setCV posix

#include <stdio.h>
#include <unistd.h>
#include <errno.h>
#include <limits.h>
#include <string.h>
#include <fcntl.h>
#include <stdlib.h>
#include <sys/types.h>
#include <sys/stat.h>

#define SECTOR_SIZE 4096

char numeFisierSursa[PATH_MAX],numeFisierDestinatie[PATH_MAX];
char buffer[SECTOR_SIZE],comanda[10];
int bytes_read;

int main(int argc,char **argv)
{
    FILE *fptr1,*fptr2;

    printf("Nume fisier sursa : ");
    scanf("%s",numeFisierSursa);

    printf("Nume fisier destinatie : ");
    scanf("%s",numeFisierDestinatie);

    int f1=open(numeFisierSursa,O_RDONLY);

    if(f1<0)
    {
	perror("Error on opening file");
	exit(1);
    }

    int f2=open(numeFisierDestinatie,O_WRONLY);

    if(f2 > 0 )
    {
	printf("Doriti sa suprascrieti continutul ? da/nu ");
	scanf("%10s",&comanda);
	if(strcmp(comanda,"da")!=0)
	{
	    printf("\nNu ati acordat permisiunea");
	    exit(5);
	}
	open(numeFisierDestinatie,O_WRONLY | O_TRUNC);
	chmod(numeFisierDestinatie,S_IRUSR | S_IWUSR);
    }


    while(1){
	bytes_read = read(f1,buffer,SECTOR_SIZE);
	if(bytes_read == 0)
		break;
	if(bytes_read == -1)
		{
			perror("error on writing");
			exit(6);
		}

	for(int i=0;buffer[i]!=NULL;i++)
	    if(buffer[i] >= 'a' && buffer[i] <= 'z')
		buffer[i]=buffer[i]-'a'+'A';


	if(write(f2,buffer,SECTOR_SIZE)<0)
	{
		perror("Error on writing");
		exit(7);
	}

    }

   if(close(f1)==-1 || close(f2)==-1)
	{
		perror("Error on closing files");
		exit(9);
	}


    return 0;
}