From: Johannes Schindelin <johannes.schindelin@xxxxxx>
While there is currently no instance of code producing this type of
packet, if the `demultiplex_sideband()` would receive a packet whose
payload is not only empty but even misses the band designator, it would
mistake it for a flush packet.
Let's defend against such a bug in the future.
Note: `demultiplex_sideband()` will treat empty flush, delim, eof and
response-end packets all alike: it will treat them as flush packets.
Since empty packets by definition are missing a band designator, this is
the best that function can do. Therefore, it would make little sense to
pass the `status` on to `demultiplex_sideband()`. Besides, fbd76cd450
(sideband: reverse its dependency on pkt-line, 2019-01-16) went out of
its way to _stop_ the code inside `demultiplex_sideband()` from relying
on anything in `pkt-line.h`; that includes the data type `enum
packet_read_status` that we would need if we were to pass `status` as a
parameter to that function.
Based on a suggestion by Jeff King.
Signed-off-by: Johannes Schindelin <johannes.schindelin@xxxxxx>
---
pkt-line.c | 8 ++++++--
1 file changed, 6 insertions(+), 2 deletions(-)
diff --git a/pkt-line.c b/pkt-line.c
index 657a702927..f72048f623 100644
--- a/pkt-line.c
+++ b/pkt-line.c
@@ -461,8 +461,10 @@ int recv_sideband(const char *me, int in_stream, int out)
enum sideband_type sideband_type;
while (1) {
- len = packet_read(in_stream, NULL, NULL, buf, LARGE_PACKET_MAX,
- 0);
+ int status = packet_read_with_status(in_stream, NULL, NULL, buf,
+ LARGE_PACKET_MAX, &len, 0);
+ if (!len && status == PACKET_READ_NORMAL)
+ BUG("missing band designator");
if (!demultiplex_sideband(me, buf, len, 0, &scratch,
&sideband_type))
continue;
@@ -520,6 +522,8 @@ enum packet_read_status packet_reader_read(struct packet_reader *reader)
reader->options);
if (!reader->use_sideband)
break;
+ if (!reader->pktlen && reader->status == PACKET_READ_NORMAL)
+ BUG("missing band designator");
if (demultiplex_sideband(reader->me, reader->buffer,
reader->pktlen, 1, &scratch,
&sideband_type))
--
gitgitgadget
