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	Prevent undefined behaviour in herodotus_reader_copy() - libgrapheme - unicode …
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	---
	commit 004bdcf210baf1a63772bb7eca452bb0aeba010b
	parent ef3e52a7f560f66df8ed1e2487872a1e62c5cedb
	Author: Laslo Hunhold <[email protected]>
	Date: Sat, 8 Oct 2022 13:13:03 +0200

	Prevent undefined behaviour in herodotus_reader_copy()

	The first part usually catches harmless cases like "NULL + 0", but the
	last part prevents integer overflow in some really crazy cases that
	are unlikely but can still happen.

	Signed-off-by: Laslo Hunhold <[email protected]>

	Diffstat:
	M src/util.c \| 20 +++++++++++++++-----

	1 file changed, 15 insertions(+), 5 deletions(-)
	---
	diff --git a/src/util.c b/src/util.c
	@@ -37,23 +37,33 @@ herodotus_reader_copy(const HERODOTUS_READER *src, HERODOTU…
	*/
	dest->type = src->type;
	if (src->type == HERODOTUS_TYPE_CODEPOINT) {
	- dest->src = ((const uint_least32_t *)(src->src)) + src->off;
	+ dest->src = (src->src == NULL) ? NULL :
	+ ((const uint_least32_t *)(src->src)) + src->off;
	} else { /* src->type == HERODOTUS_TYPE_UTF8 */
	- dest->src = ((const char *)(src->src)) + src->off;
	+ dest->src = (src->src == NULL) ? NULL :
	+ ((const char *)(src->src)) + src->off;
	}
	if (src->srclen == SIZE_MAX) {
	dest->srclen = SIZE_MAX;
	} else {
	- dest->srclen = src->srclen - src->off;
	+ dest->srclen = (src->off < src->srclen) ? src->srclen - src->o…
	}
	dest->off = 0;
	dest->terminated_by_null = src->terminated_by_null;

	for (i = 0; i < LEN(src->soft_limit); i++) {
	if (src->soft_limit[i] == SIZE_MAX) {
	- dest->soft_limit[i] = src->soft_limit[i];
	+ dest->soft_limit[i] = SIZE_MAX;
	} else {
	- dest->soft_limit[i] = src->soft_limit[i] - src->off;
	+ /*
	+ * if we have a degenerate case where the offset is
	+ * higher than the soft-limit, we simply clamp the
	+ * soft-limit to zero given we can't decide here
	+ * to release the limit and, instead, we just
	+ * prevent any more reads
	+ */
	+ dest->soft_limit[i] = (src->off < src->soft_limit[i]) ?
	+ src->soft_limit[i] - src->off : 0;
	}
	}
	}