From 6cea0ddf25c4a7d9459e15e467cac416415cf80d Mon Sep 17 00:00:00 2001
From: laentropia <aadrian887mh@gmail.com>
Date: Sat, 11 Apr 2026 11:30:04 -0600
Subject: [PATCH] test: Added further testing and fixed functions for edge
 cases

---
 include/arena.h   |  3 +--
 src/arena.c       | 36 ++++++++++++++++++++++++++++++++----
 test/test_arena.c | 39 +++++++++++++++++++++++++++++++++++++++
 3 files changed, 72 insertions(+), 6 deletions(-)

diff --git a/include/arena.h b/include/arena.h
index a01d3ff..e4b65a4 100644
--- a/include/arena.h
+++ b/include/arena.h
@@ -55,10 +55,9 @@ void arena_destroy(Arena *arena);
 ArenaPointer arena_alloc(Arena *arena, size_t size, size_t alignment);
 ArenaPointer arena_push(Arena *arena, void *data, size_t size, size_t alignment);
 ArenaErr arena_realloc(Arena *arena, size_t new_capacity);
-
 void *arena_unwrap_pointer(ArenaPointer p);
 
-SizeResult get_arena_align_padding(Arena *arena, size_t alignment);
+SizeResult arena_get_align_padding(Arena *arena, size_t alignment);
 ArenaErr arena_ensure_capacity(Arena *arena, size_t size, size_t alignment);
 // Should be moved to something like general utilities,
 // i should make one for all my c projects
diff --git a/src/arena.c b/src/arena.c
index a248b37..3953d1f 100644
--- a/src/arena.c
+++ b/src/arena.c
@@ -38,12 +38,20 @@ ArenaPointer arena_alloc(Arena *arena, size_t size, size_t alignment) {
         return (ArenaPointer) {.is_valid = false, .err = ARENA_NULL_ARG};
     }
 
-    SizeResult padding = get_arena_align_padding(arena, alignment);
+    if (size < 1) {
+        return (ArenaPointer) {.is_valid = false, .err = ARENA_INVALID_SIZE};
+    }
+
+    if (alignment < 1) {
+        return (ArenaPointer) {.is_valid = false, .err = ARENA_INVALID_ALIGN};
+    }
+
+    SizeResult padding = arena_get_align_padding(arena, alignment);
     if (!padding.is_valid) {
         return (ArenaPointer) {.is_valid = false, .err = padding.err};
     }
 
-    if (arena->offset + padding.val >= arena->capacity) {
+    if (arena->offset + padding.val + size > arena->capacity) {
         return (ArenaPointer) {.is_valid = false, .err = ARENA_OUT_OF_SPACE};
     }
 
@@ -62,7 +70,15 @@ ArenaErr arena_ensure_capacity(Arena *arena, size_t size, size_t alignment) {
         return ARENA_NULL_ARG;
     }
 
-    SizeResult padding = get_arena_align_padding(arena, alignment);
+    if (size < 1) {
+        return ARENA_INVALID_SIZE;
+    }
+
+    if (alignment < 1) {
+        return ARENA_INVALID_ALIGN;
+    }
+    
+    SizeResult padding = arena_get_align_padding(arena, alignment);
     if (!padding.is_valid) {
         return padding.err;
     }
@@ -94,6 +110,14 @@ ArenaPointer arena_push(Arena *arena, void *data, size_t size, size_t alignment)
         return (ArenaPointer) {.is_valid = false, .err = ARENA_NULL_ARG};
     }
 
+    if (size < 1) {
+        return (ArenaPointer) {.is_valid = false, .err = ARENA_INVALID_SIZE};
+    }
+
+    if (size < 1) {
+        return (ArenaPointer) {.is_valid = false, .err = ARENA_INVALID_ALIGN};
+    }
+
     ArenaErr err = arena_ensure_capacity(arena, size, alignment);
     if (err != ARENA_OK) {
         return (ArenaPointer) {.is_valid = false, .err = err};
@@ -117,6 +141,10 @@ ArenaErr arena_realloc(Arena *arena, size_t new_capacity) {
         return ARENA_NULL_ARG;
     }
 
+    if (new_capacity < 1) {
+        return ARENA_INVALID_SIZE;
+    }
+
     uint8_t *tmp = realloc(arena->buffer, new_capacity);
     if (tmp == NULL) {
         return ARENA_BAD_ALLOC;
@@ -129,7 +157,7 @@ ArenaErr arena_realloc(Arena *arena, size_t new_capacity) {
 
 
 
-SizeResult get_arena_align_padding(Arena *arena, size_t alignment) {
+SizeResult arena_get_align_padding(Arena *arena, size_t alignment) {
     if (arena == NULL) {
         return (SizeResult) {.is_valid = false, .err = ARENA_NULL_ARG};
     }
diff --git a/test/test_arena.c b/test/test_arena.c
index 927964f..873671f 100644
--- a/test/test_arena.c
+++ b/test/test_arena.c
@@ -7,6 +7,7 @@
 #include <setjmp.h>
 #include <cmocka.h>
 #include <string.h>
+#include <limits.h>
 
 #include "arena.h"
 
@@ -71,11 +72,49 @@ static void test_push_3_ints_2_doubles(void **state) {
     arena_destroy(&arena);
 }
 
+static void test_init_arena_0_cap(void **state) {
+    (void) state;
+
+    ArenaResult arena = arena_init(0);
+    assert_false(arena.is_valid);
+    assert_int_equal(arena.err, ARENA_INVALID_SIZE);
+}
+
+static void test_arena_alloc_size_0(void **state) {
+    (void) state;
+
+    ArenaResult value = arena_init(64);
+    assert_true(value.is_valid);
+    Arena arena = value.arena;
+
+    ArenaPointer pointer = arena_alloc(&arena, 0, alignof(int));
+    assert_false(pointer.is_valid);
+    assert_int_equal(pointer.err, ARENA_INVALID_SIZE);
+
+    arena_destroy(&arena);
+}
+
+static void test_arena_alloc_size_max(void **state) {
+    (void) state;
+
+    ArenaResult value = arena_init(64);
+    assert_true(value.is_valid);
+    Arena arena = value.arena;
+
+    ArenaPointer pointer = arena_alloc(&arena, SIZE_MAX, alignof(int));
+    assert_false(pointer.is_valid);
+    assert_int_equal(pointer.err, ARENA_OUT_OF_SPACE);
+
+    arena_destroy(&arena);
+}
 
 int main(void) {
     const struct CMUnitTest tests[] = {
         cmocka_unit_test(test_push_3_ints),
         cmocka_unit_test(test_push_3_ints_2_doubles),
+        cmocka_unit_test(test_init_arena_0_cap),
+        cmocka_unit_test(test_arena_alloc_size_0),
+        cmocka_unit_test(test_arena_alloc_size_max),
     };