comparison mercurial/mpatch.c @ 15033:2ef2d3a5cd2d stable

parsers: avoid pointer aliasing

Newer versions of GCC have aggressive pointer alias optimizations that
might get fooled by our pointer manipulations. These issues shouldn't
be encountered in practice because distutils compiles extensions with
-fno-strict-alias but the code was not valid according to the standard.

15032:eb87fbc6d702

static struct flist *decode(const char *bin, int len)
{
	struct flist *l;
	struct frag *lt;
	const char *data = bin + 12, *end = bin + len;
	char decode[12]; /* for dealing with alignment issues */

	/* assume worst case size, we won't have many of these lists */
	l = lalloc(len / 12);
	if (!l)
		return NULL;

	lt = l->tail;

	while (data <= end) {
		memcpy(decode, bin, 12);
		lt->start = ntohl(*(uint32_t *)decode);
		lt->end = ntohl(*(uint32_t *)(decode + 4));
		lt->len = ntohl(*(uint32_t *)(decode + 8));
		if (lt->start > lt->end)
			break; /* sanity check */
		bin = data + lt->len;
		if (bin < data)
			break; /* big data + big (bogus) len can wrap around */

patchedsize(PyObject *self, PyObject *args)
{
	long orig, start, end, len, outlen = 0, last = 0;
	int patchlen;
	char *bin, *binend, *data;
	char decode[12]; /* for dealing with alignment issues */

	if (!PyArg_ParseTuple(args, "ls#", &orig, &bin, &patchlen))
		return NULL;

	binend = bin + patchlen;
	data = bin + 12;

	while (data <= binend) {
		memcpy(decode, bin, 12);
		start = ntohl(*(uint32_t *)decode);
		end = ntohl(*(uint32_t *)(decode + 4));
		len = ntohl(*(uint32_t *)(decode + 8));
		if (start > end)
			break; /* sanity check */
		bin = data + len;
		if (bin < data)
			break; /* big data + big (bogus) len can wrap around */

15033:2ef2d3a5cd2d

static struct flist *decode(const char *bin, int len)
{
	struct flist *l;
	struct frag *lt;
	const char *data = bin + 12, *end = bin + len;
	uint32_t decode[3]; /* for dealing with alignment issues */

	/* assume worst case size, we won't have many of these lists */
	l = lalloc(len / 12);
	if (!l)
		return NULL;

	lt = l->tail;

	while (data <= end) {
		memcpy(decode, bin, 12);
		lt->start = ntohl(decode[0]);
		lt->end = ntohl(decode[1]);
		lt->len = ntohl(decode[2]);
		if (lt->start > lt->end)
			break; /* sanity check */
		bin = data + lt->len;
		if (bin < data)
			break; /* big data + big (bogus) len can wrap around */

patchedsize(PyObject *self, PyObject *args)
{
	long orig, start, end, len, outlen = 0, last = 0;
	int patchlen;
	char *bin, *binend, *data;
	uint32_t decode[3]; /* for dealing with alignment issues */

	if (!PyArg_ParseTuple(args, "ls#", &orig, &bin, &patchlen))
		return NULL;

	binend = bin + patchlen;
	data = bin + 12;

	while (data <= binend) {
		memcpy(decode, bin, 12);
		start = ntohl(decode[0]);
		end = ntohl(decode[1]);
		len = ntohl(decode[2]);
		if (start > end)
			break; /* sanity check */
		bin = data + len;
		if (bin < data)
			break; /* big data + big (bogus) len can wrap around */