From patchwork Tue Nov 30 03:38:02 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Laurent Pinchart X-Patchwork-Id: 14859 Return-Path: X-Original-To: parsemail@patchwork.libcamera.org Delivered-To: parsemail@patchwork.libcamera.org Received: from lancelot.ideasonboard.com (lancelot.ideasonboard.com [92.243.16.209]) by patchwork.libcamera.org (Postfix) with ESMTPS id 46E0ABF415 for ; Tue, 30 Nov 2021 03:38:59 +0000 (UTC) Received: from lancelot.ideasonboard.com (localhost [IPv6:::1]) by lancelot.ideasonboard.com (Postfix) with ESMTP id A6E3C60717; Tue, 30 Nov 2021 04:38:58 +0100 (CET) Authentication-Results: lancelot.ideasonboard.com; dkim=fail reason="signature verification failed" (1024-bit key; unprotected) header.d=ideasonboard.com header.i=@ideasonboard.com header.b="EIDusvJE"; dkim-atps=neutral Received: from perceval.ideasonboard.com (perceval.ideasonboard.com [IPv6:2001:4b98:dc2:55:216:3eff:fef7:d647]) by lancelot.ideasonboard.com (Postfix) with ESMTPS id 3FCE3605BA for ; Tue, 30 Nov 2021 04:38:50 +0100 (CET) Received: from pendragon.lan (62-78-145-57.bb.dnainternet.fi [62.78.145.57]) by perceval.ideasonboard.com (Postfix) with ESMTPSA id A43028F0; Tue, 30 Nov 2021 04:38:49 +0100 (CET) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=ideasonboard.com; s=mail; t=1638243529; bh=HilQ8jl7CA5hVx3Y5PCHmfR/5wqX0HIv0tjK5itDCxQ=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=EIDusvJE4/EQ7Fc7UcXtHF7F87bia+WVsgzPULLSg2Vlf3vGnWEWs8jpygY3JvJk9 8swGXOni+SkMNHHG3HZHiIz+6PtpiZ4ZJ9o7gFK9lqTFvjkAuMXdXIFWeejtaco3Qc oOhFXtldS350Pzys2RH2PuLh1grosAXMyE7jEQTM= From: Laurent Pinchart To: libcamera-devel@lists.libcamera.org Date: Tue, 30 Nov 2021 05:38:02 +0200 Message-Id: <20211130033820.18235-5-laurent.pinchart@ideasonboard.com> X-Mailer: git-send-email 2.32.0 In-Reply-To: <20211130033820.18235-1-laurent.pinchart@ideasonboard.com> References: <20211130033820.18235-1-laurent.pinchart@ideasonboard.com> MIME-Version: 1.0 Subject: [libcamera-devel] [PATCH v4 04/22] libcamera: base: Introduce UniqueFD X-BeenThere: libcamera-devel@lists.libcamera.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: libcamera-devel-bounces@lists.libcamera.org Sender: "libcamera-devel" From: Hirokazu Honda This introduces UniqueFD. It acts like unique_ptr to a file descriptor. Signed-off-by: Hirokazu Honda Signed-off-by: Laurent Pinchart Reviewed-by: Hirokazu Honda --- Changes since v2: - Rename ScopedFD to UniqueFD - Inline most functions to allow compiler optimizations - Bring the API closer to unique_ptr<> - Add swap() - Documentation cleanups - Slip FileDescriptor constructor to separate patch - Fix isValid() --- include/libcamera/base/meson.build | 1 + include/libcamera/base/unique_fd.h | 69 ++++++++++++++++ src/libcamera/base/meson.build | 1 + src/libcamera/base/unique_fd.cpp | 123 +++++++++++++++++++++++++++++ 4 files changed, 194 insertions(+) create mode 100644 include/libcamera/base/unique_fd.h create mode 100644 src/libcamera/base/unique_fd.cpp diff --git a/include/libcamera/base/meson.build b/include/libcamera/base/meson.build index f73b00917409..cca374a769cc 100644 --- a/include/libcamera/base/meson.build +++ b/include/libcamera/base/meson.build @@ -22,6 +22,7 @@ libcamera_base_headers = files([ 'span.h', 'thread.h', 'timer.h', + 'unique_fd.h', 'utils.h', ]) diff --git a/include/libcamera/base/unique_fd.h b/include/libcamera/base/unique_fd.h new file mode 100644 index 000000000000..ae4d96b75797 --- /dev/null +++ b/include/libcamera/base/unique_fd.h @@ -0,0 +1,69 @@ +/* SPDX-License-Identifier: LGPL-2.1-or-later */ +/* + * Copyright (C) 2021, Google Inc. + * + * unique_fd.h - File descriptor wrapper that owns a file descriptor. + */ + +#pragma once + +#include + +#include +#include + +namespace libcamera { + +class UniqueFD final +{ +public: + UniqueFD() + : fd_(-1) + { + } + + explicit UniqueFD(int fd) + : fd_(fd) + { + } + + UniqueFD(UniqueFD &&other) + : fd_(other.release()) + { + } + + ~UniqueFD() + { + reset(); + } + + UniqueFD &operator=(UniqueFD &&other) + { + reset(other.release()); + return *this; + } + + __nodiscard int release() + { + int fd = fd_; + fd_ = -1; + return fd; + } + + void reset(int fd = -1); + + void swap(UniqueFD &other) + { + std::swap(fd_, other.fd_); + } + + int get() const { return fd_; } + bool isValid() const { return fd_ >= 0; } + +private: + LIBCAMERA_DISABLE_COPY(UniqueFD) + + int fd_; +}; + +} /* namespace libcamera */ diff --git a/src/libcamera/base/meson.build b/src/libcamera/base/meson.build index d5254fda9cbf..b0d85bc19245 100644 --- a/src/libcamera/base/meson.build +++ b/src/libcamera/base/meson.build @@ -17,6 +17,7 @@ libcamera_base_sources = files([ 'signal.cpp', 'thread.cpp', 'timer.cpp', + 'unique_fd.cpp', 'utils.cpp', ]) diff --git a/src/libcamera/base/unique_fd.cpp b/src/libcamera/base/unique_fd.cpp new file mode 100644 index 000000000000..83d6919cf623 --- /dev/null +++ b/src/libcamera/base/unique_fd.cpp @@ -0,0 +1,123 @@ +/* SPDX-License-Identifier: LGPL-2.1-or-later */ +/* + * Copyright (C) 2021, Google Inc. + * + * unique_fd.cpp - File descriptor wrapper that owns a file descriptor + */ + +#include + +#include +#include + +#include + +/** + * \file base/unique_fd.h + * \brief File descriptor wrapper that owns a file descriptor + */ + +namespace libcamera { + +LOG_DEFINE_CATEGORY(UniqueFD) + +/** + * \class UniqueFD + * \brief unique_ptr-like wrapper for a file descriptor + * + * The UniqueFD is a wrapper that owns and manages the lifetime of a file + * descriptor. It is constructed from a numerical file descriptor, and takes + * over its ownership. The file descriptor is closed when the UniqueFD is + * destroyed, or when it is assigned another file descriptor with operator=() + * or reset(). + */ + +/** + * \fn UniqueFD::UniqueFD() + * \brief Construct a UniqueFD that owns no file descriptor + */ + +/** + * \fn UniqueFD::UniqueFD(int fd) + * \brief Construct a UniqueFD that owns \a fd + * \param[in] fd A file descriptor to manage + */ + +/** + * \fn UniqueFD::UniqueFD(UniqueFD &&other) + * \brief Move constructor, create a UniqueFD by taking over \a other + * \param[in] other The other UniqueFD + * + * Create a UniqueFD by transferring ownership of the file descriptor owned by + * \a other. Upon return, the \a other UniqueFD is invalid. + */ + +/** + * \fn UniqueFD::~UniqueFD() + * \brief Destroy the UniqueFD instance + * + * If a file descriptor is owned, it is closed. + */ + +/** + * \fn UniqueFD::operator=(UniqueFD &&other) + * \brief Move assignment operator, replace a UniqueFD by taking over \a other + * \param[in] other The other UniqueFD + * + * If this UniqueFD owns a file descriptor, the file descriptor is closed + * first. The file descriptor is then replaced by the one of \a other. Upon + * return, \a other is invalid. + * + * \return A reference to this UniqueFD + */ + +/** + * \fn UniqueFD::release() + * \brief Release ownership of the file descriptor without closing it + * + * This function releases and returns the owned file descriptor without closing + * it. The caller owns the returned value and must take care of handling its + * life time to avoid file descriptor leakages. Upon return this UniqueFD is + * invalid. + * + * \return The managed file descriptor, or -1 if no file descriptor was owned + */ + +/** + * \brief Replace the managed file descriptor + * \param[in] fd The new file descriptor to manage + * + * Close the managed file descriptor, if any, and replace it with the new \a fd. + * + * Self-resetting (passing an \a fd already managed by this instance) is invalid + * and results in undefined behaviour. + */ +void UniqueFD::reset(int fd) +{ + ASSERT(!isValid() || fd != fd_); + + std::swap(fd, fd_); + + if (fd >= 0) + close(fd); +} + +/** + * \fn UniqueFD::swap(UniqueFD &other) + * \brief Swap the managed file descriptors with another UniqueFD + * \param[in] other Another UniqueFD to swap the file descriptor with + */ + +/** + * \fn UniqueFD::get() + * \brief Retrieve the managed file descriptor + * \return The managed file descriptor, or -1 if no file descriptor is owned + */ + +/** + * \fn UniqueFD::isValid() + * \brief Check if the UniqueFD owns a valid file descriptor + * \return True if the UniqueFD owns a valid file descriptor, false otherwise + */ + +} /* namespace libcamera */