diff --git a/include/libcamera/file_descriptor.h b/include/libcamera/file_descriptor.h new file mode 100644 index 0000000000000000..f08c105998cc7559 --- /dev/null +++ b/include/libcamera/file_descriptor.h @@ -0,0 +1,46 @@ +/* SPDX-License-Identifier: LGPL-2.1-or-later */ +/* + * Copyright (C) 2019, Google Inc. + * + * file_descriptor.h - File descriptor wrapper + */ +#ifndef __LIBCAMERA_FILE_DESCRIPTOR_H__ +#define __LIBCAMERA_FILE_DESCRIPTOR_H__ + +#include + +namespace libcamera { + +class FileDescriptor final +{ +public: + explicit FileDescriptor(int fd = -1); + FileDescriptor(const FileDescriptor &other); + FileDescriptor(FileDescriptor &&other); + ~FileDescriptor(); + + FileDescriptor &operator=(const FileDescriptor &other); + FileDescriptor &operator=(FileDescriptor &&other); + + int fd() const { return fd_ ? fd_->fd() : -1; } + FileDescriptor dup() const; + +private: + class Storage + { + public: + Storage(int fd); + ~Storage(); + + int fd() const { return fd_; } + + private: + int fd_; + }; + + std::shared_ptr fd_; +}; + +} /* namespace libcamera */ + +#endif /* __LIBCAMERA_FILE_DESCRIPTOR_H__ */ diff --git a/include/libcamera/meson.build b/include/libcamera/meson.build index 99abf06099407c1f..543e6773cc5158a0 100644 --- a/include/libcamera/meson.build +++ b/include/libcamera/meson.build @@ -6,6 +6,7 @@ libcamera_api = files([ 'controls.h', 'event_dispatcher.h', 'event_notifier.h', + 'file_descriptor.h', 'geometry.h', 'logging.h', 'object.h', diff --git a/src/libcamera/file_descriptor.cpp b/src/libcamera/file_descriptor.cpp new file mode 100644 index 0000000000000000..2e531f40696be16c --- /dev/null +++ b/src/libcamera/file_descriptor.cpp @@ -0,0 +1,170 @@ +/* SPDX-License-Identifier: LGPL-2.1-or-later */ +/* + * Copyright (C) 2019, Google Inc. + * + * file_descriptor.cpp - File descriptor wrapper + */ + +#include + +#include +#include +#include + +#include "log.h" + +/** + * \file file_descriptor.h + * \brief File descriptor wrapper + */ + +namespace libcamera { + +LOG_DEFINE_CATEGORY(FileDescriptor) + +/** + * \class FileDescriptor + * \brief RAII-style wrapper for file descriptors + * + * The FileDescriptor class wraps a file descriptor (expressed as a signed + * integer) to provide an RAII-style mechanism for owning the file descriptor. + * When constructed, the FileDescriptor instance duplicates a given file + * descriptor and takes ownership of the duplicate as a resource. The copy + * constructor and assignment operator duplicate the file descriptor, while the + * move versions of those methods move the resource and make the original + * FileDescriptor invalid. When the FileDescriptor is deleted, it closes the + * file descriptor it owns, if any. + */ + +/** + * \brief Create a FileDescriptor wrapping a copy of a given \a fd + * \param[in] fd File descriptor + * + * Construct a FileDescriptor from a numerical file descriptor duplicates the + * \a fd and takes ownership of the copy. The original \a fd is left untouched, + * and the caller is responsible for closing it when appropriate. The duplicated + * file descriptor will be closed automatically when the FileDescriptor instance + * is destroyed. + */ +FileDescriptor::FileDescriptor(int fd) +{ + fd_ = std::make_shared(fd); +} + +/** + * \brief Copy constructor, create a FileDescriptor from a copy of \a other + * \param[in] other The other FileDescriptor + * + * Construct a FileDescriptor from another FileDescriptor duplicates the + * wrapped numerical file descriptor and takes ownership of the copy. The + * original FileDescriptor is left untouched, and the caller is responsible for + * closing it when appropriate. The duplicated file descriptor will be closed + * automatically when this FileDescriptor instance is destroyed. + */ +FileDescriptor::FileDescriptor(const FileDescriptor &other) + : fd_(other.fd_) +{ +} + +/** + * \brief Move constructor, create a FileDescriptor by taking over \a other + * \param[in] other The other FileDescriptor + * + * Construct a FileDescriptor by taking over a wrapped numerical file + * descriptor and taking ownership of it. The \a other FileDescriptor is + * invalidated and set to -1. The taken over file descriptor will be closed + * automatically when this FileDescriptor instance is destroyed. + */ +FileDescriptor::FileDescriptor(FileDescriptor &&other) + : fd_(std::move(other.fd_)) +{ +} + +/** + * \brief Destroy the managed file descriptor + * + * If the managed file descriptor, as returned by fd(), is not equal to -1, the + * file descriptor is closed. + */ +FileDescriptor::~FileDescriptor() +{ +} + +/** + * \brief Copy assignment operator, replace the wrapped file descriptor with a + * duplicate from \a other + * \param[in] other The other FileDescriptor + * + * Close the wrapped file descriptor (if any) and duplicate the file descriptor + * from \a other. The \a other FileDescriptor is left untouched, and the caller + * is responsible for destroying it when appropriate. The duplicated file + * descriptor will be closed automatically when this FileDescriptor instance is + * destroyed. + * + * \return A reference to this FileDescriptor + */ +FileDescriptor &FileDescriptor::operator=(const FileDescriptor &other) +{ + fd_ = other.fd_; + + return *this; +} + +/** + * \brief Move assignment operator, replace the wrapped file descriptor by + * taking over \a other + * \param[in] other The other FileDescriptor + * + * Close the wrapped file descriptor (if any) and take over the file descriptor + * from \a other. The \a other FileDescriptor is invalidated and set to -1. The + * taken over file descriptor will be closed automatically when this + * FileDescriptor instance is destroyed. + * + * \return A reference to this FileDescriptor + */ +FileDescriptor &FileDescriptor::operator=(FileDescriptor &&other) +{ + fd_ = std::move(other.fd_); + + return *this; +} + +/** + * \fn FileDescriptor::fd() + * \brief Retrieve the numerical file descriptor + * \return The numerical file descriptor, which may be -1 if the FileDescriptor + * instance doesn't own a file descriptor + */ + +/** + * \brief Duplicate a FileDescriptor + * \return A new FileDescriptor instance wrapping a duplicate of the original + * file descriptor + */ +FileDescriptor FileDescriptor::dup() const +{ + return FileDescriptor(fd_ ? fd_->fd() : -1); +} + +FileDescriptor::Storage::Storage(int fd) + : fd_(-1) +{ + if (fd < 0) + return; + + /* Failing to dup() a fd should not happen and is fatal. */ + fd_ = ::dup(fd); + if (fd_ == -1) { + int ret = -errno; + LOG(FileDescriptor, Fatal) + << "Failed to dup() fd: " << strerror(-ret); + } +} + +FileDescriptor::Storage::~Storage() +{ + if (fd_ != -1) + close(fd_); +} + +} /* namespace libcamera */ diff --git a/src/libcamera/meson.build b/src/libcamera/meson.build index c4f965bd7413b37e..722c5bc15afe52ef 100644 --- a/src/libcamera/meson.build +++ b/src/libcamera/meson.build @@ -14,6 +14,7 @@ libcamera_sources = files([ 'event_dispatcher.cpp', 'event_dispatcher_poll.cpp', 'event_notifier.cpp', + 'file_descriptor.cpp', 'formats.cpp', 'geometry.cpp', 'ipa_context_wrapper.cpp',