Print missing DLLs on library load failure (#387)

## Description of change
When the game library fails to load, recursively iterate its import
table to narrow down the missing library.

If the dependency is a commonly missing one, give the user a hint on
where to find it.

## Testing
System with an AMD GPU and LDJ-010 IIDX:
```
[2025/10/01 00:32:41] M:dependencies: bm2dx.dll
[2025/10/01 00:32:41] M:dependencies:   |-- nvEncodeAPI64.dll
[2025/10/01 00:32:41] W:dependencies:   | |-- [!] NVIDIA Graphics Driver
[2025/10/01 00:32:41] W:dependencies:   | |--     For non-NVIDIA GPUs, copy the stub file from the spice2x release .zip.
[2025/10/01 00:32:41] F:libutils: DLL failed to load - this is a common error. Please carefully read ALL of the following steps for a fix:
```

Same system, but with SDVX:
```
[2025/10/01 00:33:53] M:dependencies: soundvoltex.dll
[2025/10/01 00:33:53] M:dependencies:   |-- nvcuda.dll
[2025/10/01 00:33:53] W:dependencies:   | |-- [!] NVIDIA Graphics Driver
[2025/10/01 00:33:53] W:dependencies:   | |--     For non-NVIDIA GPUs, copy the stub file from the spice2x release .zip.
[2025/10/01 00:33:53] M:dependencies:   |-- nvcuvid.dll
[2025/10/01 00:33:53] W:dependencies:   | |-- [!] NVIDIA Graphics Driver
[2025/10/01 00:33:53] W:dependencies:   | |--     For non-NVIDIA GPUs, copy the stub file from the spice2x release .zip.
[2025/10/01 00:33:53] F:libutils: DLL failed to load - this is a common error. Please carefully read ALL of the following steps for a fix:
```

Contrived example of a missing dependency of a dependency:
```
[2025/10/01 00:30:59] M:dependencies: bm2dx.dll
[2025/10/01 00:30:59] M:dependencies:   |-- libaio.dll
[2025/10/01 00:30:59] W:dependencies:   | |-- [!] The library could not be loaded. (126)
[2025/10/01 00:30:59] M:dependencies:   |-- libaio-iob.dll
[2025/10/01 00:30:59] M:dependencies:   | |-- libaio.dll
[2025/10/01 00:30:59] M:dependencies:   |-- libaio-iob2_video.dll
[2025/10/01 00:30:59] M:dependencies:   | |-- libaio.dll
[2025/10/01 00:30:59] M:dependencies:   | |-- libaio-iob.dll
[2025/10/01 00:30:59] F:libutils: DLL failed to load - this is a common error. Please carefully read ALL of the following steps for a fix:
```

Another example of a missing file, but with 32-bit IIDX 24:
```
[2025/10/01 00:42:13] M:dependencies: bm2dx.dll
[2025/10/01 00:42:13] M:dependencies:   |-- libafp-win32.dll
[2025/10/01 00:42:13] W:dependencies:   | |-- [!] The library could not be loaded. (126)
[2025/10/01 00:42:13] M:dependencies:   |-- libafputils-win32.dll
[2025/10/01 00:42:13] M:dependencies:   | |-- libafp-win32.dll
[2025/10/01 00:42:13] F:libutils: DLL failed to load - this is a common error. Please carefully read ALL of the following steps for a fix:
```

---------

Co-authored-by: aixxe <me@aixxe.net>

src/spice2x/CMakeLists.txt

@@ -610,6 +610,7 @@ set(SOURCE_FILES ${SOURCE_FILES}
         util/lz77.cpp
         util/tapeled.cpp
         util/execexe.cpp
+        util/dependencies.cpp
 )
 
 source_group(TREE ${CMAKE_CURRENT_SOURCE_DIR} PREFIX "Source Files" FILES ${SOURCE_FILES})

src/spice2x/util/dependencies.cpp

@@ -0,0 +1,151 @@
+#include <set>
+#include "logging.h"
+#include "libutils.h"
+#include "scope_guard.h"
+#include "dependencies.h"
+
+using loader_hint = std::tuple<std::string, std::string, std::string>;
+
+namespace {
+    // list of commonly missing dependencies and tips on where to get them
+    std::vector<loader_hint> hints = {
+        {
+            "msvcr100.dll",
+            "Visual Studio 2010 (VC++ 10.0) SP1 Redistributable",
+            "Download and install from https://learn.microsoft.com/en-us/cpp/windows/latest-supported-vc-redist",
+        },
+        {
+            "d3dx9_43.dll",
+            "DirectX End-User Runtimes",
+            "Download and install from https://www.microsoft.com/en-us/download/details.aspx?id=35"
+        },
+        {
+            "nvEncodeAPI64.dll",
+            "NVIDIA Graphics Driver",
+            "For non-NVIDIA GPUs, copy the stub file from the spice2x release .zip.",
+        },
+        {
+            "nvcuda.dll",
+            "NVIDIA Graphics Driver",
+            "For non-NVIDIA GPUs, copy the stub file from the spice2x release .zip.",
+        },
+        {
+            "nvcuvid.dll",
+            "NVIDIA Graphics Driver",
+            "For non-NVIDIA GPUs, copy the stub file from the spice2x release .zip.",
+        },
+        {
+            "cpusbxpkm.dll",
+            "LovePlus Printer DLL",
+            "Copy the stub file from the spice2x release .zip.",
+        },
+    };
+
+    std::set<std::wstring> failed = {};
+
+    auto read_imports(const std::filesystem::path& path) -> std::vector<std::filesystem::path> {
+        auto result = std::vector<std::filesystem::path> {};
+        auto const file = CreateFileW(path.c_str(), GENERIC_READ, FILE_SHARE_READ, nullptr, OPEN_EXISTING, 0, nullptr);
+
+        if (file == INVALID_HANDLE_VALUE) {
+            return result;
+        }
+
+        auto const file_ = scope_guard { [file] { CloseHandle(file); } };
+        auto const mapping = CreateFileMapping(file, nullptr, PAGE_READONLY, 0, 0, nullptr);
+
+        if (!mapping) {
+            return result;
+        }
+
+        auto const mapping_ = scope_guard { [mapping] { CloseHandle(mapping); } };
+        auto const view = MapViewOfFile(mapping, FILE_MAP_READ, 0, 0, 0);
+
+        if (!view) {
+            return result;
+        }
+
+        auto const view_ = scope_guard { [view] { UnmapViewOfFile(view); } };
+        auto const dos = static_cast<PIMAGE_DOS_HEADER>(view);
+
+        if (dos->e_magic != IMAGE_DOS_SIGNATURE) {
+            return result;
+        }
+
+        auto const base = static_cast<std::uint8_t*>(view);
+        auto const nt = reinterpret_cast<PIMAGE_NT_HEADERS>(base + dos->e_lfanew);
+
+        if (nt->Signature != IMAGE_NT_SIGNATURE) {
+            return result;
+        }
+
+        auto const imports = nt->OptionalHeader.DataDirectory[IMAGE_DIRECTORY_ENTRY_IMPORT];
+
+        if (imports.VirtualAddress == 0) {
+            return result;
+        }
+
+        auto desc = reinterpret_cast<PIMAGE_IMPORT_DESCRIPTOR>(base + libutils::rva2offset(nt, imports.VirtualAddress));
+
+        while (desc->Name != 0) {
+            auto const filename = reinterpret_cast<char*>(base + libutils::rva2offset(nt, desc->Name));
+            auto entry_path = path.parent_path().append(filename);
+
+            // try to use library in the same directory if one exists
+            // otherwise, assume system library and use filename only
+            if (!std::filesystem::exists(entry_path)) {
+                entry_path = filename;
+            }
+
+            result.emplace_back(entry_path);
+            desc++;
+        }
+
+        return result;
+    }
+}
+
+namespace dependencies {
+    auto walk(const std::filesystem::path& path, const std::string& prefix) -> bool {
+        // try to load the library -- skip walking if it loads successfully
+        if (auto const module = LoadLibraryW(path.c_str())) {
+            FreeLibrary(module);
+            return true;
+        }
+
+        auto const error = GetLastError();
+        auto const filename = path.filename().string();
+
+        log_misc("dependencies", "{}{}", prefix + (prefix.empty() ? "": "|-- "), filename);
+
+        if (failed.contains(path)) {
+            return false;
+        }
+
+        failed.insert(path);
+
+        auto const dependencies = read_imports(path);
+        auto const next_prefix = prefix + (prefix.empty() ? "  ": "| ");
+
+        if (!dependencies.empty()) {
+            for (auto const& item : dependencies) {
+                walk(item, next_prefix);
+            }
+
+            return false;
+        }
+
+        for (auto const& [dll, name, hint] : hints) {
+            if (_stricmp(dll.c_str(), filename.c_str()) != 0) {
+                continue;
+            }
+
+            log_warning("dependencies", "{}|-- [!] {}", next_prefix, name.c_str());
+            log_warning("dependencies", "{}|--     {}", next_prefix, hint.c_str());
+            return false;
+        }
+
+        log_warning("dependencies", "{}|-- [!] The library could not be loaded. ({})", next_prefix, error);
+        return false;
+    }
+}

src/spice2x/util/dependencies.h

@@ -0,0 +1,8 @@
+#pragma once
+
+#include <string>
+#include <filesystem>
+
+namespace dependencies {
+    auto walk(const std::filesystem::path& path, const std::string& prefix = "") -> bool;
+}

src/spice2x/util/libutils.cpp

@@ -8,6 +8,7 @@
 #include "utils.h"
 #include "peb.h"
 #include "util/fileutils.h"
+#include "util/dependencies.h"
 
 std::filesystem::path libutils::module_file_name(HMODULE module) {
     std::wstring buf;
@@ -65,6 +66,7 @@ HMODULE libutils::load_library(const std::filesystem::path &path, bool fatal) {
 
     if (!module) {
         log_warning("libutils", "'{}' couldn't be loaded: {}", path.string(), get_last_error_string());
+        dependencies::walk(path);
         load_library_fail(path.filename().string(), fatal);
     }
 

src/spice2x/util/scope_guard.h

@@ -0,0 +1,19 @@
+#pragma once
+
+#include <functional>
+
+class scope_guard {
+private:
+    std::function<void()> f;
+public:
+    explicit scope_guard(std::function<void()>&& f) : f(std::move(f)) {}
+    ~scope_guard() {
+        f();
+    }
+
+    scope_guard(const scope_guard&) = delete;
+    scope_guard& operator=(const scope_guard&) = delete;
+
+    scope_guard(scope_guard&&) = delete;
+    scope_guard& operator=(scope_guard&&) = delete;
+};