kern: lib: Introduce pointer boxes

Pointer boxes are a way to allocate memory and associate them with one
location so that during error/exit paths, one may deallocate every buffer
with a single call

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

1 files changed, 118 insertions, 0 deletions

diff --git a/src/sys/lib/ptrbox.c b/src/sys/lib/ptrbox.c
new file mode 100644
index 0000000..b8370e5
--- /dev/null
+++ b/src/sys/lib/ptrbox.c
@@ -0,0 +1,118 @@
+/*
+ * Copyright (c) 2025 Ian Marco Moffett and L5 engineers
+ * 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.
+ * 3. Neither the name of the project nor the names of its
+ *    contributors may be used to endorse or promote products derived from
+ *    this software without specific prior written permission.
+ *
+ * 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 OWNER 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 <sys/errno.h>
+#include <sys/syslog.h>
+#include <os/kalloc.h>
+#include <lib/ptrbox.h>
+#include <string.h>
+
+/*
+ * Allocate memory and add it to an existing
+ * box
+ */
+void *
+ptrbox_alloc(size_t len, struct ptrbox *box)
+{
+    struct ptrbox_entry *ent;
+
+    if (len == 0 || box == NULL) {
+        return NULL;
+    }
+
+    ent = kalloc(sizeof(*ent));
+    if (ent == NULL) {
+        return NULL;
+    }
+
+    /* Allocate the actual data */
+    ent->data = kalloc(len);
+    if (ent->data == NULL) {
+        kfree(ent);
+        return NULL;
+    }
+
+    ent->len = len;
+    TAILQ_INSERT_TAIL(&box->q, ent, link);
+    return ent->data;
+}
+
+/*
+ * Terminate a box
+ */
+int
+ptrbox_terminate(struct ptrbox *box)
+{
+    struct ptrbox_entry *ent;
+
+    if (box == NULL) {
+        return -EINVAL;
+    }
+
+    /*
+     * Go through each entry first, reap one
+     * by one.
+     */
+    TAILQ_FOREACH(ent, &box->q, link) {
+        if (ent == NULL) {
+            continue;
+        }
+
+        kfree(ent->data);
+        printf("reaped %p\n", ent->data);
+        ent->data = NULL;
+    }
+
+    /* Reap ourselves */
+    kfree(ent);
+    return 0;
+}
+
+/*
+ * Initialize a box
+ */
+int
+ptrbox_init(struct ptrbox **box_res)
+{
+    struct ptrbox *box;
+
+    if (box_res == NULL) {
+        return -EINVAL;
+    }
+
+    box = kalloc(sizeof(*box));
+    if (box == NULL) {
+        return -ENOMEM;
+    }
+
+    box->count = 0;
+    TAILQ_INIT(&box->q);
+    *box_res = box;
+    return 0;
+}