Question

考虑以下（破碎）代码：

#include <iostream>
#include <memory>

using namespace std;

class Test {
    public:
        unique_ptr<string> s;

        Test() : s(NULL) {
        }

        void update(string& st) {
            s = unique_ptr<string>(&(st));
        }
};


void update(Test& t) {
    string s("Hello to you");
    t.update(s);
}

int main() {
    Test t;
    update(t);
    cout << *t.s << endl;
}

这里我们在方法Test::update()中有错误，我们没有制作对象的uniq副本。所以当程序在macOS下运行时，你会得到：

$ ./test
Hello t��E]�
test(44981,0x7fff99ba93c0) malloc: *** error for object 0x7fff5d45b690: pointer being freed was not allocated
*** set a breakpoint in malloc_error_break to debug
[1]    44981 abort      ./test

我已经能够使用lldb成功调试此案例。即使没有在malloc_error_break中设置断点，也只需运行应用程序，直到它被SIGABRT处理程序捕获。

lldb ./test

(lldb) target create "./test"
Current executable set to './test' (x86_64).

(lldb) run
Process 44993 launched: './test' (x86_64)
Hello t��_�
test(44993,0x7fff99ba93c0) malloc: *** error for object 0x7fff5fbff680: pointer being freed was not allocated
*** set a breakpoint in malloc_error_break to debug
Process 44993 stopped
* thread #1, queue = 'com.apple.main-thread', stop reason = signal SIGABRT
    frame #0: 0x00007fff90d6cd42 libsystem_kernel.dylib`__pthread_kill + 10
libsystem_kernel.dylib`__pthread_kill:
->  0x7fff90d6cd42 <+10>: jae    0x7fff90d6cd4c            ; <+20>
    0x7fff90d6cd44 <+12>: movq   %rax, %rdi
    0x7fff90d6cd47 <+15>: jmp    0x7fff90d65caf            ; cerror_nocancel
    0x7fff90d6cd4c <+20>: retq
Target 0: (test) stopped.

(lldb) bt
* thread #1, queue = 'com.apple.main-thread', stop reason = signal SIGABRT
  * frame #0: 0x00007fff90d6cd42 libsystem_kernel.dylib`__pthread_kill + 10
    frame #1: 0x00007fff90e5a457 libsystem_pthread.dylib`pthread_kill + 90
    frame #2: 0x00007fff90cd2420 libsystem_c.dylib`abort + 129
    frame #3: 0x00007fff90dc1fe7 libsystem_malloc.dylib`free + 530
    frame #4: 0x0000000100001f7b test`Test::~Test() [inlined] std::__1::default_delete<std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> > >::operator(this=0x00007fff5fbff730, __ptr="\a\x94\x99�\x7f\0\0��_�\x7f\0\0\x80�_�\x7f\0\00�_�\x7f\0\00�_�\x7f\0\00�_�\x7f\0\00�_�\x7f\0\00�_�\x7f\0\0��_�\x7f\0\0\x15\x1e\0\0\x01\0\0\0\x80�_�\x7f\0\n0")(std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> >*) const at memory:2397
    frame #5: 0x0000000100001f46 test`Test::~Test() [inlined] std::__1::unique_ptr<std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> >, std::__1::default_delete<std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> > > >::reset(this=0x00007fff5fbff730, __p="") at memory:2603
    frame #6: 0x0000000100001ef3 test`Test::~Test() [inlined] std::__1::unique_ptr<std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> >, std::__1::default_delete<std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> > > >::~unique_ptr(this=0x00007fff5fbff730) at memory:2571
    frame #7: 0x0000000100001ef3 test`Test::~Test() [inlined] std::__1::unique_ptr<std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> >, std::__1::default_delete<std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> > > >::~unique_ptr(this=0x00007fff5fbff730) at memory:2571
    frame #8: 0x0000000100001ef3 test`Test::~Test(this=0x00007fff5fbff730) at main.cpp:6
    frame #9: 0x0000000100001e15 test`Test::~Test(this=0x00007fff5fbff730) at main.cpp:6
    frame #10: 0x0000000100001ab6 test`main at main.cpp:28
    frame #11: 0x00007fff90c3e235 libdyld.dylib`start + 1

现在我看到问题出现在Test析构函数中，从这里开始它就是一块蛋糕。

不幸的是，尝试在macOS下使用gdb调试此案例是完全失败的。这就是我所做的：

$ gdb ./test
GNU gdb (GDB) 8.0.1
Copyright (C) 2017 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.  Type "show copying"
and "show warranty" for details.
This GDB was configured as "x86_64-apple-darwin16.7.0".
Type "show configuration" for configuration details.
For bug reporting instructions, please see:
<http://www.gnu.org/software/gdb/bugs/>.
Find the GDB manual and other documentation resources online at:
<http://www.gnu.org/software/gdb/documentation/>.
For help, type "help".
Type "apropos word" to search for commands related to "word"...
Reading symbols from test...Reading symbols from /Users/bazhenov/Developer/linear-counter/tests/test/test.dSYM/Contents/Resources/DWARF/test...done.
done.

(gdb) run
Starting program: /Users/bazhenov/Developer/linear-counter/tests/test/test
[New Thread 0x1403 of process 45204]
warning: unhandled dyld version (15)
Hello tQ�_�
test(45204,0x7fff99ba93c0) malloc: *** error for object 0x7fff5fbff650: pointer being freed was not allocated
*** set a breakpoint in malloc_error_break to debug

Thread 2 received signal SIGABRT, Aborted.
0x00007fff90d6cd42 in ?? ()

(gdb) bt
#0  0x00007fff90d6cd42 in ?? ()
#1  0x00007fff90e5a457 in ?? ()
#2  0x00007fff5fbff590 in ?? ()
#3  0x0000030700000000 in ?? ()
#4  0x00007fff5fbff590 in ?? ()
#5  0x00007fff5fbff650 in ?? ()
#6  0x00007fff5fbff5a0 in ?? ()
#7  0x00007fff90cd2420 in ?? ()
#8  0xffffffff00000018 in ?? ()
#9  0x00007fff5fbff5b0 in ?? ()
#10 0x00007fffffffffdf in ?? ()
#11 0x00000001000c4000 in ?? ()
#12 0x00007fff5fbff5f0 in ?? ()
#13 0x00007fff90dc1fe7 in ?? ()
#14 0x378b45e65b700074 in ?? ()
#15 0x00007fff99ba00ac in ?? ()
#16 0x0000000000000000 in ?? ()
(gdb)

问题是：为什么gdb无法正确展开堆栈，如果我需要使用gdb获得正确的回溯，我有哪些选项？

Answer 1

为什么gdb无法正确展开堆栈

Mac OS X Sierra与gdb存在一些问题，请参阅this post和gdb bug report。

如果我需要使用gdb
获得正确的回溯，我有哪些选项

您可以尝试降级Mac OS（不知道是否可能）或尝试从错误报告中应用temporary hack patch。

`gdb`无法展开堆栈

1 个答案: