Repository: dotnet/aspnetcore
File: src/Servers/IIS/AspNetCoreModuleV2/CommonLib/HostFxrResolver.cpp (C++)

Code before:

        if (fIsCurrentProcess64Bit == IsX64(struDotnetSubstring.QueryStr()))
        {
            // The bitness of dotnet matched with the current worker process bitness.
            return std::make_optional(struDotnetSubstring.QueryStr());
        }
    }

    Finished:
    return result;
}

BOOL HostFxrResolver::IsX64(const WCHAR* dotnetPath)
{
    std::ifstream file(dotnetPath, std::ios::binary);
    if (!file.is_open())
    {
        LOG_INFOF(L"Failed to open file %ls", dotnetPath);
        return false;
    }

    // Read the DOS header
    IMAGE_DOS_HEADER dosHeader;
    file.read(reinterpret_cast<char*>(&dosHeader), sizeof(dosHeader));
    if (dosHeader.e_magic != IMAGE_DOS_SIGNATURE) // 'MZ'
    {
        LOG_INFOF(L"%ls is not a valid executable file (missing MZ header).", dotnetPath);
        return false;
    }

    // Seek to the PE header
    file.seekg(dosHeader.e_lfanew, std::ios::beg);

    // Read the PE header
    DWORD peSignature;
    file.read(reinterpret_cast<char*>(&peSignature), sizeof(peSignature));
    if (peSignature != IMAGE_NT_SIGNATURE) // 'PE\0\0'
    {
        LOG_INFOF(L"%ls is not a valid PE file (missing PE header).", dotnetPath);
        return false;
    }

    // Read the file header
    IMAGE_FILE_HEADER fileHeader;
    file.read(reinterpret_cast<char*>(&fileHeader), sizeof(fileHeader));

    // Read the optional header magic field
    WORD magic;
    file.read(reinterpret_cast<char*>(&magic), sizeof(magic));

    // Determine the architecture based on the magic value

Review comment (bug):
Consider verifying that the file.read operation successfully read the expected number of bytes for the DOS header to handle cases of incomplete or corrupted files.
```suggestion
    if (!file.read(reinterpret_cast<char*>(&dosHeader), sizeof(dosHeader)))
    {
        LOG_INFOF(L"Failed to read DOS header from %ls", dotnetPath);
        return false;
    }
```

Code after:

        if (fIsCurrentProcess64Bit == IsX64(struDotnetSubstring.QueryStr()))
        {
            // The bitness of dotnet matched with the current worker process bitness.
            return std::make_optional(struDotnetSubstring.QueryStr());
        }
    }

    Finished:
    return result;
}

BOOL HostFxrResolver::IsX64(const WCHAR* dotnetPath)
{
    // Errors while reading from the file shouldn't throw unless
    // file.exception(bits) is set
    std::ifstream file(dotnetPath, std::ios::binary);
    if (!file.is_open())
    {
        LOG_TRACEF(L"Failed to open file %ls", dotnetPath);
        return false;
    }

    // Read the DOS header
    IMAGE_DOS_HEADER dosHeader{};
    file.read(reinterpret_cast<char*>(&dosHeader), sizeof(dosHeader));
    if (dosHeader.e_magic != IMAGE_DOS_SIGNATURE) // 'MZ'
    {
        LOG_TRACEF(L"%ls is not a valid executable file (missing MZ header).", dotnetPath);
        return false;
    }

    // Seek to the PE header
    file.seekg(dosHeader.e_lfanew, std::ios::beg);

    // Read the PE header
    DWORD peSignature{};
    file.read(reinterpret_cast<char*>(&peSignature), sizeof(peSignature));
    if (peSignature != IMAGE_NT_SIGNATURE) // 'PE\0\0'
    {
        LOG_TRACEF(L"%ls is not a valid PE file (missing PE header).", dotnetPath);
        return false;
    }

    // Read the file header
    IMAGE_FILE_HEADER fileHeader{};
    file.read(reinterpret_cast<char*>(&fileHeader), sizeof(fileHeader));

    // Read the optional header magic field
    WORD magic{};
    file.read(reinterpret_cast<char*>(&magic), sizeof(magic));