Debian Bug report logs - #286063
screen: paste of a large block of text causes random data lost

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Message #5 received at submit@bugs.debian.org (full text, mbox, reply):

From: WU Fengguang <wfg@mail.ustc.edu.cn>

To: Debian Bug Tracking System <submit@bugs.debian.org>

Subject: screen: paste of a large block of text causes random data lost

Date: Fri, 17 Dec 2004 17:24:41 +0800

Package: screen
Version: 4.0.2-4.1
Severity: important

Hi!

When pasting a large block of text into screen, the X terminal
(rxvt-unicode/mlterm/xterm) will sometimes flicker a lot, with CPU usage
at 100% for scores of seconds. The pasted text is often shorter
than the origin one: some characters are lost.

Here is one example:
1. open /usr/src/linux-2.6.8/drivers/md/raid5.c in gedit
2. copy all the contents
3. paste them to screen using command 'cat > x' and mouse middle-click
4. compare the two files:

% diff x /usr/src/linux-2.6.8/drivers/md/raid5.c
478c478,479
<       char b[BDEVNAME_SI = (raid5_conf_t *) mddev->private;
---
>       char b[BDEVNAME_SIZE];
>       raid5_conf_t *conf = (raid5_conf_t *) mddev->private;

Repeat step 3 and 4 normally gives different results.
Larger files tends to trigger this bug more often.

I was able to track down the source of flicker in screen, it lies here:
in process.c:DoProcess(p, bufp, lenp, pa)
      if (*lenp == oldlen)
        {
          if (pa)
            {
              display = d;
              return;
            }
          /* We're full, let's beep */
          debug("layer is full - beep!\n");
          WBell(p, visual_bell);
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ this line causes the flicker
          break;
        }

I have tried pasting from different sources, like firefox/kedit/urxvt,
and the problem was still there.
When pasting large block of Chinese Simplified to screen,
screen tend to get the same corrupted text.

This bug is a very random one, probably you need a large enough file(>1MB) and
many retries to reproduce it.

-- System Information:
Debian Release: 3.1
  APT prefers testing
  APT policy: (990, 'testing'), (50, 'unstable')
Architecture: i386 (i686)
Kernel: Linux 2.6.9-1-k7
Locale: LANG=zh_CN.UTF-8, LC_CTYPE=zh_CN.UTF-8 (charmap=UTF-8)

Versions of packages screen depends on:
ii  base-passwd                 3.5.7        Debian base system master password
ii  debconf                     1.4.30.10    Debian configuration management sy
ii  libc6                       2.3.2.ds1-19 GNU C Library: Shared libraries an
ii  libncursesw5                5.4-4        Shared libraries for terminal hand
ii  libpam0g                    0.76-22      Pluggable Authentication Modules l
ii  passwd                      1:4.0.3-30.4 Change and administer password and

-- debconf information:
  screen/old_upgrade_prompt: false

Message #10 received at 286063@bugs.debian.org (full text, mbox, reply):

From: Baurzhan Ismagulov <ibr@radix50.net>

To: 286063@bugs.debian.org

Subject: Re: screen: paste of a large block of text causes random data lost

Date: Thu, 28 Aug 2008 22:21:00 +0200

Yes, I have this problem almost all the time, and it's very annoying if
one doesn't notice that something has been lost.

In the meantime, I have to use C-a > to save the buffer to the
filesystem.

With kind regards,
-- 
Baurzhan Ismagulov
http://www.kz-easy.com/

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