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>

1 files changed, 94 insertions, 0 deletions

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)