Simple GDB case
浏览数：20 /
时间：2015年06月12日
to be added...
gdb a.out
[Inferior 1 (process 9718) exited with code 05]
(gdb) list
Line number 15 out of range; t.c has 14 lines.
(gdb) list 1
1 #include
2 char foo(char *s)
3 {
4 char *c=s;
5 return *(c+2);
6 }
7 int main()
8 {
9 char arr[5]="abc\n";
10 char b=foo(arr);
(gdb)
11 printf("%c\n",b);
12 printf("%s\n",arr);
13
14 }
(gdb) disass /m
Dump of assembler code for function main:
8 {
0x08048449 <+0>: push ?p
0x0804844a <+1>: mov %esp,?p
0x0804844c <+3>: and $0xfffffff0,%esp
0x0804844f <+6>: sub $0x20,%esp
9 char arr[5]="abc\n";
0x08048452 <+9>: movl $0xa636261,0x1a(%esp)
0x0804845a <+17>: movb $0x0,0x1e(%esp)
10 char b=foo(arr);
=> 0x0804845f <+22>: lea 0x1a(%esp),?x //eip
0x08048463 <+26>: mov ?x,(%esp)
0x08048466 <+29>: call 0x8048434
0x0804846b <+34>: mov %al,0x1f(%esp)
(gdb) info registers esp
esp 0xbfffefb0 0xbfffefb0
#another shell
johv@linux-8f1f:~> echo $((0xbfffefb0+0x1a))
3221221322
johv@linux-8f1f:~> echo ‘obase=16;base=10;3221221322‘ | bc
BFFFEFCA
(gdb) x /s 0xbfffefca
0xbfffefca: "abc\n" //find the "abc\n"
(gdb)
gdb) help catch
Set catchpoints to catch events.
List of catch subcommands:
catch assert -- Catch failed Ada assertions
catch catch -- Catch an exception
catch exception -- Catch Ada exceptions
catch exec -- Catch calls to exec
catch fork -- Catch calls to fork
catch syscall -- Catch system calls by their names and/or numbers
catch throw -- Catch an exception
catch vfork -- Catch calls to vfork
Type "help catch" followed by catch subcommand name for
full documentation.
Type "apropos word" to search for commands related to "word".
Command name abbreviations are allowed if unambiguous.
(gdb)
(gdb) info breakpoints
Num Type Disp Enb Address What
7 breakpoint keep y 0x08048440 in foo
at t.c:5
breakpoint already hit 1 time
8 catchpoint keep y syscall ""
9 breakpoint keep y exception catch
10 catchpoint keep y fork
(gdb) disable breakpoints 7
(gdb)
condition
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