LLDB Python访问iOS变量？

Question

作为调试可能与我的UIVIews相关的问题的一部分,我想编写一个从LLDB运行的python脚本.我曾想过在断点和所有视图子节点中提取视图的所有设置,以允许我比较状态.我查看了关于该主题的WWDC视频,然后花时间阅读lldb.llvm.org/scripting.html上的内容,并没有发现它们非常有用.网络搜索示例导致与这些示例没有什么实质性的不同.

我的问题是我正试图找出如何在断点处访问iOS变量.我见过的例子做了转换数字和模仿shell命令之类的事情.有趣的东西,但对我的目的没用.我一直在通过"脚本帮助(lldb.SBValue)"之类的帮助信息阅读我的方式,但由于结果很大并且不清楚使用模式是什么,所以它很慢.我觉得如何遍历一些iOS对象的一个​​很好的例子可以帮助我理解系统.有谁知道一个或可以分享一段代码？

更新:

我写这篇文章是为了帮助我追踪UIView使用中的一个错误.我想做更多的工作来改进它,看看我是否可以显示整个视图树,但这足以解决我的问题,所以我会把它放在这里以节省其他时间.

import lldb
max_depth = 6
filters = {'_view':'UIView *', '_layer':'CALayer *', '_viewFlags':'struct'}

def print_value(var, depth, prefix):
    """ print values and recurse """
    global max_depth
    local_depth = max_depth - depth
    pad = ' ' * local_depth
    name = var.GetName()
    typ = str(var.GetType()).split('\n')[0].split('{')[0].split(':')[0].strip()

    found = name in filters.keys() # only visit filter items children
    if found:
        found = (filters.get(name) == typ)

    value = var.GetValue()
    if value is None or str(value) == '0x00000000':
        value = ''
    else:
        value = ' Val: %s' % value

    if var.GetNumChildren() == 0 and var.IsInScope():
        path = lldb.SBStream()
        var.GetExpressionPath(path)
        path = ' pathData: %s' % path.GetData()
    else:
        path = ''

    print '^' * local_depth, prefix, ' Adr:', var.GetAddress(), ' Name:', name, ' Type:', typ, value, path

    if var.GetNumChildren() > 0:
        if local_depth < 2 or found:
            print pad, var.GetNumChildren(), 'children, to depth', local_depth + 1
            counter = 0
            for subvar in var:
                subprefix = '%d/%d' % (counter, var.GetNumChildren())
                print_value(subvar, depth - 1, subprefix)
                counter += 1

def printvh (debugger, command_line, result, dict):
    """ print view hierarchy """
    global max_depth
    args = command_line.split()
    if len(args) > 0:
        var = lldb.frame.FindVariable(args[0])
        depth = max_depth
        if len(args) > 1:
            depth = int(args[1])
            max_depth = depth
        print_value(var, depth, 'ROOT')
    else:
        print 'pass a variable name and optional depth'

我将以下内容添加到我的.lldbinit中:

script import os, sys
# So that files in my dir takes precedence.
script sys.path[:0] = [os.path.expanduser("~/lldbpy")]
script import views
command script add -f views.printvh printvh

这样我就可以在LLDB提示符下键入"printvh self 3".

Answer 1

也许这会有所帮助.这是一个在遇到断点时如何转储简单局部变量的示例.我没有正确地显示char*数组,我不知道我应该如何获取这些数据以显示它像"帧变量"会显示它但我稍后会在我有空闲时间后想出来.

struct datastore {
  int val1;
  int val2;
  struct {
     int val3;
  } subdata;
  char *name;
};

int main (int argc, char **argv)
{
  struct datastore data = {1, 5, {3}, "a string"};
  return data.val2;
}

Current executable set to 'a.out' (x86_64).
(lldb) br se -l 13
Breakpoint created: 1: file ='a.c', line = 13, locations = 1
(lldb) br comm add -s python
Enter your Python command(s). Type 'DONE' to end.
> def printvar_or_children(var):
>   if var.GetNumChildren() == 0 and var.IsInScope():
>     path = lldb.SBStream()
>     var.GetExpressionPath(path)
>     print '%s: %s' % (path.GetData(), var.GetValue())
>   else: 
>     for subvar in var:
>       printvar_or_children(subvar)
> 
> print 'variables visible at breakpoint %s' % bp_loc
> for var in frame.arguments:
>   printvar_or_children(var)
> for var in frame.locals:
>   printvar_or_children(var)
> 
> DONE
(lldb) r
variables visible at breakpoint 1.1: where = a.out`main + 51 at a.c:13, address = 0x0000000100000f33, resolved, hit count = 1 
argc: 1
*(*(argv)): '/'
data.val1: 1
data.val2: 5
data.subdata.val3: 3
*(data.name): 'a'
Process 84865 stopped
* thread #1: tid = 0x1f03, 0x0000000100000f33 a.out`main + 51 at a.c:13, stop reason = breakpoint 1.1
    frame #0: 0x0000000100000f33 a.out`main + 51 at a.c:13
   10   int main (int argc, char **argv)
   11   {
   12     struct datastore data = {1, 5, {3}, "a string"};
-> 13     return data.val2;
(lldb)

提示 - 出于理智的考虑,我在侧面文本编辑器中处理python并在我进行实验时将其粘贴到lldb中.

如果你在lldb中使用frame variable命令来探索给定停止位置的变量,那么你可以通过在'frame'对象中提供给你的断点python命令的SBFrame来访问它们.

希望有助于您入门.