Linux：有没有办法在不停止/暂停进程（SIGSTOP）的情况下使用 ptrace？

Question

我正在尝试将程序从 Windows 移植到 Linux。当我发现Linux 上
没有“真正的”对应项时，我遇到了一个问题；ReadProcessMemory我寻找替代方案，发现了ptrace一个强大的进程调试器。
我快速用 C++ 编写了两个小型控制台应用程序进行测试ptrace，然后在程序中使用它。

测试应用程序

这是tracee；它每 50 毫秒打印两个整数，同时每次将它们的值加 1。

#include <QCoreApplication>
#include <QThread>
#include <iostream>

using namespace std;

class Sleeper : public QThread
{
public:
    static void usleep(unsigned long usecs){QThread::usleep(usecs);}
    static void msleep(unsigned long msecs){QThread::msleep(msecs);}
    static void sleep(unsigned long secs){QThread::sleep(secs);}
};

int main(int argc, char *argv[])
{
    QCoreApplication a(argc, argv);

    int value = 145;
    int i = 0;

    do {
    cout << "i: " << i << " " << "Value: " << value << endl;
    value++;
    i++;
    Sleeper::msleep(50);
    } while (true);

    return a.exec();
}

记忆测试

这是追踪器；它询问进程名称并使用命令检索 PID pidof -s，然后ptrace附加到进程并每 500 毫秒检索内存地址的值，共 10 次。

#include <QCoreApplication>
#include <QThread>
#include <iostream>
#include <string>
#include <sys/ptrace.h>
#include <errno.h>

using namespace std;

class Sleeper : public QThread
{
public:
    static void usleep(unsigned long usecs){QThread::usleep(usecs);}
    static void msleep(unsigned long msecs){QThread::msleep(msecs);}
    static void sleep(unsigned long secs){QThread::sleep(secs);}
};

int main(int argc, char *argv[])
{
    QCoreApplication a(argc, argv);

    char process_name[50];
    cout << "Process name: ";
    cin >> process_name;

    char command[sizeof(process_name) + sizeof("pidof -s ")];
    snprintf(command, sizeof(command), "pidof -s %s", process_name);

    FILE* shell = popen(command, "r");
    char pidI[sizeof(shell)];
    fgets(pidI, sizeof(pidI), shell);
    pclose(shell);

    pid_t pid = atoi(pidI);
    cout << "The PID is " << pid << endl;

    long status = ptrace(PTRACE_ATTACH, pid, NULL, NULL);
    cout << "Status: " << status << endl;
    cout << "Error: " << errno << endl;

    unsigned long addr = 0x012345; // Example address, not the true one
    int i = 0;
    do {
    status = ptrace(PTRACE_PEEKDATA, pid, addr, NULL);
    cout << "Status: " << status << endl;
    cout << "Error: " << errno << endl;
    i++;
    Sleeper::msleep(500);
    } while (i < 10);

    status = ptrace(PTRACE_DETACH, pid, NULL, NULL);
    cout << "Status: " << status << endl;
    cout << "Error: " << errno << endl;

    return a.exec();
}

一切工作正常，但 TestApp 被暂停 (SIGSTOP)，直到ptrace与其分离。
另外，当它附加到进程时，状态为0，错误为2；第一次尝试检索内存地址值时失败，状态为 -1，错误为 3。这正常吗？
有没有办法阻止 ptrace 向进程发送 SIGSTOP 信号？我已经尝试使用PTRACE_SEIZE代替PTRACE_ATTACH，但它不起作用：状态 -1 和错误 3。

更新：在MemoryTest中使用Sleeper“do-while”循环之前修复了第一个内存地址值检索的问题，即使秒、毫秒或微秒的值为0。为什么？

Answer 1

经过大量研究后，我非常确定没有一种方法可以ptrace在不停止进程的情况下使用。
我找到了一个真正的ReadProcessMemory对应物，称为process_vm_readv，它要简单得多。

我发布代码是希望能够帮助处于我（以前）情况的人。

非常感谢mkrautz帮助用这个漂亮的函数编写 MemoryTest 代码。

#include <QCoreApplication>
#include <QThread>
#include <sys/uio.h>
#include <stdint.h>
#include <stdio.h>
#include <errno.h>
#include <string.h>
#include <iostream>

using namespace std;

class Sleeper : public QThread
{
public:
    static void usleep(unsigned long usecs){QThread::usleep(usecs);}
    static void msleep(unsigned long msecs){QThread::msleep(msecs);}
    static void sleep(unsigned long secs){QThread::sleep(secs);}
};

int main(int argc, char *argv[])
{
    QCoreApplication a(argc, argv);

    char process_name[50];
    cout << "Process name: ";
    cin >> process_name;

    char command[sizeof(process_name) + sizeof("pidof -s ")];
    snprintf(command, sizeof(command), "pidof -s %s", process_name);

    FILE* shell = popen(command, "r");
    char pidI[sizeof(shell)];
    fgets(pidI, sizeof(pidI), shell);
    pclose(shell);

    pid_t pid = atoi(pidI);

    cout << "The PID is " << pid << endl;

    if (pid == 0)
        return false;

    struct iovec in;
    in.iov_base = (void *) 0x012345; // Example address, not the true one
    in.iov_len = 4;

    uint32_t foo;

    struct iovec out;
    out.iov_base = &foo;
    out.iov_len = sizeof(foo);

    do {
        ssize_t nread = process_vm_readv(pid, &out, 1, &in, 1, 0);
        if (nread == -1) {
            fprintf(stderr, "error: %s", strerror(errno));
        } else if (nread != in.iov_len) {
            fprintf(stderr, "error: short read of %li bytes", (ssize_t)nread);
        }
        cout << foo << endl;
        Sleeper::msleep(500);
    } while (true);

    return a.exec();
}