Function IsDebuggerPresent

Utilities/Thread.cpp:127–186

#ifndef _WIN32
bool IsDebuggerPresent()
{
#if defined(__APPLE__) || defined(__DragonFly__) || defined(__FreeBSD__) || defined(__NetBSD__) || defined(__OpenBSD__)
	int mib[] = {
		CTL_KERN,
		KERN_PROC,
		KERN_PROC_PID,
		getpid(),
# if defined(__NetBSD__) || defined(__OpenBSD__)
		sizeof(struct kinfo_proc),
		1,
# endif
	};
	u_int miblen = std::size(mib);
	struct kinfo_proc info;
	usz size = sizeof(info);

	if (sysctl(mib, miblen, &info, &size, NULL, 0))
	{
		return false;
	}

	return info.KP_FLAGS & P_TRACED;
#else
	char buf[4096];
	fs::file status_fd("/proc/self/status");
	if (!status_fd)
	{
		std::fprintf(stderr, "Failed to open /proc/self/status\n");
		return false;
	}

	const auto num_read = status_fd.read(buf, sizeof(buf) - 1);
	if (num_read == 0 || num_read == umax)
	{
		std::fprintf(stderr, "Failed to read /proc/self/status (%d)\n", errno);
		return false;
	}

	buf[num_read] = '\0';
	std::string_view status = buf;

	const auto found = status.find("TracerPid:");
	if (found == umax)
	{
		std::fprintf(stderr, "Failed to find 'TracerPid:' in /proc/self/status\n");
		return false;
	}

	for (const char* cp = status.data() + found + 10; cp <= status.data() + num_read; ++cp)
	{
		if (!std::isspace(*cp))
		{
			return std::isdigit(*cp) != 0 && *cp != '0';
		}
	}

	return false;