Re: program to remove duplicates

ok i wrote this duplicates remover but i dont know if it has no errors etc
heres the code you may comment if you some errors, alternatives or improvements (note i wrote it among the time i posted on it and that moment here so its kinda speedy draft (i reused old routines for loading files etc)
#include<windows.h>
#include<stdio.h>
  void StrCopyMaxNBytes(char* dest, char* src, int n)
  {
   for(int i=0; i<n; i++) { dest[i]=src[i]; if(!src[i]) break;  }
  }
  //list of file names
  const int FileNameListEntry_name_max = 500;
  struct FileNameListEntry { char name[FileNameListEntry_name_max]; unsigned int file_size; };
  FileNameListEntry* FileNameList = NULL;
  int FileNameList_Size = 0;
  void FileNameList_AddOne(char* name, unsigned int file_size)
  {
      FileNameList_Size++;
      FileNameList = (FileNameListEntry*) realloc(FileNameList, FileNameList_Size * sizeof(FileNameListEntry) );
      StrCopyMaxNBytes((char*)&FileNameList[FileNameList_Size-1].name, name, FileNameListEntry_name_max);
      FileNameList[FileNameList_Size-1].file_size = file_size;
      return ;
  }
  // collect list of filenames
  WIN32_FIND_DATA ffd;
  void ReadDIrectoryFileNamesToList(char* dir)
  {
   HANDLE h = FindFirstFile(dir, &ffd);
   if(!h) { printf("error reading directory"); exit(-1);}
   do  {
    if (!(ffd.dwFileAttributes & FILE_ATTRIBUTE_DIRECTORY))
    {
      FileNameList_AddOne(ffd.cFileName, ffd.nFileSizeLow);
      if(ffd.nFileSizeHigh!=0) { printf("this program only work for files up to 4GB"); exit(-1);}
    }
   }
   while (FindNextFile(h, &ffd));
  }
#include <sys/stat.h>
  int GetFileSize2(char *filename)
  {
     struct stat st;
     if (stat(filename, &st)==0) return (int) st.st_size;
     printf("error obtaining file size for %s", filename); exit(-1);
     return -1;
  }
  int FolderExist(char *name)
  {
     static struct stat st;
     if(stat(name, &st) == 0 && S_ISDIR(st.st_mode)) return 1;
     return 0;
  }
//////////
   unsigned char* bytes2 = NULL;
   int bytes2_size = 0;
   int bytes2_allocked = 0;
   unsigned char* bytes2_resize(int size)
    {
    bytes2_size=size;
    if((bytes2_size+100)*2<bytes2_allocked | bytes2_size>bytes2_allocked)
    return  bytes2=(unsigned char*)realloc(bytes2, (bytes2_allocked=(bytes2_size+100)*2)*sizeof(unsigned char));
    }
   void bytes2_load(unsigned char* name)
   {
     int flen = GetFileSize2(name);
     FILE *f = fopen(name, "rb");
     if(!f) {  printf( "errot: cannot open file %s for load  ", name); exit(-1); }
     int loaded = fread(bytes2_resize(flen), 1, flen, f);
     fclose(f);
    }
/////////////////
   unsigned char* bytes1 = NULL;
   int bytes1_size = 0;
   int bytes1_allocked = 0;
   unsigned char* bytes1_resize(int size)
    {
    bytes1_size=size;
    if((bytes1_size+100)*2<bytes1_allocked | bytes1_size>bytes1_allocked)
    return  bytes1=(unsigned char*)realloc(bytes1, (bytes1_allocked=(bytes1_size+100)*2)*sizeof(unsigned char));
    }
   void bytes1_load(unsigned char* name)
   {
     int flen = GetFileSize2(name);
     FILE *f = fopen(name, "rb");
     if(!f) {  printf( "errot: cannot open file %s for load  ", name); exit(-1); }
     int loaded = fread(bytes1_resize(flen), 1, flen, f);
     fclose(f);
    }
/////////////
int CompareTwoFilesByContentsAndSayIfEqual(char* file_a, char* file_b)
{
    bytes1_load(file_a);
    bytes2_load(file_b);
    if(bytes1_size!=bytes2_size) { printf("\n something is wrong compared files assumed to be be same size"); exit(-1); }
    for(unsigned int i=0; i<=bytes1_size;i++)
      if(bytes1[i]!=bytes2[i]) return 0;
   return 1;
}
#include<direct.h>
#include <dirent.h>
#include <errno.h>
int duplicates_moved = 0;
void MoveDuplicateToSubdirectory(char*name)
{
    if(!FolderExist("duplicates"))
    {
     int n =  _mkdir("duplicates");
     if(n) { printf ("\n i cannot create subfolder"); exit(-1); }
    }
   static char renamed[1000];
   int n = snprintf(renamed, sizeof(renamed), "duplicates\%s", name);
   if(rename(name, renamed))
    {printf("\n rename %s %s failed", name, renamed); exit(-1);}
   duplicates_moved++;
}
int main()
{
     printf("\n (RE)MOVE FILE DUPLICATES");
     printf("\n ");
     printf("\n this program searches for binaric (comparec byute to byte)");
     printf("\n duplicates/multiplicates of files in its own");
     printf("\n folder (no search in subdirectories, just flat)");
     printf("\n and if found it copies it into 'duplicates'");
     printf("\n subfolder it creates  If you want to remove that");
     printf("\n duplicates you may delete the subfolder then,");
     printf("\n if you decided to not remove just move the contents");
     printf("\n of 'duplicates' subfolder back");
     printf("\n ");
     printf("\n note this program not work on files larger than 4GB ");
     printf("\n and no warranty at all youre responsible for any dameges ");
     printf("\n if use of this program would eventually do - i just wrote ");
     printf("\n the code and it work for me but not tested it to much besides");
     printf("\n ");
     printf("\n september 2024");
     printf("\n ");
     printf("\n starting.. ");
    ReadDIrectoryFileNamesToList("*");
//    for(int i=0; i< FileNameList_Size; i++)
//        printf("\n %d %s %d", i, FileNameList[i].name, FileNameList[i].file_size );
    for(int i=0; i< FileNameList_Size; i++)
    {
     for(int j=i+1; j< FileNameList_Size; j++)
     {
       if(FileNameList[i].file_size!=FileNameList[j].file_size) continue;
       if( CompareTwoFilesByContentsAndSayIfEqual(FileNameList[i].name, FileNameList[j].name))
       {
       //   printf("\nduplicate found (%s) ", FileNameList[j].name);
          MoveDuplicateToSubdirectory(FileNameList[j].name);
       }
     }
    }
   printf(" \n\n %d duplicates moved \n\n\n", duplicates_moved);
   return 'ok';
}