diff -r e79a60b3a7cb -r 7c3ff86ee9d4 ucx/basic_mempool.c
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/ucx/basic_mempool.c	Tue May 23 11:11:28 2023 +0200
@@ -0,0 +1,235 @@
+/*
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS HEADER.
+ *
+ * Copyright 2021 Mike Becker, Olaf Wintermann All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ *   1. Redistributions of source code must retain the above copyright
+ *      notice, this list of conditions and the following disclaimer.
+ *
+ *   2. Redistributions in binary form must reproduce the above copyright
+ *      notice, this list of conditions and the following disclaimer in the
+ *      documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
+ * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include "cx/basic_mempool.h"
+#include "cx/utils.h"
+#include <string.h>
+
+#define of_chk_(n) if (SIZE_MAX - sizeof(cx_destructor_func) < (n)) return NULL
+
+/** Internal structure for denoting pooled memory. */
+typedef struct {
+    /** The destructor. */
+    cx_destructor_func destructor;
+    /**
+     * Access to the first byte of the polled memory.
+     */
+    char c;
+} cx_basic_mempool_memory;
+
+static int cx_basic_mempool_chcap(
+        struct cx_basic_mempool_s *pool,
+        size_t newcap
+) {
+    if (newcap < pool->ndata) {
+        return 1;
+    }
+
+    size_t newcapsz;
+    if (cx_szmul(newcap, sizeof(void *), &newcapsz)) {
+        return 1;
+    }
+
+    void **data = realloc(pool->data, newcapsz);
+    if (data) {
+        pool->data = data;
+        pool->size = newcap;
+        return 0;
+    } else {
+        return 1;
+    }
+}
+
+void *cx_malloc_basic_mempool(
+        void *data,
+        size_t n
+) {
+    of_chk_(n);
+    struct cx_basic_mempool_s *pool = data;
+
+    if (pool->ndata >= pool->size) {
+        size_t newcap = pool->size * 2;
+        if (newcap < pool->size || cx_basic_mempool_chcap(pool, newcap)) {
+            return NULL;
+        }
+    }
+
+    cx_basic_mempool_memory *mem = malloc(sizeof(cx_destructor_func) + n);
+    if (mem == NULL) {
+        return NULL;
+    }
+
+    mem->destructor = NULL;
+    pool->data[pool->ndata] = mem;
+    pool->ndata++;
+
+    return &(mem->c);
+}
+
+void *cx_calloc_basic_mempool(
+        void *data,
+        size_t nelem,
+        size_t elsize
+) {
+    size_t msz;
+    if (cx_szmul(nelem, elsize, &msz)) {
+        return NULL;
+    }
+    void *ptr = cx_malloc_basic_mempool(data, msz);
+    if (ptr == NULL) {
+        return NULL;
+    }
+    memset(ptr, 0, nelem * elsize);
+    return ptr;
+}
+
+void *cx_realloc_basic_mempool(
+        void *data,
+        void *ptr,
+        size_t n
+) {
+    of_chk_(n);
+    struct cx_basic_mempool_s *pool = data;
+
+    char *mem = ((char *) ptr) - sizeof(cx_destructor_func);
+    char *newm = (char *) realloc(mem, n + sizeof(cx_destructor_func));
+    if (newm == NULL) {
+        return NULL;
+    }
+    if (mem != newm) {
+        cx_for_n(i, pool->ndata) {
+            if (pool->data[i] == mem) {
+                pool->data[i] = newm;
+                return newm + sizeof(cx_destructor_func);
+            }
+        }
+        abort();
+    } else {
+        return newm + sizeof(cx_destructor_func);
+    }
+}
+
+void cx_free_basic_mempool(
+        void *data,
+        void *ptr
+) {
+    struct cx_basic_mempool_s *pool = data;
+
+    cx_basic_mempool_memory *mem = (cx_basic_mempool_memory *)
+            ((char *) ptr - sizeof(cx_destructor_func));
+    cx_for_n(i, pool->ndata) {
+        if (mem == pool->data[i]) {
+            if (mem->destructor != NULL) {
+                mem->destructor(&(mem->c));
+            }
+            free(mem);
+            size_t last_index = pool->ndata - 1;
+            if (i != last_index) {
+                pool->data[i] = pool->data[last_index];
+                pool->data[last_index] = NULL;
+            }
+            pool->ndata--;
+            return;
+        }
+    }
+    abort();
+}
+
+void cx_basic_mempool_destroy(CxMempool *p) {
+    struct cx_basic_mempool_s *pool = (struct cx_basic_mempool_s *) p;
+    cx_basic_mempool_memory *mem;
+    cx_for_n(i, pool->ndata) {
+        mem = (cx_basic_mempool_memory *) pool->data[i];
+        if (mem) {
+            if (mem->destructor) {
+                mem->destructor(&(mem->c));
+            }
+            free(mem);
+        }
+    }
+    free(pool->data);
+    free((void *) p->allocator);
+    free(pool);
+}
+
+void cx_basic_mempool_set_destr(
+        __attribute__((__unused__)) CxMempool *pool,
+        void *ptr,
+        cx_destructor_func func
+) {
+    *(cx_destructor_func *) ((char *) ptr - sizeof(cx_destructor_func)) = func;
+}
+
+static cx_allocator_class cx_basic_mempool_allocator_class = {
+        cx_malloc_basic_mempool,
+        cx_realloc_basic_mempool,
+        cx_calloc_basic_mempool,
+        cx_free_basic_mempool
+};
+
+static cx_mempool_class cx_basic_mempool_class = {
+        cx_basic_mempool_destroy,
+        cx_basic_mempool_set_destr,
+};
+
+CxMempool *cxBasicMempoolCreate(size_t capacity) {
+    size_t poolsize;
+    if (cx_szmul(capacity, sizeof(void *), &poolsize)) {
+        return NULL;
+    }
+
+    struct cx_basic_mempool_s *pool =
+            malloc(sizeof(struct cx_basic_mempool_s));
+    if (pool == NULL) {
+        return NULL;
+    }
+
+
+    CxAllocator *provided_allocator = malloc(sizeof(CxAllocator));
+    if (!provided_allocator) {
+        free(pool);
+        return NULL;
+    }
+    provided_allocator->cl = &cx_basic_mempool_allocator_class;
+    provided_allocator->data = pool;
+
+    pool->base.cl = &cx_basic_mempool_class;
+    pool->base.allocator = provided_allocator;
+
+    pool->data = malloc(poolsize);
+    if (pool->data == NULL) {
+        free(provided_allocator);
+        free(pool);
+        return NULL;
+    }
+
+    pool->ndata = 0;
+    pool->size = capacity;
+
+    return (CxMempool *) pool;
+}