Graphics Programs Reference
In-Depth Information
Function "strcpy" not defined.
Make breakpoint pending on future shared library load? (y or [n]) y
Breakpoint 2 (strcpy) pending.
(gdb) break 8
Breakpoint 3 at 0x80483d7: file char_array2.c, line 8.
(gdb)
When the program is run, the
strcpy()
breakpoint is resolved. At each
breakpoint, we're going to look at EIP and the instructions it points to. Notice
that the memory location for EIP at the middle breakpoint is different.
(gdb) run
Starting program: /home/reader/booksrc/char_array2
Breakpoint 4 at 0xb7f076f4
Pending breakpoint "strcpy" resolved
Breakpoint 1, main () at char_array2.c:7
7 strcpy(str_a, "Hello, world!\n");
(gdb) i r eip
eip 0x80483c4 0x80483c4 <main+16>
(gdb) x/5i $eip
0x80483c4 <main+16>: mov DWORD PTR [esp+4],0x80484c4
0x80483cc <main+24>: lea eax,[ebp-40]
0x80483cf <main+27>: mov DWORD PTR [esp],eax
0x80483d2 <main+30>: call 0x80482c4 <strcpy@plt>
0x80483d7 <main+35>: lea eax,[ebp-40]
(gdb) continue
Continuing.
Breakpoint 4, 0xb7f076f4 in strcpy () from /lib/tls/i686/cmov/libc.so.6
(gdb) i r eip
eip 0xb7f076f4 0xb7f076f4 <strcpy+4>
(gdb) x/5i $eip
0xb7f076f4 <strcpy+4>: mov esi,DWORD PTR [ebp+8]
0xb7f076f7 <strcpy+7>: mov eax,DWORD PTR [ebp+12]
0xb7f076fa <strcpy+10>: mov ecx,esi
0xb7f076fc <strcpy+12>: sub ecx,eax
0xb7f076fe <strcpy+14>: mov edx,eax
(gdb) continue
Continuing.
Breakpoint 3, main () at char_array2.c:8
8 printf(str_a);
(gdb) i r eip
eip 0x80483d7 0x80483d7 <main+35>
(gdb) x/5i $eip
0x80483d7 <main+35>: lea eax,[ebp-40]
0x80483da <main+38>: mov DWORD PTR [esp],eax
0x80483dd <main+41>: call 0x80482d4 <printf@plt>
0x80483e2 <main+46>: leave
0x80483e3 <main+47>: ret
(gdb)
