include/internal/catch_debugger.cpp

/*
 *  Created by Phil on 27/12/2010.
 *  Copyright 2010 Two Blue Cubes Ltd. All rights reserved.
 *
 *  Distributed under the Boost Software License, Version 1.0. (See accompanying
 *  file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
 *
 */

#include "catch_debugger.h"
#include "catch_errno_guard.h"
#include "catch_stream.h"
#include "catch_platform.h"

#if defined(CATCH_PLATFORM_MAC) || defined(CATCH_PLATFORM_IPHONE)

#  include <assert.h>
#  include <stdbool.h>
#  include <sys/types.h>
#  include <unistd.h>
#  include <cstddef>
#  include <ostream>

#ifdef __apple_build_version__
    // These headers will only compile with AppleClang (XCode)
    // For other compilers (Clang, GCC, ... ) we need to exclude them
#  include <sys/sysctl.h>
#endif

    namespace Catch {
        #ifdef __apple_build_version__
        // The following function is taken directly from the following technical note:
        // https://developer.apple.com/library/archive/qa/qa1361/_index.html

        // Returns true if the current process is being debugged (either
        // running under the debugger or has a debugger attached post facto).
        bool isDebuggerActive(){
            int                 mib[4];
            struct kinfo_proc   info;
            std::size_t         size;

            // Initialize the flags so that, if sysctl fails for some bizarre
            // reason, we get a predictable result.

            info.kp_proc.p_flag = 0;

            // Initialize mib, which tells sysctl the info we want, in this case
            // we're looking for information about a specific process ID.

            mib[0] = CTL_KERN;
            mib[1] = KERN_PROC;
            mib[2] = KERN_PROC_PID;
            mib[3] = getpid();

            // Call sysctl.

            size = sizeof(info);
            if( sysctl(mib, sizeof(mib) / sizeof(*mib), &info, &size, nullptr, 0) != 0 ) {
                Catch::cerr() << "\n** Call to sysctl failed - unable to determine if debugger is active **\n" << std::endl;
                return false;
            }

            // We're being debugged if the P_TRACED flag is set.

            return ( (info.kp_proc.p_flag & P_TRACED) != 0 );
        }
        #else
        bool isDebuggerActive() {
            // We need to find another way to determine this for non-appleclang compilers on macOS
            return false;
        }
        #endif
    } // namespace Catch

#elif defined(CATCH_PLATFORM_LINUX)
    #include <fstream>
    #include <string>

    namespace Catch{
        // The standard POSIX way of detecting a debugger is to attempt to
        // ptrace() the process, but this needs to be done from a child and not
        // this process itself to still allow attaching to this process later
        // if wanted, so is rather heavy. Under Linux we have the PID of the
        // "debugger" (which doesn't need to be gdb, of course, it could also
        // be strace, for example) in /proc/$PID/status, so just get it from
        // there instead.
        bool isDebuggerActive(){
            // Libstdc++ has a bug, where std::ifstream sets errno to 0
            // This way our users can properly assert over errno values
            ErrnoGuard guard;
            std::ifstream in("/proc/self/status");
            for( std::string line; std::getline(in, line); ) {
                static const int PREFIX_LEN = 11;
                if( line.compare(0, PREFIX_LEN, "TracerPid:\t") == 0 ) {
                    // We're traced if the PID is not 0 and no other PID starts
                    // with 0 digit, so it's enough to check for just a single
                    // character.
                    return line.length() > PREFIX_LEN && line[PREFIX_LEN] != '0';
                }
            }

            return false;
        }
    } // namespace Catch
#elif defined(_MSC_VER)
    extern "C" __declspec(dllimport) int __stdcall IsDebuggerPresent();
    namespace Catch {
        bool isDebuggerActive() {
            return IsDebuggerPresent() != 0;
        }
    }
#elif defined(__MINGW32__)
    extern "C" __declspec(dllimport) int __stdcall IsDebuggerPresent();
    namespace Catch {
        bool isDebuggerActive() {
            return IsDebuggerPresent() != 0;
        }
    }
#else
    namespace Catch {
       bool isDebuggerActive() { return false; }
    }
#endif // Platform