How to detect if the current process is being run by GDB

On Windows there is an API, IsDebuggerPresent, to check if process is under debugging. At Linux, we can check this with another way (not so efficient).

Check “/proc/self/status” for “TracerPid” attribute.

Example code:

#include <sys/stat.h>
#include <string.h>
#include <fcntl.h>
#include <unistd.h>
#include <ctype.h>

bool debuggerIsAttached()
{
    char buf[4096];

    const int status_fd = open("/proc/self/status", O_RDONLY);
    if (status_fd == -1)
        return false;

    const ssize_t num_read = read(status_fd, buf, sizeof(buf) - 1);
    close(status_fd);

    if (num_read <= 0)
        return false;

    buf[num_read] = '\0';
    constexpr char tracerPidString[] = "TracerPid:";
    const auto tracer_pid_ptr = strstr(buf, tracerPidString);
    if (!tracer_pid_ptr)
        return false;

    for (const char* characterPtr = tracer_pid_ptr + sizeof(tracerPidString) - 1; characterPtr <= buf + num_read; ++characterPtr)
    {
        if (isspace(*characterPtr))
            continue;
        else
            return isdigit(*characterPtr) != 0 && *characterPtr != '0';
    }

    return false;
}