[PATCH v2 5/6] virsh: Report errors from stream callbacks

[Michal Privoznik <mprivozn@xxxxxxxxxx>]

There are couple of callbacks we pass to virStreamSendAll(),
virStreamRecvAll() or its sparse variants. However, none of these
callbacks reports error if one occurs and neither do the
virStream* functions leaving user with very unhelpful error
message:

  error: cannot receive data from volume fedora.img
  error: An error occurred, but the cause is unknown

Signed-off-by: Michal Privoznik <mprivozn@xxxxxxxxxx>
---
 tools/virsh-util.c   | 38 +++++++++++++++++++++++++++++---------
 tools/virsh-util.h   |  2 +-
 tools/virsh-volume.c |  8 ++++++--
 3 files changed, 36 insertions(+), 12 deletions(-)

diff --git a/tools/virsh-util.c b/tools/virsh-util.c
index 44be3ad64..183f4c8bb 100644
--- a/tools/virsh-util.c
+++ b/tools/virsh-util.c
@@ -147,9 +147,15 @@ virshStreamSink(virStreamPtr st ATTRIBUTE_UNUSED,
                 size_t nbytes,
                 void *opaque)
 {
-    int *fd = opaque;
+    virshStreamCallbackDataPtr cbData = opaque;
+    int fd = cbData->fd;
+    const char *filename = cbData->filename;
+    int ret;
 
-    return safewrite(*fd, bytes, nbytes);
+    if ((ret = safewrite(fd, bytes, nbytes)) < 0)
+        virReportSystemError(errno, _("unable to write to %s"), filename);
+
+    return ret;
 }
 
 
@@ -161,8 +167,13 @@ virshStreamSource(virStreamPtr st ATTRIBUTE_UNUSED,
 {
     virshStreamCallbackDataPtr cbData = opaque;
     int fd = cbData->fd;
+    const char *filename = cbData->filename;
+    int ret;
 
-    return saferead(fd, bytes, nbytes);
+    if ((ret = saferead(fd, bytes, nbytes)) < 0)
+        virReportSystemError(errno, _("unable to read from %s"), filename);
+
+    return ret;
 }
 
 
@@ -173,10 +184,13 @@ virshStreamSourceSkip(virStreamPtr st ATTRIBUTE_UNUSED,
 {
     virshStreamCallbackDataPtr cbData = opaque;
     int fd = cbData->fd;
+    const char *filename = cbData->filename;
     off_t cur;
 
-    if ((cur = lseek(fd, offset, SEEK_CUR)) == (off_t) -1)
+    if ((cur = lseek(fd, offset, SEEK_CUR)) == (off_t) -1) {
+        virReportSystemError(errno, _("unable to seek in %s"), filename);
         return -1;
+    }
 
     return 0;
 }
@@ -187,14 +201,20 @@ virshStreamSkip(virStreamPtr st ATTRIBUTE_UNUSED,
                 long long offset,
                 void *opaque)
 {
-    int *fd = opaque;
+    virshStreamCallbackDataPtr cbData = opaque;
+    int fd = cbData->fd;
+    const char *filename = cbData->filename;
     off_t cur;
 
-    if ((cur = lseek(*fd, offset, SEEK_CUR)) == (off_t) -1)
+    if ((cur = lseek(fd, offset, SEEK_CUR)) == (off_t) -1) {
+        virReportSystemError(errno, _("unable to seek in %s"), filename);
         return -1;
+    }
 
-    if (ftruncate(*fd, cur) < 0)
+    if (ftruncate(fd, cur) < 0) {
+        virReportSystemError(errno, _("unable to truncate %s"), filename);
         return -1;
+    }
 
     return 0;
 }
@@ -207,12 +227,12 @@ virshStreamInData(virStreamPtr st ATTRIBUTE_UNUSED,
                   void *opaque)
 {
     virshStreamCallbackDataPtr cbData = opaque;
-    vshControl *ctl = cbData->ctl;
     int fd = cbData->fd;
+    const char *filename = cbData->filename;
     int ret;
 
     if ((ret = virFileInData(fd, inData, offset)) < 0)
-        vshError(ctl, "%s", _("Unable to get current position in stream"));
+        virReportSystemError(errno, _("unable to seek in %s"), filename);
 
     return ret;
 }
diff --git a/tools/virsh-util.h b/tools/virsh-util.h
index 9a0af3513..0babb311b 100644
--- a/tools/virsh-util.h
+++ b/tools/virsh-util.h
@@ -60,8 +60,8 @@ virshStreamSink(virStreamPtr st,
 typedef struct _virshStreamCallbackData virshStreamCallbackData;
 typedef virshStreamCallbackData *virshStreamCallbackDataPtr;
 struct _virshStreamCallbackData {
-    vshControl *ctl;
     int fd;
+    const char *filename;
 };
 
 int
diff --git a/tools/virsh-volume.c b/tools/virsh-volume.c
index 0736bdcdb..ea4660fee 100644
--- a/tools/virsh-volume.c
+++ b/tools/virsh-volume.c
@@ -698,8 +698,8 @@ cmdVolUpload(vshControl *ctl, const vshCmd *cmd)
         goto cleanup;
     }
 
-    cbData.ctl = ctl;
     cbData.fd = fd;
+    cbData.filename = file;
 
     if (vshCommandOptBool(cmd, "sparse"))
         flags |= VIR_STORAGE_VOL_UPLOAD_SPARSE_STREAM;
@@ -795,6 +795,7 @@ cmdVolDownload(vshControl *ctl, const vshCmd *cmd)
     bool created = false;
     virshControlPtr priv = ctl->privData;
     unsigned int flags = 0;
+    virshStreamCallbackData cbData;
 
     if (vshCommandOptULongLong(ctl, cmd, "offset", &offset) < 0)
         return false;
@@ -821,6 +822,9 @@ cmdVolDownload(vshControl *ctl, const vshCmd *cmd)
         created = true;
     }
 
+    cbData.fd = fd;
+    cbData.filename = file;
+
     if (!(st = virStreamNew(priv->conn, 0))) {
         vshError(ctl, _("cannot create a new stream"));
         goto cleanup;
@@ -831,7 +835,7 @@ cmdVolDownload(vshControl *ctl, const vshCmd *cmd)
         goto cleanup;
     }
 
-    if (virStreamSparseRecvAll(st, virshStreamSink, virshStreamSkip, &fd) < 0) {
+    if (virStreamSparseRecvAll(st, virshStreamSink, virshStreamSkip, &cbData) < 0) {
         vshError(ctl, _("cannot receive data from volume %s"), name);
         goto cleanup;
     }
-- 
2.13.0

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