```

feat: Add initial CBOR format support with libcbor integration (squahsed commit)

- Add ENABLE_CBOR_SUPPORT CMake flag to conditionally enable CBOR functionality
- Integrate libcbor dependency with CMake find_package and conditional compilation
- Add basic parser_cbor.c and parser_cbor.h files with foundational structures
- Implement initial CBOR parsing functions with libcbor as low-level parser
- Add necessary format switch statements throughout codebase for CBOR support
- Introduce lyd_parse_data_mem_len() high-level function for parsing CBOR from memory
  (required because CBOR binary data may contain null bytes, making strlen() unreliable)
- Build complete CBOR parser that constructs libyang data trees
- Link parsed CBOR data with schema trees for validation
- Fix initial memory allocation errors and remove dead code

This commit establishes the foundation for CBOR support in libyang, allowing the
library to be built with or without CBOR capabilities based on build configuration.
```

Author: MeherRushi

CMakeLists.txt

@@ -238,6 +238,7 @@ set(format_sources
     src/*.h
     src/plugins_exts/*
     src/plugins_types/*)
+
 #
 # options
 #
@@ -256,6 +257,7 @@ option(ENABLE_YANGLINT_INTERACTIVE "Enable interactive CLI yanglint" ON)
 option(ENABLE_TOOLS "Build binary tools 'yanglint' and 'yangre'" ON)
 option(ENABLE_COMMON_TARGETS "Define common custom target names such as 'doc' or 'uninstall', may cause conflicts when using add_subdirectory() to build this project" ON)
 option(BUILD_SHARED_LIBS "By default, shared libs are enabled. Turn off for a static build." ON)
+option(ENABLE_CBOR_SUPPORT "Enable CBOR support with libcbor" ON)
 set(YANG_MODULE_DIR "${CMAKE_INSTALL_PREFIX}/${CMAKE_INSTALL_DATADIR}/yang/modules/libyang" CACHE STRING "Directory where to copy the YANG modules to")
 
 if(ENABLE_INTERNAL_DOCS)
@@ -323,6 +325,42 @@ if(ENABLE_COVERAGE)
     gen_coverage_enable(${ENABLE_TESTS})
 endif()
 
+if(ENABLE_CBOR_SUPPORT)
+    find_package(PkgConfig)
+    if(PKG_CONFIG_FOUND)
+        pkg_check_modules(LIBCBOR REQUIRED libcbor)
+        if(LIBCBOR_FOUND)
+            message(STATUS "libcbor found, enabling CBOR support")
+            add_definitions(-DENABLE_CBOR_SUPPORT)
+            include_directories(${LIBCBOR_INCLUDE_DIRS})
+            # Add CBOR parser files to the library sources
+            list(APPEND libsrc src/parser_cbor.c)
+            list(APPEND headers src/parser_cbor.h)
+            # Add CBOR files to format sources
+            list(APPEND format_sources src/parser_cbor.c src/parser_cbor.h)
+        else()
+            message(FATAL_ERROR "libcbor not found! Please install libcbor development package or disable CBOR support with -DENABLE_CBOR_SUPPORT=OFF")
+        endif()
+    else()
+        # Fallback to find_path and find_library if pkg-config is not available
+        find_path(LIBCBOR_INCLUDE_DIR cbor.h)
+        find_library(LIBCBOR_LIBRARY cbor)
+        if(LIBCBOR_INCLUDE_DIR AND LIBCBOR_LIBRARY)
+            message(STATUS "libcbor found via find_path/find_library, enabling CBOR support")
+            add_definitions(-DENABLE_CBOR_SUPPORT)
+            include_directories(${LIBCBOR_INCLUDE_DIR})
+            set(LIBCBOR_LIBRARIES ${LIBCBOR_LIBRARY})
+            # Add CBOR parser files to the library sources
+            list(APPEND libsrc src/parser_cbor.c)
+            list(APPEND headers src/parser_cbor.h)
+            # Add CBOR files to format sources
+            list(APPEND format_sources src/parser_cbor.c src/parser_cbor.h)
+        else()
+            message(FATAL_ERROR "libcbor not found! Please install libcbor development package or disable CBOR support with -DENABLE_CBOR_SUPPORT=OFF")
+        endif()
+    endif()
+endif()
+
 if ("${BUILD_TYPE_UPPER}" STREQUAL "DEBUG")
     # enable before adding tests to let them detect that format checking is available - one of the tests is format checking
     source_format_enable(0.77)
@@ -427,6 +465,11 @@ find_package(PCRE2 10.21 REQUIRED)
 include_directories(${PCRE2_INCLUDE_DIRS})
 target_link_libraries(yang ${PCRE2_LIBRARIES})
 
+# link libcbor if CBOR support is enabled
+if(ENABLE_CBOR_SUPPORT)
+    target_link_libraries(yang ${LIBCBOR_LIBRARIES})
+endif()
+
 # XXHash include and library
 find_package(XXHash)
 if(XXHASH_FOUND)
@@ -521,4 +564,4 @@ add_custom_target(cclean
         COMMAND make clean
         COMMAND find . -iname '*cmake*' -not -name CMakeLists.txt -not -path './CMakeModules*' -exec rm -rf {} +
         COMMAND rm -rf Makefile Doxyfile
-        WORKING_DIRECTORY ${CMAKE_CURRENT_SOURCE_DIR})
+        WORKING_DIRECTORY ${CMAKE_CURRENT_SOURCE_DIR})