maint: Factor handling of GetModuleFileNameW

libmamba/src/core/util_os.cpp

@@ -47,29 +47,45 @@ static_assert(std::is_same_v<mamba::DWORD, ::DWORD>);
 
 namespace mamba
 {
-    // Heavily inspired by https://github.com/gpakosz/whereami/
-    // check their source to add support for other OS
-    fs::u8path get_self_exe_path()
-    {
+
 #ifdef _WIN32
+    fs::u8path get_hmodule_path(HMODULE hModule)
+    {
         std::wstring buffer(MAX_PATH, '\0');
-        DWORD size = GetModuleFileNameW(NULL, (wchar_t*) buffer.c_str(), (DWORD) buffer.size());
-        if (size == 0)
-        {
-            throw std::runtime_error("Could find location of the micromamba executable!");
-        }
-        else if (size == buffer.size())
+        DWORD new_size = MAX_PATH;
+        DWORD size = 0;
+        // There's unfortunately no way to know how much space is needed,
+        // so we just keep doubling the size of the buffer until the path fits.
+        while (true)
         {
-            DWORD new_size = size;
-            do
+            size = GetModuleFileNameW(hModule, buffer.data(), static_cast<DWORD>(buffer.size()));
+            if (size == 0)
             {
-                new_size *= 2;
-                buffer.reserve(new_size);
-                size = GetModuleFileNameW(NULL, (wchar_t*) buffer.c_str(), (DWORD) buffer.size());
-            } while (new_size == size);
+                throw mamba::mamba_error(
+                    "Could find the filename of the module handle. (GetModuleFileNameW failed)",
+                    mamba_error_code::internal_failure
+                );
+            }
+            if (size < new_size)
+            {
+                break;
+            }
+
+            new_size *= 2;
+            buffer.resize(new_size);
         }
-        buffer.resize(buffer.find(L'\0'));
+        buffer.resize(size);
         return fs::absolute(buffer);
+    }
+#endif
+
+    // Heavily inspired by https://github.com/gpakosz/whereami/
+    // check their source to add support for other OS
+    fs::u8path get_self_exe_path()
+    {
+#ifdef _WIN32
+        HMODULE hModule = NULL;  // references file used to create the calling process
+        return get_hmodule_path(hModule);
 #elif defined(__APPLE__)
         uint32_t size = PATH_MAX;
         std::vector<char> buffer(size);
@@ -107,29 +123,7 @@ namespace mamba
                 mamba_error_code::internal_failure
             );
         }
-        std::wstring buffer(MAX_PATH, '\0');
-        DWORD new_size = MAX_PATH;
-        DWORD size = 0;
-        while (true)
-        {
-            size = GetModuleFileNameW(hModule, buffer.data(), static_cast<DWORD>(buffer.size()));
-            if (size == 0)
-            {
-                throw mamba::mamba_error(
-                    "Could find the filename of the libmamba's module handle. (GetModuleFileNameW failed)",
-                    mamba_error_code::internal_failure
-                );
-            }
-            if (size < new_size)
-            {
-                break;
-            }
-
-            new_size *= 2;
-            buffer.resize(new_size);
-        }
-        buffer.resize(size);
-        return fs::absolute(buffer);
+        return get_hmodule_path(hModule);
 #else
         fs::u8path libmamba_path;
         Dl_info dl_info;