[PATCH 2/3] tools/xenconsoled: Possibly perform repeated xc_readconsolering() hypercalls

[Andrew Cooper <andrew.cooper3@citrix.com>]

The size of the Xen console ring is runtime configurable, so the statically
sized 16k buffer is not necessarily sufficient.  Make repeated
xc_readconsolering() hypercalls while Xen managed to completely fill the
provided buffer.

Also, change the buffer to being static to save on stack space.

Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
CC: Ian Campbell <Ian.Campbell@citrix.com>
CC: Ian Jackson <Ian.Jackson@eu.citrix.com>
---
 tools/console/daemon/io.c |   15 +++++++++++----
 1 file changed, 11 insertions(+), 4 deletions(-)

diff --git a/tools/console/daemon/io.c b/tools/console/daemon/io.c
index 313b256..b1268fa 100644
--- a/tools/console/daemon/io.c
+++ b/tools/console/daemon/io.c
@@ -909,17 +909,24 @@ static void handle_xs(void)
 
 static void handle_hv_logs(xc_evtchn *xce_handle)
 {
-	char buffer[1024*16];
+	static char buffer[1024*16];
 	char *bufptr = buffer;
-	unsigned int size = sizeof(buffer);
+	unsigned int size;
 	static uint32_t index = 0;
 	evtchn_port_or_error_t port;
 
 	if ((port = xc_evtchn_pending(xce_handle)) == -1)
 		return;
 
-	if (xc_readconsolering(xc, bufptr, &size, 0, 1, &index) == 0 && size > 0) {
+	do
+	{
 		int logret;
+
+		size = sizeof(buffer);
+		if (xc_readconsolering(xc, bufptr, &size, 0, 1, &index) != 0 ||
+		    size == 0)
+			break;
+
 		if (log_time_hv)
 			logret = write_with_timestamp(log_hv_fd, buffer, size,
 						      &log_time_hv_needts);
@@ -929,7 +936,7 @@ static void handle_hv_logs(xc_evtchn *xce_handle)
 		if (logret < 0)
 			dolog(LOG_ERR, "Failed to write hypervisor log: "
 				       "%d (%s)", errno, strerror(errno));
-	}
+	} while (size == sizeof(buffer));
 
 	(void)xc_evtchn_unmask(xce_handle, port);
 }
-- 
1.7.10.4