[질문]C code : 하위폴더에 있는 모든 euc-kr 파일을 utf-8으로 바꾸기

#define _XOPEN_SOURCE 500  
#include<stdio.h>
#include<stdlib.h>
#include<ftw.h>            // 디렉토리 순환함수
#include<string.h>
#include<iconv.h>
#include<unistd.h>
#include<errno.h>
#include<fcntl.h>
 
int euc_to_utf(const char *fpath)
{
   iconv_t cd = iconv_open("UTF-8", "EUC-KR");
   if(cd == (iconv_t)(-1))
   {
      perror("iconv_open :");
      return -1;
   }
 
   char inBuf[BUFSIZE];
   char outBuf[BUFSIZE*2];
   int inBufSize = sizeof(inBuf);
   int outBufSize = sizeof(outBuf);
   memset(outBuf, 0, outBufSize);
 
   int inFd = open(fpath, O_RDWR);
   if(inFd == -1)
   {
      perror("Input file : ");
      return -1;
   }
 
   int outFd = open(fpath, O_WRONLY | O_CREAT);
   if(outFd == -1)
   {
      perror("Output file : ");
      return -1;
   }
 
   size_t readBytes = read(inFd, inBuf, sizeof(inBuf));
   inBuf[readBytes] = '\0';
 
   // file convert
   size_t writeBytes = sizeof(outBuf);
   char* in = inBuf;
   char* out = outBuf;
   if(iconv(cd, &in, &readBytes, &out, &writeBytes) == -1) {
      printf("Failed to iconv errno: %d  EILSEQ: %d\n", errno, EILSEQ);
      exit(-1);
   } else {
      outBuf[writeBytes] = '\0';
      write(outFd, outBuf, writeBytes);
      close(outFd);
   }
   close(inFd);
 
   return 0;
}
 
static int conver_helper(const char *fpath, const struct stat *sb, int tflag, struct FTW *ftwbuf)
{
   switch(tflag)
   {
      case FTW_D:          // fpath is a directory
      case FTW_DP:         // All of the files and subdirectories whithin fpath have been processed
         if(euc_to_utf(fpath) == -1)
            printf("파일변환 실패 ! ");
         break;
      case FTW_F:          // fpath is normal file
      case FTW_SL:         // fpath is symbolic link, and FTW_PHYS was set in flags
      default:
         puts("do nothing");
   }
   return 0;
}
 
int main(int argc, char** argv)
{
   const char* file_to_conv = ".";
   int flags = 0;
   flags |= FTW_DEPTH;// post-order traverse
 
   if(argc == 2)
      file_to_conv = argv[1];
 
   if(nftw(file_to_conv, conver_helper, 10, flags) == -1)
   {
      perror("nftw");
      exit(EXIT_FAILURE);
   }
 
   return 0;
}