get_buffer()

binding.c

#include <assert.h>
#include <limits.h>
#include <node_api.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>

static int arg_buf(
  napi_env env,
  napi_value value,
  unsigned char** buffer,
  int* length
) {
  assert(*buffer == NULL);
  assert(*length == 0);
  bool is_buffer;
  assert(napi_is_buffer(env, value, &is_buffer) == napi_ok);
  assert(is_buffer);
  size_t size = 0;
  assert(napi_get_buffer_info(env, value, (void**) buffer, &size) == napi_ok);
  assert(*buffer != NULL);
  assert(size <= INT_MAX);
  *length = (int) size;
  assert(*length >= 0);
  return 1;
}

static napi_value get_buffer(napi_env env, napi_callback_info info) {
  size_t argc = 1;
  napi_value argv[1];
  assert(napi_get_cb_info(env, info, &argc, argv, NULL, NULL) == napi_ok);
  assert(argc == 1);
  unsigned char* buffer = NULL;
  int buffer_length = 0;
  assert(arg_buf(env, argv[0], &buffer, &buffer_length));
  assert(buffer != NULL);
  printf("buffer_length=%i\n", buffer_length);
  return NULL;
}

static napi_value Init(napi_env env, napi_value exports) {
  napi_value fn_get_buffer;
  assert(napi_create_function(env, NULL, 0, get_buffer, NULL, &fn_get_buffer) == napi_ok);
  assert(napi_set_named_property(env, exports, "get_buffer", fn_get_buffer) == napi_ok);
  return exports;
}

NAPI_MODULE(NODE_GYP_MODULE_NAME, Init)

binding.gyp

{
  "targets": [
    {
      "target_name": "binding",
      "sources": [ "binding.c" ]
    },
    {
      "target_name": "copy",
      "type": "none",
      "dependencies": [ "binding" ],
      "copies": [
        {
          'destination': '<(module_root_dir)',
          'files': ['<(module_root_dir)/build/Release/binding.node']
        }
      ]
    }
  ]
}

index.js

var binding = require('./binding.node');
var crypto = require('crypto');

console.log('process.version=' + process.version);

console.log('testing Buffer.alloc(0)...');
binding.get_buffer(Buffer.alloc(0));

console.log('testing cipher.update(Buffer.alloc(0))...');
var key = Buffer.alloc(32, 255);
var iv = Buffer.alloc(16);
var cipher = crypto.createCipheriv('aes-256-ctr', key, iv);
binding.get_buffer(cipher.update(Buffer.alloc(0)));

package.json

{
  "name": "get_buffer",
  "version": "1.0.0",
  "main": "index.js",
  "files": [
    "binding.c",
    "index.js"
  ],
  "author": "Joran Dirk Greef",
  "license": "MIT",
  "scripts": {
    "postinstall": "node-gyp clean"
  },
  "engines": {
    "node": ">=10.0.0"
  }
}