AK+Kernel: Escape JSON keys & values

Grab the escaping logic from JSON string value serialization and use
it for serializing all keys and values.

Fixes #3917.

AK/JsonArraySerializer.h

@@ -61,7 +61,7 @@ public:
     {
         begin_item();
         m_builder.append('"');
-        m_builder.append(value);
+        m_builder.append_escaped_for_json(value);
         m_builder.append('"');
     }
 
@@ -69,7 +69,7 @@ public:
     {
         begin_item();
         m_builder.append('"');
-        m_builder.append(value);
+        m_builder.append_escaped_for_json(value);
         m_builder.append('"');
     }
 
@@ -77,7 +77,7 @@ public:
     {
         begin_item();
         m_builder.append('"');
-        m_builder.append(value);
+        m_builder.append_escaped_for_json(value);
         m_builder.append('"');
     }
 

AK/JsonObject.h

@@ -158,33 +158,8 @@ inline void JsonValue::serialize(Builder& builder) const
 {
     switch (m_type) {
     case Type::String: {
-        auto size = m_value.as_string->length();
         builder.append("\"");
-        for (size_t i = 0; i < size; i++) {
-            char ch = m_value.as_string->characters()[i];
-            switch (ch) {
-            case '\e':
-                builder.append("\\u001B");
-                break;
-            case '\b':
-                builder.append("\\b");
-                break;
-            case '\n':
-                builder.append("\\n");
-                break;
-            case '\t':
-                builder.append("\\t");
-                break;
-            case '\"':
-                builder.append("\\\"");
-                break;
-            case '\\':
-                builder.append("\\\\");
-                break;
-            default:
-                builder.append(ch);
-            }
-        }
+        builder.append_escaped_for_json({ m_value.as_string->characters(), m_value.as_string->length() });
         builder.append("\"");
     } break;
     case Type::Array:

AK/JsonObjectSerializer.h

@@ -59,7 +59,7 @@ public:
     {
         begin_item(key);
         m_builder.append('"');
-        m_builder.append(value);
+        m_builder.append_escaped_for_json(value);
         m_builder.append('"');
     }
 
@@ -67,7 +67,7 @@ public:
     {
         begin_item(key);
         m_builder.append('"');
-        m_builder.append(value);
+        m_builder.append_escaped_for_json(value);
         m_builder.append('"');
     }
 
@@ -75,7 +75,7 @@ public:
     {
         begin_item(key);
         m_builder.append('"');
-        m_builder.append(value);
+        m_builder.append_escaped_for_json(value);
         m_builder.append('"');
     }
 
@@ -154,7 +154,7 @@ private:
         m_empty = false;
 
         m_builder.append('"');
-        m_builder.append(key);
+        m_builder.append_escaped_for_json(key);
         m_builder.append("\":");
     }
 

AK/StringBuilder.cpp

@@ -144,4 +144,32 @@ void StringBuilder::append(const Utf32View& utf32_view)
     }
 }
 
+void StringBuilder::append_escaped_for_json(const StringView& string)
+{
+    for (auto ch : string) {
+        switch (ch) {
+        case '\e':
+            append("\\u001B");
+            break;
+        case '\b':
+            append("\\b");
+            break;
+        case '\n':
+            append("\\n");
+            break;
+        case '\t':
+            append("\\t");
+            break;
+        case '\"':
+            append("\\\"");
+            break;
+        case '\\':
+            append("\\\\");
+            break;
+        default:
+            append(ch);
+        }
+    }
+}
+
 }

AK/StringBuilder.h

@@ -49,6 +49,8 @@ public:
     void appendf(const char*, ...);
     void appendvf(const char*, va_list);
 
+    void append_escaped_for_json(const StringView&);
+
     template<typename... Parameters>
     void appendff(StringView fmtstr, const Parameters&... parameters)
     {

Kernel/KBufferBuilder.cpp

@@ -93,4 +93,32 @@ void KBufferBuilder::appendf(const char* fmt, ...)
     va_end(ap);
 }
 
+void KBufferBuilder::append_escaped_for_json(const StringView& string)
+{
+    for (auto ch : string) {
+        switch (ch) {
+        case '\e':
+            append("\\u001B");
+            break;
+        case '\b':
+            append("\\b");
+            break;
+        case '\n':
+            append("\\n");
+            break;
+        case '\t':
+            append("\\t");
+            break;
+        case '\"':
+            append("\\\"");
+            break;
+        case '\\':
+            append("\\\\");
+            break;
+        default:
+            append(ch);
+        }
+    }
+}
+
 }

Kernel/KBufferBuilder.h

@@ -45,6 +45,8 @@ public:
     void appendf(const char*, ...);
     void appendvf(const char*, va_list);
 
+    void append_escaped_for_json(const StringView&);
+
     template<typename... Parameters>
     void appendff(StringView fmtstr, const Parameters&... parameters)
     {