From 2d465afc7fa5c28b4c5684dd127d68449c5954bc Mon Sep 17 00:00:00 2001
From: seajee <teapods@proton.me>
Date: Sat, 10 Jan 2026 17:42:14 +0100
Subject: [PATCH] v1.1.2 Minor changes; check result of alloc in arena_copy()

---
 arena.h | 71 +++++++++++++++++++++++++++++++--------------------------
 test.c  |  2 ++
 2 files changed, 41 insertions(+), 32 deletions(-)

diff --git a/arena.h b/arena.h
index a69f9b4..18add9f 100644
--- a/arena.h
+++ b/arena.h
@@ -1,4 +1,4 @@
-// arena.h - v1.1.1 - MIT License
+// arena.h - v1.1.2 - MIT License
 // single header library for region-based memory management.
 //
 // [License and changelog]
@@ -61,6 +61,20 @@
 // with a specified region capacity. It will override the default
 // ARENA_REGION_CAPACITY.
 //
+//     void arena_free(Arena *a)
+//
+// This function frees all of the regions allocated in the specified arena
+// which invalidates all the pointers associated with the arena. The arena can
+// still be reused. If the arena was created with arena_create() the
+// configured region_capacity will be retained.
+//
+//     void arena_reset(Arena *a)
+//
+// This function resets an arena by keeping all of the regions allocated but
+// invalidates all of the pointers associated with the specified arena.
+// Warning: this functions may cause fragmentation, consider setting an
+// appropriate region capacity.
+//
 //     void *arena_alloc(Arena *a, size_t size)
 //
 // This function allocates a buffer of <size> bytes into the specified arena
@@ -76,20 +90,6 @@
 // This functions acts like the strdup() function but it instead allocates on
 // the specified arena. It duplicates a string in the arena.
 //
-//     void arena_free(Arena *a)
-//
-// This function frees all of the regions allocated in the specified arena
-// which invalidates all the pointers associated with the arena. The arena can
-// still be reused. If the arena was created with arena_create() the
-// configured region_capacity will be retained.
-//
-//     void arena_reset(Arena *a)
-//
-// This function resets an arena by keeping all of the regions allocated but
-// invalidates all of the pointers associated with the specified arena.
-// Warning: this functions may cause fragmentation, consider setting an
-// appropriate region capacity.
-//
 // [Notes]
 //
 // This library is not Thread-safe.
@@ -125,7 +125,7 @@ int main(void)
 #endif // ARENA_REGION_CAPACITY
 
 #ifndef ARENA_ALIGNMENT
-#    define ARENA_ALIGNMENT sizeof(max_align_t)
+#    define ARENA_ALIGNMENT alignof(max_align_t)
 #endif // ARENA_ALIGNMENT
 
 #ifndef ARENA_NO_ASSERT
@@ -166,13 +166,15 @@ typedef struct Arena {
     size_t region_capacity;
 } Arena;
 
+// Arena management
 Arena arena_create(size_t region_capacity);
 void arena_free(Arena *a);
+void arena_reset(Arena *a);
 
+// Allocation other utilities
 void *arena_alloc(Arena *a, size_t size);
 void *arena_copy(Arena *a, const void *src, size_t size);
 char *arena_strdup(Arena *a, const char *s);
-void arena_reset(Arena *a);
 
 #ifdef __cplusplus
 }
@@ -212,6 +214,19 @@ void arena_free(Arena *a)
     // a->region_capacity = 0;
 }
 
+void arena_reset(Arena *a)
+{
+    if (a == NULL) {
+        return;
+    }
+
+    for (Arena_Region *cur = a->head; cur != NULL; cur = cur->next) {
+        cur->count = 0;
+    }
+
+    a->tail = a->head;
+}
+
 void *arena_alloc(Arena *a, size_t size)
 {
     if (a == NULL || size == 0) {
@@ -242,7 +257,7 @@ void *arena_alloc(Arena *a, size_t size)
     if (a->head == NULL) {
         a->head = (Arena_Region*)ARENA_MALLOC(sizeof(*a->head) + alloc_size);
         if (a->head == NULL) {
-            ARENA_ASSERT(false && "Reallocation failed");
+            ARENA_ASSERT(false && "Allocation failed");
             return NULL;
         }
 
@@ -272,7 +287,7 @@ void *arena_alloc(Arena *a, size_t size)
     // If not found append a new region
     a->tail->next = (Arena_Region*)ARENA_MALLOC(sizeof(*a->tail) + alloc_size);
     if (a->tail->next == NULL) {
-        ARENA_ASSERT(false && "Reallocation failed");
+        ARENA_ASSERT(false && "Allocation failed");
         return NULL;
     }
 
@@ -291,6 +306,10 @@ void *arena_copy(Arena *a, const void *src, size_t size)
     }
 
     void *copy = arena_alloc(a, size);
+    if (copy == NULL) {
+        return NULL;
+    }
+
     memcpy(copy, src, size);
 
     return copy;
@@ -306,19 +325,6 @@ char *arena_strdup(Arena *a, const char *s)
     return (char*)arena_copy(a, s, strlen(s) + 1);
 }
 
-void arena_reset(Arena *a)
-{
-    if (a == NULL) {
-        return;
-    }
-
-    for (Arena_Region *cur = a->head; cur != NULL; cur = cur->next) {
-        cur->count = 0;
-    }
-
-    a->tail = a->head;
-}
-
 #ifdef __cplusplus
 }
 #endif // __cplusplus
@@ -328,6 +334,7 @@ void arena_reset(Arena *a)
 /*
  * Revision history:
  *
+ *     1.1.2 (2026-01-10) Minor changes; check result of alloc in arena_copy()
  *     1.1.1 (2025-11-18) Implement memory alignment; improve docs
  *     1.1.0 (2025-11-18) New helper functions: arena_copy(), arena_strdup()
  *     1.0.3 (2025-09-10) Renamed parameter bytes to size in arena_alloc()
diff --git a/test.c b/test.c
index 8eaf989..9bef270 100644
--- a/test.c
+++ b/test.c
@@ -25,6 +25,8 @@ void arena_print(Arena arena)
 
 int main(void)
 {
+    printf("Alignment: %zu\n", ARENA_ALIGNMENT);
+
     Arena a = {0};
 
     arena_alloc(&a, 4012);