From 25288281d1e72c8e6c264525926a200511407ac7 Mon Sep 17 00:00:00 2001 From: Laurent Pinchart Date: Thu, 16 Apr 2020 01:01:53 +0300 Subject: libcamera: file: Add read/write support Add basic support to read and write data from/to a file, along with retrieving and setting the current read/write position. Signed-off-by: Laurent Pinchart Reviewed-by: Kieran Bingham --- include/libcamera/internal/file.h | 6 +++ src/libcamera/file.cpp | 109 ++++++++++++++++++++++++++++++++++++++ 2 files changed, 115 insertions(+) diff --git a/include/libcamera/internal/file.h b/include/libcamera/internal/file.h index e3e72132..9b6d011f 100644 --- a/include/libcamera/internal/file.h +++ b/include/libcamera/internal/file.h @@ -49,6 +49,12 @@ public: int error() const { return error_; } ssize_t size() const; + off_t pos() const; + off_t seek(off_t pos); + + ssize_t read(const Span &data); + ssize_t write(const Span &data); + Span map(off_t offset = 0, ssize_t size = -1, MapFlag flags = MapNoOption); bool unmap(uint8_t *addr); diff --git a/src/libcamera/file.cpp b/src/libcamera/file.cpp index c471bde3..d99a1806 100644 --- a/src/libcamera/file.cpp +++ b/src/libcamera/file.cpp @@ -237,6 +237,115 @@ ssize_t File::size() const return st.st_size; } +/** + * \brief Return current read or write position + * + * If the file is closed, this function returns 0. + * + * \return The current read or write position + */ +off_t File::pos() const +{ + if (!isOpen()) + return 0; + + return lseek(fd_, 0, SEEK_CUR); +} + +/** + * \brief Set the read or write position + * \param[in] pos The desired position + * \return The resulting offset from the beginning of the file on success, or a + * negative error code otherwise + */ +off_t File::seek(off_t pos) +{ + if (!isOpen()) + return -EINVAL; + + off_t ret = lseek(fd_, pos, SEEK_SET); + if (ret < 0) + return -errno; + + return ret; +} + +/** + * \brief Read data from the file + * \param[in] data Memory to read data into + * + * Read at most \a data.size() bytes from the file into \a data.data(), and + * return the number of bytes read. If less data than requested is available, + * the returned byte count may be smaller than the requested size. If no more + * data is available, 0 is returned. + * + * The position of the file as returned by pos() is advanced by the number of + * bytes read. If an error occurs, the position isn't modified. + * + * \return The number of bytes read on success, or a negative error code + * otherwise + */ +ssize_t File::read(const Span &data) +{ + if (!isOpen()) + return -EINVAL; + + size_t readBytes = 0; + ssize_t ret = 0; + + /* Retry in case of interrupted system calls. */ + while (readBytes < data.size()) { + ret = ::read(fd_, data.data() + readBytes, + data.size() - readBytes); + if (ret <= 0) + break; + + readBytes += ret; + } + + if (ret < 0 && !readBytes) + return -errno; + + return readBytes; +} + +/** + * \brief Write data to the file + * \param[in] data Memory containing data to be written + * + * Write at most \a data.size() bytes from \a data.data() to the file, and + * return the number of bytes written. If the file system doesn't have enough + * space for the data, the returned byte count may be less than requested. + * + * The position of the file as returned by pos() is advanced by the number of + * bytes written. If an error occurs, the position isn't modified. + * + * \return The number of bytes written on success, or a negative error code + * otherwise + */ +ssize_t File::write(const Span &data) +{ + if (!isOpen()) + return -EINVAL; + + size_t writtenBytes = 0; + + /* Retry in case of interrupted system calls. */ + while (writtenBytes < data.size()) { + ssize_t ret = ::write(fd_, data.data() + writtenBytes, + data.size() - writtenBytes); + if (ret <= 0) + break; + + writtenBytes += ret; + } + + if (data.size() && !writtenBytes) + return -errno; + + return writtenBytes; +} + /** * \brief Map a region of the file in the process memory * \param[in] offset The region offset within the file -- cgit v1.2.1