[PINTOS PROJECT 3] VIRTUAL MEMORY_Anonymous Page

1. load_segment()

static bool
load_segment (struct file *file, off_t ofs, uint8_t *upage,
		uint32_t read_bytes, uint32_t zero_bytes, bool writable) {
	ASSERT ((read_bytes + zero_bytes) % PGSIZE == 0);
	ASSERT (pg_ofs (upage) == 0);
	ASSERT (ofs % PGSIZE == 0);

	off_t read_ofs = ofs;
	while (read_bytes > 0 || zero_bytes > 0) {
		/* Do calculate how to fill this page.
		 * We will read PAGE_READ_BYTES bytes from FILE
		 * and zero the final PAGE_ZERO_BYTES bytes. */
		size_t page_read_bytes = read_bytes < PGSIZE ? read_bytes : PGSIZE;
		size_t page_zero_bytes = PGSIZE - page_read_bytes;

		/* Set up aux to pass information to the lazy_load_segment. */

		struct vmpage_info *aux = malloc(sizeof (struct vmpage_info));
		aux->file = file;
		aux->ofs = read_ofs;
		aux -> page_read_bytes = page_read_bytes;
		aux -> page_zero_bytes = page_zero_bytes;
		
		if (!vm_alloc_page_with_initializer (VM_ANON, upage,
					writable, lazy_load_segment, aux)){
			free(aux);
			return false;
		}

		/* Advance. */
		read_bytes -= page_read_bytes;
		zero_bytes -= page_zero_bytes;
		upage += PGSIZE;
		read_ofs += PGSIZE;
	}
	return true;
}

2. lazy_load_segment()

: load_segment() -> vm_alloc_page_with_initializer() -> lazy_load_segment() 순서로 실행

bool lazy_load_segment (struct page *page, void *aux) {
	struct vmpage_info* info = (struct vmpage_info*) aux;
	if (page == NULL) return false;

	/* load proper info to page */
	if (info -> page_read_bytes > 0) {
		file_seek (info -> file, info -> ofs);
		if (file_read (info -> file, page -> frame ->kva, info -> page_read_bytes) != (off_t) info -> page_read_bytes) {
			vm_dealloc_page (page);
			return false;
		}
	}
	memset (page -> va + info -> page_read_bytes, 0, info -> page_zero_bytes);
	file_close (info -> file);
	free (info);
	return true;
}