linux下如何一步一步调试

[starstargao]

如题

[starstargao]

跟综一个别人写的加密算法
AES
快点
各位大侠，指导我如何使用

[wxywh]

用gdb中的step.
具体看http://www.csdn.net/develop/read_article.asp?id=19384

[Kernel_Don]

编译时用gcc -ggdb3 -o exefile sourfile
然后
gdb exefile
break 断点位置
run
step
...

[yhbttfile]

使用GDB。

下面是一个例子：
Chapter 3. A Sample gdb Session
You can use this manual at your leisure to read all about gdb. However, a handful of commands are enough to get started using the debugger. This chapter illustrates those commands.

One of the preliminary versions of gnu m4 (a generic macro processor) exhibits the following bug: sometimes, when we change its quote strings from the default, the commands used to capture one macro definition within another stop working. In the following short m4 session, we define a macro foo which expands to 0000; we then use the m4 built-in defn to define bar as the same thing. However, when we change the open quote string to QUOTE and the close quote string to UNQUOTE, the same procedure fails to define a new synonym baz:

$ cd gnu/m4
$ ./m4define(foo,0000)foo
0000
define(bar,defn(`foo'))bar
0000
changequote(QUOTE,UNQUOTE)define(baz,defn(QUOTEfooUNQUOTE))bazC-d
m4: End of input: 0: fatal error: EOF in string

Let us use gdb to try to see what is going on.

$ gdb m4
gdb is free software and you are welcome to distribute copies
of it under certain conditions; type "show copying" to see
the conditions.
There is absolutely no warranty for gdb; type "show warranty"
for details.

gdb 6.0, Copyright 1999 Free Software Foundation, Inc...
(gdb)

gdb reads only enough symbol data to know where to find the rest when needed; as a result, the first prompt comes up very quickly. We now tell gdb to use a narrower display width than usual, so that examples fit in this manual.

(gdb) set width 70
We need to see how the m4 built-in changequote works. Having looked at the source, we know the relevant subroutine is m4_changequote, so we set a breakpoint there with the gdb break command.

(gdb) break m4_changequote
Breakpoint 1 at 0x62f4: file builtin.c, line 879.

Using the run command, we start m4 running under gdb control; as long as control does not reach the m4_changequote subroutine, the program runs as usual:

(gdb) run
Starting program: /work/Editorial/gdb/gnu/m4/m4
define(foo,0000)foo
0000

To trigger the breakpoint, we call changequote. gdb suspends execution of m4, displaying information about the context where it stops.

changequote(QUOTE,UNQUOTE)

Breakpoint 1, m4_changequote (argc=3, argv=0x33c70)
at builtin.c:879
879 if (bad_argc(TOKEN_DATA_TEXT(argv[0]),argc,1,3))

Now we use the command n (next) to advance execution to the next line of the current function.

(gdb) n
882 set_quotes((argc = 2) ? TOKEN_DATA_TEXT(argv[1]) : nil,

set_quotes looks like a promising subroutine. We can go into it by using the command s (step) instead of next. step goes to the next line to be executed in any subroutine, so it steps into set_quotes.

(gdb) s
set_quotes (lq=0x34c78 "QUOTE", rq=0x34c88 "UNQUOTE")
at input.c:530
530 if (lquote != def_lquote)

The display that shows the subroutine where m4 is now suspended (and its arguments) is called a stack frame display. It shows a summary of the stack. We can use the backtrace command (which can also be spelled bt), to see where we are in the stack as a whole: the backtrace command displays a stack frame for each active subroutine.

(gdb) bt
#0 set_quotes (lq=0x34c78 "QUOTE", rq=0x34c88 "UNQUOTE")
at input.c:530
#1 0x6344 in m4_changequote (argc=3, argv=0x33c70)
at builtin.c:882
#2 0x8174 in expand_macro (sym=0x33320) at macro.c:242
#3 0x7a88 in expand_token (obs=0x0, t=209696, td=0xf7fffa30)
at macro.c:71
#4 0x79dc in expand_input () at macro.c:40
#5 0x2930 in main (argc=0, argv=0xf7fffb20) at m4.c:195

We step through a few more lines to see what happens. The first two times, we can use s; the next two times we use n to avoid falling into the xstrdup subroutine.

(gdb) s
0x3b5c 532 if (rquote != def_rquote)
(gdb) s
0x3b80 535 lquote = (lq == nil || *lq == '\0') ? def_lquote : xstrdup(lq);
(gdb) n
536 rquote = (rq == nil || *rq == '\0') ? def_rquote : xstrdup(rq);
(gdb) n
538 len_lquote = strlen(rquote);

The last line displayed looks a little odd; we can examine the variables lquote and rquote to see if they are in fact the new left and right quotes we specified. We use the command p (print) to see their values.

(gdb) p lquote
$1 = 0x35d40 "QUOTE"
(gdb) p rquote
$2 = 0x35d50 "UNQUOTE"

lquote and rquote are indeed the new left and right quotes. To look at some context, we can display ten lines of source surrounding the current line with the l (list) command.

(gdb) l
533 xfree(rquote);
534
535 lquote = (lq == nil || *lq == '\0') ? def_lquote : xstrdup (lq);
536 rquote = (rq == nil || *rq == '\0') ? def_rquote : xstrdup (rq);
537
538 len_lquote = strlen(rquote);
539 len_rquote = strlen(lquote);
540 }
541
542 void

Let us step past the two lines that set len_lquote and len_rquote, and then examine the values of those variables.

(gdb) n
539 len_rquote = strlen(lquote);
(gdb) n
540 }
(gdb) p len_lquote
$3 = 9
(gdb) p len_rquote
$4 = 7

That certainly looks wrong, assuming len_lquote and len_rquote are meant to be the lengths of lquote and rquote respectively. We can set them to better values using the p command, since it can print the value of any expression--and that expression can include subroutine calls and assignments.

(gdb) p len_lquote=strlen(lquote)
$5 = 7
(gdb) p len_rquote=strlen(rquote)
$6 = 9

Is that enough to fix the problem of using the new quotes with the m4 built-in defn? We can allow m4 to continue executing with the c (continue) command, and then try the example that caused trouble initially:

(gdb) c
Continuing.

define(baz,defn(QUOTEfooUNQUOTE))

baz
0000

Success! The new quotes now work just as well as the default ones. The problem seems to have been just the two typos defining the wrong lengths. We allow m4 exit by giving it an EOF as input:

C-d
Program exited normally.

The message Program exited normally. is from gdb; it indicates m4 has finished executing. We can end our gdb session with the gdb quit command.

(gdb) quit

[fzel_net]

gcc -g xxx.c
gdb

[mechgoukiteng]

GDB啊


要是调试内核就使用KDB

[vcprogrammer]

http://bbs.chinaunix.net/forum/viewtopic.php?t=275020
在win下可视化调试

[superAfx]

gcc -g abc.c -o abc// -g代表带调试的编译,即在可执行文件中加入了调试信息,通常abc会比
gcc abc.c -o abc所产生的abc大许多
///////////////////////////////////////////////////////////////////////////////
gdb abc//-- 调试abc
-break main//-- 在main函数的入口处设置断点,一运行就会碰到此断点
-r //-- run运行程序,程序会在断点处停下,这里在main()处停下
-s //-- step,单步调试
-print var//-- 将此时的变量值打印出来var为变量名
//-- 调试结束以后...
- q//-- 退出

[anonimousboy]

insight 图形化
ddd 图形化
gdb 非图形化

强烈建议上两个