#263: libssh2_channel_read for exec ends unpredictably
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Reporter: xtravar | Owner:
Type: defect | Status: new
Priority: normal | Milestone: 1.4.3
Component: API | Version: 1.4.2
Keywords: | Blocked By:
Blocks: |
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Problem: libssh2_channel_exec is returning EOF sooner than expected
randomly
Client Platform: iOS
Versions tried: 1.4.3, 1.4.4-20130409
*Tried with blocking & non-blocking
*Piped to 'tee' to verify the process isn't ending prematurely (the file
gets written out completely)
*Same problem does not happen with SCP
*Never happens on the first run of the code
My code vaguely looks like:
{{{
chan = libssh2_channel_open_session(session);
libssh2_channel_exec(chan, "convert \"test.jpg\" -quality 60 -resize 100%
-format JPEG - 2>/dev/null | tee converttest.jpg")
// loop until read returns 0 (eof also becomes true at this point)
libssh2_channel_close(chan);
}}}
The problem happens after a few runs of the code on the same command.
It's fairly reproducible. I have some trace output that might be useful.
Good run:
Conn: Allocated new channel ID#2
Conn: Opening Channel - win 262144 pack 32768
Socket: Sent 52/52 bytes at 0x8a9775c
Failure Event: -37 - Would block
Socket: Recved 52/16384 bytes to 0x8a93734+0
Conn: Connection Established - ID: 2/1 win: 0/262144 pack: 32768/32768
Conn: starting request(exec) on channel 2/1, message=convert "cover.jpg"
-quality 60 -resize 100% -format JPEG -
Socket: Sent 52/52 bytes at 0x8a9775c
Socket: Recved 88/16384 bytes to 0x8a93734+0
Conn: Window adjust for channel 2/1, adding 2097152 bytes, new
window_size=2097152
Conn: channel_read() wants 10240 bytes from channel 2/1 stream #0
Failure Event: -37 - would block
Conn: channel_read() wants 10240 bytes from channel 2/1 stream #0
Socket: Recved 116/16384 bytes to 0x8a93734+0
Conn: 8192 bytes packet_add() for 2/1/0
Conn: channel_read() got 8192 of data from 2/1/0 [ul]
Socket: Recved 376/16384 bytes to 0x8a93734+0
Conn: 8192 bytes packet_add() for 2/1/0
Conn: 4096 bytes packet_add() for 2/1/0
Conn: 851 bytes packet_add() for 2/1/0
Conn: EOF received for channel 2/1
Conn: Channel 2 received request type exit-status (wr 0)
Conn: Exit status 0 received for channel 2/1
Conn: Close received for channel 2/1
Conn: channel_read() got 8192 of data from 2/1/0 [ul]
Conn: channel_read() got 2048 of data from 2/1/0
Conn: channel_read() got 2048 of data from 2/1/0 [ul]
Conn: channel_read() got 851 of data from 2/1/0 [ul]
Conn: Sending EOF on channel 2/1
Socket: Sent 36/36 bytes at 0x8a9775c
Conn: Closing channel 2/1
Socket: Sent 36/36 bytes at 0x8a9775c
Bad run:
Conn: Allocated new channel ID#2
Conn: Opening Channel - win 262144 pack 32768
Socket: Sent 52/52 bytes at 0x8a9775c
Failure Event: -37 - Would block
Socket: Recved 52/16384 bytes to 0x8a93734+0
Conn: Connection Established - ID: 2/1 win: 0/262144 pack: 32768/32768
Conn: starting request(exec) on channel 2/1, message=convert "cover.jpg"
-quality 60 -resize 100% -format JPEG -
Socket: Sent 52/52 bytes at 0x8a9775c
Socket: Recved 88/16384 bytes to 0x8a93734+0
Conn: Window adjust for channel 2/1, adding 2097152 bytes, new
window_size=2097152
Conn: channel_read() wants 10240 bytes from channel 2/1 stream #0
Failure Event: -37 - would block
Conn: channel_read() wants 10240 bytes from channel 2/1 stream #0
Socket: Recved 116/16384 bytes to 0x8a93734+0
Conn: 8007 bytes packet_add() for 2/1/0
Conn: channel_read() got 8007 of data from 2/1/0 [ul]
Failure Event: -37 - would block
Conn: channel_read() wants 10240 bytes from channel 2/1 stream #0
Socket: Recved 116/16384 bytes to 0x8a93734+0
Failure Event: -37 - would block
Conn: channel_read() wants 10240 bytes from channel 2/1 stream #0
Socket: Recved 82/16384 bytes to 0x8a93734+0
Conn: 4096 bytes packet_add() for 2/1/0
Conn: channel_read() got 4096 of data from 2/1/0 [ul]
Socket: Recved 176/16384 bytes to 0x8a93734+0
Conn: 851 bytes packet_add() for 2/1/0
Conn: Channel 2 received request type exit-status (wr 0)
Conn: Exit status 0 received for channel 2/1
Conn: EOF received for channel 2/1
Conn: Close received for channel 2/1
Conn: channel_read() got 851 of data from 2/1/0 [ul]
Conn: Sending EOF on channel 2/1
Socket: Sent 36/36 bytes at 0x8a9775c
Conn: Closing channel 2/1
Socket: Sent 36/36 bytes at 0x8a9775c
--
Ticket URL: <https://trac.libssh2.org/ticket/263>
libssh2 <https://trac.libssh2.org/>
C library for writing portable SSH2 clients
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