Rancid hangs

[Mike Hyde]

Have you upgraded expect latley?  I had the same problem, and it turned out
that the version of expect caused it to hang.  There was a patch posted on
this list, I have attacked it below:

disclaimer: i am not at all sure that this is the proper way to fix

this problem (where rancid's *logins hang while collecting info from

devices on linux platforms with tcl8.3* and expect 5.32*) or if it

will have adverse affects on other expect scripts.

what is happening (usually amid write term or show config, cisco-ism

or juniper-ism) is the last chunk of data before the prompt has been

read into the internal ("channel") buffer, expect asks for more data,

but instead of tcl reading from the buffer or checking if the file

descriptor is actually ready for reading, it just calls read() via

expect's ExpInputProc() where it hangs with the router waiting for

input (until the router's session-timeout expires).

i believe this is due to Tcl_WaitForEvent() not differentiating properly

between timeout and "ready_for_read", but i did not unwrap the maze of

callbacks within tcl and don't have time to right now.

the (inefficient) patch below makes sure the filedescriptor is

set non-blocking, so the read will return immediately if the FD

is not ready for reading and thus give the tcl timer functions the

opportunity to timeout an operation (and apparently look at the internal

buffer for more data). i have no idea why this doesnt happen/affect netbsd.

it works for me with tcl8.3.b2 and expect 5.32.1 on the linux box i have

freewill-access to, or at least do-diffs completed flawlessly 4 times,

whereas before it barely even got out of the gate. i think this is

RedCrap 6.1 or so...uname says Linux 2.2.16-22, but i'm guessing that's

just the kernel and i'm blissfully unaware of where all the other version

info is hidden.

you'll have to apply this to your expect 5.32.1 source; cd expect-5.32;

patch < patchfile; make install

- - - - - - - - - - - - - c u t h e r e - - - - - - - - - - - - - -

*** exp_chan.c.FCS Tue Aug 14 16:55:54 2001

--- exp_chan.c Tue Aug 14 16:59:25 2001

***************

*** 119,124 ****

--- 119,125 ----

* nonblocking, the read will never block.

*/


+ fcntl(esPtr->fdin, F_SETFL, O_NONBLOCK);

bytesRead = read(esPtr->fdin, buf, (size_t) toRead);

/*printf("ExpInputProc: read(%d,,) = %d\r\n",esPtr->fdin,bytesRead);*/

if (bytesRead > -1) {