archive_read_format_zip_cleanup(struct archive_read *a)
{
	struct zip *zip;
	struct zip_entry *zip_entry, *next_zip_entry;

	zip = (struct zip *)(a->format->data);

#ifdef HAVE_ZLIB_H
	if (zip->stream_valid)
		inflateEnd(&zip->stream);
#endif

#if HAVE_LZMA_H && HAVE_LIBLZMA
    if (zip->zipx_lzma_valid) {
		lzma_end(&zip->zipx_lzma_stream);
	}
#endif

#ifdef HAVE_BZLIB_H
	if (zip->bzstream_valid) {
		BZ2_bzDecompressEnd(&zip->bzstream);
	}
#endif

	free(zip->uncompressed_buffer);

	if (zip->ppmd8_valid)
		__archive_ppmd8_functions.Ppmd8_Free(&zip->ppmd8);

	if (zip->zip_entries) {
		zip_entry = zip->zip_entries;
		while (zip_entry != NULL) {
			next_zip_entry = zip_entry->next;
			archive_string_free(&zip_entry->rsrcname);
			free(zip_entry);
			zip_entry = next_zip_entry;
		}
	}
	free(zip->decrypted_buffer);
	if (zip->cctx_valid)
		archive_decrypto_aes_ctr_release(&zip->cctx);
	if (zip->hctx_valid)
		archive_hmac_sha1_cleanup(&zip->hctx);
	free(zip->iv);
	free(zip->erd);
	free(zip->v_data);
	archive_string_free(&zip->format_name);
	free(zip);
	(a->format->data) = NULL;
	return (ARCHIVE_OK);
}
The software does not sufficiently track and release allocated memory after it has been used, which slowly consumes remaining memory.