Re: [fetchmail-devel] [patch][RFC] proper kill management of the MDA process

[Fabio R. <ro...@in...>]

>In the past there was a discussion with subject "the message fetch should be 
>completed before quitting" on the fetchmail-user mailing list. It was clear 
the 
>possibility of delivering incomplete mail messages when fetchmail is 
>interrupted during a mail dispatching process. The issue doesn't lead to a 
loss 
>of mail but produces some garbage in the maildir/mailbox (corrupted 
duplicated 
>messages).
>
>The problem is related to the use of the popen() function which doesn't 
>provide the PID number of the MDA process. In this way is not possible to 
track 
>properly the MDA process, i.e. to kill it in response to a quit command 
issued 
>to fetchmail. Using the killpg() in response to the SIGINT (or SIGTERM) 
signal 
>doesn't help because it kills the parent process before killing the child 
>process.
>
>Here is attached a first proposal to solve the issue, it seems to work on my 
>system. As I don't know the fetchmail code I'm pretty sure there are some 
>mistakes. First of all I don't understand the reason in the original 
>release_sink() function there is no check of the return from popen(). For 
this 
>reason I kept the same behavior with the new implementation. I also modified 
>the SIGCHLD handler to reuse the waiting procedure for the forked MDA 
process.

Has anyone tried the patch? Is the implementation correct? As it solves a 
problem with the current fetchmail release I think it's a starting point to fix 
the above described problem.

Fabio