gcc4.4下实现backtrace代码

 最近在一块新的板子下作开发， 有些变量发生异常（就是我们不想到的值），可以加上backtrace，知道是哪个函数调用它，导致出现异常， 就像死机了，你可以gdb和core文件用bt 命令，查看死机在哪里（有一种 情况 不能看见， 就是发生信号异常不在本文范围 ）， 本人感觉还有用， 关说不炼、假把式，下面是实现代码：

首先实现核心代码backtrace函数：

 

extern void * __libc_stack_end;

# define BOUNDED_N(PTR, N) (PTR)
#define BOUNDED_1(PTR) BOUNDED_N (PTR, 1)
/* Get some notion of the current stack. Need not be exactly the top
of the stack, just something somewhere in the current frame. */
#ifndef CURRENT_STACK_FRAME
# define CURRENT_STACK_FRAME ({ char __csf; &__csf; })
#endif

/* By default we assume that the stack grows downward. */
#ifndef INNER_THAN
# define INNER_THAN <
#endif

/* By default assume the `next' pointer in struct layout points to the
next struct layout. */
#ifndef ADVANCE_STACK_FRAME
# define ADVANCE_STACK_FRAME(next) BOUNDED_1 ((struct layout *) (((int)next) - 4))
#endif

/* By default, the frame pointer is just what we get from gcc. */
#ifndef FIRST_FRAME_POINTER
# define FIRST_FRAME_POINTER (__builtin_frame_address (0) - 4)
#endif

int backtrace (void **array, int size)
{
struct layout *current;
void *top_frame;
void *top_stack;
int cnt = 0;

top_frame = FIRST_FRAME_POINTER;
top_stack = CURRENT_STACK_FRAME;

/* We skip the call to this function, it makes no sense to record it. */
current = BOUNDED_1 ((struct layout *) top_frame);
while (cnt <size)
{
if ((void *) current->fp INNER_THAN top_stack
|| !((void *) current->fp INNER_THAN __libc_stack_end))
{
/* This means the address is out of range. Note that for the
toplevel we see a frame pointer with value NULL which clearly is
out of range. */
break;
}

array[cnt] = current->lr;
cnt++;

current = ADVANCE_STACK_FRAME (current->fp);
}
/*
* In leaf function
* gcc not push lr when call it
*/
printf(" ");
return cnt;
}

extern void * __libc_stack_end;

# define BOUNDED_N(PTR, N) (PTR)
#define BOUNDED_1(PTR) BOUNDED_N (PTR, 1)
/* Get some notion of the current stack.  Need not be exactly the top
   of the stack, just something somewhere in the current frame.  */
#ifndef CURRENT_STACK_FRAME
# define CURRENT_STACK_FRAME  ({ char __csf; &__csf; })
#endif

/* By default we assume that the stack grows downward.  */
#ifndef INNER_THAN
# define INNER_THAN <
#endif

/* By default assume the `next' pointer in struct layout points to the
   next struct layout.  */
#ifndef ADVANCE_STACK_FRAME
# define ADVANCE_STACK_FRAME(next) BOUNDED_1 ((struct layout *) (((int)next) - 4))
#endif

/* By default, the frame pointer is just what we get from gcc.  */
#ifndef FIRST_FRAME_POINTER
# define FIRST_FRAME_POINTER  (__builtin_frame_address (0) - 4)
#endif

int backtrace (void **array, int size)
{
    struct layout *current;
    void *top_frame;
    void *top_stack;
    int cnt = 0;

    top_frame = FIRST_FRAME_POINTER;
    top_stack = CURRENT_STACK_FRAME;

    /* We skip the call to this function, it makes no sense to record it.  */
    current = BOUNDED_1 ((struct layout *) top_frame);
    while (cnt < size)
    {
        if ((void *) current->fp INNER_THAN top_stack
                || !((void *) current->fp INNER_THAN __libc_stack_end))
        {
            /* This means the address is out of range.  Note that for the
               toplevel we see a frame pointer with value NULL which clearly is
               out of range.  */
            break;
        }

        array[cnt] = current->lr;
        cnt++;

        current = ADVANCE_STACK_FRAME (current->fp);
    }
    /*
     * In leaf function
     * gcc not push lr when call it
     */
    printf(" ");
    return cnt;
}

下面就是将她加入一个文件中了

 

 

/**
* @fn writeToFile
* @brief backtrace写入文件
* @param[in] *pIndex: 目录
* *pAppend: 附加信息
* @param[out]
* @return BSTAR_OK BSTAR_FAIL
*/
int writeToFile(constchar *pIndex, constchar* pAppend)
{
int j, nptrs = 0;
void *buffer[100];
char str[1024] = {0};
int fd = 0;

if(NULL == pIndex)
{
fprintf(stderr, "the Index is NULL!\n");
return -1;
}

if((fd = open(pIndex, O_RDWR|O_APPEND, 0644)) < 0)
{
fd = open(pIndex, O_RDWR|O_CREAT|O_APPEND, 0644);
}

nptrs = backtrace(buffer, 100);

if(NULL != pAppend)
{
write(fd, pAppend, strlen(pAppend));
memset(str, 0, 1024);
}

for (j = 0; j < nptrs; j++)
{
sprintf(str, "%p\n", buffer[j]);
write(fd, str, strlen(str));
memset(str, 0, 1024);
}

write(fd, "================\n", strlen("================\n"));
close(fd);

return 0;
}

/**
 * @fn          writeToFile
 * @brief       backtrace写入文件
 * @param[in]   *pIndex: 目录
 *              *pAppend: 附加信息
 * @param[out]
 * @return      BSTAR_OK    BSTAR_FAIL
 */
int writeToFile(const char *pIndex, const char* pAppend)
{
    int j, nptrs = 0;
    void *buffer[100];
    char str[1024] = {0};
    int fd = 0;

    if(NULL == pIndex)
    {
       fprintf(stderr, "the Index is NULL!\n");
       return -1;
    }

    if((fd = open(pIndex, O_RDWR|O_APPEND, 0644)) < 0)
    {
        fd = open(pIndex, O_RDWR|O_CREAT|O_APPEND, 0644);
    }

    nptrs = backtrace(buffer, 100);

    if(NULL != pAppend)
    {
        write(fd, pAppend, strlen(pAppend));
        memset(str, 0, 1024);
    }

    for (j = 0; j < nptrs; j++)
    {
        sprintf(str, "%p\n", buffer[j]);
        write(fd, str, strlen(str));
        memset(str, 0, 1024);
    }

    write(fd, "================\n", strlen("================\n"));
    close(fd);

    return 0;
}

好了，就是这些了， 你可以将她编写成so库， 那样就方便调用了