static int overlay_symbol_update()

in EmbeddedPkg/Library/FdtLib/fdt_overlay.c [741:864]

• 85 lines of code
• 22 McCabe index (conditional complexity)

static int overlay_symbol_update(void *fdt, void *fdto)
{
	int root_sym, ov_sym, prop, path_len, fragment, target;
	int len, frag_name_len, ret, rel_path_len;
	const char *s, *e;
	const char *path;
	const char *name;
	const char *frag_name;
	const char *rel_path;
	const char *target_path;
	char *buf;
	void *p;

	ov_sym = fdt_subnode_offset(fdto, 0, "__symbols__");

	/* if no overlay symbols exist no problem */
	if (ov_sym < 0)
		return 0;

	root_sym = fdt_subnode_offset(fdt, 0, "__symbols__");

	/* it no root symbols exist we should create them */
	if (root_sym == -FDT_ERR_NOTFOUND)
		root_sym = fdt_add_subnode(fdt, 0, "__symbols__");

	/* any error is fatal now */
	if (root_sym < 0)
		return root_sym;

	/* iterate over each overlay symbol */
	fdt_for_each_property_offset(prop, fdto, ov_sym) {
		path = fdt_getprop_by_offset(fdto, prop, &name, &path_len);
		if (!path)
			return path_len;

		/* verify it's a string property (terminated by a single \0) */
		if (path_len < 1 || memchr(path, '\0', path_len) != &path[path_len - 1])
			return -FDT_ERR_BADVALUE;

		/* keep end marker to avoid strlen() */
		e = path + path_len;

		/* format: /<fragment-name>/__overlay__/<relative-subnode-path> */

		if (*path != '/')
			return -FDT_ERR_BADVALUE;

		/* get fragment name first */
		s = strchr(path + 1, '/');
		if (!s)
			return -FDT_ERR_BADOVERLAY;

		frag_name = path + 1;
		frag_name_len = s - path - 1;

		/* verify format; safe since "s" lies in \0 terminated prop */
		len = sizeof("/__overlay__/") - 1;
		if ((e - s) < len || memcmp(s, "/__overlay__/", len))
			return -FDT_ERR_BADOVERLAY;

		rel_path = s + len;
		rel_path_len = e - rel_path;

		/* find the fragment index in which the symbol lies */
		ret = fdt_subnode_offset_namelen(fdto, 0, frag_name,
					       frag_name_len);
		/* not found? */
		if (ret < 0)
			return -FDT_ERR_BADOVERLAY;
		fragment = ret;

		/* an __overlay__ subnode must exist */
		ret = fdt_subnode_offset(fdto, fragment, "__overlay__");
		if (ret < 0)
			return -FDT_ERR_BADOVERLAY;

		/* get the target of the fragment */
		ret = overlay_get_target(fdt, fdto, fragment, &target_path);
		if (ret < 0)
			return ret;
		target = ret;

		/* if we have a target path use */
		if (!target_path) {
			ret = get_path_len(fdt, target);
			if (ret < 0)
				return ret;
			len = ret;
		} else {
			len = strlen(target_path);
		}

		ret = fdt_setprop_placeholder(fdt, root_sym, name,
				len + (len > 1) + rel_path_len + 1, &p);
		if (ret < 0)
			return ret;

		if (!target_path) {
			/* again in case setprop_placeholder changed it */
			ret = overlay_get_target(fdt, fdto, fragment, &target_path);
			if (ret < 0)
				return ret;
			target = ret;
		}

		buf = p;
		if (len > 1) { /* target is not root */
			if (!target_path) {
				ret = fdt_get_path(fdt, target, buf, len + 1);
				if (ret < 0)
					return ret;
			} else
				memcpy(buf, target_path, len + 1);

		} else
			len--;

		buf[len] = '/';
		memcpy(buf + len + 1, rel_path, rel_path_len);
		buf[len + 1 + rel_path_len] = '\0';
	}

	return 0;
}