libunwind查看其他进程的堆栈

 g++ -g3 -o main main.cpp -std=c++11 -lunwind -lunwind-x86_64 -lunwind-ptrace

 

#include <iostream>
#include <libunwind.h>
#include <libunwind-ptrace.h>
#include <unistd.h>
#include <sys/ptrace.h>
#include <sys/wait.h>
#include <cxxabi.h>
#include <cstdio>

int wait4stop(pid_t pid) {
    int status = 99;
    do {
        if (waitpid(pid, &status, 0) == -1 || WIFEXITED(status) || WIFSIGNALED(status))
            return 0;
    } while(!WIFSTOPPED(status));
    return 1;
}

void get_backtrace(pid_t pid) {
    unw_cursor_t cursor, resume_cursor;
    unw_context_t context;
    unw_word_t ip, sp, off;

    unw_addr_space_t addr_space = unw_create_addr_space(&_UPT_accessors, __BYTE_ORDER__);
    if (!addr_space) 
        std::cerr << "Failed to create address space" << std::endl;

    unw_getcontext(&context);

    if (-1 == ptrace(PTRACE_ATTACH, pid, nullptr, nullptr))
        std::cerr << "Failed to ptrace" << std::endl;

    if (!wait4stop(pid))
        std::cerr << "wait SIGSTOP of ptrace failed" << std::endl;

    void *rctx = _UPT_create(pid);

    if (rctx == nullptr) 
        std::cerr << "Failed to _UPT_create" << std::endl;

    if (unw_init_remote(&cursor, addr_space, rctx))
        std::cerr << "unw_init_remote failed" << std::endl;

    resume_cursor = cursor;

    const size_t bufflen = 256;
    char *buff = new char[bufflen];

    do {
        char *name = "23333";
        unw_get_reg(&cursor, UNW_REG_IP, &ip);
        unw_get_reg(&cursor, UNW_REG_SP, &sp);

        // 获取函数名字
        if (0 == unw_get_proc_name(&cursor, buff, bufflen, &off)) {
            int status = 99;
            printf("%s---", buff);
            // 如果符号表中没有找到buff的函数名
            if ((name = abi::__cxa_demangle(buff, nullptr, nullptr, &status)) == 0)
                name = buff;
        }
        printf("%s.\n", name);
    } while (unw_step(&cursor) > 0);

    delete[] buff;
    _UPT_resume(addr_space, &resume_cursor, rctx);
    _UPT_destroy(rctx);

    // 然后是将进程结束中断
    ptrace(PTRACE_DETACH, pid, nullptr, nullptr);
}

int main(int argc, char **argv) {
    if (argc < 2) 
        std::cerr << "please input pid" << std::endl;

    pid_t pid = std::atoi(argv[1]);
    get_backtrace(pid);
    return 0;
}