Move json util code to common

So that it can be shared by CE CDM extraction tool later.

Test: m wv_factory_extraction_tool
Bug: 414642286
Change-Id: I6dba70227ce2789dd3686ebbf6ed3a0dbf68dc00

libwvdrmengine/tools/factory_upload_tool/Android.bp

@@ -35,6 +35,7 @@ cc_binary {
         "aosp/src/properties_android.cpp",
         "aosp/src/BccParser.cpp",
         "aosp/src/WidevineProvisioner.cpp",
+        "common/src/json_utils.cpp",
         "common/src/WidevineOemcryptoInterface.cpp",
     ],
     include_dirs: [

libwvdrmengine/tools/factory_upload_tool/aosp/src/WidevineProvisioner.cpp

@@ -20,6 +20,7 @@
 #include <utility>
 
 #include "WidevineOemcryptoInterface.h"
+#include "json_utils.h"
 #include "log.h"
 #include "properties.h"
 #include "string_conversions.h"
@@ -32,51 +33,6 @@ const std::vector<std::vector<uint8_t>> kAuthorizedEekRoots = {
      0x62, 0xDC, 0x3E, 0x61, 0xAB, 0x57, 0x48, 0x7D, 0x75, 0x37, 0x29,
      0xAD, 0x76, 0x80, 0x32, 0xD2, 0xB3, 0xCB, 0x63, 0x58, 0xD9},
 };
-
-std::string EscapeJson(const std::string& input) {
-  std::string result;
-  for (std::string::const_iterator c = input.begin(); c != input.end(); ++c) {
-    switch (*c) {
-      case '\"':
-        result += "\\\"";
-        break;
-      case '\\':
-        result += "\\\\";
-        break;
-      case '\b':
-        result += "\\b";
-        break;
-      case '\f':
-        result += "\\f";
-        break;
-      case '\n':
-        result += "\\n";
-        break;
-      case '\r':
-        result += "\\r";
-        break;
-      case '\t':
-        result += "\\t";
-        break;
-      default:
-        result += *c;
-        break;
-    }
-  }
-  return result;
-}
-
-std::string StringMapToJson(
-    const std::map<std::string, std::string>& string_map) {
-  std::string json = "{";
-  for (const auto& value_pair : string_map) {
-    json.append("\"" + value_pair.first + "\": " + "\"" + value_pair.second +
-                "\",");
-  }
-  json.resize(json.size() - 1);  // Remove the last comma.
-  json.append("}");
-  return json;
-}
 }  // namespace
 
 WidevineProvisioner::WidevineProvisioner() {

libwvdrmengine/tools/factory_upload_tool/common/include/json_utils.h

@@ -0,0 +1,19 @@
+// Copyright 2025 Google LLC. All Rights Reserved. This file and proprietary
+// source code may only be used and distributed under the Widevine License
+// Agreement.
+
+#ifndef WIDEVINE_JSON_UTILS_H_
+#define WIDEVINE_JSON_UTILS_H_
+
+#include <map>
+#include <string>
+
+namespace widevine {
+
+std::string EscapeJson(const std::string& input);
+std::string StringMapToJson(
+    const std::map<std::string, std::string>& string_map);
+
+}  // namespace widevine
+
+#endif  // WIDEVINE_JSON_UTILS_H_

libwvdrmengine/tools/factory_upload_tool/common/src/json_utils.cpp

@@ -0,0 +1,63 @@
+// Copyright 2025 Google LLC. All Rights Reserved. This file and proprietary
+// source code may only be used and distributed under the Widevine License
+// Agreement.
+
+#include "json_utils.h"
+
+#include <sstream>
+
+namespace widevine {
+
+std::string EscapeJson(const std::string& input) {
+  std::string result;
+  for (const char& c : input) {
+    switch (c) {
+      case '\"':
+        result += "\\\"";
+        break;
+      case '\\':
+        result += "\\\\";
+        break;
+      case '\b':
+        result += "\\b";
+        break;
+      case '\f':
+        result += "\\f";
+        break;
+      case '\n':
+        result += "\\n";
+        break;
+      case '\r':
+        result += "\\r";
+        break;
+      case '\t':
+        result += "\\t";
+        break;
+      default:
+        result += c;
+        break;
+    }
+  }
+  return result;
+}
+
+std::string StringMapToJson(
+    const std::map<std::string, std::string>& string_map) {
+  if (string_map.empty()) {
+    return "{}";
+  }
+  std::ostringstream json_stream;
+  json_stream << "{";
+  bool is_first_element = true;
+  for (const auto& pair : string_map) {
+    if (!is_first_element) {
+      json_stream << ",";
+    }
+    json_stream << "\"" << pair.first << "\": \"" << pair.second << "\"";
+    is_first_element = false;
+  }
+  json_stream << "}";
+  return json_stream.str();
+}
+
+}  // namespace widevine