[JSch-users] JSch SFTP copy deadlock and code fix

[James L. <jam...@de...>]

Dear Dr. Yamanaka,

Thank you for JSch!

While using JSch via the Apache Commons VFS API, I encountered VFS-627
<https://issues.apache.org/jira/browse/VFS-627>. I root caused the issue
and found a deadlock in JSch. A patch against JSch 0.1.55 that fixes the
issue is below. I also posted a detailed investigation of the problem and a
simple test program to reproduce the issue at:
https://github.com/jlentini/SftpCopyDeadlock

I hope this fix can be included in a future version of JSch. If you would
like more information or the patch in a different format, please let me
know.

Regards,
-james

James Lentini

---

    Prevent read/write deadlock by allocating sufficient receive buffer
space

diff --git a/src/main/java/com/jcraft/jsch/ChannelSftp.java
b/src/main/java/com/jcraft/jsch/ChannelSftp.java
index f76d1d5..3ac036f 100644
--- a/src/main/java/com/jcraft/jsch/ChannelSftp.java
+++ b/src/main/java/com/jcraft/jsch/ChannelSftp.java
@@ -224,7 +224,7 @@ public class ChannelSftp extends ChannelSession{

       PipedOutputStream pos=new PipedOutputStream();
       io.setOutputStream(pos);
-      PipedInputStream pis=new MyPipedInputStream(pos, rmpsize);
+      PipedInputStream pis=new MyPipedInputStream(pos, rq.size()*rmpsize);
       io.setInputStream(pis);

       io_in=io.in;