提交 3a1e2e92 编写于 作者: M Michal Privoznik

Introduce virStreamSparseRecvAll

This is just a wrapper over new functions that have been just
introduced: virStreamRecvFlags(), virStreamRecvHole(). It's very
similar to virStreamRecvAll() except it handles sparse streams
well.
Signed-off-by: NMichal Privoznik <mprivozn@redhat.com>
上级 87e4a842
......@@ -104,9 +104,9 @@ int virStreamSendAll(virStreamPtr st,
* @nbytes: size of the data array
* @opaque: optional application provided data
*
* The virStreamSinkFunc callback is used together
* with the virStreamRecvAll function for libvirt to
* provide the data that has been received.
* The virStreamSinkFunc callback is used together with the
* virStreamRecvAll or virStreamSparseRecvAll functions for
* libvirt to provide the data that has been received.
*
* The callback will be invoked multiple times,
* providing data in small chunks. The application
......@@ -129,6 +129,33 @@ int virStreamRecvAll(virStreamPtr st,
virStreamSinkFunc handler,
void *opaque);
/**
* virStreamSinkHoleFunc:
* @st: the stream object
* @length: stream hole size
* @opaque: optional application provided data
*
* This callback is used together with the virStreamSparseRecvAll
* function for libvirt to provide the size of a hole that
* occurred in the stream.
*
* The callback may be invoked multiple times as holes are found
* during processing a stream. The application should create the
* hole in the stream target and then return. A return value of
* -1 at any time will abort the receive operation.
*
* Returns 0 on success,
* -1 upon error
*/
typedef int (*virStreamSinkHoleFunc)(virStreamPtr st,
long long length,
void *opaque);
int virStreamSparseRecvAll(virStreamPtr stream,
virStreamSinkFunc handler,
virStreamSinkHoleFunc holeHandler,
void *opaque);
typedef enum {
VIR_STREAM_EVENT_READABLE = (1 << 0),
VIR_STREAM_EVENT_WRITABLE = (1 << 1),
......
......@@ -668,6 +668,129 @@ virStreamRecvAll(virStreamPtr stream,
}
/**
* virStreamSparseRecvAll:
* @stream: pointer to the stream object
* @handler: sink callback for writing data to application
* @holeHandler: stream hole callback for skipping holes
* @opaque: application defined data
*
* Receive the entire data stream, sending the data to the
* requested data sink @handler and calling the skip @holeHandler
* to generate holes for sparse stream targets. This is simply a
* convenient alternative to virStreamRecvFlags, for apps that do
* blocking-I/O.
*
* An example using this with a hypothetical file download
* API looks like:
*
* int mysink(virStreamPtr st, const char *buf, int nbytes, void *opaque) {
* int *fd = opaque;
*
* return write(*fd, buf, nbytes);
* }
*
* int myskip(virStreamPtr st, long long offset, void *opaque) {
* int *fd = opaque;
*
* return lseek(*fd, offset, SEEK_CUR) == (off_t) -1 ? -1 : 0;
* }
*
* virStreamPtr st = virStreamNew(conn, 0);
* int fd = open("demo.iso", O_WRONLY);
*
* virConnectDownloadSparseFile(conn, st);
* if (virStreamSparseRecvAll(st, mysink, myskip, &fd) < 0) {
* ...report an error ...
* goto done;
* }
* if (virStreamFinish(st) < 0)
* ...report an error...
* virStreamFree(st);
* close(fd);
*
* Note that @opaque data is shared between both @handler and
* @holeHandler callbacks.
*
* Returns 0 if all the data was successfully received. The caller
* should invoke virStreamFinish(st) to flush the stream upon
* success and then virStreamFree(st).
*
* Returns -1 upon any error, with virStreamAbort() already
* having been called, so the caller need only call virStreamFree().
*/
int
virStreamSparseRecvAll(virStreamPtr stream,
virStreamSinkFunc handler,
virStreamSinkHoleFunc holeHandler,
void *opaque)
{
char *bytes = NULL;
size_t want = VIR_NET_MESSAGE_LEGACY_PAYLOAD_MAX;
const unsigned int flags = VIR_STREAM_RECV_STOP_AT_HOLE;
int ret = -1;
VIR_DEBUG("stream=%p handler=%p holeHandler=%p opaque=%p",
stream, handler, holeHandler, opaque);
virResetLastError();
virCheckStreamReturn(stream, -1);
virCheckNonNullArgGoto(handler, cleanup);
virCheckNonNullArgGoto(holeHandler, cleanup);
if (stream->flags & VIR_STREAM_NONBLOCK) {
virReportError(VIR_ERR_OPERATION_INVALID, "%s",
_("data sinks cannot be used for non-blocking streams"));
goto cleanup;
}
if (VIR_ALLOC_N(bytes, want) < 0)
goto cleanup;
for (;;) {
int got, offset = 0;
long long holeLen;
const unsigned int holeFlags = 0;
got = virStreamRecvFlags(stream, bytes, want, flags);
if (got == -3) {
if (virStreamRecvHole(stream, &holeLen, holeFlags) < 0) {
virStreamAbort(stream);
goto cleanup;
}
if (holeHandler(stream, holeLen, opaque) < 0) {
virStreamAbort(stream);
goto cleanup;
}
continue;
} else if (got < 0) {
goto cleanup;
} else if (got == 0) {
break;
}
while (offset < got) {
int done;
done = (handler)(stream, bytes + offset, got - offset, opaque);
if (done < 0) {
virStreamAbort(stream);
goto cleanup;
}
offset += done;
}
}
ret = 0;
cleanup:
VIR_FREE(bytes);
if (ret != 0)
virDispatchError(stream->conn);
return ret;
}
/**
* virStreamEventAddCallback:
* @stream: pointer to the stream object
......
......@@ -764,6 +764,7 @@ LIBVIRT_3.4.0 {
virStreamRecvFlags;
virStreamRecvHole;
virStreamSendHole;
virStreamSparseRecvAll;
} LIBVIRT_3.1.0;
# .... define new API here using predicted next version number ....
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