my dup2

#include <fcntl.h>
#include <stdio.h>
#include <unistd.h>

int mydup(int i_OldFd, int i_NewFd);

int main(void)
{
int fd = -1;
fd = open("tests.c", O_RDONLY);

if(fd < 0)
{
printf("error.\n");
return -1;
}

printf("the old_fd:%d.\n", fd);

int tmp = mydup(fd, 100);

printf("the new_fd:%d.\n",tmp);
return 1;
}

int mydup(int i_OldFd, int i_NewFd)
{
if(i_OldFd < 0 || i_OldFd >256)
{
printf("Oldfd is wrong.\n");
return -1;
}

if(i_NewFd < 0 || i_NewFd > 256)
{
printf("Newfd is wrong.\n");
return -1;
}

if( i_NewFd == i_OldFd)
return i_OldFd;

int i_Arrayfd[256];
int count = 0;
close(i_NewFd);

do
{
i_Arrayfd[count] = dup(i_OldFd);
if(i_Arrayfd[count] == -1)
{
printf("dup error.\n");
break;
}
count++;

}while(i_Arrayfd[count-1] != i_NewFd);

for(int i = 0; i < count-1 ; i++)
{
close(i_Arrayfd[i]);
}

return i_Arrayfd[count-1];
}

巴特西