[libvirt] [PATCH v3 09/31] Introduce virStreamSparseSendAll
Michal Privoznik
mprivozn at redhat.com
Tue May 16 14:03:49 UTC 2017
This is just a wrapper over new function that have been just
introduced: virStreamSendHole() . It's very similar to
virStreamSendAll() except it handles sparse streams well.
Signed-off-by: Michal Privoznik <mprivozn at redhat.com>
---
include/libvirt/libvirt-stream.h | 65 +++++++++++++++-
src/libvirt-stream.c | 159 +++++++++++++++++++++++++++++++++++++++
src/libvirt_public.syms | 1 +
3 files changed, 222 insertions(+), 3 deletions(-)
diff --git a/include/libvirt/libvirt-stream.h b/include/libvirt/libvirt-stream.h
index a5e69a1c1..d18d43140 100644
--- a/include/libvirt/libvirt-stream.h
+++ b/include/libvirt/libvirt-stream.h
@@ -71,9 +71,9 @@ int virStreamRecvHole(virStreamPtr,
* @nbytes: size of the data array
* @opaque: optional application provided data
*
- * The virStreamSourceFunc callback is used together
- * with the virStreamSendAll function for libvirt to
- * obtain the data that is to be sent.
+ * The virStreamSourceFunc callback is used together with
+ * the virStreamSendAll and virStreamSparseSendAll functions
+ * for libvirt to obtain the data that is to be sent.
*
* The callback will be invoked multiple times,
* fetching data in small chunks. The application
@@ -96,6 +96,65 @@ int virStreamSendAll(virStreamPtr st,
virStreamSourceFunc handler,
void *opaque);
+/**
+ * virStreamSourceHoleFunc:
+ * @st: the stream object
+ * @inData: are we in data section
+ * @length: how long is the section we are currently in
+ * @opaque: optional application provided data
+ *
+ * The virStreamSourceHoleFunc callback is used together with the
+ * virStreamSparseSendAll function for libvirt to obtain the
+ * length of section stream is currently in.
+ *
+ * Moreover, upon successful return, @length should be updated
+ * with how many bytes are left until the current section ends
+ * (either data section or hole section). Also the stream is
+ * currently in data section, @inData should be set to a non-zero
+ * value and vice versa.
+ *
+ * NB: there's an implicit hole at the end of each file. If
+ * that's the case, @inData and @length should be both set to 0.
+ *
+ * This function should not adjust the current position within
+ * the file.
+ *
+ * Returns 0 on success,
+ * -1 upon error
+ */
+typedef int (*virStreamSourceHoleFunc)(virStreamPtr st,
+ int *inData,
+ long long *length,
+ void *opaque);
+
+/**
+ * virStreamSourceSkipFunc:
+ * @st: the stream object
+ * @length: stream hole size
+ * @opaque: optional application provided data
+ *
+ * This callback is used together with the virStreamSparseSendAll
+ * to skip holes in the underlying file as reported by
+ * virStreamSourceHoleFunc.
+ *
+ * The callback may be invoked multiple times as holes are found
+ * during processing a stream. The application should skip
+ * processing the hole in the stream source and then return.
+ * A return value of -1 at any time will abort the send operation.
+ *
+ * Returns 0 on success,
+ * -1 upon error.
+ */
+typedef int (*virStreamSourceSkipFunc)(virStreamPtr st,
+ long long length,
+ void *opaque);
+
+int virStreamSparseSendAll(virStreamPtr st,
+ virStreamSourceFunc handler,
+ virStreamSourceHoleFunc holeHandler,
+ virStreamSourceSkipFunc skipHandler,
+ void *opaque);
+
/**
* virStreamSinkFunc:
*
diff --git a/src/libvirt-stream.c b/src/libvirt-stream.c
index 6bf4c4f29..4cbe5eee1 100644
--- a/src/libvirt-stream.c
+++ b/src/libvirt-stream.c
@@ -574,6 +574,165 @@ virStreamSendAll(virStreamPtr stream,
}
+/**
+ * virStreamSparseSendAll:
+ * @stream: pointer to the stream object
+ * @handler: source callback for reading data from application
+ * @holeHandler: source callback for determining holes
+ * @skipHandler: skip holes as reported by @holeHandler
+ * @opaque: application defined data
+ *
+ * Send the entire data stream, reading the data from the
+ * requested data source. This is simply a convenient alternative
+ * to virStreamSend, for apps that do blocking-I/O.
+ *
+ * An example using this with a hypothetical file upload
+ * API looks like
+ *
+ * int mysource(virStreamPtr st, char *buf, int nbytes, void *opaque) {
+ * int *fd = opaque;
+ *
+ * return read(*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;
+ * }
+ *
+ * int myindata(virStreamPtr st, int *inData,
+ * long long *offset, void *opaque) {
+ * int *fd = opaque;
+ *
+ * if (@fd in hole) {
+ * *inData = 0;
+ * *offset = holeSize;
+ * } else {
+ * *inData = 1;
+ * *offset = dataSize;
+ * }
+ *
+ * return 0;
+ * }
+ *
+ * virStreamPtr st = virStreamNew(conn, 0);
+ * int fd = open("demo.iso", O_RDONLY);
+ *
+ * virConnectUploadFile(conn, st);
+ * if (virStreamSparseSendAll(st,
+ * mysource,
+ * myindata,
+ * myskip,
+ * &fd) < 0) {
+ * ...report an error ...
+ * goto done;
+ * }
+ * if (virStreamFinish(st) < 0)
+ * ...report an error...
+ * virStreamFree(st);
+ * close(fd);
+ *
+ * Note that @opaque data are shared between @handler, @holeHandler and @skipHandler.
+ *
+ * Returns 0 if all the data was successfully sent. The caller
+ * should invoke virStreamFinish(st) to flush the stream upon
+ * success and then virStreamFree.
+ *
+ * Returns -1 upon any error, with virStreamAbort() already
+ * having been called, so the caller need only call
+ * virStreamFree().
+ */
+int virStreamSparseSendAll(virStreamPtr stream,
+ virStreamSourceFunc handler,
+ virStreamSourceHoleFunc holeHandler,
+ virStreamSourceSkipFunc skipHandler,
+ void *opaque)
+{
+ char *bytes = NULL;
+ size_t want = VIR_NET_MESSAGE_LEGACY_PAYLOAD_MAX;
+ int ret = -1;
+ unsigned long long dataLen = 0;
+
+ VIR_DEBUG("stream=%p handler=%p holeHandler=%p opaque=%p",
+ stream, handler, holeHandler, opaque);
+
+ virResetLastError();
+
+ virCheckStreamReturn(stream, -1);
+ virCheckNonNullArgGoto(handler, cleanup);
+ virCheckNonNullArgGoto(holeHandler, cleanup);
+ virCheckNonNullArgGoto(skipHandler, cleanup);
+
+ if (stream->flags & VIR_STREAM_NONBLOCK) {
+ virReportError(VIR_ERR_OPERATION_INVALID, "%s",
+ _("data sources cannot be used for non-blocking streams"));
+ goto cleanup;
+ }
+
+ if (VIR_ALLOC_N(bytes, want) < 0)
+ goto cleanup;
+
+ for (;;) {
+ int inData, got, offset = 0;
+ long long sectionLen;
+ const unsigned int skipFlags = 0;
+
+ if (!dataLen) {
+ if (holeHandler(stream, &inData, §ionLen, opaque) < 0) {
+ virStreamAbort(stream);
+ goto cleanup;
+ }
+
+ if (!inData && sectionLen) {
+ if (virStreamSendHole(stream, sectionLen, skipFlags) < 0) {
+ virStreamAbort(stream);
+ goto cleanup;
+ }
+
+ if (skipHandler(stream, sectionLen, opaque) < 0) {
+ virReportSystemError(errno, "%s",
+ _("unable to skip hole"));
+ virStreamAbort(stream);
+ goto cleanup;
+ }
+ continue;
+ } else {
+ dataLen = sectionLen;
+ }
+ }
+
+ if (want > dataLen)
+ want = dataLen;
+
+ got = (handler)(stream, bytes, want, opaque);
+ if (got < 0) {
+ virStreamAbort(stream);
+ goto cleanup;
+ }
+ if (got == 0)
+ break;
+ while (offset < got) {
+ int done;
+ done = virStreamSend(stream, bytes + offset, got - offset);
+ if (done < 0)
+ goto cleanup;
+ offset += done;
+ dataLen -= done;
+ }
+ }
+ ret = 0;
+
+ cleanup:
+ VIR_FREE(bytes);
+
+ if (ret != 0)
+ virDispatchError(stream->conn);
+
+ return ret;
+}
+
+
/**
* virStreamRecvAll:
* @stream: pointer to the stream object
diff --git a/src/libvirt_public.syms b/src/libvirt_public.syms
index 37fc4e224..fac77fbea 100644
--- a/src/libvirt_public.syms
+++ b/src/libvirt_public.syms
@@ -765,6 +765,7 @@ LIBVIRT_3.4.0 {
virStreamRecvHole;
virStreamSendHole;
virStreamSparseRecvAll;
+ virStreamSparseSendAll;
} LIBVIRT_3.1.0;
# .... define new API here using predicted next version number ....
--
2.13.0
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