linux下调试办法

最新推荐文章于 2024-07-16 09:37:01 发布

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本文主要探讨了Linux环境下，当程序出现coredump错误时的调试方法。coredump通常由访问越界、非法引用等内存问题引起，理解其原因并学会有效调试是解决这类问题的关键。

一：starce

1：系统调用

 可以跟踪一个程序的执行的全过程，对于学习内存管理来说是很好的学习途径

执行语句分析：

zhao@zhao:~/ming/543390/charpter05$ ./0501

8

8

zhao@zhao:~/ming/543390/charpter05$ strace ./0501

execve("./0501", ["./0501"], [/* 22 vars */]) = 0      //创建子进程并载入执行程序

brk(0)                                  = 0x25bf000     //进程的初始地址

access("/etc/ld.so.nohwcap", F_OK)      = -1 ENOENT (No such file or directory)

//调用access函数检验/etc/ld.so.nohwcap是否存在

mmap(NULL, 8192, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7efd85da6000

//使用mmap函数进行匿名内存映射，以此来获得8192	B内存空间，起始地址 0x7efd85da6000

access("/etc/ld.so.preload", R_OK)      = -1 ENOENT (No such file or directory)

open("/etc/ld.so.cache", O_RDONLY|O_CLOEXEC) = 3

//调用open函数尝试打开文件，返回的文件描述符为3

fstat(3, {st_mode=S_IFREG|0644, st_size=128075, ...}) = 0

//使用fstat函数获得/etc/ld.so.cache文件信息。

mmap(NULL, 128075, PROT_READ, MAP_PRIVATE, 3, 0) = 0x7efd85d86000

//调用mmap函数将/etc/ld.so.cache文件映射到内存

close(3)                                = 0

//关闭文件描述符3指向的文件

access("/etc/ld.so.nohwcap", F_OK)      = -1 ENOENT (No such file or directory)

open("/usr/lib/x86_64-linux-gnu/libstdc++.so.6", O_RDONLY|O_CLOEXEC) = 3

read(3, "\177ELF\2\1\1\3\0\0\0\0\0\0\0\0\3\0>\0\1\0\0\0 \235\10\0\0\0\0\0"..., 832) = 832

//调用open和read，从/usr/lib/x86_64-linux-gnu/libstdc++.so.6该libc库文件中读取832字节，即读取//elf头信息。这里是获得进程的进入点！

fstat(3, {st_mode=S_IFREG|0644, st_size=1566440, ...}) = 0

mmap(NULL, 3675136, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_DENYWRITE, 3, 0) = 0x7efd85801000

mprotect(0x7efd85973000, 2097152, PROT_NONE) = 0

//使用mpprotect函数对0x7efd85973000开始的2097152字节空间进行保护

mmap(0x7efd85b73000, 49152, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0x172000) = 0x7efd85b73000

mmap(0x7efd85b7f000, 13312, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_ANONYMOUS, -1, 0) = 0x7efd85b7f000

close(3)                                = 0

access("/etc/ld.so.nohwcap", F_OK)      = -1 ENOENT (No such file or directory)

open("/lib/x86_64-linux-gnu/libc.so.6", O_RDONLY|O_CLOEXEC) = 3

read(3, "\177ELF\2\1\1\3\0\0\0\0\0\0\0\0\3\0>\0\1\0\0\0P\t\2\0\0\0\0\0"..., 832) = 832

fstat(3, {st_mode=S_IFREG|0755, st_size=1868984, ...}) = 0

mmap(NULL, 3971488, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_DENYWRITE, 3, 0) = 0x7efd85437000

mprotect(0x7efd855f7000, 2097152, PROT_NONE) = 0

mmap(0x7efd857f7000, 24576, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0x1c0000) = 0x7efd857f7000

mmap(0x7efd857fd000, 14752, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_ANONYMOUS, -1, 0) = 0x7efd857fd000

close(3)                                = 0

access("/etc/ld.so.nohwcap", F_OK)      = -1 ENOENT (No such file or directory)

open("/lib/x86_64-linux-gnu/libm.so.6", O_RDONLY|O_CLOEXEC) = 3

read(3, "\177ELF\2\1\1\3\0\0\0\0\0\0\0\0\3\0>\0\1\0\0\0\0V\0\0\0\0\0\0"..., 832) = 832

fstat(3, {st_mode=S_IFREG|0644, st_size=1088952, ...}) = 0

mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7efd85d85000

mmap(NULL, 3178744, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_DENYWRITE, 3, 0) = 0x7efd8512e000

mprotect(0x7efd85236000, 2093056, PROT_NONE) = 0

mmap(0x7efd85435000, 8192, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0x107000) = 0x7efd85435000

close(3)                                = 0

access("/etc/ld.so.nohwcap", F_OK)      = -1 ENOENT (No such file or directory)

open("/lib/x86_64-linux-gnu/libgcc_s.so.1", O_RDONLY|O_CLOEXEC) = 3

read(3, "\177ELF\2\1\1\0\0\0\0\0\0\0\0\0\3\0>\0\1\0\0\0p*\0\0\0\0\0\0"..., 832) = 832

fstat(3, {st_mode=S_IFREG|0644, st_size=89696, ...}) = 0

mmap(NULL, 2185488, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_DENYWRITE, 3, 0) = 0x7efd84f18000

mprotect(0x7efd84f2e000, 2093056, PROT_NONE) = 0

mmap(0x7efd8512d000, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0x15000) = 0x7efd8512d000

close(3)                                = 0

mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7efd85d84000

mmap(NULL, 8192, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7efd85d82000

arch_prctl(ARCH_SET_FS, 0x7efd85d82740) = 0

mprotect(0x7efd857f7000, 16384, PROT_READ) = 0

mprotect(0x7efd85435000, 4096, PROT_READ) = 0

mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7efd85d81000

mprotect(0x7efd85b73000, 40960, PROT_READ) = 0

mprotect(0x600000, 4096, PROT_READ)     = 0

mprotect(0x7efd85da8000, 4096, PROT_READ) = 0

munmap(0x7efd85d86000, 128075)          = 0

//调用munmap函数，将文件从内存中去映射

brk(0)                                  = 0x25bf000

brk(0x25f1000)                          = 0x25f1000

fstat(0, {st_mode=S_IFCHR|0620, st_rdev=makedev(136, 11), ...}) = 0

read(0, ^CProcess 6838 detached

 <detached ...>

zhao@zhao:~/ming/543390/charpter05$ 

2：gdb调试

新建一个专门存放core文件的目录 cd /data/coredump/

然后把路径设置在这里边，并设置存储格式为core.文件名.线程名

linux默认不生成coredump文件，需要设置大小和权限：ulimit -c [size]

查看coredump文件的ELF头部：readelf  -h  core.0505.7315

注意产生coredump的原因是断错误，对应内存区间里的数据段等，主要是访问越界或者是一些非法的引用导致的

root@zhao:/home/zhao/ming/543390/charpter05# gdb 0505 core.0505.7315 

可执行文件应该和core文件一起调试！

2：top linux的资源管理器

2：vargrind内存分析

root@zhao:/home/zhao/ming/543390/charpter05# /usr/bin/valgrind ./0508

#include<iostream>

#include<stdlib.h>

using namespace std;

void func(){

    int *x=(int *)malloc( 10 * sizeof ( int ) ) ;

    x[10]=0;

}

int main(){

    func();

    cout<<"done"<<endl;

    return 0;

}

==17523== Memcheck, a memory error detector

==17523== Copyright (C) 2002-2015, and GNU GPL'd, by Julian Seward et al.

==17523== Using Valgrind-3.11.0 and LibVEX; rerun with -h for copyright info

==17523== Command: ./0508

==17523== 

==17523== Invalid write of size 4            //可以看出这里有一个非法写操作

==17523==    at 0x4008B7: func() (0508test.cpp:6)

==17523==    by 0x4008C8: main (0508test.cpp:9)

==17523==  Address 0x5ab6ca8 is 0 bytes after a block of size 40 alloc'd

==17523==    at 0x4C2DB8F: malloc (in /usr/lib/valgrind/vgpreload_memcheck-amd64-linux.so)

==17523==    by 0x4008AA: func() (0508test.cpp:5)

==17523==    by 0x4008C8: main (0508test.cpp:9)

==17523== 

done

==17523== 

==17523== HEAP SUMMARY:    //内存泄漏

==17523==     in use at exit: 72,744 bytes in 2 blocks

==17523==   total heap usage: 3 allocs, 1 frees, 73,768 bytes allocated

==17523== 

==17523== LEAK SUMMARY:

==17523==    definitely lost: 40 bytes in 1 blocks

==17523==    indirectly lost: 0 bytes in 0 blocks

==17523==      possibly lost: 0 bytes in 0 blocks

==17523==    still reachable: 72,704 bytes in 1 blocks

==17523==         suppressed: 0 bytes in 0 blocks

==17523== Rerun with --leak-check=full to see details of leaked memory

==17523== 

==17523== For counts of detected and suppressed errors, rerun with: -v

==17523== ERROR SUMMARY: 1 errors from 1 contexts (suppressed: 0 from 0)

root@zhao:/home/zhao/ming/543390/charpter05# 