include/lae_arena.h

@@ -30,6 +30,15 @@ typedef struct {
     };
 } ArenaPointer;
 
+typedef struct {
+    bool is_valid;
+
+    union {
+        ArenaErr err;
+        Allocator allocator;
+    };
+} ArenaAllocResult;
+
 typedef struct {
     bool is_valid;
     union {
@@ -54,4 +63,6 @@ ArenaSizeResult arena_get_align_padding(Arena *arena, size_t alignment);
 // I shouldn't cover.
 ArenaErr arena_ensure_capacity(Arena *arena, size_t size, size_t alignment);
 
+ArenaAllocResult arena_get_allocator(Arena *arena);
+
 #endif // !RENA_H

src/lae_arena.c

@@ -1,5 +1,6 @@
 #include "lae_arena.h"
 #include "lae_allocator.h"
+#include <stdalign.h>
 #include <stdbool.h>
 #include <stddef.h>
 #include <stdint.h>
@@ -14,6 +15,16 @@ struct Arena {
     Allocator allocator;
 };
 
+static void *arena_allocator_alloc(void *ctx, size_t size, size_t alignment);
+static void *arena_allocator_realloc(
+    void *ctx,
+    void *pointer,
+    size_t old_size,
+    size_t new_size,
+    size_t alignment);
+static void
+arena_allocator_free(void *ctx, void *pointer, size_t size, size_t alignment);
+
 ArenaErr arena_init(Arena **arena, Allocator allocator, size_t capacity) {
     if (arena == NULL) {
         return ARENA_NULL_ARG;
@@ -23,14 +34,15 @@ ArenaErr arena_init(Arena **arena, Allocator allocator, size_t capacity) {
         return ARENA_INVALID_SIZE;
     }
 
-    Arena *new_arena = allocator.alloc(allocator.ctx, sizeof(Arena));
+    Arena *new_arena =
+        allocator.alloc(allocator.ctx, sizeof(Arena), alignof(Arena));
     if (new_arena == NULL) {
         return ARENA_BAD_ALLOC;
     }
 
-    void *buffer = allocator.alloc(allocator.ctx, capacity);
+    void *buffer = allocator.alloc(allocator.ctx, capacity, 0);
     if (buffer == NULL) {
-        allocator.free(allocator.ctx, new_arena, capacity);
+        allocator.free(allocator.ctx, new_arena, capacity, 0);
         return ARENA_BAD_ALLOC;
     }
 
@@ -52,11 +64,12 @@ ArenaErr arena_destroy(Arena **arena) {
     }
 
     Arena *tmp = *arena;
-    tmp->allocator.free(tmp->allocator.ctx, tmp->buffer, tmp->capacity);
+    tmp->allocator.free(tmp->allocator.ctx, tmp->buffer, tmp->capacity, 0);
     tmp->buffer = NULL;
     tmp->offset = 0;
     tmp->capacity = 0;
-    tmp->allocator.free(tmp->allocator.ctx, *arena, sizeof(Arena));
+    tmp->allocator
+        .free(tmp->allocator.ctx, *arena, sizeof(Arena), alignof(Arena));
     *arena = NULL;
 
     return ARENA_OK;
@@ -200,7 +213,8 @@ ArenaErr arena_resize(Arena *arena, size_t new_capacity) {
         arena->allocator.ctx,
         arena->buffer,
         arena->capacity,
-        new_capacity);
+        new_capacity,
+        0);
     if (tmp == NULL) {
         return ARENA_BAD_ALLOC;
     }
@@ -233,3 +247,40 @@ void *arena_unwrap_pointer(ArenaPointer p) {
     }
     return p.arena->buffer + p.offset;
 }
+
+static void *arena_allocator_alloc(void *ctx, size_t size, size_t alignment) {
+    Arena *arena = ctx;
+
+    return arena_unwrap_pointer(arena_alloc(arena, size, alignment));
+}
+
+static void *arena_allocator_realloc(
+    void *ctx,
+    void *pointer,
+    size_t old_size,
+    size_t new_size,
+    size_t alignment) {
+    return NULL;
+}
+
+static void
+arena_allocator_free(void *ctx, void *pointer, size_t size, size_t alignment) {
+    return;
+}
+
+ArenaAllocResult arena_get_allocator(Arena *arena) {
+    if (arena == NULL) {
+        return (ArenaAllocResult){
+            .is_valid = false,
+            .err = ARENA_NULL_ARG,
+        };
+    }
+
+    Allocator allocator = {
+        .alloc = arena_allocator_alloc,
+        .realloc = arena_allocator_realloc,
+        .free = arena_allocator_free,
+        .ctx = arena};
+
+    return (ArenaAllocResult){.is_valid = true, .allocator = allocator};
+}

xmake.lua

@@ -78,12 +78,12 @@ if has_config("tests") then
 	target("test_arena")
 	set_kind("binary")
 
+	add_files("test/test_arena.c")
+
 	add_deps("lae_arena")
 
 	add_packages("cmocka")
 
-	add_files("test/test_arena.c")
-
 	add_tests("default")
 
 	if has_config("asan") then