core: Add xmalloc() implementation

Signed-off-by: Chloe M. <chloe@mirocom.org>

core/xmalloc.c

@@ -0,0 +1,24 @@
+/*
+ * Copyright (c) 2026, Chloe M.
+ * Provided under the BSD-3 clause
+ */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <stddef.h>
+#include <assert.h>
+#include "blobchain/memlib.h"
+
+void *
+xmalloc(size_t sz)
+{
+    void *p;
+
+    assert(sz != 0 && "xmalloc size cannot be zero!");
+    if ((p = malloc(sz)) == NULL) {
+        printf("fatal: out of memory\n");
+        exit(1);
+    }
+
+    return p;
+}

inc/blobchain/memlib.h

@@ -0,0 +1,18 @@
+/*
+ * Copyright (c) 2026, Chloe M.
+ * Provided under the BSD-3 clause
+ */
+
+#ifndef BLOBCHAIN_MEMLIB_H
+#define BLOBCHAIN_MEMLIB_H 1
+
+/*
+ * Allocate memory and exit upon failure
+ *
+ * @sz: Number of bytes to allocate
+ *
+ * Always returns on success
+ */
+void *xmalloc(size_t sz);
+
+#endif  /* !BLOBCHAIN_MEMLIB_H */