内存转储格式如gdb中的xxd

时间:2012-02-10 18:47:58

标签: python debugging gdb pretty-print

我正在尝试检查包含二进制格式化消息的缓冲区,但也包含字符串数据。举个例子,我正在使用这个C代码:

int main (void) {
    char buf[100] = "\x01\x02\x03\x04String Data\xAA\xBB\xCC";

    return 0;
}

我想得到一个buf的十六进制转储,格式类似于xxd(我不在乎它是否完全匹配,我真的在寻找什么是一个带有可打印字符的十六进制转储。)

在GDB内部我可以使用类似的东西:

(gdb) x /100bx buf
0x7fffffffdf00: 0x01    0x02    0x03    0x04    0x53    0x74    0x72    0x69
0x7fffffffdf08: 0x6e    0x67    0x20    0x44    0x61    0x74    0x61    0xaa
0x7fffffffdf10: 0xbb    0xcc    0x00    0x00    0x00    0x00    0x00    0x00
0x7fffffffdf18: 0x00    0x00    0x00    0x00    0x00    0x00    0x00    0x00
0x7fffffffdf20: 0x00    0x00    0x00    0x00    0x00    0x00    0x00    0x00
0x7fffffffdf28: 0x00    0x00    0x00    0x00    0x00    0x00    0x00    0x00
0x7fffffffdf30: 0x00    0x00    0x00    0x00    0x00    0x00    0x00    0x00
0x7fffffffdf38: 0x00    0x00    0x00    0x00    0x00    0x00    0x00    0x00
0x7fffffffdf40: 0x00    0x00    0x00    0x00    0x00    0x00    0x00    0x00
0x7fffffffdf48: 0x00    0x00    0x00    0x00    0x00    0x00    0x00    0x00
0x7fffffffdf50: 0x00    0x00    0x00    0x00    0x00    0x00    0x00    0x00
0x7fffffffdf58: 0x00    0x00    0x00    0x00    0x00    0x00    0x00    0x00

这很好,但很难以这种方式挑选字符串......或者我可以使用

(gdb) x /100bs buf
0x7fffffffdf00:  "\001\002\003\004String Data\252\273\314"
0x7fffffffdf13:  ""
0x7fffffffdf14:  ""
0x7fffffffdf15:  ""
0x7fffffffdf16:  ""
0x7fffffffdf17:  ""
...

这使得难以阅读二进制部分...我正在处理的实际消息中也有很多ascii nul,所以它真的看起来像是一团糟。

我能想到的最好的就是这样做:

(gdb) dump binary memory dump.bin buf buf+100

然后

$ xxd dump.bin
0000000: 0102 0304 5374 7269 6e67 2044 6174 61aa  ....String Data.
0000010: bbcc 0000 0000 0000 0000 0000 0000 0000  ................
0000020: 0000 0000 0000 0000 0000 0000 0000 0000  ................
0000030: 0000 0000 0000 0000 0000 0000 0000 0000  ................
0000040: 0000 0000 0000 0000 0000 0000 0000 0000  ................
0000050: 0000 0000 0000 0000 0000 0000 0000 0000  ................
0000060: 0000 0000                                ....

但每次这样做都很痛苦。我认为之前有人想过这个,所以想知道是否有人在gdb中找到了办法。另外,你会以这种方式丢失原始内存中的地址。

我正在使用内置python支持的GDB 7.4,所以我愿意使用漂亮的打印机或类似的,但我不知道如何设置它。

5 个答案:

答案 0 :(得分:65)

(gdb) define xxd
>dump binary memory dump.bin $arg0 $arg0+$arg1
>shell xxd dump.bin
>end
(gdb) xxd &j 10 
0000000: 0000 0000 0000 0000 0000 0000 4d8c a7f7  ............M...
0000010: ff7f 0000 0000 0000 0000 0000 c8d7 ffff  ................
0000020: ff7f 0000 0000 0000

似乎很容易; - )

您可能会编写一个Python脚本(现代GDB版本具有嵌入式Python解释器)来执行相同操作,并且无需“外出”。

答案 1 :(得分:24)

所以,我最终玩了python界面并想出了这个:

import gdb
from curses.ascii import isgraph

def groups_of(iterable, size, first=0):
    first = first if first != 0 else size
    chunk, iterable = iterable[:first], iterable[first:]
    while chunk:
        yield chunk
        chunk, iterable = iterable[:size], iterable[size:]

class HexDump(gdb.Command):
    def __init__(self):
        super (HexDump, self).__init__ ('hex-dump', gdb.COMMAND_DATA)

    def invoke(self, arg, from_tty):
        argv = gdb.string_to_argv(arg)
        if len(argv) != 2:
            raise gdb.GdbError('hex-dump takes exactly 2 arguments.')
        addr = gdb.parse_and_eval(argv[0]).cast(
            gdb.lookup_type('void').pointer())
        try:
            bytes = int(gdb.parse_and_eval(argv[1]))
        except ValueError:
            raise gdb.GdbError('Byte count numst be an integer value.')

        inferior = gdb.selected_inferior()

        align = gdb.parameter('hex-dump-align')
        width = gdb.parameter('hex-dump-width')
        if width == 0:
            width = 16

        mem = inferior.read_memory(addr, bytes)
        pr_addr = int(str(addr), 16)
        pr_offset = width

        if align:
            pr_offset = width - (pr_addr % width)
            pr_addr -= pr_addr % width

        for group in groups_of(mem, width, pr_offset):
            print '0x%x: ' % (pr_addr,) + '   '*(width - pr_offset),
            print ' '.join(['%02X' % (ord(g),) for g in group]) + \
                '   ' * (width - len(group) if pr_offset == width else 0) + ' ',
            print ' '*(width - pr_offset) +  ''.join(
                [g if isgraph(g) or g == ' ' else '.' for g in group])
            pr_addr += width
            pr_offset = width

class HexDumpAlign(gdb.Parameter):
    def __init__(self):
        super (HexDumpAlign, self).__init__('hex-dump-align',
                                            gdb.COMMAND_DATA,
                                            gdb.PARAM_BOOLEAN)

    set_doc = 'Determines if hex-dump always starts at an "aligned" address (see hex-dump-width'
    show_doc = 'Hex dump alignment is currently'

class HexDumpWidth(gdb.Parameter):
    def __init__(self):
        super (HexDumpWidth, self).__init__('hex-dump-width',
                                            gdb.COMMAND_DATA,
                                            gdb.PARAM_INTEGER)

    set_doc = 'Set the number of bytes per line of hex-dump'

    show_doc = 'The number of bytes per line in hex-dump is'

HexDump()
HexDumpAlign()
HexDumpWidth()

我意识到它可能不是最美丽和最优雅的解决方案,但它可以完成工作并作为初稿起作用。它可以包含在~/.gdbinit中:

python
sys.path.insert(0, '/path/to/module/dir')
import hexdump
end

然后可以像上面的程序一样使用:

(gdb) hex-dump buf 100
0x7fffffffdf00:  01 02 03 04 53 74 72 69 6E 67 20 44 61 74 61 AA  ....String Data.
0x7fffffffdf10:  BB CC 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
0x7fffffffdf20:  00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
0x7fffffffdf30:  00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
0x7fffffffdf40:  00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
0x7fffffffdf50:  00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
0x7fffffffdf60:  00 00 00 00                                      ....

以及其他一些措施:

(gdb) set hex-dump-align on
Determines if hex-dump always starts at an "aligned" address (see hex-dump-width
(gdb) hex-dump &buf[5] 95
0x7fffffffdf00:                 74 72 69 6E 67 20 44 61 74 61 AA       tring Data.
0x7fffffffdf10:  BB CC 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
0x7fffffffdf20:  00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
0x7fffffffdf30:  00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
0x7fffffffdf40:  00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
0x7fffffffdf50:  00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
0x7fffffffdf60:  00 00 00 00                                      ....

(gdb) set hex-dump-width 8
Set the number of bytes per line of hex-dump
(gdb) hex-dump &buf[5] 95
0x7fffffffdf00:                 74 72 69       tri
0x7fffffffdf08:  6E 67 20 44 61 74 61 AA  ng Data.
0x7fffffffdf10:  BB CC 00 00 00 00 00 00  ........
0x7fffffffdf18:  00 00 00 00 00 00 00 00  ........
0x7fffffffdf20:  00 00 00 00 00 00 00 00  ........
0x7fffffffdf28:  00 00 00 00 00 00 00 00  ........
0x7fffffffdf30:  00 00 00 00 00 00 00 00  ........
0x7fffffffdf38:  00 00 00 00 00 00 00 00  ........
0x7fffffffdf40:  00 00 00 00 00 00 00 00  ........
0x7fffffffdf48:  00 00 00 00 00 00 00 00  ........
0x7fffffffdf50:  00 00 00 00 00 00 00 00  ........
0x7fffffffdf58:  00 00 00 00 00 00 00 00  ........
0x7fffffffdf60:  00 00 00 00              ....

没有承诺没有错误:)。如果人们感兴趣的话,我可能会在github或其他东西中坚持下去。

我只用GDB 7.4测试过它。

答案 2 :(得分:2)

User FatalError

解决方案的改编版本
  • 适用于python 3
  • 添加了一个hex-col-header
  • 长度参数可选
  • 重命名为hd

实施例

hd 0xbfffe4f1

hd 0xbfffe4f1 500

import gdb
from curses.ascii import isgraph

def groups_of(iterable, size, first=0):
    first = first if first != 0 else size
    chunk, iterable = iterable[:first], iterable[first:]
    while chunk:
        yield chunk
        chunk, iterable = iterable[:size], iterable[size:]

class HexDump(gdb.Command):
    def __init__(self):
        super (HexDump, self).__init__ ('hd', gdb.COMMAND_DATA)

    def invoke(self, arg, from_tty):
        argv = gdb.string_to_argv(arg)

        addr = gdb.parse_and_eval(argv[0]).cast(
            gdb.lookup_type('void').pointer())
        if len(argv) == 2:
             try:
                 bytes = int(gdb.parse_and_eval(argv[1]))
             except ValueError:
                 raise gdb.GdbError('Byte count numst be an integer value.')
        else:
             bytes = 500

        inferior = gdb.selected_inferior()

        align = gdb.parameter('hex-dump-align')
        width = gdb.parameter('hex-dump-width')
        if width == 0:
            width = 16

        mem = inferior.read_memory(addr, bytes)
        pr_addr = int(str(addr), 16)
        pr_offset = width

        if align:
            pr_offset = width - (pr_addr % width)
            pr_addr -= pr_addr % width
        start=(pr_addr) & 0xff;


        print ('            ' , end="")
        print ('  '.join(['%01X' % (i&0x0f,) for i in range(start,start+width)]) , end="")
        print ('  ' , end="")       
        print (' '.join(['%01X' % (i&0x0f,) for i in range(start,start+width)]) )

        for group in groups_of(mem, width, pr_offset):
            print ('0x%x: ' % (pr_addr,) + '   '*(width - pr_offset), end="")
            print (' '.join(['%02X' % (ord(g),) for g in group]) + \
                '   ' * (width - len(group) if pr_offset == width else 0) + ' ', end="")    
            print (' '*(width - pr_offset) +  ' '.join(
                [chr( int.from_bytes(g, byteorder='big')) if isgraph( int.from_bytes(g, byteorder='big')   ) or g == ' ' else '.' for g in group]))
            pr_addr += width
            pr_offset = width

class HexDumpAlign(gdb.Parameter):
    def __init__(self):
        super (HexDumpAlign, self).__init__('hex-dump-align',
                                            gdb.COMMAND_DATA,
                                            gdb.PARAM_BOOLEAN)

    set_doc = 'Determines if hex-dump always starts at an "aligned" address (see hex-dump-width'
    show_doc = 'Hex dump alignment is currently'

class HexDumpWidth(gdb.Parameter):
    def __init__(self):
        super (HexDumpWidth, self).__init__('hex-dump-width',
                                            gdb.COMMAND_DATA,
                                            gdb.PARAM_INTEGER)

    set_doc = 'Set the number of bytes per line of hex-dump'

    show_doc = 'The number of bytes per line in hex-dump is'

HexDump()
HexDumpAlign()
HexDumpWidth()

答案 3 :(得分:1)

不幸的是,@ FatalError和@gunthor的版本对我不起作用,所以我自己写了另一个版本。这就是它的样子:

(gdb) xxd hello_string 0xc
00000001_00000f87:                  48 656c 6c6f 0957 6f72         Hello.Wor
00000001_00000f90: 6c64 0a                                  ld.

较新版本的xxd支持-o标志,该标志允许指定要添加到显示的偏移量的偏移量(始终从0000000开始)。

如果xxd -o不可用,则可以使用以下内容正确对齐并显示xxd'的位置地址。

xxd命令:

define xxd
    dump binary memory /tmp/dump.bin $arg0 $arg0+$arg1
    eval "shell xxd-o %p /tmp/dump.bin", $arg0
end

可以说是丑陋的perl脚本xxd-oxxd有偏移量):

#!/usr/bin/env perl
use IPC::Open2; 
$SIG{'__WARN__'} = sub{ die "$0: $!\n" };

my $offset = shift // "0";
$offset = oct($offset) if $offset =~ /^0/;
my $base = $offset >= 2**32 ? 16 : 8;

my $zeroes = $offset % 16;
my $padding = 1 + int($zeroes / 2) + 2*$zeroes;
my $bytestr = "\0" x $zeroes;
{ local $/; $bytestr .= <> }

open2(\*XXD_OUT, \*XXD_IN, "xxd") or die "xxd is not available!";
print XXD_IN $bytestr; close XXD_IN;

if ($zeroes) {
    $_ = <XXD_OUT>;
    s/^(.{50}).{$zeroes}/$1 . (' ' x $zeroes)/ge;
    s/^([[:xdigit:]]+:).{$padding}/$1 . (' ' x $padding)/ge;
    my $newoff = sprintf("%0${base}x",hex($1)+$offset) =~ s/^(.{8})(.{8})$/$1_$2/r;
    s/^([[:xdigit:]]+):/$newoff:/g;
    print
}
while (<XXD_OUT>) {
    s/^([[:xdigit:]]+)(?=:)/sprintf("%0${base}x", hex($1)+$offset-$offset%16) =~ s[^(.{8})(.{8})$][$1_$2]r/ge;
    print
}

欢迎改进! : - )

答案 4 :(得分:0)

我自己的贡献,来自Employed Russian解决方案和Roger Lipscombe的评论:

  • 使用xxd,
  • 保留地址(xxd -o)
  • size参数是可选的
  • 包括小文档

脚本(已通过gdb 7.8.1测试):

define xxd
  if $argc < 2
    set $size = sizeof(*$arg0)
  else
    set $size = $arg1
  end
  dump binary memory dump.bin $arg0 ((void *)$arg0)+$size
  eval "shell xxd -o %d dump.bin; rm dump.bin", ((void *)$arg0)
end
document xxd
  Dump memory with xxd command (keep the address as offset)

  xxd addr [size]
    addr -- expression resolvable as an address
    size -- size (in byte) of memory to dump
            sizeof(*addr) is used by default
end

示例:

(gdb) p &m_data
$1 = (data_t *) 0x200130dc <m_data>

(gdb) p sizeof(m_data)
$2 = 32

(gdb) xxd &m_data 32
200130dc: 0300 0000 e87c 0400 0000 0000 0100 0000  .....|..........
200130ec: 0c01 0000 b831 0020 0100 0000 0100 0000  .....1. ........

(gdb) xxd &m_data
200130dc: 0300 0000 e87c 0400 0000 0000 0100 0000  .....|..........
200130ec: 0c01 0000 b831 0020 0100 0000 0100 0000  .....1. ........

(gdb) help xxd
  Dump memory with xxd command (keep the address as offset)

  xxd addr [size]
    addr -- expression resolvable as an address
    size -- size (in byte) of memory to dump
            sizeof(*addr) is used by default