From: "Daniel P. Berrange" <berrange@redhat.com>

Date: Wed, 30 Aug 2017 14:53:59 +0100

Subject: [PATCH] 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>

---

 include/io/channel.h       |  90 +++++++++++++++++++++++++++++++++++++++

 io/channel.c               |  94 +++++++++++++++++++++++++++++++++++++++++

 tests/io-channel-helpers.c | 102 ++++-----------------------------------------

 3 files changed, 193 insertions(+), 93 deletions(-)

diff --git a/include/io/channel.h b/include/io/channel.h

index db9bb022a1..e11a62ea50 100644

--- a/include/io/channel.h

+++ b/include/io/channel.h

@@ -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

diff --git a/io/channel.c b/io/channel.c

index 1cfb8b33a2..5e8c2f0a91 100644

--- a/io/channel.c

+++ b/io/channel.c

@@ -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)

diff --git a/tests/io-channel-helpers.c b/tests/io-channel-helpers.c

index 05e5579cf8..5430e1389d 100644

--- a/tests/io-channel-helpers.c

+++ b/tests/io-channel-helpers.c

@@ -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,

-                                 &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;;

-    }

+    qio_channel_writev_all(data->src,

+                           data->inputv,

+                           data->niov,

+                           &data->writeerr);

     return NULL;

 }

@@ -117,38 +58,13 @@ 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,

-                                &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;;

-    }

+    qio_channel_readv_all(data->dst,

+                          data->outputv,

+                          data->niov,

+                          &data->readerr);

     return NULL;

 }