We found a problem with ftp transfer using libcurl (7.23 and 7.25)
inside an application which is receiving unix signals (SIGUSR1,
SIGUSR2...) almost continuously. (Linux 2.4, PowerPC, HAVE_POLL_FINE
defined).
Curl_socket_check() uses poll() to wait for the socket, and retries it
when a signal is received (EINTR). However, if a signal is received and
it also happens that the timeout has been reached, Curl_socket_check()
returns -1 instead of 0 (indicating an error instead of a timeout).
In our case, the result is an aborted connection even before the ftp
banner is received from the server, and a return value of
CURLE_OUT_OF_MEMORY from curl_easy_perform() (Curl_pp_multi_statemach(),
in pingpong.c, actually returns OOM if Curl_socket_check() fails :-)
Funny to debug on a system on which OOM is a possible cause).
Bug: http://curl.haxx.se/mail/lib-2012-07/0122.html
If a socket is larger than FD_SETSIZE, avoid using FD_SET() on the
platforms where this is possible.
Bug: http://curl.haxx.se/bug/view.cgi?id=3413274
Reported by: Tim Starling
Just internal stuff...
Curl_safefree is now a macro defined in memdebug.h instead of a function
prototyped in url.h and implemented in url.c, so inclusion of url.h is no
longer required in order to simply use Curl_safefree.
Provide definition of macro WHILE_FALSE in setup_once.h in order to allow
other macros such as DEBUGF and DEBUGASSERT, and code using it, to compile
without 'conditional expression is constant' warnings.
The WHILE_FALSE stuff fixes 150+ MSVC compiler warnings.
POLLIN, and sets POLLERR without setting POLLIN and POLLOUT. In some
libcurl code execution paths this could trigger busy wait loops with
high CPU usage until a timeout condition aborted the loop.
This fix for Curl_poll adresses the above in a libcurl-wide mode.
select/poll calls will only be retried upon EINTR failures as
it previously was in lib/select.c revision 1.29
In this way Curl_socket_ready() and Curl_poll() will again fail
on any select/poll errors different than EINTR.
to find that it crashed miserably, and this was due to some select()isms left
in the code. This was due to API restrictions in c-ares 1.3.x, but with the
upcoming c-ares 1.4.0 this is no longer the case so now libcurl runs much
better with c-ares and the multi interface with > 1024 file descriptors in
use.
I also switched from calloc() to malloc() as a minor performance boost since
the rest of the code fills in the structs fine anyway - and they must for the
case when we use the stack-based auto variable array instead of the allocated
one.
I made the loop filling in poll_fds[] break when poll_nfds is reached as a
minor speed improvement.
Curl_socket_ready(), Curl_poll() and Curl_select() when these are called
with a zero timeout or a timeout value indicating a blocking call should
be performed.
These unnecessary calls to gettimeofday() got introduced in 7.16.2 when
fixing 'timeout would restart when signal caught while awaiting socket
events' on 20 March 2007.
- Move some loop breaking logic from the while clause into the loop,
avoiding compiler warning 'assignment within conditional expression'
function that deprecates the curl_multi_socket() function. Using the new
function the application tell libcurl what action that was found in the
socket that it passes in. This gives a significant performance boost as it
allows libcurl to avoid a call to poll()/select() for every call to
curl_multi_socket*().
to complete with no delay and actually find out what happened with
the socket. As well as detection of socket send()able condition.
This also allows removal of a Cygwin specific block of code.
or Curl_poll() with a non-zero timeout both functions would restart the
specified timeout. This could even lead to the extreme case that if a
signal arrived with a frecuency lower to the specified timeout neither
function would ever exit.
Added experimental symbol definition check CURL_ACKNOWLEDGE_EINTR in
Curl_select() and Curl_poll(). When compiled with CURL_ACKNOWLEDGE_EINTR
defined both functions will return as soon as a signal is caught. Use it
at your own risk, all calls to these functions in the library should be
revisited and checked before fully supporting this feature.
Curl_poll() which is called whenever not a single valid file descriptor is
passed to these functions.
Improve readibility using a poll() macro to replace WSApoll().
(http://curl.haxx.se/bug/view.cgi?id=1603712) (known bug #36) --limit-rate
(CURLOPT_MAX_SEND_SPEED_LARGE and CURLOPT_MAX_RECV_SPEED_LARGE) are broken
on Windows (since 7.16.0, but that's when they were introduced as previous
to that the limiting logic was made in the application only and not in the
library). It was actually also broken on select()-based systems (as apposed
to poll()) but we haven't had any such reports. We now use select(), Sleep()
or delay() properly to sleep a while without waiting for anything input or
output when the rate limiting is activated with the easy interface.
HTTP upload was disconnected:
"What appears to be happening is that my system (Linux 2.6.17 and 2.6.13) is
setting *only* POLLHUP on poll() when the conditions in my previous mail
occur. As you can see, select.c:Curl_select() does not check for POLLHUP. So
basically what was happening, is poll() was returning immediately (with
POLLHUP set), but when Curl_select() looked at the bits, neither POLLERR or
POLLOUT was set. This still caused Curl_readwrite() to be called, which
quickly returned. Then the transfer() loop kept continuing at full speed
forever."
