diff mbox series

[3/3] mcstrans: ensure transitivity in compare functions

Message ID 20240131125623.45758-3-cgzones@googlemail.com (mailing list archive)
State Accepted
Commit fc2822a47485
Delegated to: Petr Lautrbach
Headers show
Series [1/3] libsepol: ensure transitivity in compare functions | expand

Commit Message

Christian Göttsche Jan. 31, 2024, 12:56 p.m. UTC 
Ensure comparison functions used by qsort(3) fulfill transitivity, since
otherwise the resulting array might not be sorted correctly or worse[1]
in case of integer overflows.

[1]: https://www.qualys.com/2024/01/30/qsort.txt

Signed-off-by: Christian Göttsche <cgzones@googlemail.com>
---
 mcstrans/src/mcstrans.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)
diff mbox series

Patch

diff --git a/mcstrans/src/mcstrans.c b/mcstrans/src/mcstrans.c
index af3f507e..fded3235 100644
--- a/mcstrans/src/mcstrans.c
+++ b/mcstrans/src/mcstrans.c
@@ -952,9 +952,13 @@  find_in_hashtable(const char *range, domain_t *domain, context_map_node_t **tabl
 	return trans;
 }
 
+#define spaceship_cmp(a, b) (((a) > (b)) - ((a) < (b)))
+
 static int
 string_size(const void *p1, const void *p2) {
-	return strlen(*(char **)p2) - strlen(*(char **)p1);
+	size_t len1 = strlen(*(const char *const *)p2);
+	size_t len2 = strlen(*(const char *const *)p1);
+	return spaceship_cmp(len1, len2);
 }
 
 static int
@@ -965,7 +969,7 @@  word_size(const void *p1, const void *p2) {
 	int w2_len=strlen(w2->text);
 	if (w1_len == w2_len)
 		return strcmp(w1->text, w2->text);
-	return (w2_len - w1_len);
+	return spaceship_cmp(w2_len, w1_len);
 }
 
 static void