symbols_with_dbghelp.cpp

#ifdef CPPTRACE_GET_SYMBOLS_WITH_DBGHELP

#include <cpptrace/cpptrace.hpp>
#include "symbols/symbols.hpp"
#include "platform/dbghelp_syminit_manager.hpp"

#include <memory>
#include <mutex>
#include <regex>
#include <stdexcept>
#include <system_error>
#include <vector>

#include <windows.h>
#include <dbghelp.h>

namespace cpptrace {
namespace detail {
namespace dbghelp {
    // SymFromAddr only returns the function's name. In order to get information about parameters,
    // important for C++ stack traces where functions may be overloaded, we have to manually use
    // Windows DIA to walk debug info structures. Resources:
    // https://web.archive.org/web/20201027025750/http://www.debuginfo.com/articles/dbghelptypeinfo.html
    // https://web.archive.org/web/20201203160805/http://www.debuginfo.com/articles/dbghelptypeinfofigures.html
    // https://github.com/DynamoRIO/dynamorio/blob/master/ext/drsyms/drsyms_windows.c#L1370-L1439
    // TODO: Currently unable to detect rvalue references
    // TODO: Currently unable to detect const
    enum class SymTagEnum {
        SymTagNull, SymTagExe, SymTagCompiland, SymTagCompilandDetails, SymTagCompilandEnv,
        SymTagFunction, SymTagBlock, SymTagData, SymTagAnnotation, SymTagLabel, SymTagPublicSymbol,
        SymTagUDT, SymTagEnum, SymTagFunctionType, SymTagPointerType, SymTagArrayType,
        SymTagBaseType, SymTagTypedef, SymTagBaseClass, SymTagFriend, SymTagFunctionArgType,
        SymTagFuncDebugStart, SymTagFuncDebugEnd, SymTagUsingNamespace, SymTagVTableShape,
        SymTagVTable, SymTagCustom, SymTagThunk, SymTagCustomType, SymTagManagedType,
        SymTagDimension, SymTagCallSite, SymTagInlineSite, SymTagBaseInterface, SymTagVectorType,
        SymTagMatrixType, SymTagHLSLType, SymTagCaller, SymTagCallee, SymTagExport,
        SymTagHeapAllocationSite, SymTagCoffGroup, SymTagMax
    };

    enum class IMAGEHLP_SYMBOL_TYPE_INFO {
        TI_GET_SYMTAG, TI_GET_SYMNAME, TI_GET_LENGTH, TI_GET_TYPE, TI_GET_TYPEID, TI_GET_BASETYPE,
        TI_GET_ARRAYINDEXTYPEID, TI_FINDCHILDREN, TI_GET_DATAKIND, TI_GET_ADDRESSOFFSET,
        TI_GET_OFFSET, TI_GET_VALUE, TI_GET_COUNT, TI_GET_CHILDRENCOUNT, TI_GET_BITPOSITION,
        TI_GET_VIRTUALBASECLASS, TI_GET_VIRTUALTABLESHAPEID, TI_GET_VIRTUALBASEPOINTEROFFSET,
        TI_GET_CLASSPARENTID, TI_GET_NESTED, TI_GET_SYMINDEX, TI_GET_LEXICALPARENT, TI_GET_ADDRESS,
        TI_GET_THISADJUST, TI_GET_UDTKIND, TI_IS_EQUIV_TO, TI_GET_CALLING_CONVENTION,
        TI_IS_CLOSE_EQUIV_TO, TI_GTIEX_REQS_VALID, TI_GET_VIRTUALBASEOFFSET,
        TI_GET_VIRTUALBASEDISPINDEX, TI_GET_IS_REFERENCE, TI_GET_INDIRECTVIRTUALBASECLASS,
        TI_GET_VIRTUALBASETABLETYPE, TI_GET_OBJECTPOINTERTYPE, IMAGEHLP_SYMBOL_TYPE_INFO_MAX
    };

    enum class BasicType {
        btNoType = 0, btVoid = 1, btChar = 2, btWChar = 3, btInt = 6, btUInt = 7, btFloat = 8,
        btBCD = 9, btBool = 10, btLong = 13, btULong = 14, btCurrency = 25, btDate = 26,
        btVariant = 27, btComplex = 28, btBit = 29, btBSTR = 30, btHresult = 31
    };

    // SymGetTypeInfo utility
    template<typename T, IMAGEHLP_SYMBOL_TYPE_INFO SymType, bool FAILABLE = false>
    T get_info(ULONG type_index, HANDLE proc, ULONG64 modbase) {
        T info;
        if(
            !SymGetTypeInfo(
                proc,
                modbase,
                type_index,
                static_cast<::IMAGEHLP_SYMBOL_TYPE_INFO>(SymType),
                &info
            )
        ) {
            if(FAILABLE) {
                return (T)-1;
            } else {
                throw internal_error(
                    "SymGetTypeInfo failed: {}", std::system_error(GetLastError(), std::system_category()).what()
                );
            }
        }
        return info;
    }

    template<IMAGEHLP_SYMBOL_TYPE_INFO SymType, bool FAILABLE = false>
    std::string get_info_wchar(ULONG type_index, HANDLE proc, ULONG64 modbase) {
        WCHAR* info;
        if(
            !SymGetTypeInfo(proc, modbase, type_index, static_cast<::IMAGEHLP_SYMBOL_TYPE_INFO>(SymType), &info)
        ) {
            throw internal_error(
                "SymGetTypeInfo failed: {}", std::system_error(GetLastError(), std::system_category()).what()
            );
        }
        // special case to properly free a buffer and convert string to narrow chars, only used for
        // TI_GET_SYMNAME
        static_assert(
            SymType == IMAGEHLP_SYMBOL_TYPE_INFO::TI_GET_SYMNAME,
            "get_info_wchar called with unexpected IMAGEHLP_SYMBOL_TYPE_INFO"
        );
        std::wstring wstr(info);
        std::string str;
        str.reserve(wstr.size());
        for(const auto c : wstr) {
            str.push_back(static_cast<char>(c));
        }
        LocalFree(info);
        return str;
    }

    // Translate basic types to string
    static std::string get_basic_type(ULONG type_index, HANDLE proc, ULONG64 modbase) {
        auto basic_type = get_info<BasicType, IMAGEHLP_SYMBOL_TYPE_INFO::TI_GET_BASETYPE>(
            type_index,
            proc,
            modbase
        );
        //auto length = get_info<ULONG64, IMAGEHLP_SYMBOL_TYPE_INFO::TI_GET_LENGTH>(type_index, proc, modbase);
        switch(basic_type) {
            case BasicType::btNoType:
                return "<no basic type>";
            case BasicType::btVoid:
                return "void";
            case BasicType::btChar:
                return "char";
            case BasicType::btWChar:
                return "wchar_t";
            case BasicType::btInt:
                return "int";
            case BasicType::btUInt:
                return "unsigned int";
            case BasicType::btFloat:
                return "float";
            case BasicType::btBool:
                return "bool";
            case BasicType::btLong:
                return "long";
            case BasicType::btULong:
                return "unsigned long";
            default:
                return "<unknown basic type>";
        }
    }

    static std::string resolve_type(ULONG type_index, HANDLE proc, ULONG64 modbase);

    struct class_name_result {
        bool has_class_name;
        std::string name;
    };
    // Helper for member pointers
    static class_name_result lookup_class_name(ULONG type_index, HANDLE proc, ULONG64 modbase) {
        DWORD class_parent_id = get_info<DWORD, IMAGEHLP_SYMBOL_TYPE_INFO::TI_GET_CLASSPARENTID, true>(
            type_index,
            proc,
            modbase
        );
        if(class_parent_id == (DWORD)-1) {
            return {false, ""};
        } else {
            return {true, resolve_type(class_parent_id, proc, modbase)};
        }
    }

    struct type_result {
        std::string base;
        std::string extent;
    };
    // Resolve more complex types
    // returns [base, extent]
    static type_result lookup_type(ULONG type_index, HANDLE proc, ULONG64 modbase) {
        auto tag = get_info<SymTagEnum, IMAGEHLP_SYMBOL_TYPE_INFO::TI_GET_SYMTAG>(type_index, proc, modbase);
        switch(tag) {
            case SymTagEnum::SymTagBaseType:
                return {get_basic_type(type_index, proc, modbase), ""};
            case SymTagEnum::SymTagPointerType: {
                DWORD underlying_type_id = get_info<DWORD, IMAGEHLP_SYMBOL_TYPE_INFO::TI_GET_TYPEID>(
                    type_index,
                    proc,
                    modbase
                );
                bool is_ref = get_info<BOOL, IMAGEHLP_SYMBOL_TYPE_INFO::TI_GET_IS_REFERENCE>(
                    type_index,
                    proc,
                    modbase
                );
                std::string pp = is_ref ? "&" : "*"; // pointer punctuator
                auto class_name_res = lookup_class_name(type_index, proc, modbase);
                if(class_name_res.has_class_name) {
                    pp = class_name_res.name + "::" + pp;
                }
                const auto type = lookup_type(underlying_type_id, proc, modbase);
                if(type.extent.empty()) {
                    return {type.base + (pp.size() > 1 ? " " : "") + pp, ""};
                } else {
                    return {type.base + "(" + pp, ")" + type.extent};
                }
            }
            case SymTagEnum::SymTagArrayType: {
                DWORD underlying_type_id = get_info<DWORD, IMAGEHLP_SYMBOL_TYPE_INFO::TI_GET_TYPEID>(
                    type_index,
                    proc,
                    modbase
                );
                DWORD length = get_info<DWORD, IMAGEHLP_SYMBOL_TYPE_INFO::TI_GET_COUNT>(
                    type_index,
                    proc,
                    modbase
                );
                const auto type = lookup_type(underlying_type_id, proc, modbase);
                return {type.base, "[" + std::to_string(length) + "]" + type.extent};
            }
            case SymTagEnum::SymTagFunctionType: {
                DWORD return_type_id = get_info<DWORD, IMAGEHLP_SYMBOL_TYPE_INFO::TI_GET_TYPEID>(
                    type_index,
                    proc,
                    modbase
                );
                DWORD n_children = get_info<DWORD, IMAGEHLP_SYMBOL_TYPE_INFO::TI_GET_COUNT, true>(
                    type_index,
                    proc,
                    modbase
                );
                DWORD class_parent_id = get_info<DWORD, IMAGEHLP_SYMBOL_TYPE_INFO::TI_GET_CLASSPARENTID, true>(
                    type_index,
                    proc,
                    modbase
                );
                int n_ignore = class_parent_id != (DWORD)-1; // ignore this param
                // this must be ignored before TI_FINDCHILDREN_PARAMS::Count is set, else error
                n_children -= n_ignore;
                // return type
                const auto return_type = lookup_type(return_type_id, proc, modbase);
                if(n_children == 0) {
                    return {return_type.base, "()" + return_type.extent};
                } else {
                    // alignment should be fine
                    std::size_t sz = sizeof(TI_FINDCHILDREN_PARAMS) +
                                    (n_children) * sizeof(TI_FINDCHILDREN_PARAMS::ChildId[0]);
                    TI_FINDCHILDREN_PARAMS* children = (TI_FINDCHILDREN_PARAMS*) new char[sz];
                    children->Start = 0;
                    children->Count = n_children;
                    if(
                        !SymGetTypeInfo(
                            proc, modbase, type_index,
                            static_cast<::IMAGEHLP_SYMBOL_TYPE_INFO>(
                                IMAGEHLP_SYMBOL_TYPE_INFO::TI_FINDCHILDREN
                            ),
                            children
                        )
                    ) {
                        throw internal_error(
                            "SymGetTypeInfo failed: {}",
                            std::system_error(GetLastError(), std::system_category()).what()
                        );
                    }
                    // get children type
                    std::string extent = "(";
                    if(children->Start != 0) {
                        throw internal_error("Error: children->Start == 0");
                    }
                    for(std::size_t i = 0; i < n_children; i++) {
                        extent += (i == 0 ? "" : ", ") + resolve_type(children->ChildId[i], proc, modbase);
                    }
                    extent += ")";
                    delete[] (char*) children;
                    return {return_type.base, extent + return_type.extent};
                }
            }
            case SymTagEnum::SymTagFunctionArgType: {
                DWORD underlying_type_id =
                    get_info<DWORD, IMAGEHLP_SYMBOL_TYPE_INFO::TI_GET_TYPEID>(type_index, proc, modbase);
                return {resolve_type(underlying_type_id, proc, modbase), ""};
            }
            case SymTagEnum::SymTagTypedef:
            case SymTagEnum::SymTagEnum:
            case SymTagEnum::SymTagUDT:
            case SymTagEnum::SymTagBaseClass:
                return {
                    get_info_wchar<IMAGEHLP_SYMBOL_TYPE_INFO::TI_GET_SYMNAME>(type_index, proc, modbase), ""
                };
            default:
                return {
                    "<unknown type " +
                        std::to_string(static_cast<std::underlying_type<SymTagEnum>::type>(tag)) +
                        ">",
                    ""
                };
        };
    }

    static std::string resolve_type(ULONG type_index, HANDLE proc, ULONG64 modbase) {
        const auto type = lookup_type(type_index, proc, modbase);
        return type.base + type.extent;
    }

    struct function_info {
        HANDLE proc;
        ULONG64 modbase;
        int counter;
        int n_children;
        int n_ignore;
        std::string str;
    };

    // Enumerates function parameters
    static BOOL __stdcall enumerator_callback(
        PSYMBOL_INFO symbol_info,
        ULONG,
        PVOID data
    ) {
        function_info* ctx = (function_info*)data;
        if(ctx->counter++ >= ctx->n_children) {
            return false;
        }
        if(ctx->n_ignore-- > 0) {
            return true; // just skip
        }
        ctx->str += resolve_type(symbol_info->TypeIndex, ctx->proc, ctx->modbase);
        if(ctx->counter < ctx->n_children) {
            ctx->str += ", ";
        }
        return true;
    }

    std::recursive_mutex dbghelp_lock;

    // TODO: Handle backtrace_pcinfo calling the callback multiple times on inlined functions
    stacktrace_frame resolve_frame(HANDLE proc, frame_ptr addr) {
        // The get_frame_object_info() ends up being inexpensive, at on my machine
        //                                         debug           release
        // uncached trace resolution (29 frames)   1.9-2.1 ms      1.4-1.8 ms
        // cached trace resolution   (29 frames)   1.1-1.2 ms      0.2-0.4 ms
        // get_frame_object_info()                 0.001-0.002 ms  0.0003-0.0006 ms
        // At some point it might make sense to make an option to control this.
        auto object_frame = get_frame_object_info(addr);
        const std::lock_guard<std::recursive_mutex> lock(dbghelp_lock); // all dbghelp functions are not thread safe
        alignas(SYMBOL_INFO) char buffer[sizeof(SYMBOL_INFO) + MAX_SYM_NAME * sizeof(TCHAR)];
        SYMBOL_INFO* symbol = (SYMBOL_INFO*)buffer;
        symbol->SizeOfStruct = sizeof(SYMBOL_INFO);
        symbol->MaxNameLen = MAX_SYM_NAME;
        union { DWORD64 a; DWORD b; } displacement;
        IMAGEHLP_LINE64 line;
        bool got_line = SymGetLineFromAddr64(proc, addr, &displacement.b, &line);
        if(SymFromAddr(proc, addr, &displacement.a, symbol)) {
            if(got_line) {
                IMAGEHLP_STACK_FRAME frame;
                frame.InstructionOffset = symbol->Address;
                // https://docs.microsoft.com/en-us/windows/win32/api/dbghelp/nf-dbghelp-symsetcontext
                // "If you call SymSetContext to set the context to its current value, the
                // function fails but GetLastError returns ERROR_SUCCESS."
                // This is the stupidest fucking api I've ever worked with.
                if(SymSetContext(proc, &frame, nullptr) == FALSE && GetLastError() != ERROR_SUCCESS) {
                    std::fprintf(stderr, "Stack trace: Internal error while calling SymSetContext\n");
                    return {
                        addr,
                        object_frame.object_address,
                        { static_cast<std::uint32_t>(line.LineNumber) },
                        nullable<std::uint32_t>::null(),
                        line.FileName,
                        symbol->Name,
                        false
                    };
                }
                DWORD n_children = get_info<DWORD, IMAGEHLP_SYMBOL_TYPE_INFO::TI_GET_COUNT, true>(
                    symbol->TypeIndex,
                    proc,
                    symbol->ModBase
                );
                DWORD class_parent_id = get_info<DWORD, IMAGEHLP_SYMBOL_TYPE_INFO::TI_GET_CLASSPARENTID, true>(
                    symbol->TypeIndex,
                    proc,
                    symbol->ModBase
                );
                function_info fi {
                    proc,
                    symbol->ModBase,
                    0,
                    int(n_children),
                    class_parent_id != (DWORD)-1,
                    ""
                };
                SymEnumSymbols(proc, 0, nullptr, enumerator_callback, &fi);
                std::string signature = symbol->Name + std::string("(") + fi.str + ")";
                // There's a phenomina with DIA not inserting commas after template parameters. Fix them here.
                static std::regex comma_re(R"(,(?=\S))");
                signature = std::regex_replace(signature, comma_re, ", ");
                return {
                    addr,
                    object_frame.object_address,
                    { static_cast<std::uint32_t>(line.LineNumber) },
                    nullable<std::uint32_t>::null(),
                    line.FileName,
                    signature,
                    false,
                };
            } else {
                return {
                    addr,
                    object_frame.object_address,
                    nullable<std::uint32_t>::null(),
                    nullable<std::uint32_t>::null(),
                    "",
                    symbol->Name,
                    false
                };
            }
        } else {
            return {
                addr,
                object_frame.object_address,
                nullable<std::uint32_t>::null(),
                nullable<std::uint32_t>::null(),
                "",
                "",
                false
            };
        }
    }

    std::vector<stacktrace_frame> resolve_frames(const std::vector<frame_ptr>& frames) {
        const std::lock_guard<std::recursive_mutex> lock(dbghelp_lock); // all dbghelp functions are not thread safe
        std::vector<stacktrace_frame> trace;
        trace.reserve(frames.size());

        // TODO: When does this need to be called? Can it be moved to the symbolizer?
        SymSetOptions(SYMOPT_ALLOW_ABSOLUTE_SYMBOLS);
        HANDLE proc = GetCurrentProcess();
        if(get_cache_mode() == cache_mode::prioritize_speed) {
            get_syminit_manager().init(proc);
        } else {
            if(!SymInitialize(proc, NULL, TRUE)) {
                throw internal_error("SymInitialize failed");
            }
        }
        for(const auto frame : frames) {
            try {
                trace.push_back(resolve_frame(proc, frame));
            } catch(...) { // NOSONAR
                if(!detail::should_absorb_trace_exceptions()) {
                    throw;
                }
                auto entry = null_frame;
                entry.raw_address = frame;
                trace.push_back(entry);
            }
        }
        if(get_cache_mode() != cache_mode::prioritize_speed) {
            if(!SymCleanup(proc)) {
                throw internal_error("SymCleanup failed");
            }
        }
        return trace;
    }
}
}
}

#endif