Hello,

This patch makes the progress update function get called when
poll()/select() in select.c are interrupted by a signal. As discussed in
the previous thread (http://curl.haxx.se/mail/lib-2008-03/0011.html),
the purpose is to allow applications using libcurl to cleanly abort
operations upon receiving a signal in the middle of performing a request
with libcurl.

The progress update function can call a user-defined progress callback,
which lets the user abort the request by returning an error value.
Assuming that select.c is (should be) the only place where libcurl
blocks (on poll()/select()), a signal will now interrupt the blocking
call, run the progress callback, and give the user the possibility to
abort if it has to, instead of looping back to poll()/select() and
blocking for an unknown amount of time.

The patch is based on the source code of the new 7.18.1 release.

Regards,

-- 
Pierre Ynard
"Une âme dans un corps, c'est comme un dessin sur une feuille de papier."