Simple File listing using Nodejs Addon (Node C API )

FilesListing_using_nodejs_addon.md

/**  By Umar <Jukoo> */ 

#include <node_api.h>

/**
 * NOTE: GNU/Linux  Compatible only
 */
#ifndef  __linux__
#error "Reserved Only for GNU/Linux OS x86 (glibc)"
#endif

#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <fcntl.h>
#include <dirent.h>
#include <sys/types.h>
#include <assert.h>
#include <stdio.h>
#include <sys/cdefs.h>

#include <errno.h>

#ifdef __ptr_t
#define _nullable (__ptr_t) 0
#else
#define _nullable  (void *) 0
#endif

#define __dptr_t  DIR*

#define  MAX_DIRENT_CONTENT 0xff

static int err_ref = 0 ;
static __u_char dirent_content_list[MAX_DIRENT_CONTENT] = {0} ;

/**
 * @fn fsl_show_dirent_content(const char * )
 * @brief  list  directory content
 * @param  const char *  -  path
 * @return void * - [nullable mean fail]
 */
static void *
fsl_show_dirent_content(const char * dirname)
{
  int i =0 ;
  assert(dirname != _nullable) ;
  __dptr_t dirent_status =  opendir(dirname)  ;

  if (!dirent_status){
    err_ref=errno ;
    return _nullable;
  }

  struct  dirent *  dirent_explorer  = _nullable ;

  char content_name[MAX_DIRENT_CONTENT]={0} ;
  while ( (dirent_explorer = readdir(dirent_status)) != _nullable )
  {
    sprintf(content_name ,"%s\n" ,dirent_explorer->d_name) ;
    strcat(dirent_content_list , content_name) ;
    explicit_bzero(content_name ,  MAX_DIRENT_CONTENT) ;

  }

  return dirent_content_list ;
}

/**
 * @fn list_target_directory(napi_env , napi_callback_info)
 * @brief method expose to node
 * @param   napi_env
 * @param   napi_callback_info
 * @return  napi_value
 */
static  napi_value
list_target_directory(napi_env env , napi_callback_info  info)
{
  napi_status  rc  ;
  napi_value   internal  ;

  size_t   argc= 1;
  napi_value args[1] ;

  rc = napi_get_cb_info(env, info  ,&argc , args ,  _nullable ,_nullable) ;
  assert(rc  == napi_ok);

  if (argc == 0  ) {
    napi_throw_type_error(env  , _nullable , "requier 1 argument position") ;
    return _nullable ;
  }

  napi_valuetype  expected_type ;
  rc = napi_typeof(env , args[0], &expected_type) ;

  char cbuff[MAX_DIRENT_CONTENT] ={0};
  size_t size ;

  rc = napi_get_value_string_utf8(env , args[0] , cbuff, MAX_DIRENT_CONTENT, &size) ;

  if(rc != napi_ok ) {
    napi_throw_type_error(env ,  _nullable,"Fail to get string value") ;
    return _nullable ;
  }

  __u_char  *content = (__u_char *) fsl_show_dirent_content(cbuff) ;

  if (!content  && err_ref !=0 ){
    napi_throw_type_error(env, _nullable ,strerror(err_ref)) ;
    return _nullable ;
  }

  rc = napi_create_string_utf8(env , content  , strlen(content) ,  &internal) ;

  if (rc != napi_ok)return _nullable ;

  explicit_bzero(content ,  MAX_DIRENT_CONTENT) ;
  return internal ;
}

/**
 * @fn  fsl_init(napi_env , napi_value)
 * @brief  initialize and set some  properties for exposed functions
 * @param  napi_env
 * @param  napi_value
 * @return napi_value
 */
static  napi_value
fsl_init(napi_env env  , napi_value exports)
{
  napi_value  internal ;
  napi_status rc ;

  rc = napi_create_function(env , _nullable , 0 ,  list_target_directory , _nullable, &internal) ;
  if (rc  != napi_ok) return _nullable ;

  rc = napi_set_named_property(env ,exports ,   "list_target_directory" ,  internal) ;
  if (rc  != napi_ok) return _nullable ;

  return exports ;
}

NAPI_MODULE(NODE_GYP_MODULE_NAME ,  fsl_init)

On My test.js file

const myaddon = require("./build/Release/myaddon")

let files = myaddon.list_target_directory("/home")
        
console.log(files)