segtree: allocate memory for arrays on heap

Huge sets may cause stack to be exhausted.
So, put allocate memory for arrays in
interval_map_decompose() function on heap.

Signed-off-by: Oleksandr Natalenko <oleksandr@natalenko.name>
Signed-off-by: Florian Westphal <fw@strlen.de>

1 files changed, 10 insertions, 1 deletions

diff --git a/src/segtree.c b/src/segtree.c
index 5b6cdd1d..78657de1 100644
--- a/src/segtree.c
+++ b/src/segtree.c
@@ -608,12 +608,18 @@ static int expr_value_cmp(const void *p1, const void *p2)
 
 void interval_map_decompose(struct expr *set)
 {
-	struct expr *elements[set->size], *ranges[set->size * 2];
+	struct expr **elements, **ranges;
 	struct expr *i, *next, *low = NULL, *end;
 	unsigned int n, m, size;
 	mpz_t range, p;
 	bool interval;
 
+	if (set->size == 0)
+		return;
+
+	elements = xmalloc_array(set->size, sizeof(struct expr *));
+	ranges = xmalloc_array(set->size * 2, sizeof(struct expr *));
+
 	mpz_init(range);
 	mpz_init(p);
 
@@ -728,4 +734,7 @@ void interval_map_decompose(struct expr *set)
 
 		compound_expr_add(set, i);
 	}
+
+	xfree(ranges);
+	xfree(elements);
 }