// duplicate file
int
file_dup(int fd1, int fd2) {
int ret;
struct file *file1, *file2;
if ((ret = fd2file(fd1, &file1)) != 0) {
return ret;
}
if ((ret = fd_array_alloc(fd2, &file2)) != 0) {
return ret;
}
fd_array_dup(file2, file1);
return file2->fd;
}
// 我们来看一下复制files_struct的函数dup_fs
int
dup_fs(struct files_struct *to, struct files_struct *from) {
// cprintf("[dup_fs]\n");
assert(to != NULL && from != NULL);
assert(files_count(to) == 0 && files_count(from) > 0);
if ((to->pwd = from->pwd) != NULL) {
vop_ref_inc(to->pwd); // 增加引用就可以了
}
int i;
struct file *to_file = to->fd_array, *from_file = from->fd_array;
for (i = 0; i < FILES_STRUCT_NENTRY; i ++, to_file ++, from_file ++) {
if (from_file->status == FD_OPENED) {
/* alloc_fd first */
to_file->status = FD_INIT;
fd_array_dup(to_file, from_file);
}
}
return 0;
}
