core: Add support for pointer boxes

Pointer boxes are a way to manage memory and have all references
released after operation, this way they do not need to be manually
managed.

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

2 files changed, 61 insertions, 0 deletions

diff --git a/head/defconf/ptrbox.h b/head/defconf/ptrbox.h
new file mode 100644
index 0000000..3358595
--- /dev/null
+++ b/head/defconf/ptrbox.h
@@ -0,0 +1,58 @@
+/*
+ * Copyright (c) 2026, Apollo Telephone Laboratories.
+ * Provided under the BSD-3 clause.
+ */
+
+#ifndef DEFCONF_PTRBOX_H
+#define DEFCONF_PTRBOX_H 1
+
+#include <sys/queue.h>
+#include <stdint.h>
+#include <stddef.h>
+
+/*
+ * Represents a pointer box entry
+ *
+ * @data:  Allocated data
+ * @link:  TAILQ link
+ */
+struct ptrbox_entry {
+    void *data;
+    TAILQ_ENTRY(ptrbox_entry) link;
+};
+
+/*
+ * A pointer box stores references to memory to be freed later on
+ *
+ * @entries:        Entries within pointer box
+ * @entry_count:    Number of pointer box entries
+ */
+struct ptrbox {
+    TAILQ_HEAD(, ptrbox_entry) entries;
+    size_t entry_count;
+};
+
+/*
+ * Wrapper over strdup() but saved in a pointer box
+ *
+ * @ptrbox:  Pointer box to allocate into
+ * @s:       String to dup
+ *
+ * Returns the base of the dup'd string on success, otherwise
+ * NULL on failure.
+ */
+char *ptrbox_strdup(struct ptrbox *ptrbox, const char *s);
+
+/*
+ * Initialize a pointer box
+ */
+int ptrbox_init(struct ptrbox *ptrbox);
+
+/*
+ * Destroy a pointer box and all of its entries
+ *
+ * @ptrbox: Pointer box to destroy
+ */
+void ptrbox_destroy(struct ptrbox *ptrbox);
+
+#endif  /* !DEFCONF_PTRBOX_H */
diff --git a/head/defconf/state.h b/head/defconf/state.h
index 524af3b..aa99105 100644
--- a/head/defconf/state.h
+++ b/head/defconf/state.h
@@ -9,16 +9,19 @@
 #include <stdint.h>
 #include <stddef.h>
 #include <stdio.h>
+#include "defconf/ptrbox.h"
 
 /*
  * DEFCONF state machine
  *
  * @in_fp:      Input file pointer
  * @lex_cache:  Putback cache
+ * @ptrbox:     Global pointer box
  */
 struct defconf_state {
     FILE *in_fp;
     int lex_cache;
+    struct ptrbox ptrbox;
 };
 
 /*