with-open-file problem of sbcl

[deftsp]

Code: Select all

(with-open-file (in  #P"/sys/class/net/eth0/statistics/rx_bytes" :direction :input)
  (read in))


This code can work with clisp but sbcl fail.

I copy file sys/class/net/eth0/statistics/rx_bytes to my home folder, and with-open-file works.

I don't know why? Is this sbcl's bug?

[findinglisp]

Hmm... good question. When I try it, SBCL just hangs. I can interrupt it with C-c in a term window, but it never returns. A simple "cat /sys/class/net/eth0/statistics/rx_bytes" works just fine. This is with SBCL 1.0.17 on Fedora 8 (2.6.25.11 kernel).

[deftsp]

Hmm... good question. When I try it, SBCL just hangs. I can interrupt it with C-c in a term window, but it never returns. A simple "cat /sys/class/net/eth0/statistics/rx_bytes" works just fine. This is with SBCL 1.0.17 on Fedora 8 (2.6.25.11 kernel).

SBCL 1.0.18 1.0.19 on Debian sid (2.6.26-1-686) suck too.

[findinglisp]

I would post it to the SBCL developer's mailing list and see what they have to say.

[metageek]

A simpler test case:

Code: Select all

(let
    ((f (open #P"/sys/class/net/eth0/statistics/rx_bytes" :direction :input)))
  (read-char f))


This hangs for me, which shows that the bug isn't tied specifically to (with-open-file) or (read).

[deftsp]

I would post it to the SBCL developer's mailing list and see what they have to say.

Have you posted it to sbcl mailing list. I haven't see at gmane.lisp.steel-bank.devel.

[Exolon]

Does it happen with other weird 'virtual' mounted files - i.e. in /dev, /proc?

[deftsp]

Does it happen with other weird 'virtual' mounted files - i.e. in /dev, /proc?

I test"/proc/stat" for read read-line with sbcl 1.0.20, it works.

"/sys/class/net/eth0/statistics/rx_bytes" still hang.

[smithzv]

I think this is a bug, and a known issue for the sbcl people. In fact, I have a recollection of reading something about this and sbcl-devel a few months ago. I have searched throught the archives and found this,

http://sourceforge.net/mailarchive/mess ... hacker.com

So maybe snoop around that thread.

If you really need to access that data, you might go through the shell. Using trivial shell, something like this would work:

Code: Select all

(read-from-string
   (trivial-shell:shell-command
      "cat /sys/class/net/eth0/statistics/rx_bytes" ))


But, really this is a kludge at best.


Zach

[deftsp]

Thank you very very much!

I think this is a bug, and a known issue for the sbcl people. In fact, I have a recollection of reading something about this and sbcl-devel a few months ago. I have searched throught the archives and found this,

http://sourceforge.net/mailarchive/mess ... hacker.com

So maybe snoop around that thread.

If you really need to access that data, you might go through the shell. Using trivial shell, something like this would work:

Code: Select all

(read-from-string
   (trivial-shell:shell-command
      "cat /sys/class/net/eth0/statistics/rx_bytes" ))


But, really this is a kludge at best.


Zach