LLDB指令

平时开发的过程中使用Xcode都是图形化操作习惯了,要是脱离了xcode你还能调试代码吗,恩,Xcode已经把我们惯坏了,不管怎样,作为一个开发对于了解图形操作背后的东西应该要了解。

申明:本文的[]都表示命令简写

一、增加方法断点

  • breakpoint set --name[-n] "方法名称"
  • breakpoint set --address[-a] 方法的内存地址
15428751580151.jpg

上面4个都是等价的,通过breakpoint list查看已经添加的断点

  • 模糊设置断点 breakpoint set -r 方法名称,r 是正则的意思

    (lldb) breakpoint set -r foo
    Breakpoint 2: 136 locations.
    

    发现有136个地方包含了foo字符串的方法,通过breakpoint list查看可以知道在哪里有这个方法,输出太多这边就截取一部分。

    (lldb) breakpoint list
    Current breakpoints:
    1: file = '/Users/fangshufeng/Desktop/thirdPart/image/Image/Image/ViewController.m', line = 24, exact_match = 0, locations = 1, resolved = 1, hit count = 2
    
      1.1: where = Image`-[ViewController touchesBegan:withEvent:] + 77 at ViewController.m:24, address = 0x000000010a4f768d, resolved, hit count = 2 
    
    2: regex = 'foo', locations = 136, resolved = 136, hit count = 2
      2.1: where = Image`-[ViewController foo] + 23 at ViewController.m:30, address = 0x000000010a4f76f7, resolved, hit count = 2 
      2.2: where = libbsm.0.dylib`au_print_xml_footer, address = 0x000000010ce5d665, resolved, hit count = 0 
      2.3: where = libsystem_kernel.dylib`proc_reset_footprint_interval, address = 0x000000010d5254ed, resolved, hit count = 0 
      
     [...]
      
    
  • 开关断点

    • breakpoint disable 断点编号(让某个断点不可用但是不是删除)
    • breakpoint enable 断点编号(让断点由不可用到可用)
    • breakpoint delete 断点编号 (删除断点不可恢复,需重新添加,不加编号则让你选择是否全部删除)
15428758913025.jpg

二、线程断点

源码调试

这个平时用的最多了,看下图

  • thread continue [continue] [c ] : 程序继续
  • thread step-over [next] [n] : 单步运⾏,把子函数当做整体⼀一步执行
  • thread step-in [step] [s] : 单步运⾏,遇到子函数会进入⼦函数
  • thread step-out [finish] : 直接执行完函数,返回函数调用处

太常用不贴代码了

15428763316698.jpg
  • thread backtrace [bt]:查看调用栈回溯
15428766389548.jpg

如图有时想查看代码的调用堆栈,但是xcode无法查看全,左边的地方只能看到部分,当然你可以点击这个地方,去查看。

15428767683217.jpg

也可以通过命令thread backtrace或者bt

15428770034517.jpg

frame为栈帧的意思,想了解函数栈帧的点击此处

  • frame variable :查看函数栈帧内的局部变量的值
(lldb) frame variable
(ViewController *) self = 0x00007fe390a04960
(SEL) _cmd = "touchesBegan:withEvent:"
(__NSSetM *) touches = 0x0000600003d30640 1 element
(UITouchesEvent *) event = 0x0000600000f66250
(int) a = 10

我们知道oc的方法内置了self_cmd参数,所以上面有self_cmd

汇编代码调试

开启汇编模式

15428781223072.jpg

和源码的区别是

  • ni : 单步运⾏,把子函数当做整体⼀一步执行
  • si: 单步运⾏,遇到子函数会进入⼦函数

三、内存断点

有时候想看某个内存发生改变的时候触发断点

  • watchpoint set variable 变量
  • watchpoint set variable 地址

我们给vc增加一个属性bar

- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event {
    NSLog(@"fff");
    [self foo];
  
}


- (void)foo {
    NSLog(@"--foo--");
    NSLog(@"--foo2--");
    NSLog(@"--foo3--");
    
    for ( int i = 0; i < 3; i++) {
        self.bar += 10;
    }
}

通过该命令,每当内存地址内容被修改都会断到

15428798696567.jpg

还可以配合watchpoint command使用

  • watchpoint command add 断点编号:当内存断点触发的时候执行一些操作

每次改变都会输出值。


15428800472134.jpg
 watchpoint command add 1 // 1 表示 watchpoint 断点编号
Enter your debugger command(s).  Type 'DONE' to end.
> p self.bar;
> DONE // DONE 表示命令输入结束

相关指令如下,见名知意了不需要作介绍了

  • watchpoint list
  • watchpoint disable 断点编号
  • watchpoint enable 断点编号
  • watchpoint delete 断点编号
  • watchpoint command list 断点编号
  • watchpoint command delete 断点编号

四、不常用但很实用的指令

场景1:

15428794369809.jpg

要想代码执行到31行的断点的时候直接返回,不想执行后面的代码,就可以通过thread return指令,当代码执行到31行断点时,thread return可以实现。

场景2:有时崩溃了直接到main函数了,无法知道崩溃的地方

都知道下面的代码会崩溃

15428804652206.jpg

此时崩溃在下面的main函数处

15428805038949.jpg

终端输出信息

15428805244685.jpg

并不知道函数崩溃在哪一行可以使用image lookup指令

(lldb) image lookup -a 0x00000001022365db
      Address: Image[0x00000001000015db] (Image.__TEXT.__text + 203)
      Summary: Image`-[ViewController touchesBegan:withEvent:] + 139 at ViewController.m:30
      

发现崩溃在ViewControllertouchesBegan:withEvent:在30行处。

image lookup周边

  • image lookup -t 类:查看类的属性
(lldb) image lookup -t UIView
Best match found in /Users/fangshufeng/Library/Developer/Xcode/DerivedData/Image-cncplmezlusnyackyzpyppykazhf/Build/Products/Debug-iphonesimulator/Image.app/Image:
id = {0x00001063}, name = "UIView", byte-size = 8, decl = UIView.h:143, compiler_type = "@interface UIView : UIResponder
@property ( readonly,getter = layerClass,setter = ,nonatomic,class ) Class layerClass;
@property ( getter = isUserInteractionEnabled,setter = setUserInteractionEnabled:,assign,readwrite,nonatomic ) BOOL userInteractionEnabled;
@property ( getter = tag,setter = setTag:,assign,readwrite,nonatomic ) NSInteger tag;
@property ( readonly,getter = layer,setter = ,nonatomic ) CALayer * layer;
@property ( readonly,getter = canBecomeFocused,setter = ,nonatomic ) BOOL canBecomeFocused;
@property ( readonly,getter = isFocused,setter = ,nonatomic ) BOOL focused;
@property ( getter = semanticContentAttribute,setter = setSemanticContentAttribute:,assign,readwrite,nonatomic ) UISemanticContentAttribute semanticContentAttribute;
@property ( readonly,getter = effectiveUserInterfaceLayoutDirection,setter = ,nonatomic ) UIUserInterfaceLayoutDirection effectiveUserInterfaceLayoutDirection;
@end"
  • image lookup -n 方法名称:查看方法的位置
(lldb) image lookup -n foo
1 match found in /Users/fangshufeng/Library/Developer/Xcode/DerivedData/Image-cncplmezlusnyackyzpyppykazhf/Build/Products/Debug-iphonesimulator/Image.app/Image:
        Address: Image[0x0000000100001660] (Image.__TEXT.__text + 224)
        Summary: Image`-[ViewController foo] at ViewController.m:33
        
  • image lookup -o -f :可以查看内存的偏移量,这个再逆向中很常用

还有一些常见的指令比如ppoexpression就不说了。

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