Method Map

util/system/filemap.cpp:221–269

    }

    inline TMapResult Map(i64 offset, size_t size) {
        assert(File_.IsOpen());

        if (offset > Length_) {
            ythrow yexception() << "Can't map something at offset " << offset << " of '" << DbgName_ << "' with length " << Length_;
        }

        if (offset + (i64)size > Length_) {
            ythrow yexception() << "Can't map " << (unsigned long)size << " bytes at offset " << offset << " of '" << DbgName_ << "' with length " << Length_;
        }

        TMapResult result;

        i64 base = DownToGranularity(offset);
        result.Head = (i32)(offset - base);
        size += result.Head;

#if defined(_win_)
        result.Ptr = MapViewOfFile(Mapping_,
                                   (Mode_ & oAccessMask) == oRdOnly ? FILE_MAP_READ : (Mode_ & oAccessMask) == oCopyOnWr ? FILE_MAP_COPY
                                                                                                                         : FILE_MAP_WRITE,
                                   Hi32(base), Lo32(base), size);
#else
    #if defined(_unix_)
        if (Mode_ & oNotGreedy) {
    #endif
            result.Ptr = mmap((caddr_t) nullptr, size, ModeToMmapProt(Mode_), ModeToMmapFlags(Mode_), File_.GetHandle(), base);

            if (result.Ptr == MAP_FAILED) {
                result.Ptr = nullptr;
            }
    #if defined(_unix_)
        } else {
            result.Ptr = PtrStart_ ? static_cast<caddr_t>(PtrStart_) + base : nullptr;
        }
    #endif
#endif
        if (result.Ptr != nullptr || size == 0) { // allow map of size 0
            result.Size = size;
        } else {
            ythrow yexception() << "Can't map " << (unsigned long)size << " bytes at offset " << offset << " of '" << DbgName_ << "': " << LastSystemErrorText();
        }
        NSan::Unpoison(result.Ptr, result.Size);
        if (Mode_ & oPrecharge) {
            NPrivate::Precharge(result.Ptr, result.Size, 0, result.Size);
        }

        return result;
    }

#if defined(_win_)
    inline bool Unmap(void* ptr, size_t) {