bson_lifetimes - Man Page

A bson_t <> may contain its data directly or may contain pointers to heap-allocated memory. Overwriting an existing bson_t <> or allowing a stack-allocated bson_t <> to go out of scope may cause a memory leak. A bson_t <> should always be destroyed with bson_destroy() <>.

Bson_t out Parameters

A bson_t <> pointer used as an out parameter must point to valid overwritable storage for a new bson_t <> which must be one of:

  1. Uninitialized storage for a bson_t <>.
  2. A zero-initialized bson_t <> object.
  3. A bson_t <> object initialized with BSON_INITIALIZER.
  4. A bson_t <> object not created with bson_new() <> that was destroyed with bson_destroy() <>.

This can be on the stack:

bson_t stack_doc = BSON_INITIALIZER;
example_get_doc (&stack_doc);
bson_destroy (&stack_doc);

Or on the heap:

bson_t *heap_doc = bson_malloc (sizeof (bson_t));
example_get_doc (heap_doc);
bson_destroy (heap_doc);
bson_free (heap_doc);

Omitting bson_destroy() <> in either case may cause memory leaks.

Warning:

Passing a bson_t <> pointer obtained from bson_new() <> as an out parameter will result in a leak of the bson_t <> struct.

bson_t *heap_doc = bson_new ();
example_get_doc (heap_doc);
bson_destroy (heap_doc); // Leaks the `bson_t` struct!

Author

MongoDB, Inc

Info

Apr 17, 2026 2.3.0 libbson