I think I now know under which rare circumstances this happens and it is a
bug in libssh2.
I can simulate it with (e.g. a packet is not completly written and the
attempt to write the rest creates EAGAIN):
In below simulation the 10 packet is reduced by 30 bytes and the attempt to
write the 30 bytes later creates an EAGAIN.
--- src/channel.c 2009-02-07 14:52:54.000000000 +0000
+++ src/channel_sim.c 2009-02-07 14:52:28.000000000 +0000
@@ -1733,6 +1733,7 @@
libssh2_channel_write_ex(LIBSSH2_CHANNEL * channel, int stream_id,
const char *buf, size_t buflen)
{
+ static count=0;
LIBSSH2_SESSION *session = channel->session;
libssh2pack_t rc;
@@ -1772,10 +1773,15 @@
}
while (buflen > 0) {
+ count++;
if (channel->write_state == libssh2_NB_state_allocated) {
+ if (count == 10) {
+ channel->write_bufwrite = buflen-30;
+ channel->write_s = channel->write_packet;
+ } else {
channel->write_bufwrite = buflen;
channel->write_s = channel->write_packet;
-
+ }
*(channel->write_s++) =
stream_id ? SSH_MSG_CHANNEL_EXTENDED_DATA :
SSH_MSG_CHANNEL_DATA;
@@ -1842,9 +1848,13 @@
}
if (channel->write_state == libssh2_NB_state_created) {
+ if (count == 11) {
+ rc = PACKET_EAGAIN;
+ } else {
rc = libssh2_packet_write(session, channel->write_packet,
channel->write_s -
channel->write_packet);
+ }
if (rc == PACKET_EAGAIN) {
_libssh2_debug(session, LIBSSH2_DBG_CONN,
"libssh2_packet_write returned EAGAIN");
My solution to this is:
--- src/channel.c 2009-02-06 23:57:47.000000000 +0000
+++ src/channel_new.c 2009-02-06 23:57:42.000000000 +0000
@@ -1771,6 +1771,7 @@
channel->write_state = libssh2_NB_state_allocated;
}
+ buflen -= channel->write_bufwrote;
while (buflen > 0) {
if (channel->write_state == libssh2_NB_state_allocated) {
channel->write_bufwrite = buflen;
Regards
Markus
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