Architecture — cJSON Qualification

Requirement: The cJSON parser implements a recursive-descent algorithm operating on a UTF-8 byte stream. Control flow passes through tokenizer, value parser, and object/array constructors. ARCH_PARSER_FLOW

status: active tags: architecture, parsing links outgoing: REQ_CJSON_PARSE_VALID, REQ_CJSON_NO_UB, REQ_CJSON_STACK_BOUNDED links incoming: REQ_CJSON_PARSE_VALID, REQ_CJSON_NO_UB, REQ_CJSON_STACK_BOUNDED, REQ_CJSON_STRING_SAFE, ARCH_COMPONENT_DECOMPOSITION

Requirement: The cJSON printer traverses an in-memory cJSON object graph, emitting formatted or unformatted JSON text through a bounded output buffer. ARCH_PRINTER_FLOW

status: active tags: architecture, printing links outgoing: REQ_CJSON_PRINT_VALID, REQ_CJSON_ARITH_SAFE links incoming: REQ_CJSON_PRINT_VALID, REQ_CJSON_ARITH_SAFE

Requirement: Memory management uses the standard C malloc/free allocator by default, with an optional hook mechanism (cJSON_InitHooks) that allows integration with a safety-qualified memory allocator. ARCH_MEMORY_MODEL

status: active tags: architecture, memory links outgoing: REQ_CJSON_MEMORY_SAFE links incoming: REQ_CJSON_MEMORY_SAFE

Requirement: The cJSON data model is a tagged union (cJSON struct) supporting six value types: null, boolean, number, string, array, object. Arrays are linked lists of cJSON items; objects are linked lists of cJSON items with associated string keys. ARCH_DATA_MODEL

status: active tags: architecture, datamodel links incoming: REQ_CJSON_UTILS_RFC, REQ_CJSON_STRING_SAFE, REQ_CJSON_CODE_QUALITY

Requirement: The cJSON module boundary is defined by cJSON.h. All public API functions are marked CJSON_PUBLIC. Internal helpers (parse_, print_, ensure_, etc.) are static and not part of the external interface. The cJSON_Utils extension provides JSON Patch and JSON Pointer operations on top of the core API. ARCH_MODULE_BOUNDARY

status: active tags: architecture, interface links outgoing: REQ_CJSON_NULL_PTR_SAFE links incoming: REQ_CJSON_NULL_PTR_SAFE, REQ_CJSON_UTILS_RFC, REQ_CJSON_CODE_QUALITY, REQ_CJSON_REPRODUCIBLE, REQ_CJSON_TRACEABILITY, IMPL_SOURCE, IMPL_DELIVERABLE

Component Architecture (PlantUML)

Requirement: Component Decomposition — cJSON Core and Utils ARCH_COMPONENT_DECOMPOSITION

status: active tags: architecture, decomposition links outgoing: REQ_CJSON_PARSE_VALID, ARCH_PARSER_FLOW

The cJSON core (cJSON.c) contains four subsystems: Parser: recursive-descent JSON tokenizer and value constructor Printer: tree-walk JSON serializer to buffer Memory Management: malloc/free with optional hook replacement Object Model: tagged-union cJSON struct with linked-list children for arrays/objects The cJSON Utils (cJSON_Utils.c) builds on the core with JSON Patch (RFC 6902), JSON Pointer (RFC 6901), and Sort/Merge utilities. All components interface with the C standard library for string and memory operations.

Parser Flow (PlantUML)

Data Model (PlantUML)

Safety Architecture — Freedom from Interference

Requirement: Freedom from Interference Measures ARCH_FFI_MEASURES

status: active tags: architecture, ffi, safety links outgoing: REQ_CJSON_STACK_BOUNDED, REQ_CJSON_MEMORY_SAFE links incoming: REQ_CJSON_STACK_BOUNDED

FFI measures in cJSON: No global state — all state is in caller-owned cJSON* objects Memory allocation hooks enable replacement with a qualified allocator Bounded stack depth via CJSON_NESTING_LIMIT (default 1000) No thread synchronization performed inside the library Integrator responsibilities: Provide a qualified allocator via cJSON_InitHooks Validate all inputs before API calls Check all return values for error indicators Handle error paths at the integration boundary Ensure inputs respect nesting limits