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, 99 insertions, 0 deletions

diff --git a/src/sys/include/lib/ptrbox.h b/src/sys/include/lib/ptrbox.h
new file mode 100644
index 0000000..a84a760
--- /dev/null
+++ b/src/sys/include/lib/ptrbox.h
@@ -0,0 +1,99 @@
+/*
+ * 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.
+ */
+
+#ifndef _PTRBOX_H_
+#define _PTRBOX_H_  1
+
+#include <sys/queue.h>
+
+struct ptrbox_entry;
+struct ptrbox;
+
+/*
+ * Represents an allocate entry within a
+ * pointer box
+ *
+ * @data: Allocated data
+ * @len: Length of allocated data
+ * @link: Queue link
+ */
+struct ptrbox_entry {
+    void *data;
+    size_t len;
+    TAILQ_ENTRY(ptrbox_entry) link;
+};
+
+/*
+ * Represents a RAII styled pointer box
+ *
+ * @count: Number of entries
+ * @q: Entry queue
+ *
+ * Memory is allocated and placed into a pointer
+ * box
+ *
+ * Why?: One call to free them all
+ */
+struct ptrbox {
+    size_t count;
+    TAILQ_HEAD(, ptrbox_entry) q;
+};
+
+/*
+ * Initialize a new pointer box
+ *
+ * @box_res: Pointer box is written here
+ *
+ * Returns zero on success, otherwise a less than
+ * zero value on failure
+ */
+int ptrbox_init(struct ptrbox **box_res);
+
+/*
+ * Terminate the box from its life and kill its
+ * children. Used for RAII-styled cleanups.
+ *
+ * Returns zero on success, otherwise a less than
+ * zero value on failure.
+ */
+int ptrbox_terminate(struct ptrbox *box);
+
+/*
+ * Allocate memory and put it into a pointer
+ * box for RAII style handling
+ *
+ * @len: Length of memory to allocate
+ * @box: Pointer box to use
+ *
+ * Returns the allocated memory base on success, otherwise
+ * a value of NULL on failure.
+ */
+void *ptrbox_alloc(size_t len, struct ptrbox *box);
+
+#endif  /* !_PTRBOX_H_ */