Concerning
What does * mean before 0x405130?
I am not familiar with the gdb disassembler, but it seems to be jmp *0x405130an indirect pointer jump. Instead of parsing what is in 0x405130, you should discard 4 bytes of memory. I bet you will find a different address there, and if you break this location, you will find the code printf()(as you can read, disassemblies may be a different story).
, _imp__printf printf(), printf().
:
Litle poking around , jmp *0x405130 GAS/AT & T jmp [0x405130] Intel.
, , gdb x/xw 0x405130 , 0x00005274 ( , , 0x405130). , jmp [0x405130] 0x00005274, ( gdb , .
, _imp_printf - , 0x405130, 0x00005274, . 0x405130. . , , , - (, , ), . - , 0x405130 , printf().
, printf() , , .
GDB:
, - , DLL DLL. "hello world", MinGW, GDB:
C:\temp>\mingw\bin\gdb test.exe
GNU gdb (GDB) 7.1
Copyright (C) 2010 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law. Type "show copying"
and "show warranty" for details.
This GDB was configured as "mingw32".
For bug reporting instructions, please see:
<http://www.gnu.org/software/gdb/bugs/>...
Reading symbols from C:\temp/test.exe...done.
(gdb) disas main
Dump of assembler code for function main:
0x004012f0 <+0>: push %ebp
0x004012f1 <+1>: mov %esp,%ebp
0x004012f3 <+3>: sub $0x8,%esp
0x004012f6 <+6>: and $0xfffffff0,%esp
0x004012f9 <+9>: mov $0x0,%eax
0x004012fe <+14>: add $0xf,%eax
0x00401301 <+17>: add $0xf,%eax
0x00401304 <+20>: shr $0x4,%eax
0x00401307 <+23>: shl $0x4,%eax
0x0040130a <+26>: mov %eax,-0x4(%ebp)
0x0040130d <+29>: mov -0x4(%ebp),%eax
0x00401310 <+32>: call 0x401850 <_alloca>
0x00401315 <+37>: call 0x4013d0 <__main>
0x0040131a <+42>: movl $0x403000,(%esp)
0x00401321 <+49>: call 0x4018b0 <printf>
0x00401326 <+54>: mov $0x0,%eax
0x0040132b <+59>: leave
0x0040132c <+60>: ret
End of assembler dump.
, printf() :
(gdb) disas printf
Dump of assembler code for function printf:
0x004018b0 <+0>: jmp *0x4050f8 ; <<-- indirect jump
0x004018b6 <+6>: nop
0x004018b7 <+7>: nop
End of assembler dump.
_imp__printf symiol ...
(gdb) disas 0x4050f8
Dump of assembler code for function _imp__printf:
0x004050f8 <+0>: clc ; <<-- how can this be printf()?
0x004050f9 <+1>: push %ecx
0x004050fa <+2>: add %al,(%eax)
End of assembler dump.
...
(gdb) x/xw 0x4050f8
0x4050f8 <_imp__printf>: 0x000051f8 ; <<-- 0x000051f8 is an invalid pointer
main() :
(gdb) break main
Breakpoint 1 at 0x40131a: file c:/temp/test.c, line 5.
(gdb) run
Starting program: C:\temp/test.exe
[New Thread 11204.0x2bc8]
Error while mapping shared library sections:
C:\WINDOWS\SysWOW64\ntdll32.dll: No such file or directory.
Breakpoint 1, main () at c:/temp/test.c:5
5 printf( "hello world\n");
printf() :
(gdb) disas printf
Dump of assembler code for function printf:
0x004018b0 <+0>: jmp *0x4050f8
0x004018b6 <+6>: nop
0x004018b7 <+7>: nop
End of assembler dump.
_imp__printf : :
(gdb) x/xw 0x4050f8
0x4050f8 <_imp__printf>: 0x77bd27c2
, _imp__printf, , , , . printf(), MSVCRT.DLL:
(gdb) disas _imp__printf
Dump of assembler code for function printf:
0x77bd27c2 <+0>: push $0x10
0x77bd27c4 <+2>: push $0x77ba4770
0x77bd27c9 <+7>: call 0x77bc84c4 <strerror+554>
0x77bd27ce <+12>: mov $0x77bf1cc8,%esi
0x77bd27d3 <+17>: push %esi
0x77bd27d4 <+18>: push $0x1
0x77bd27d6 <+20>: call 0x77bcca49 <msvcrt!_lock+4816>
0x77bd27db <+25>: pop %ecx
0x77bd27dc <+26>: pop %ecx
0x77bd27dd <+27>: andl $0x0,-0x4(%ebp)
0x77bd27e1 <+31>: push %esi
0x77bd27e2 <+32>: call 0x77bd400d <wscanf+3544>
0x77bd27e7 <+37>: mov %eax,-0x1c(%ebp)
0x77bd27ea <+40>: lea 0xc(%ebp),%eax
0x77bd27ed <+43>: push %eax
0x77bd27ee <+44>: pushl 0x8(%ebp)
0x77bd27f1 <+47>: push %esi
0x77bd27f2 <+48>: call 0x77bd3330 <wscanf+251>
0x77bd27f7 <+53>: mov %eax,-0x20(%ebp)
0x77bd27fa <+56>: push %esi
0x77bd27fb <+57>: pushl -0x1c(%ebp)
0x77bd27fe <+60>: call 0x77bd4099 <wscanf+3684>
0x77bd2803 <+65>: add $0x18,%esp
0x77bd2806 <+68>: orl $0xffffffff,-0x4(%ebp)
0x77bd280a <+72>: call 0x77bd281d <printf+91>
0x77bd280f <+77>: mov -0x20(%ebp),%eax
0x77bd2812 <+80>: call 0x77bc84ff <strerror+613>
0x77bd2817 <+85>: ret
0x77bd2818 <+86>: mov $0x77bf1cc8,%esi
0x77bd281d <+91>: push %esi
0x77bd281e <+92>: push $0x1
0x77bd2820 <+94>: call 0x77bccab0 <msvcrt!_lock+4919>
0x77bd2825 <+99>: pop %ecx
0x77bd2826 <+100>: pop %ecx
0x77bd2827 <+101>: ret
0x77bd2828 <+102>: int3
0x77bd2829 <+103>: int3
0x77bd282a <+104>: int3
0x77bd282b <+105>: int3
0x77bd282c <+106>: int3
End of assembler dump.
, , , , ( GDB ).
, , C , , . MinGW MSVDRT.DLL, Windows, ( - ) Visual Studio - , V++ Express ( ).