io: add new qio_channel_{readv, writev, read, write}_all functions
These functions wait until they are able to read / write the full requested data buffer(s). Reviewed-by: Eric Blake <eblake@redhat.com> Signed-off-by: Daniel P. Berrange <berrange@redhat.com>
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50ea44f077
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d4622e5588
@ -268,6 +268,58 @@ ssize_t qio_channel_writev_full(QIOChannel *ioc,
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size_t nfds,
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Error **errp);
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/**
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* qio_channel_readv_all:
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* @ioc: the channel object
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* @iov: the array of memory regions to read data into
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* @niov: the length of the @iov array
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* @errp: pointer to a NULL-initialized error object
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*
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* Read data from the IO channel, storing it in the
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* memory regions referenced by @iov. Each element
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* in the @iov will be fully populated with data
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* before the next one is used. The @niov parameter
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* specifies the total number of elements in @iov.
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*
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* The function will wait for all requested data
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* to be read, yielding from the current coroutine
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* if required.
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*
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* If end-of-file occurs before all requested data
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* has been read, an error will be reported.
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*
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* Returns: 0 if all bytes were read, or -1 on error
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*/
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int qio_channel_readv_all(QIOChannel *ioc,
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const struct iovec *iov,
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size_t niov,
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Error **errp);
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/**
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* qio_channel_writev_all:
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* @ioc: the channel object
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* @iov: the array of memory regions to write data from
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* @niov: the length of the @iov array
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* @errp: pointer to a NULL-initialized error object
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*
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* Write data to the IO channel, reading it from the
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* memory regions referenced by @iov. Each element
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* in the @iov will be fully sent, before the next
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* one is used. The @niov parameter specifies the
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* total number of elements in @iov.
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*
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* The function will wait for all requested data
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* to be written, yielding from the current coroutine
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* if required.
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*
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* Returns: 0 if all bytes were written, or -1 on error
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*/
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int qio_channel_writev_all(QIOChannel *ioc,
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const struct iovec *iov,
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size_t niov,
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Error **erp);
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/**
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* qio_channel_readv:
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* @ioc: the channel object
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@ -330,6 +382,44 @@ ssize_t qio_channel_write(QIOChannel *ioc,
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size_t buflen,
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Error **errp);
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/**
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* qio_channel_read_all:
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* @ioc: the channel object
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* @buf: the memory region to read data into
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* @buflen: the number of bytes to @buf
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* @errp: pointer to a NULL-initialized error object
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*
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* Reads @buflen bytes into @buf, possibly blocking or (if the
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* channel is non-blocking) yielding from the current coroutine
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* multiple times until the entire content is read. If end-of-file
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* occurs it will return an error rather than a short-read. Otherwise
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* behaves as qio_channel_read().
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*
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* Returns: 0 if all bytes were read, or -1 on error
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*/
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int qio_channel_read_all(QIOChannel *ioc,
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char *buf,
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size_t buflen,
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Error **errp);
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/**
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* qio_channel_write_all:
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* @ioc: the channel object
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* @buf: the memory region to write data into
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* @buflen: the number of bytes to @buf
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* @errp: pointer to a NULL-initialized error object
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*
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* Writes @buflen bytes from @buf, possibly blocking or (if the
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* channel is non-blocking) yielding from the current coroutine
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* multiple times until the entire content is written. Otherwise
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* behaves as qio_channel_write().
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*
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* Returns: 0 if all bytes were written, or -1 on error
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*/
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int qio_channel_write_all(QIOChannel *ioc,
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const char *buf,
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size_t buflen,
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Error **errp);
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/**
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* qio_channel_set_blocking:
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* @ioc: the channel object
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94
io/channel.c
94
io/channel.c
@ -22,6 +22,7 @@
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#include "io/channel.h"
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#include "qapi/error.h"
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#include "qemu/main-loop.h"
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#include "qemu/iov.h"
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bool qio_channel_has_feature(QIOChannel *ioc,
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QIOChannelFeature feature)
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@ -85,6 +86,79 @@ ssize_t qio_channel_writev_full(QIOChannel *ioc,
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}
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int qio_channel_readv_all(QIOChannel *ioc,
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const struct iovec *iov,
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size_t niov,
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Error **errp)
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{
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int ret = -1;
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struct iovec *local_iov = g_new(struct iovec, niov);
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struct iovec *local_iov_head = local_iov;
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unsigned int nlocal_iov = niov;
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nlocal_iov = iov_copy(local_iov, nlocal_iov,
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iov, niov,
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0, iov_size(iov, niov));
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while (nlocal_iov > 0) {
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ssize_t len;
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len = qio_channel_readv(ioc, local_iov, nlocal_iov, errp);
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if (len == QIO_CHANNEL_ERR_BLOCK) {
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qio_channel_wait(ioc, G_IO_IN);
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continue;
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} else if (len < 0) {
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goto cleanup;
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} else if (len == 0) {
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error_setg(errp,
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"Unexpected end-of-file before all bytes were read");
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goto cleanup;
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}
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iov_discard_front(&local_iov, &nlocal_iov, len);
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}
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ret = 0;
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cleanup:
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g_free(local_iov_head);
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return ret;
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}
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int qio_channel_writev_all(QIOChannel *ioc,
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const struct iovec *iov,
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size_t niov,
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Error **errp)
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{
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int ret = -1;
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struct iovec *local_iov = g_new(struct iovec, niov);
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struct iovec *local_iov_head = local_iov;
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unsigned int nlocal_iov = niov;
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nlocal_iov = iov_copy(local_iov, nlocal_iov,
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iov, niov,
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0, iov_size(iov, niov));
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while (nlocal_iov > 0) {
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ssize_t len;
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len = qio_channel_writev(ioc, local_iov, nlocal_iov, errp);
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if (len == QIO_CHANNEL_ERR_BLOCK) {
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qio_channel_wait(ioc, G_IO_OUT);
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continue;
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}
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if (len < 0) {
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goto cleanup;
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}
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iov_discard_front(&local_iov, &nlocal_iov, len);
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}
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ret = 0;
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cleanup:
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g_free(local_iov_head);
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return ret;
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}
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ssize_t qio_channel_readv(QIOChannel *ioc,
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const struct iovec *iov,
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size_t niov,
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@ -123,6 +197,26 @@ ssize_t qio_channel_write(QIOChannel *ioc,
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}
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int qio_channel_read_all(QIOChannel *ioc,
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char *buf,
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size_t buflen,
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Error **errp)
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{
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struct iovec iov = { .iov_base = buf, .iov_len = buflen };
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return qio_channel_readv_all(ioc, &iov, 1, errp);
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}
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int qio_channel_write_all(QIOChannel *ioc,
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const char *buf,
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size_t buflen,
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Error **errp)
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{
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struct iovec iov = { .iov_base = (char *)buf, .iov_len = buflen };
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return qio_channel_writev_all(ioc, &iov, 1, errp);
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}
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int qio_channel_set_blocking(QIOChannel *ioc,
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bool enabled,
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Error **errp)
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@ -21,6 +21,7 @@
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#include "qemu/osdep.h"
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#include "io-channel-helpers.h"
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#include "qapi/error.h"
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#include "qemu/iov.h"
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struct QIOChannelTest {
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QIOChannel *src;
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@ -37,77 +38,17 @@ struct QIOChannelTest {
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};
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static void test_skip_iovec(struct iovec **iov,
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size_t *niov,
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size_t skip,
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struct iovec *old)
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{
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size_t offset = 0;
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size_t i;
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for (i = 0; i < *niov; i++) {
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if (skip < (*iov)[i].iov_len) {
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old->iov_len = (*iov)[i].iov_len;
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old->iov_base = (*iov)[i].iov_base;
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(*iov)[i].iov_len -= skip;
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(*iov)[i].iov_base += skip;
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break;
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} else {
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skip -= (*iov)[i].iov_len;
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if (i == 0 && old->iov_base) {
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(*iov)[i].iov_len = old->iov_len;
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(*iov)[i].iov_base = old->iov_base;
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old->iov_len = 0;
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old->iov_base = NULL;
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}
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offset++;
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}
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}
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*iov = *iov + offset;
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*niov -= offset;
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}
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/* This thread sends all data using iovecs */
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static gpointer test_io_thread_writer(gpointer opaque)
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{
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QIOChannelTest *data = opaque;
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struct iovec *iov = data->inputv;
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size_t niov = data->niov;
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struct iovec old = { 0 };
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qio_channel_set_blocking(data->src, data->blocking, NULL);
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while (niov) {
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ssize_t ret;
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ret = qio_channel_writev(data->src,
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iov,
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niov,
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&data->writeerr);
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if (ret == QIO_CHANNEL_ERR_BLOCK) {
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if (data->blocking) {
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error_setg(&data->writeerr,
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"Unexpected I/O blocking");
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break;
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} else {
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qio_channel_wait(data->src,
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G_IO_OUT);
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continue;
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}
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} else if (ret < 0) {
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break;
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} else if (ret == 0) {
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error_setg(&data->writeerr,
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"Unexpected zero length write");
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break;
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}
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test_skip_iovec(&iov, &niov, ret, &old);
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}
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qio_channel_writev_all(data->src,
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data->inputv,
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data->niov,
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&data->writeerr);
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return NULL;
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}
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@ -117,38 +58,13 @@ static gpointer test_io_thread_writer(gpointer opaque)
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static gpointer test_io_thread_reader(gpointer opaque)
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{
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QIOChannelTest *data = opaque;
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struct iovec *iov = data->outputv;
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size_t niov = data->niov;
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struct iovec old = { 0 };
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qio_channel_set_blocking(data->dst, data->blocking, NULL);
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while (niov) {
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ssize_t ret;
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ret = qio_channel_readv(data->dst,
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iov,
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niov,
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&data->readerr);
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if (ret == QIO_CHANNEL_ERR_BLOCK) {
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if (data->blocking) {
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error_setg(&data->readerr,
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"Unexpected I/O blocking");
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break;
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} else {
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qio_channel_wait(data->dst,
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G_IO_IN);
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continue;
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}
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} else if (ret < 0) {
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break;
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} else if (ret == 0) {
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break;
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}
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test_skip_iovec(&iov, &niov, ret, &old);
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}
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qio_channel_readv_all(data->dst,
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data->outputv,
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data->niov,
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&data->readerr);
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return NULL;
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}
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