[보류] 퍼미션을 유지하면서 파일을 복사하는 프로그램 작성중 도와주세요=>일단 혼자 해보도록하겠습니다 ㅠ

#include <errno.h> 
#include <fcntl.h> 
#include <pthread.h> 
#include <stdio.h> 
#include <stdlib.h> 
#include <string.h> 
#include <unistd.h> 
#include <sys/stat.h> 
#include <sys/types.h> 
#define PERMS (S_IRUSR | S_IWUSR) 
#define READ_FLAGS O_RDONLY 
#define WRITE_FLAGS (O_WRONLY | O_CREAT | O_TRUNC) 
static int readwrite(int fromfd, int tofd) 
{ 
char buf[1024]; 
int bytesread; 
if((bytesread = read(fromfd, buf, 1024)) < 0) return -1; 
if(bytesread == 0) return 0; 
if(write(tofd, buf, bytesread) < 0) return -1; 
return bytesread; 
} 
 
 
static int copyfile(int fromfd, int tofd) 
{ 
int bytesread; int totalbytes = 0; 
while((bytesread = readwrite(fromfd, tofd)) > 0) 
totalbytes += bytesread; 
return totalbytes; 
} 
static void *copyfilemalloc(void *arg) 
{ 
int *bytesp; int infd, outfd; 
infd = *((int *)(arg)); 
outfd = *((int *)(arg) +1); 
if((bytesp = (int *)malloc(sizeof(int))) == NULL) 
return NULL; 
*bytesp = copyfile(infd, outfd); close(infd); close(outfd); 
return bytesp; 
} 
 
 
int main(int argc, char *argv[]) 
{ 
int *bytesptr; int error; int fds[2]; pthread_t tid; 
if(argc != 3){ 
fprintf(stderr, "Usage : %s fromfile tofile\n",argv[0]); 
return 1; 
} 
if(((fds[0] = open(argv[1], READ_FLAGS)) == -1) || 
((fds[1] = open(argv[2], WRITE_FLAGS, PERMS)) == -1)){ 
perror("Failed to open the files"); return 2; 
} 
if(error = pthread_create(&tid, NULL, copyfilemalloc, fds)){ 
fprintf(stderr, "Failed to create thread: %s\n", strerror(error)); 
return 3; 
} 
if(error = pthread_join(tid, (void **)&bytesptr)){ 
fprintf(stderr, "Failed to join thread: %s\n", strerror(error)); 
return 4; 
} 
printf("Number of bytes copied: %d\n", *bytesptr); 
return 0; 
}