[loader] Preserve nxlink argv markers

src/core/loader/homebrew_nxlink.cpp

@@ -0,0 +1,109 @@
+// SPDX-FileCopyrightText: Copyright 2026 Eden Emulator Project
+// SPDX-License-Identifier: GPL-3.0-or-later
+
+#include "core/loader/homebrew_nxlink.h"
+
+#include <cctype>
+
+namespace Loader::HomebrewNxlink {
+namespace {
+
+std::optional<std::string> GetLastArgvToken(std::string_view argv_string) {
+    while (!argv_string.empty() && argv_string.back() == '\0') {
+        argv_string.remove_suffix(1);
+    }
+
+    std::optional<std::string_view> last_token;
+    bool in_token = false;
+    bool quoted = false;
+    size_t token_begin = 0;
+    size_t token_size = 0;
+
+    for (size_t i = 0; i <= argv_string.size(); i++) {
+        const char c = i < argv_string.size() ? argv_string[i] : '\0';
+
+        if (!in_token) {
+            if (c == '\0' || std::isspace(static_cast<unsigned char>(c))) {
+                continue;
+            }
+
+            in_token = true;
+            token_size = 0;
+            if (c == '"') {
+                quoted = true;
+                token_begin = i + 1;
+            } else {
+                quoted = false;
+                token_begin = i;
+                token_size = 1;
+            }
+            continue;
+        }
+
+        const bool token_end =
+            quoted ? c == '"' || c == '\0'
+                   : c == '\0' || std::isspace(static_cast<unsigned char>(c));
+        if (token_end) {
+            if (token_size != 0) {
+                last_token = argv_string.substr(token_begin, token_size);
+            }
+            in_token = false;
+            quoted = false;
+            token_size = 0;
+            continue;
+        }
+
+        token_size++;
+    }
+
+    if (!last_token) {
+        return std::nullopt;
+    }
+    return std::string{*last_token};
+}
+
+void AppendArgvToken(std::string& argv_string, std::string_view token) {
+    while (!argv_string.empty() && argv_string.back() == '\0') {
+        argv_string.pop_back();
+    }
+    if (!argv_string.empty()) {
+        argv_string.push_back(' ');
+    }
+    argv_string.append(token);
+}
+
+} // namespace
+
+bool IsArgvMarker(std::string_view token) {
+    if (token.size() != ArgvMarkerSize || token.substr(8) != ArgvMarkerSuffix) {
+        return false;
+    }
+
+    for (size_t i = 0; i < 8; i++) {
+        if (!std::isxdigit(static_cast<unsigned char>(token[i]))) {
+            return false;
+        }
+    }
+
+    return true;
+}
+
+std::optional<std::string> GetArgvMarker(std::string_view argv_string) {
+    auto last_token = GetLastArgvToken(argv_string);
+    if (!last_token || !IsArgvMarker(*last_token)) {
+        return std::nullopt;
+    }
+    return last_token;
+}
+
+std::optional<std::string> PrepareArgv(std::string& argv_string,
+                                       std::string_view inherited_marker) {
+    auto marker = GetArgvMarker(argv_string);
+    if (!marker && IsArgvMarker(inherited_marker)) {
+        AppendArgvToken(argv_string, inherited_marker);
+        marker = std::string{inherited_marker};
+    }
+    return marker;
+}
+
+} // namespace Loader::HomebrewNxlink