#include "sysconfig-header.h"

static bool subpartition_page_aligned(const struct sysconfig_subpartition *part,
				      uint64_t page_size)
{
	// It shall be page-aligned.
	if (part->size % page_size || part->offset % page_size) {
		return false;
	}

	return true;
}

static bool subpartition_not_on_page0(const struct sysconfig_subpartition *part,
				      uint64_t page_size)
{
	return part->offset >= page_size;
}

static bool subpartition_out_of_range(const struct sysconfig_subpartition *part,
				      uint64_t page_size,
				      uint64_t partition_size)
{
	// It shall fit into sysconfig partition size.
	if (part->size > partition_size ||
	    part->offset > partition_size - part->size) {
		return false;
	}

	return true;
}

static bool subpartition_disjoint(const struct sysconfig_subpartition *part_a,
				  const struct sysconfig_subpartition *part_b)
{
	return part_a->offset + part_a->size <= part_b->offset ||
	       part_b->offset + part_b->size <= part_a->offset;
}

bool
sysconfig_header_valid(const struct sysconfig_header *header,
		       uint64_t page_size, uint64_t partition_size)
{
	// Conditions:
	// 1. valid magic.
	// 2. valid crc.
	// 3. sub-partition fits into partition.
	// 4. sub-partitions do not overlap.
	// 5. the first page is reserved for header.

	if (memcmp(header->magic, SYSCONFIG_HEADER_MAGIC_STR,
		   sizeof(header->magic))) {
		syshdrP("Header has invalid magic.\n");
		return false;
	}

	if (header->crc_value !=
	    sysconfig_header_crc32(0, (const uint8_t *)header,
				   offsetof(struct sysconfig_header,
					    crc_value))) {
		syshdrP("Header has invalid crc.\n");
		return false;
	}

	struct sysconfig_subpartition all_parts[] = { header->abr_metadata,
						      header->sysconfig_data,
						      header->vb_metadata_a,
						      header->vb_metadata_b,
						      header->vb_metadata_r };

	int i, j;
	int num_subparts =
		sizeof(all_parts) / sizeof(struct sysconfig_subpartition);
	for (i = 0; i < num_subparts; i++) {
		if (!subpartition_page_aligned(&all_parts[i], page_size)) {
			syshdrP("sub-partition %d is not page-aligned\n", i);
			return false;
		}

		if (!subpartition_out_of_range(&all_parts[i], page_size,
					       partition_size)) {
			syshdrP("sub-partition %d is out-of-range\n", i);
			return false;
		}

		if (!subpartition_not_on_page0(&all_parts[i], page_size)) {
			syshdrP("sub-partition %d occupies page0 reserved for header\n",
				i);
			return false;
		}

		for (j = i + 1; j < num_subparts; j++) {
			if (!subpartition_disjoint(&all_parts[i],
						   &all_parts[j])) {
				syshdrP("sub-partition %d and %d overlap\n", i,
					j);
				return false;
			}
		}
	}

	return true;
}

bool sysconfig_header_equal(const struct sysconfig_header *lhs,
			    const struct sysconfig_header *rhs)
{
	return memcmp(lhs, rhs, offsetof(struct sysconfig_header, crc_value)) ==
	       0;
}

void update_sysconfig_header_magic_and_crc(struct sysconfig_header *header)
{
	memcpy(header->magic, SYSCONFIG_HEADER_MAGIC_STR,
	       sizeof(header->magic));
	memset(header->reserved, 0, 4);
	header->crc_value = sysconfig_header_crc32(
		0, (const uint8_t *)header,
		offsetof(struct sysconfig_header, crc_value));
}