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Subject: [libssh2] #255: libssh2_channel_write_ex returns zero

[libssh2] #255: libssh2_channel_write_ex returns zero

From: libssh2 Trac <trac_at_libssh2.stuge.se>
Date: Thu, 31 Jan 2013 14:37:12 -0000

#255: libssh2_channel_write_ex returns zero
 Reporter: ncm | Owner:
     Type: defect | Status: new
 Priority: normal | Milestone: 1.4.3
Component: misc | Version: 1.4.2
 Keywords: | Blocked By:
   Blocks: |
 Sometimes {{{libssh2_channel_write_ex()}}} returns zero when writing from
 non-zero-length buffer. As I understand it, this should never happen:
 it should either return a positive number of bytes written, or a negative
 value such as {{{_EAGAIN}}}.

 The zero may be coming from {{{src/channel.c}}},
 {{{_libssh2_channel_write()}}}, c. line 2015, when rc is zero:
    if(channel->local.window_size <= 0)
        /* there's no room for data so we stop */
        return (rc==LIBSSH2_ERROR_EAGAIN?rc:0);
 {{{rc}}} gets its value from {{{_libssh2_transport_read()}}}, which
 returns zero
 when {{{session->socket_state}}} is {{{LIBSSH2_SOCKET_DISCONNECTED}}}. I
 have not
 discovered any other way for {{{_transport_read()}}} to return zero.

 Another way for {{{_write_ex()}}} to return zero would be if
 {{{channel->local.packet_size}}} were to be set to zero.

 Also, it seems as if {{{session->socket_block_directions}}} should
 be assigned {{{LIBSSH2_SESSION_BLOCK_INBOUND}}} when
 {{{channel->local.window_size}}} is found to be zero, but it is not.

Ticket URL: <https://trac.libssh2.org/ticket/255>
libssh2 <https://trac.libssh2.org/>
C library for writing portable SSH2 clients
libssh2-devel http://cool.haxx.se/cgi-bin/mailman/listinfo/libssh2-devel
Received on 2013-01-31

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