Merge pull request #277 from PJK/cjson2cbor

Add a CBOR to cJSON example

.circleci/config.yml

@@ -5,11 +5,12 @@ commands:
     steps:
     - run: sudo apt-get update
     - run: sudo apt-get install -y cmake ${TOOLCHAIN_PACKAGES}
-    - run: sudo apt install libcmocka-dev
+    - run: sudo apt install libcmocka-dev libcjson-dev
   build:
     steps:
     - run: >
         cmake -DWITH_TESTS=ON \
+          -DWITH_EXAMPLES=ON \
           -DCMAKE_BUILD_TYPE=Debug \
           -DSANITIZE=OFF \
           -DCOVERAGE="${CMAKE_COVERAGE:='OFF'}" \

examples/CMakeLists.txt

@@ -22,6 +22,10 @@ if(CJSON_FOUND)
     add_executable(cjson2cbor cjson2cbor.c)
     target_include_directories(cjson2cbor PUBLIC ${CJSON_INCLUDE_DIRS})
     target_link_libraries(cjson2cbor cbor ${CJSON_LIBRARY})
+
+    add_executable(cbor2cjson cbor2cjson.c)
+    target_include_directories(cbor2cjson PUBLIC ${CJSON_INCLUDE_DIRS})
+    target_link_libraries(cbor2cjson cbor ${CJSON_LIBRARY})
 endif()
 
 file(COPY data DESTINATION .)

examples/cbor2cjson.c

@@ -0,0 +1,123 @@
+/*
+ * Copyright (c) 2014-2020 Pavel Kalvoda <me@pavelkalvoda.com>
+ *
+ * libcbor is free software; you can redistribute it and/or modify
+ * it under the terms of the MIT license. See LICENSE for details.
+ */
+
+#include <cjson/cJSON.h>
+#include <stdio.h>
+#include <string.h>
+
+#include "cbor.h"
+
+void usage(void) {
+  printf("Usage: cbor2cjson [input file]\n");
+  exit(1);
+}
+
+cJSON* cbor_to_cjson(cbor_item_t* item) {
+  switch (cbor_typeof(item)) {
+    case CBOR_TYPE_UINT:
+      return cJSON_CreateNumber(cbor_get_int(item));
+    case CBOR_TYPE_NEGINT:
+      return cJSON_CreateNumber(-1 - cbor_get_int(item));
+    case CBOR_TYPE_BYTESTRING:
+      // cJSON only handles null-terminated string -- binary data would have to
+      // be escaped
+      return cJSON_CreateString("Unsupported CBOR item: Bytestring");
+    case CBOR_TYPE_STRING:
+      if (cbor_string_is_definite(item)) {
+        // cJSON only handles null-terminated string
+        char* null_terminated_string = malloc(cbor_string_length(item) + 1);
+        memcpy(null_terminated_string, cbor_string_handle(item),
+               cbor_string_length(item));
+        null_terminated_string[cbor_string_length(item)] = 0;
+        cJSON* result = cJSON_CreateString(null_terminated_string);
+        free(null_terminated_string);
+        return result;
+      }
+      return cJSON_CreateString("Unsupported CBOR item: Chunked string");
+    case CBOR_TYPE_ARRAY: {
+      cJSON* result = cJSON_CreateArray();
+      for (size_t i = 0; i < cbor_array_size(item); i++) {
+        cJSON_AddItemToArray(result, cbor_to_cjson(cbor_array_get(item, i)));
+      }
+      return result;
+    }
+    case CBOR_TYPE_MAP: {
+      cJSON* result = cJSON_CreateObject();
+      for (size_t i = 0; i < cbor_map_size(item); i++) {
+        char* key = malloc(128);
+        snprintf(key, 128, "Surrogate key %zu", i);
+        // JSON only support string keys
+        if (cbor_isa_string(cbor_map_handle(item)[i].key) &&
+            cbor_string_is_definite(cbor_map_handle(item)[i].key)) {
+          size_t key_length = cbor_string_length(cbor_map_handle(item)[i].key);
+          if (key_length > 127) key_length = 127;
+          // Null-terminated madness
+          memcpy(key, cbor_string_handle(cbor_map_handle(item)[i].key),
+                 key_length);
+          key[key_length] = 0;
+        }
+
+        cJSON_AddItemToObject(result, key,
+                              cbor_to_cjson(cbor_map_handle(item)[i].value));
+        free(key);
+      }
+      return result;
+    }
+    case CBOR_TYPE_TAG:
+      return cJSON_CreateString("Unsupported CBOR item: Tag");
+    case CBOR_TYPE_FLOAT_CTRL:
+      if (cbor_float_ctrl_is_ctrl(item)) {
+        if (cbor_is_bool(item)) return cJSON_CreateBool(cbor_get_bool(item));
+        if (cbor_is_null(item)) return cJSON_CreateNull();
+        return cJSON_CreateString("Unsupported CBOR item: Control value");
+      }
+      return cJSON_CreateNumber(cbor_float_get_float(item));
+  }
+
+  return cJSON_CreateNull();
+}
+
+/*
+ * Reads CBOR data from a file and outputs JSON using cJSON
+ * $ ./examples/cbor2cjson examples/data/nested_array.cbor
+ */
+
+int main(int argc, char* argv[]) {
+  if (argc != 2) usage();
+  FILE* f = fopen(argv[1], "rb");
+  if (f == NULL) usage();
+  fseek(f, 0, SEEK_END);
+  size_t length = (size_t)ftell(f);
+  fseek(f, 0, SEEK_SET);
+  unsigned char* buffer = malloc(length);
+  fread(buffer, length, 1, f);
+
+  /* Assuming `buffer` contains `length` bytes of input data */
+  struct cbor_load_result result;
+  cbor_item_t* item = cbor_load(buffer, length, &result);
+  free(buffer);
+
+  if (result.error.code != CBOR_ERR_NONE) {
+    printf(
+        "There was an error while reading the input near byte %zu (read %zu "
+        "bytes in total): ",
+        result.error.position, result.read);
+    exit(1);
+  }
+
+  cJSON* cjson_item = cbor_to_cjson(item);
+  char* json_string = cJSON_Print(cjson_item);
+  printf("%s\n", json_string);
+  free(json_string);
+  fflush(stdout);
+
+  /* Deallocate the result */
+  cbor_decref(&item);
+  cJSON_Delete(cjson_item);
+
+  fclose(f);
+}

examples/cjson2cbor.c

@@ -111,7 +111,7 @@ void cjson_cbor_stream_decode(cJSON *source,
 }
 
 void usage(void) {
-  printf("Usage: cjson [input JSON file]\n");
+  printf("Usage: cjson2cbor [input JSON file]\n");
   exit(1);
 }
 

src/cbor.c

@@ -313,7 +313,7 @@ static void _cbor_nested_describe(cbor_item_t *item, FILE *out, int indent) {
     case CBOR_TYPE_NEGINT: {
       fprintf(out, "%*s[CBOR_TYPE_NEGINT] ", indent, " ");
       fprintf(out, "Width: %dB, ", _pow(2, cbor_int_get_width(item)));
-      fprintf(out, "Value: -%" PRIu64 " -1\n", cbor_get_int(item));
+      fprintf(out, "Value: -%" PRIu64 " - 1\n", cbor_get_int(item));
       break;
     }
     case CBOR_TYPE_BYTESTRING: {