io: add new qio_channel_{readv, writev, read, write}_all functions (d4622e55) · Commits · SUMMER2020 / students / proj-2021291

include/io/channel.h

+90 −0

Original line number	Diff line number	Diff line
		@@ -268,6 +268,58 @@ ssize_t qio_channel_writev_full(QIOChannel *ioc,
		size_t nfds,
		Error **errp);

		/**
		* qio_channel_readv_all:
		* @ioc: the channel object
		* @iov: the array of memory regions to read data into
		* @niov: the length of the @iov array
		* @errp: pointer to a NULL-initialized error object
		*
		* Read data from the IO channel, storing it in the
		* memory regions referenced by @iov. Each element
		* in the @iov will be fully populated with data
		* before the next one is used. The @niov parameter
		* specifies the total number of elements in @iov.
		*
		* The function will wait for all requested data
		* to be read, yielding from the current coroutine
		* if required.
		*
		* If end-of-file occurs before all requested data
		* has been read, an error will be reported.
		*
		* Returns: 0 if all bytes were read, or -1 on error
		*/
		int qio_channel_readv_all(QIOChannel *ioc,
		const struct iovec *iov,
		size_t niov,
		Error **errp);


		/**
		* qio_channel_writev_all:
		* @ioc: the channel object
		* @iov: the array of memory regions to write data from
		* @niov: the length of the @iov array
		* @errp: pointer to a NULL-initialized error object
		*
		* Write data to the IO channel, reading it from the
		* memory regions referenced by @iov. Each element
		* in the @iov will be fully sent, before the next
		* one is used. The @niov parameter specifies the
		* total number of elements in @iov.
		*
		* The function will wait for all requested data
		* to be written, yielding from the current coroutine
		* if required.
		*
		* Returns: 0 if all bytes were written, or -1 on error
		*/
		int qio_channel_writev_all(QIOChannel *ioc,
		const struct iovec *iov,
		size_t niov,
		Error **erp);

		/**
		* qio_channel_readv:
		* @ioc: the channel object
		@@ -330,6 +382,44 @@ ssize_t qio_channel_write(QIOChannel *ioc,
		size_t buflen,
		Error **errp);

		/**
		* qio_channel_read_all:
		* @ioc: the channel object
		* @buf: the memory region to read data into
		* @buflen: the number of bytes to @buf
		* @errp: pointer to a NULL-initialized error object
		*
		* Reads @buflen bytes into @buf, possibly blocking or (if the
		* channel is non-blocking) yielding from the current coroutine
		* multiple times until the entire content is read. If end-of-file
		* occurs it will return an error rather than a short-read. Otherwise
		* behaves as qio_channel_read().
		*
		* Returns: 0 if all bytes were read, or -1 on error
		*/
		int qio_channel_read_all(QIOChannel *ioc,
		char *buf,
		size_t buflen,
		Error **errp);
		/**
		* qio_channel_write_all:
		* @ioc: the channel object
		* @buf: the memory region to write data into
		* @buflen: the number of bytes to @buf
		* @errp: pointer to a NULL-initialized error object
		*
		* Writes @buflen bytes from @buf, possibly blocking or (if the
		* channel is non-blocking) yielding from the current coroutine
		* multiple times until the entire content is written. Otherwise
		* behaves as qio_channel_write().
		*
		* Returns: 0 if all bytes were written, or -1 on error
		*/
		int qio_channel_write_all(QIOChannel *ioc,
		const char *buf,
		size_t buflen,
		Error **errp);

		/**
		* qio_channel_set_blocking:
		* @ioc: the channel object

io/channel.c

+94 −0

Original line number	Diff line number	Diff line
		@@ -22,6 +22,7 @@
		#include "io/channel.h"
		#include "qapi/error.h"
		#include "qemu/main-loop.h"
		#include "qemu/iov.h"

		bool qio_channel_has_feature(QIOChannel *ioc,
		QIOChannelFeature feature)
		@@ -85,6 +86,79 @@ ssize_t qio_channel_writev_full(QIOChannel *ioc,
		}



		int qio_channel_readv_all(QIOChannel *ioc,
		const struct iovec *iov,
		size_t niov,
		Error **errp)
		{
		int ret = -1;
		struct iovec *local_iov = g_new(struct iovec, niov);
		struct iovec *local_iov_head = local_iov;
		unsigned int nlocal_iov = niov;

		nlocal_iov = iov_copy(local_iov, nlocal_iov,
		iov, niov,
		0, iov_size(iov, niov));

		while (nlocal_iov > 0) {
		ssize_t len;
		len = qio_channel_readv(ioc, local_iov, nlocal_iov, errp);
		if (len == QIO_CHANNEL_ERR_BLOCK) {
		qio_channel_wait(ioc, G_IO_IN);
		continue;
		} else if (len < 0) {
		goto cleanup;
		} else if (len == 0) {
		error_setg(errp,
		"Unexpected end-of-file before all bytes were read");
		goto cleanup;
		}

		iov_discard_front(&local_iov, &nlocal_iov, len);
		}

		ret = 0;

		cleanup:
		g_free(local_iov_head);
		return ret;
		}

		int qio_channel_writev_all(QIOChannel *ioc,
		const struct iovec *iov,
		size_t niov,
		Error **errp)
		{
		int ret = -1;
		struct iovec *local_iov = g_new(struct iovec, niov);
		struct iovec *local_iov_head = local_iov;
		unsigned int nlocal_iov = niov;

		nlocal_iov = iov_copy(local_iov, nlocal_iov,
		iov, niov,
		0, iov_size(iov, niov));

		while (nlocal_iov > 0) {
		ssize_t len;
		len = qio_channel_writev(ioc, local_iov, nlocal_iov, errp);
		if (len == QIO_CHANNEL_ERR_BLOCK) {
		qio_channel_wait(ioc, G_IO_OUT);
		continue;
		}
		if (len < 0) {
		goto cleanup;
		}

		iov_discard_front(&local_iov, &nlocal_iov, len);
		}

		ret = 0;
		cleanup:
		g_free(local_iov_head);
		return ret;
		}

		ssize_t qio_channel_readv(QIOChannel *ioc,
		const struct iovec *iov,
		size_t niov,
		@@ -123,6 +197,26 @@ ssize_t qio_channel_write(QIOChannel *ioc,
		}


		int qio_channel_read_all(QIOChannel *ioc,
		char *buf,
		size_t buflen,
		Error **errp)
		{
		struct iovec iov = { .iov_base = buf, .iov_len = buflen };
		return qio_channel_readv_all(ioc, &iov, 1, errp);
		}


		int qio_channel_write_all(QIOChannel *ioc,
		const char *buf,
		size_t buflen,
		Error **errp)
		{
		struct iovec iov = { .iov_base = (char *)buf, .iov_len = buflen };
		return qio_channel_writev_all(ioc, &iov, 1, errp);
		}


		int qio_channel_set_blocking(QIOChannel *ioc,
		bool enabled,
		Error **errp)

tests/io-channel-helpers.c

+9 −93

Original line number	Diff line number	Diff line
		@@ -21,6 +21,7 @@
		#include "qemu/osdep.h"
		#include "io-channel-helpers.h"
		#include "qapi/error.h"
		#include "qemu/iov.h"

		struct QIOChannelTest {
		QIOChannel *src;
		@@ -37,77 +38,17 @@ struct QIOChannelTest {
		};


		static void test_skip_iovec(struct iovec **iov,
		size_t *niov,
		size_t skip,
		struct iovec *old)
		{
		size_t offset = 0;
		size_t i;

		for (i = 0; i < *niov; i++) {
		if (skip < (*iov)[i].iov_len) {
		old->iov_len = (*iov)[i].iov_len;
		old->iov_base = (*iov)[i].iov_base;

		(*iov)[i].iov_len -= skip;
		(*iov)[i].iov_base += skip;
		break;
		} else {
		skip -= (*iov)[i].iov_len;

		if (i == 0 && old->iov_base) {
		(*iov)[i].iov_len = old->iov_len;
		(*iov)[i].iov_base = old->iov_base;
		old->iov_len = 0;
		old->iov_base = NULL;
		}

		offset++;
		}
		}

		iov = iov + offset;
		*niov -= offset;
		}


		/* This thread sends all data using iovecs */
		static gpointer test_io_thread_writer(gpointer opaque)
		{
		QIOChannelTest *data = opaque;
		struct iovec *iov = data->inputv;
		size_t niov = data->niov;
		struct iovec old = { 0 };

		qio_channel_set_blocking(data->src, data->blocking, NULL);

		while (niov) {
		ssize_t ret;
		ret = qio_channel_writev(data->src,
		iov,
		niov,
		qio_channel_writev_all(data->src,
		data->inputv,
		data->niov,
		&data->writeerr);
		if (ret == QIO_CHANNEL_ERR_BLOCK) {
		if (data->blocking) {
		error_setg(&data->writeerr,
		"Unexpected I/O blocking");
		break;
		} else {
		qio_channel_wait(data->src,
		G_IO_OUT);
		continue;
		}
		} else if (ret < 0) {
		break;
		} else if (ret == 0) {
		error_setg(&data->writeerr,
		"Unexpected zero length write");
		break;
		}

		test_skip_iovec(&iov, &niov, ret, &old);
		}

		return NULL;
		}
		@@ -117,39 +58,14 @@ static gpointer test_io_thread_writer(gpointer opaque)
		static gpointer test_io_thread_reader(gpointer opaque)
		{
		QIOChannelTest *data = opaque;
		struct iovec *iov = data->outputv;
		size_t niov = data->niov;
		struct iovec old = { 0 };

		qio_channel_set_blocking(data->dst, data->blocking, NULL);

		while (niov) {
		ssize_t ret;

		ret = qio_channel_readv(data->dst,
		iov,
		niov,
		qio_channel_readv_all(data->dst,
		data->outputv,
		data->niov,
		&data->readerr);

		if (ret == QIO_CHANNEL_ERR_BLOCK) {
		if (data->blocking) {
		error_setg(&data->readerr,
		"Unexpected I/O blocking");
		break;
		} else {
		qio_channel_wait(data->dst,
		G_IO_IN);
		continue;
		}
		} else if (ret < 0) {
		break;
		} else if (ret == 0) {
		break;
		}

		test_skip_iovec(&iov, &niov, ret, &old);
		}

		return NULL;
		}