+/**
+ * Send data as shared memory to a file descriptor.
+ *
+ * \param buf The buffer holding the data to be sent.
+ * \param size The size of \a buf.
+ * \param fd_ptr A pointer to the file descriptor.
+ *
+ * This function is used as the \a max_size handler in a \ref para_buffer
+ * structure. If used this way, it is called by \ref para_printf() whenever
+ * the buffer passed to para_printf() is about to exceed its maximal size.
+ *
+ * This function creates a shared memory area large enough to hold
+ * the content given by \a buf and \a size and sends the identifier
+ * of this area to the file descriptor given by \a fd_ptr.
+ *
+ * \return Zero if \a buf is \p NULL or \a size is zero. Negative on errors,
+ * and positive on success.
+ */
+int pass_buffer_as_shm(char *buf, size_t size, void *fd_ptr)