From patchwork Sat Aug 21 20:18:18 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Christian Schoenebeck X-Patchwork-Id: 12451051 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-15.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 647B3C4338F for ; Sat, 21 Aug 2021 21:13:01 +0000 (UTC) Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id DF2346125F for ; Sat, 21 Aug 2021 21:13:00 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org DF2346125F Authentication-Results: mail.kernel.org; dmarc=fail (p=quarantine dis=none) header.from=crudebyte.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=nongnu.org Received: from localhost ([::1]:58552 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1mHYIW-0002AI-2n for qemu-devel@archiver.kernel.org; Sat, 21 Aug 2021 17:13:00 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:57432) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1mHYHG-00007H-Eh for qemu-devel@nongnu.org; Sat, 21 Aug 2021 17:11:42 -0400 Received: from lizzy.crudebyte.com ([91.194.90.13]:43873) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1mHYHC-0001WJ-6e for qemu-devel@nongnu.org; Sat, 21 Aug 2021 17:11:42 -0400 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=crudebyte.com; s=lizzy; h=Cc:To:Subject:Date:From:References:In-Reply-To: Message-Id:Content-Type:Content-Transfer-Encoding:MIME-Version:Content-ID: Content-Description; bh=Ihfx/i5DNU+G4x66QNtBztFtNjftz3znLfp5inBsl2c=; b=XH5Oz LhB+4tiX0w5g+MfP7h1502rt6GzM1ecxyGrj3tpwIHxLt0UYF2kw17qEfUWqH/phA+nzNFQljROa6 KD8/I54KKd08lUaxXIBEFbhCuOMtFkWZoUY5VgWrT1tt8S7OCDxdqnkLOnX4UbBsRTAetdb8bWlEH M5O/Efh2+zCr9oPmo+IJqgFlCOXDwRpMpS+LP1tqZUNE5B9iLDtPen4Wbdc1uVd7oWgeJ4J9x9VLt yUdfzd/wWr9L4z2E3q5RK896a9PWhNQ5icSQoOEguWJJbq0it0sjZMUb9pK9t4oKak5BUltmVuSyT /cnEfUSLRfU68vpBuhkIXyXbFLQqQ==; Message-Id: In-Reply-To: References: From: Christian Schoenebeck Date: Sat, 21 Aug 2021 22:18:18 +0200 Subject: [PATCH 1/5] qemu/qarray.h: introduce QArray To: qemu-devel@nongnu.org Cc: Greg Kurz Received-SPF: none client-ip=91.194.90.13; envelope-from=a1925f3bb2560f2f19558dbc6d4309d3bb17529d@lizzy.crudebyte.com; helo=lizzy.crudebyte.com X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, SPF_HELO_NONE=0.001, SPF_NONE=0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" Implements deep auto free of arrays while retaining common C-style squared bracket access. Signed-off-by: Christian Schoenebeck --- include/qemu/qarray.h | 148 ++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 148 insertions(+) create mode 100644 include/qemu/qarray.h diff --git a/include/qemu/qarray.h b/include/qemu/qarray.h new file mode 100644 index 0000000000..230a556e81 --- /dev/null +++ b/include/qemu/qarray.h @@ -0,0 +1,148 @@ +/* + * QArray - deep auto free C-array + * + * Copyright (c) 2021 Crudebyte + * + * Authors: + * Christian Schoenebeck + * + * Permission is hereby granted, free of charge, to any person obtaining a copy + * of this software and associated documentation files (the "Software"), to deal + * in the Software without restriction, including without limitation the rights + * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell + * copies of the Software, and to permit persons to whom the Software is + * furnished to do so, subject to the following conditions: + * + * The above copyright notice and this permission notice shall be included in + * all copies or substantial portions of the Software. + * + * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR + * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, + * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL + * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER + * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, + * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN + * THE SOFTWARE. + */ +#ifndef QEMU_QARRAY_H +#define QEMU_QARRAY_H + +/** + * QArray provides a mechanism to access arrays in common C-style (e.g. by + * square bracket [] operator) in conjunction with reference variables that + * perform deep auto free of the array when leaving the scope of the auto + * reference variable. That means not only is the array itself automatically + * freed, but also memory dynamically allocated by the individual array + * elements. + * + * Example: + * + * Consider the following user struct @c Foo which shall be used as scalar + * (element) type of an array: + * @code + * typedef struct Foo { + * int i; + * char *s; + * } Foo; + * @endcode + * and assume it has the following function to free memory allocated by @c Foo + * instances: + * @code + * void free_foo(Foo *foo) { + * free(foo->s); + * } + * @endcode + * Add the following to a shared header file: + * @code + * DECLARE_QARRAY_TYPE(Foo); + * @endcode + * and the following to a C unit file: + * @code + * DEFINE_QARRAY_TYPE(Foo, free_foo); + * @endcode + * Finally the array may then be used like this: + * @code + * void doSomething(int n) { + * QArrayRef(Foo) foos = NULL; + * QARRAY_CREATE(Foo, foos, n); + * for (size_t i = 0; i < n; ++i) { + * foos[i].i = i; + * foos[i].s = calloc(4096, 1); + * snprintf(foos[i].s, 4096, "foo %d", i); + * } + * } + * @endcode + */ + +/** + * Declares an array for the passed @a scalar_type. + * + * This is typically used from a shared header file. + * + * @param scalar_type - type of the individual array elements + */ +#define DECLARE_QARRAY_TYPE(scalar_type) \ + typedef struct QArray##scalar_type { \ + size_t len; \ + scalar_type first[]; \ + } QArray##scalar_type; \ + \ + void qarray_create_##scalar_type(scalar_type **auto_var, size_t len); \ + void qarray_auto_free_##scalar_type(scalar_type **auto_var); \ + +/** + * Defines an array for the passed @a scalar_type and appropriate + * @a scalar_cleanup_func. + * + * @param scalar_type - type of the individual array elements + * @param scalar_cleanup_func - appropriate function to free memory dynamically + * allocated by individual array elements before + */ +#define DEFINE_QARRAY_TYPE(scalar_type, scalar_cleanup_func) \ + void qarray_create_##scalar_type(scalar_type **auto_var, size_t len) \ + { \ + qarray_auto_free_##scalar_type(auto_var); \ + QArray##scalar_type *arr = g_malloc0(sizeof(QArray##scalar_type) + \ + len * sizeof(scalar_type)); \ + arr->len = len; \ + *auto_var = &arr->first[0]; \ + } \ + \ + void qarray_auto_free_##scalar_type(scalar_type **auto_var) \ + { \ + scalar_type *first = (*auto_var); \ + if (!first) { \ + return; \ + } \ + QArray##scalar_type *arr = (QArray##scalar_type *) ( \ + ((char *)first) - offsetof(QArray##scalar_type, first) \ + ); \ + for (size_t i = 0; i < arr->len; ++i) { \ + scalar_cleanup_func(&arr->first[i]); \ + } \ + g_free(arr); \ + } \ + +/** + * Used to declare a reference variable (unique pointer) for an array. After + * leaving the scope of the reference variable, the associated array is + * automatically freed. + * + * @param scalar_type - type of the individual array elements + */ +#define QArrayRef(scalar_type) \ + __attribute((__cleanup__(qarray_auto_free_##scalar_type))) scalar_type* + +/** + * Allocates a new array of passed @a scalar_type with @a len number of array + * elements and assigns the created array to the reference variable + * @a auto_var. + * + * @param scalar_type - type of the individual array elements + * @param auto_var - destination reference variable + * @param len - amount of array elements to be allocated immediately + */ +#define QARRAY_CREATE(scalar_type, auto_var, len) \ + qarray_create_##scalar_type((&auto_var), len) + +#endif /* QEMU_QARRAY_H */