From 8485ad25e42c922cbbe52f12d6084d5767be1f83 Mon Sep 17 00:00:00 2001
From: Ivar Fatland <fatland99@hotmail.com>
Date: Sat, 13 Dec 2025 16:47:40 +0100
Subject: [PATCH] bounds checked arrays

---
 cig.h                |  8 ++++++
 dyn_array.c          | 15 ++++++++++
 test_dynamic_array.c | 67 ++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 90 insertions(+)

diff --git a/cig.h b/cig.h
index cd68e38..4cf96a3 100644
--- a/cig.h
+++ b/cig.h
@@ -180,6 +180,14 @@ size_t arr_cap(void *this);
 
 #define arr_pop(THIS) (arr_shrink(THIS, 1), THIS[arr_len(THIS)])
 
+void dyn_array_bounds_check_func(void *this, size_t index, const char *file, int line);
+
+#define arr_get(THIS, INDEX) \
+	(dyn_array_bounds_check_func(THIS, INDEX, __FILE__, __LINE__), (THIS)[INDEX])
+
+#define arr_set(THIS, INDEX, VALUE) \
+	(dyn_array_bounds_check_func(THIS, INDEX, __FILE__, __LINE__), (THIS)[INDEX] = (VALUE))
+
 #define STATIC_ASSERT(expr) ((void)sizeof(char[(expr) ? 1 : -1]))
 
 bool dyn_array_contains_func(void *this, uint8_t *value);
diff --git a/dyn_array.c b/dyn_array.c
index 32ecd28..c5ece80 100644
--- a/dyn_array.c
+++ b/dyn_array.c
@@ -96,6 +96,21 @@ bool dyn_array_contains_cmp_func(void *this, uint8_t *value, dyn_array_eq_fn eq)
 	return false;
 }
 
+void dyn_array_bounds_check_func(void *this, size_t index, const char *file, int line) {
+	size_t len = arr_len(this);
+	if (index >= len) {
+		fprintf(
+			stderr,
+			"%s:%d: array index %zu out of bounds (length is %zu)\n",
+			file,
+			line,
+			index,
+			len
+		);
+		exit(1);
+	}
+}
+
 void dyn_array_insert_sorted_func(void **this_ptr, const void *value, dyn_array_cmp_fn cmp, const char *file, int line) {
 	void *this = *this_ptr;
 	dyn_array_header_t *header = PTR_FROM_FIELD_PTR(dyn_array_header_t, bytes, this);
diff --git a/test_dynamic_array.c b/test_dynamic_array.c
index e55da38..08a591b 100644
--- a/test_dynamic_array.c
+++ b/test_dynamic_array.c
@@ -293,3 +293,70 @@ Test(dynamic_arrays, contains_cmp_key_value_map) {
 	}
 }
 
+Test(dynamic_arrays, get_valid_indices) {
+	with_borrow(alloc) {
+		int *arr = make_arr(alloc, int);
+		arr_append(arr, 10);
+		arr_append(arr, 20);
+		arr_append(arr, 30);
+		arr_append(arr, 40);
+		
+		cr_assert_eq(arr_get(arr, 0), 10);
+		cr_assert_eq(arr_get(arr, 1), 20);
+		cr_assert_eq(arr_get(arr, 2), 30);
+		cr_assert_eq(arr_get(arr, 3), 40);
+	}
+}
+
+Test(dynamic_arrays, set_valid_indices) {
+	with_borrow(alloc) {
+		int *arr = make_arr(alloc, int);
+		arr_append(arr, 10);
+		arr_append(arr, 20);
+		arr_append(arr, 30);
+		
+		arr_set(arr, 0, 100);
+		arr_set(arr, 1, 200);
+		arr_set(arr, 2, 300);
+		
+		cr_assert_eq(arr_get(arr, 0), 100);
+		cr_assert_eq(arr_get(arr, 1), 200);
+		cr_assert_eq(arr_get(arr, 2), 300);
+	}
+}
+
+Test(dynamic_arrays, get_out_of_bounds, .exit_code = 1) {
+	with_borrow(alloc) {
+		int *arr = make_arr(alloc, int);
+		arr_append(arr, 10);
+		arr_append(arr, 20);
+		
+		(void)arr_get(arr, 2);
+	}
+}
+
+Test(dynamic_arrays, set_out_of_bounds, .exit_code = 1) {
+	with_borrow(alloc) {
+		int *arr = make_arr(alloc, int);
+		arr_append(arr, 10);
+		arr_append(arr, 20);
+		
+		arr_set(arr, 2, 999);
+	}
+}
+
+Test(dynamic_arrays, get_empty_array, .exit_code = 1) {
+	with_borrow(alloc) {
+		int *arr = make_arr(alloc, int);
+		(void)arr_get(arr, 0);
+	}
+}
+
+Test(dynamic_arrays, set_empty_array, .exit_code = 1) {
+	with_borrow(alloc) {
+		int *arr = make_arr(alloc, int);
+		arr_set(arr, 0, 42);
+	}
+}
+
+