%rcx
400d9e: 64 48 33 0c 25 28 00 xor %fs:0x28,%rcx
400da5: 00 00
400da7: 74 24 je 400dcd <main+0x127>
400da9: eb 1d jmp 400dc8 <main+0x122>
400dab: 48 89 c3 mov %rax,%rbx
400dae: 48 8d 85 d0 fd ff ff lea -0x230(%rbp),%rax
400db5: 48 89 c7 mov %rax,%rdi
400db8: e8 53 fd ff ff callq 400b10 <std::basic_fstream<char, std::char_traits<char> >::~basic_fstream()@plt>
400dbd: 48 89 d8 mov %rbx,%rax
400dc0: 48 89 c7 mov %rax,%rdi
400dc3: e8 b8 fd ff ff callq 400b80 <_Unwind_Resume@plt>
400dc8: e8 63 fd ff ff callq 400b30 <__stack_chk_fail@plt>
400dcd: 48 81 c4 38 02 00 00 add $0x238,%rsp
400dd4: 5b pop %rbx
400dd5: 5d pop %rbp
400dd6: c3 retqobjdump -S a.out 显示出汇编和C++的混合符号代码，不宜读，不推荐
0000000000400ca6 <main>:
400ca6: 55 push %rbp
400ca7: 48 89 e5 mov %rsp,%rbp
400caa: 53 push %rbx
400cab: 48 81 ec 38 02 00 00 sub $0x238,%rsp
400cb2: 64 48 8b 04 25 28 00 mov %fs:0x28,%rax
400cb9: 00 00
400cbb: 48 89 45 e8 mov %rax,-0x18(%rbp)
400cbf: 31 c0 xor %eax,%eax
400cc1: 48 8d 85 d0 fd ff ff lea -0x230(%rbp),%rax
400cc8: 48 89 c7 mov %rax,%rdi
400ccb: e8 50 fe ff ff callq 400b20 <_ZNSt13basic_fstreamIcSt11char_traitsIcEEC1Ev@plt>
400cd0: bf 64 00 00 00 mov $0x64,%edi
400cd5: e8 b6 fd ff ff callq 400a90 <_Znam@plt>
400cda: 48 89 85 c8 fd ff ff mov %rax,-0x238(%rbp)
400ce1: be 10 00 00 00 mov $0x10,%esi
400ce6: bf 08 00 00 00 mov $0x8,%edi
400ceb: e8 3a 01 00 00 callq 400e2a <_ZStorSt13_Ios_OpenmodeS_>
400cf0: 89 c2 mov %eax,%edx
400cf2: 48 8d 85 d0 fd ff ff lea -0x230(%rbp),%rax
400cf9: be c4 0e 40 00 mov $0x400ec4,%esi
400cfe: 48 89 c7 mov %rax,%rdi
400d01: e8 8a fe ff ff callq 400b90 <_ZNSt13basic_fstreamIcSt11char_traitsIcEE4openEPKcSt13_Ios_Openmode@plt>
400d06: 48 8d 85 d0 fd ff ff lea -0x230(%rbp),%rax
400d0d: 48 89 c7 mov %rax,%rdi
400d10: e8 3b fe ff ff callq 400b50 <_ZNSt13basic_fstreamIcSt11char_traitsIcEE7is_openEv@plt>
400d15: 83 f0 01 xor $0x1,%eax
400d18: 84 c0 test %al,%al
400d1a: 74 1c je 400d38 <main+0x92>
400d1c: be cb 0e 40 00 mov $0x400ecb,%esi
400d21: bf c0 20 60 00 mov $0x6020c0,%edi
400d26: e8 b5 fd ff ff callq 400ae0 <_ZStlsISt11char_traitsIcEERSt13basic_ostreamIcT_ES5_PKc@plt>
400d2b: be 60 0b 40 00 mov $0x400b60,%esi
400d30: 48 89 c7 mov %rax,%rdi
400d33: e8 08 fe ff ff callq 400b40 <_ZNSolsEPFRSoS_E@plt>
400d38: 48 8b 8d c8 fd ff ff mov -0x238(%rbp),%rcx
400d3f: 48 8d 85 d0 fd ff ff lea -0x230(%rbp),%rax
400d46: ba 64 00 00 00 mov $0x64,%edx
400d4b: 48 89 ce mov %rcx,%rsi
400d4e: 48 89 c7 mov %rax,%rdi
400d51: e8 aa fd ff ff callq 400b00 <_ZNSi7getlineEPcl@plt>
400d56: 48 8b 85 c8 fd ff ff mov -0x238(%rbp),%rax
400d5d: 48 89 c6 mov %rax,%rsi
400d60: bf c0 20 60 00 mov $0x6020c0,%edi
400d65: e8 76 fd ff ff callq 400ae0 <_ZStlsISt11char_traitsIcEERSt13basic_ostreamIcT_ES5_PKc@plt>
400d6a: be 60 0b 40 00 mov $0x400b60,%esi
400d6f: 48 89 c7 mov %rax,%rdi
400d72: e8 c9 fd ff ff callq 400b40 <_ZNSolsEPFRSoS_E@plt>
400d77: 48 8d 85 d0 fd ff ff lea -0x230(%rbp),%rax
400d7e: 48 89 c7 mov %rax,%rdi
400d81: e8 6a fd ff ff callq 400af0 <_ZNSt13basic_fstreamIcSt11char_traitsIcEE5closeEv@plt>
400d86: 48 8d 85 d0 fd ff ff lea -0x230(%rbp),%rax
400d8d: 48 89 c7 mov %rax,%rdi
400d90: e8 7b fd ff ff callq 400b10 <_ZNSt13basic_fstreamIcSt11char_traitsIcEED1Ev@plt>
400d95: b8 00 00 00 00 mov $0x0,%eax
400d9a: 48 8b 4d e8 mov -0x18(%rbp),%rcx
400d9e: 64 48 33 0c 25 28 00 xor %fs:0x28,%rcx
400da5: 00 00
400da7: 74 24 je 400dcd <main+0x127>
400da9: eb 1d jmp 400dc8 <main+0x122>
400dab: 48 89 c3 mov %rax,%rbx
400dae: 48 8d 85 d0 fd ff ff lea -0x230(%rbp),%rax
400db5: 48 89 c7 mov %rax,%rdi
400db8: e8 53 fd ff ff callq 400b10 <_ZNSt13basic_fstreamIcSt11char_traitsIcEED1Ev@plt>
400dbd: 48 89 d8 mov %rbx,%rax
400dc0: 48 89 c7 mov %rax,%rdi
400dc3: e8 b8 fd ff ff callq 400b80 <_Unwind_Resume@plt>
400dc8: e8 63 fd ff ff callq 400b30 <__stack_chk_fail@plt>
400dcd: 48 81 c4 38 02 00 00 add $0x238,%rsp
400dd4: 5b pop %rbx
400dd5: 5d pop %rbp
400dd6: c3 retq