Function use_pack

packfile.c:704–783

}

unsigned char *use_pack(struct packed_git *p,
		struct pack_window **w_cursor,
		off_t offset,
		unsigned long *left)
{
	struct pack_window *win = *w_cursor;

	/* Since packfiles end in a hash of their content and it's
	 * pointless to ask for an offset into the middle of that
	 * hash, and the in_window function above wouldn't match
	 * don't allow an offset too close to the end of the file.
	 */
	if (!p->pack_size && p->pack_fd == -1 && open_packed_git(p))
		die("packfile %s cannot be accessed", p->pack_name);
	if (offset > (p->pack_size - p->repo->hash_algo->rawsz))
		die("offset beyond end of packfile (truncated pack?)");
	if (offset < 0)
		die(_("offset before end of packfile (broken .idx?)"));

	if (!win || !in_window(p->repo, win, offset)) {
		if (win)
			win->inuse_cnt--;
		for (win = p->windows; win; win = win->next) {
			if (in_window(p->repo, win, offset))
				break;
		}
		if (!win) {
			size_t window_align;
			off_t len;
			struct repo_settings *settings;

			/* lazy load the settings in case it hasn't been setup */
			prepare_repo_settings(p->repo);
			settings = &p->repo->settings;

			window_align = settings->packed_git_window_size / 2;

			if (p->pack_fd == -1 && open_packed_git(p))
				die("packfile %s cannot be accessed", p->pack_name);

			CALLOC_ARRAY(win, 1);
			win->offset = (offset / window_align) * window_align;
			len = p->pack_size - win->offset;
			if (len > settings->packed_git_window_size)
				len = settings->packed_git_window_size;
			win->len = (size_t)len;
			pack_mapped += win->len;

			while (settings->packed_git_limit < pack_mapped &&
			       unuse_one_window(p->repo->objects))
				; /* nothing */
			win->base = xmmap_gently(NULL, win->len,
				PROT_READ, MAP_PRIVATE,
				p->pack_fd, win->offset);
			if (win->base == MAP_FAILED)
				die_errno(_("packfile %s cannot be mapped%s"),
					  p->pack_name, mmap_os_err());
			if (!win->offset && win->len == p->pack_size