ptrace.cxx

// cosmos
#include <cosmos/error/ApiError.hxx>
#include <cosmos/proc/ptrace.hxx>
#include <cosmos/utils.hxx>
 
namespace cosmos::ptrace {
 
std::optional<long> trace(const Request req, const ProcessID pid, void *addr, void *data) {
        const auto is_peek =
                req == Request::PEEKDATA ||
                req == Request::PEEKTEXT ||
                req == Request::PEEKUSER;
 
        if (is_peek) {
                // PEEK requests have difficult error handling, we need to
                // explicitly reset the errno.
                reset_errno();
        }
 
        const auto ret = ::ptrace(
                        static_cast<__ptrace_request>(to_integral(req)),
                        to_integral(pid), addr, data);
 
        if (ret == -1) {
                if (is_peek && !is_errno_set()) {
                        // we actually peeked a -1
                        return ret;
                }
 
                cosmos_throw (ApiError("ptrace()"));
        }
 
        // only these ptrace requests return meaningful data, otherwise just
        // zero on success.
        if (is_peek || req == Request::SECCOMP_GET_FILTER || req == Request::GET_SYSCALL_INFO) {
                return ret;
        }
 
        return std::nullopt;
}
 
void traceme() {
        // all arguments except the request are ignored.
        // this is not clearly documented but I checked the kernel code to verify.
        trace(Request::TRACEME, ProcessID{0}, nullptr, nullptr);
}
 
} // end ns