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backtrace test
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‎tools/backtrace/README.md‎

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用于打印调用栈，示例在examples中
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学习于
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> https://blog.csdn.net/nanfeibuyi/article/details/81203021
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>
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> https://blog.csdn.net/littlefang/article/details/17654419
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代码有小部分改动。
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编译时注意 加上
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-fno-omit-frame-pointer
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‎tools/backtrace/examples/Makefile‎

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all:test main
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test:lib.c lib.h
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gcc -g lib.c -fPIC -shared -o libtest.so
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main:main.c
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gcc -g main.c -L./ -ltest -o main
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.PHONY:clean
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clean:
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rm -rf main *.o *.so

‎tools/backtrace/examples/lib.c‎

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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <execinfo.h>
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#include <unistd.h>
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#include "lib.h"
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void exec_shell(char *cmd, char *buf, int buf_size)
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{
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FILE *fp = NULL;
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fp = popen(cmd, "r");
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if(fp == NULL) {
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return;
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}
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while(fgets(buf, buf_size, fp) != NULL);
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pclose(fp);
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return ;
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}
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int get_backtrace_string(void* bt,char* buff,int buff_size)
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{
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char cmd[128] = {0};
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char property[256]={0};
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char not_care1[128]={0},not_care2[128]={0},not_care3[128]={0};
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char library_path[256]={0};
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char exe_path[256],function_name[256];
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char maps_line[1024]={0};
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void* offset_start,*offset_end;
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int maps_column_num=0, n;
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FILE* fd_maps=NULL;
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fd_maps=fopen("/proc/self/maps","r");
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unsigned long exe_symbol_offset=0;
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char unknow_position[12] ="??:?\n";
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unsigned char unknow_position_len = strlen(unknow_position);
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if(fd_maps==NULL)
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{
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return -1;
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}
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while(NULL!=fgets(maps_line,sizeof(maps_line),fd_maps))
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{
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maps_column_num=sscanf(maps_line,"%p-%p\t%s\t%s\t%s\t%s\t%s"
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,&offset_start
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,&offset_end
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,property
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,not_care1
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,not_care2
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,not_care3
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,library_path);
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if(maps_column_num==7&&bt>=offset_start&&bt<=offset_end)
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{
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//printf("=== get in bt: %p, maps_line: %s\n", bt, maps_line);
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break;
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}
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}
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fclose(fd_maps);
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n = readlink("/proc/self/exe", exe_path, sizeof(exe_path));
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exe_path[n] = 0;
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if(0==strcmp(exe_path,library_path))
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{
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exe_symbol_offset=(unsigned long)bt;
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}
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else
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{
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exe_symbol_offset=(char*)bt-(char*)offset_start;
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}
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snprintf(cmd,sizeof(cmd),"addr2line -Cfp -e %s 0x%lx",library_path,exe_symbol_offset);
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//printf("cmd: %s\n", cmd);
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exec_shell(cmd, buff, buff_size);
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//printf("buff: %s\n", buff);
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if(0==memcmp(&buff[strlen(buff) - unknow_position_len],unknow_position, unknow_position_len))
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{
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snprintf(cmd,sizeof(cmd),"addr2line -Cifp -e %s 0x%lx",library_path,exe_symbol_offset);
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//printf("cmd1: %s\n", cmd);
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exec_shell(cmd, function_name, sizeof(function_name));
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function_name[strlen(function_name)-1]='\0';
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snprintf(buff,buff_size,"%s(%s+0x%lx)\n",library_path,function_name,exe_symbol_offset);
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}
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return 0;
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}
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/*
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如果使用my_backtrace
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如果源代码编译时使用了-O1或-O2优化选项，可执行代码会把ebp/rbp/rsp寄存器当作普通寄存器使用，导致backtrace失败。
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为了防止这种情况发生，可以在编译时使用-O2 -fno-omit-frame-pointer 或-Og 来避免优化中使用上述寄存器。
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系统自带的backtrace函数是通过读取操作系统的一个全局信息区，在多线程并发调用时，会造成严重的锁冲突
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*/
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#define STACKCALL __attribute__((regparm(1),noinline))
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void ** STACKCALL getEBP(void){
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void **ebp=NULL;
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__asm__ __volatile__("mov %%rbp, %0;\n\t"
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:"=m"(ebp) /* 输出 */
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: /* 输入 */
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:"memory"); /* 不受影响的寄存器 */
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return (void **)(*ebp);
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}
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int my_backtrace(void **buffer,int size){
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int frame=0;
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void ** ebp;
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void **ret=NULL;
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unsigned long long func_frame_distance=0;
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if(buffer!=NULL && size >0)
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{
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ebp=getEBP();
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func_frame_distance=(unsigned long long)(*ebp) - (unsigned long long)ebp;
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while(ebp&& frame<size
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&&(func_frame_distance< (1ULL<<24))//assume function ebp more than 16M
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&&(func_frame_distance>0))
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{
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ret=ebp+1;
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buffer[frame++]=*ret;
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ebp=(void**)(*ebp);
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func_frame_distance=(unsigned long long)(*ebp) - (unsigned long long)ebp;
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}
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}
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return frame;
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}
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#define BACKTRACE_SIZE 30
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void bt_show()
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{
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int i;
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void *array[BACKTRACE_SIZE];
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char buf[2048] = {0};
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#if 1
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//用get_backtrace_string
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//backtrace or my_backtrace
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int stack_num = backtrace(array, BACKTRACE_SIZE);
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for(i = 0; i < stack_num; i++) {
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get_backtrace_string(array[i], buf, 2048);
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printf(" [%02d] %s\n", i, buf);
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}
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#else
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//用系统的backtrace_symbols,需要释放
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//backtrace or my_backtrace
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int stack_num = backtrace(array, BACKTRACE_SIZE);
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printf("stack_num: %d\n", stack_num);
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char **stacktrace = backtrace_symbols(array, stack_num);
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if(stacktrace == NULL){
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return;
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}
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for(i = 0; i < stack_num; i++) {
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printf(" [%02d] %s\n", i, stacktrace[i]);
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}
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free(stacktrace);
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#endif
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}
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void hello()
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{
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printf("hello world\n");
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test_inline();
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}

‎tools/backtrace/examples/lib.h‎

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#ifndef _LIB_H_
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#define _LIB_H_
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void hello();
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void bt_show();
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static inline void test_inline()
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{
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bt_show();
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}
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#endif

‎tools/backtrace/examples/main.c‎

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#include "lib.h"
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void main()
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{
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hello();
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}

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