core: Add pointer box / RAII impl

Signed-off-by: Ian Moffett <ian@mirocom.org>

1 files changed, 132 insertions, 0 deletions

diff --git a/core/ptrbox.c b/core/ptrbox.c
new file mode 100644
index 0000000..2bdaa9c
--- /dev/null
+++ b/core/ptrbox.c
@@ -0,0 +1,132 @@
+/*
+ * Copyright (c) 2026, Chloe M.
+ * Provided under the BSD-3 clause
+ */
+
+#include <stddef.h>
+#include <stdint.h>
+#include <errno.h>
+#include <stdlib.h>
+#include <string.h>
+#include "cescal/ptrbox.h"
+
+/*
+ * Allocate a pointer box entry to be used
+ */
+static struct ptrbox_entry *
+ptrbox_alloc_entry(void)
+{
+    struct ptrbox_entry *entry;
+
+    if ((entry = malloc(sizeof(*entry))) == NULL) {
+        return NULL;
+    }
+
+    entry->data = NULL;
+    entry->next = NULL;
+    return entry;
+}
+
+static int
+ptrbox_push_entry(struct ptrbox *ptrbox, struct ptrbox_entry *entry)
+{
+    if (ptrbox == NULL || entry == NULL) {
+        errno = EINVAL;
+        return -1;
+    }
+
+    if (ptrbox->head == NULL || ptrbox->tail == NULL) {
+        ptrbox->head = entry;
+        ptrbox->tail = entry;
+    } else {
+        ptrbox->head->next = entry;
+        ptrbox->head = entry;
+    }
+
+    return 0;
+}
+
+int
+ptrbox_init(struct ptrbox *ptrbox)
+{
+    if (ptrbox == NULL) {
+        errno = EINVAL;
+        return -1;
+    }
+
+    ptrbox->head = NULL;
+    ptrbox->tail = NULL;
+    return 0;
+}
+
+void *
+ptrbox_alloc(struct ptrbox *ptrbox, size_t len)
+{
+    struct ptrbox_entry *entry;
+    void *p;
+
+    if (ptrbox == NULL || len == 0) {
+        errno = EINVAL;
+        return NULL;
+    }
+
+    if ((p = malloc(len)) == NULL) {
+        return NULL;
+    }
+
+    if ((entry = ptrbox_alloc_entry()) == NULL) {
+        free(p);
+        return NULL;
+    }
+
+    entry->data = p;
+    if (ptrbox_push_entry(ptrbox, entry) < 0) {
+        free(p);
+        free(entry);
+        return NULL;
+    }
+
+    return 0;
+}
+
+char *
+ptrbox_strdup(struct ptrbox *ptrbox, const char *s)
+{
+    char *sdup;
+    size_t slen;
+
+    if (ptrbox == NULL || s == NULL) {
+        errno = EINVAL;
+        return NULL;
+    }
+
+    slen = strlen(s) + 1;
+    if ((sdup = ptrbox_alloc(ptrbox, slen)) == NULL) {
+        return NULL;
+    }
+
+    memcpy(sdup, s, slen);
+    return sdup;
+}
+
+void
+ptrbox_destroy(struct ptrbox *ptrbox)
+{
+    struct ptrbox_entry *entry, *tmp;
+
+    if (ptrbox == NULL) {
+        return;
+    }
+
+    if ((entry = ptrbox->tail) == NULL) {
+        return;
+    }
+
+    while (entry != NULL) {
+        tmp = entry;
+        entry = entry->next;
+
+        free(tmp->data);
+        free(tmp);
+    }
+}