0577f4f81e
Provide a struct iov_iter and some related functions to encapsulate an iterator used when reading and writing files. This will be used with the new 'file' uclass. While it is modelled on Linux, I/O vectors have been omitted for now. These can be added later without updating the interface used by the uclass. Signed-off-by: Simon Glass <sjg@chromium.org>
86 lines
1.9 KiB
C
86 lines
1.9 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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/*
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* Iterator for I/O, modelled on Linux but significantly simplified
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*
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* Copyright 2025 Simon Glass <sjg@chromium.org>
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*/
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#ifndef __IOVEC_H
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#define __IOVEC_H
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#include <linux/types.h>
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/**
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* enum iov_type_t - defines the type of this I/O vector
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*
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* @OIV_BUF: Simple buffer with a size
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*/
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enum iov_type_t {
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OIV_BUF,
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};
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/**
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* struct iov_iter - holds an interator for I/O
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*
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* Do not use this directly. Instead, call copy_to_iter()
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*
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* Note that this is much simpler than the Linux version, but can be extended
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* later as needed. It is introduced so that we can use the desired API for
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* read(), etc. It is also commented properly.
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*
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* @type: Type of the iterator (always OIV_BUF)
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* @data_source: true if this iterator produces data, false if it consumes it
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* @offset: Current offset within the buffer
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* @buf: Contiguous data buffer to use (other things could be added to the
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* union later)
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* @count: Size of data buffer
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*/
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struct iov_iter {
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enum iov_type_t type;
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bool data_source;
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ssize_t offset;
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union {
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void *ubuf;
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};
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ssize_t count;
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};
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/**
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* iter_iov_ptr() - Get a pointer to the current position
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*
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* @iter: Iterator to examine
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* Return: pointer to the start of the buffer portion to read/write
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*/
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static inline void *iter_iov_ptr(const struct iov_iter *iter)
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{
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return iter->ubuf + iter->offset;
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};
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/**
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* iter_iov_avail() - Get the number of bytes available at the current postiion
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*
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* @iter: iterator to examine
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* Return: number of bytes which can be read/written
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*/
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static inline ssize_t iter_iov_avail(const struct iov_iter *iter)
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{
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return iter->count - iter->offset;
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};
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static inline void iter_ubuf(struct iov_iter *iter, bool data_source, void *buf,
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size_t count)
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{
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*iter = (struct iov_iter) {
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.data_source = data_source,
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.ubuf = buf,
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.count = count,
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};
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}
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static inline void iter_advance(struct iov_iter *iter, size_t len)
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{
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iter->offset += len;
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}
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#endif
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