int main(){
int fd;
fd = dup2(1, 9);
printf("The result by dup2 is %d\n", fd);
fd = mydup2(2, 5);
printf("The result by mydup2 is %d\n", fd);
return 0;
}
int main(void)
{
int fd = -1;
fd = mydup2(0,10);
if(fd < 0) {
perror("mydup2");
return -1;
}
printf("fd = %d\n",fd);
return 0;
}
int
main(int argc, char *argv[]) {
int fd1, fd2;
if (argc != 2) {
err_quit("Usage: %s file", argv[0]);
}
if ((fd1 = open(argv[1], O_RDONLY)) < 0) {
err_sys("Can't open file `%s`", argv[1]);
}
fd2 = mydup2(fd1, 42);
lseek(fd1, 0, SEEK_END);
check_fd(fd1);
check_fd(fd2);
}
int mydup2(int oldfd, int newfd)
{
int tfd;
if (newfd < 0)
return -1;
if (newfd == oldfd)
return newfd;
close(newfd);
if ((tfd == dup(oldfd)) == newfd)
{
return newfd;
} else {
mydup2(oldfd, newfd);
clsose(tfd);
}
return newfd;
}
int
main(void){
printf("%d\n", mydup2(0, 99));
// printf("%d, %d, %d", mydup2(5, 10), mydup2(5, 4), mydup2(5, 1));
return 1;
}
