Hello.
I have found interesting bug in multi libcurl interface.
It is serious, because as result of this bug, program can enter infinite
loop, hanging
execution of whole program.
Distinctive feature of this bug is, that "running" becomes negative
without being equal to zero.
Example:
still_running=4
still_running=4
still_running=3
still_running=1
still_running=-2
still_running=-4
still_running=-6
still_running=-8
still_running=-10
...
program enters infinite loop despite the fact that all easy handles are
"finished" (some with timeouts)
I can easily correct bug just changing the main loop to:
while(still_running>0)
But this is ugly because there is bug somewhere inside of libcurl.
It is not easy for me to find it because I'm not familiar with libcurl
sources, but it will be easy for you guys :)
I can reproduce this bug in ~70% of cases, on 64bit and on 32bit linux.
How to reproduce:
c-ares-1.7.3 (required):
./configure --enable-debug --disable-optimize --enable-curldebug
--disable-symbol-hiding
curl-7.21.2:
./configure --enable-debug --disable-optimize --enable-warnings
--enable-curldebug --enable-ares=/usr/local/lib --disable-ipv6
--disable-threaded-resolver
Source code in attachment.
Just run it. If its finished - bug missed. If its stuck printing
still_rinning=-... its a bug
By the way, bug is closely related to urls used for curling. If those
urls change, bug can disappear ..
I tried it with different combination of urls, it disappears ... So its
better to try it now while it works.
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#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/time.h>
#include <unistd.h>
#include <curl/curl.h>
size_t
WriteMemoryCallback(void *ptr, size_t size, size_t nmemb, void *data)
{
int realsize = size * nmemb;
return realsize;
}
int main(int argc, char **argv)
{
CURL *http_handles[500];
CURLM *multi_handle;
CURLMsg *msg; /* for picking up messages with the transfer status */
int msgs_left; /* how many messages are left */
int still_running; /* keep number of running handles */
int timeout=0,i;
char *urls[] = {
"http://www.final4ever.com/vb/full-movies/476546-tsubomi-sticky-thick-sex-oned427.html";,
"http://www.asianforumer.com/censored-jav-download-links/198326-tsubomi-sticky-thick-sex-oned427.html";,
"http://jetdl.com/download/+Bz+Miad+461+Tsubomi+P+Bullying+/3yww4";,
"http://x-cornerz.com/2010/11/tsubomi-get-losing-ones-virginity-man-2-ekdv-133/";,
"http://forum.isengaje.com/showthread.php?p=511021";,
"http://warezhaven.org/porn-adult/adult-video-clips/1053470-asian-movie-star-jav9-update-dialy-6.html";,
"http://www.javmoviez.com/2010_07_01_archive.html";,
"http://www.intporn.com/forums/asian-jav-movies/1132315-asian-movie-star-jav9-update-dialy-41.html";,
"http://www.pornbb.org/post9371487.html";,
"http://blog.jav4you.com/2010/08/kaz-052-misaki-sakura-ero-idol-fellatio/";,
"http://blog.jav4you.com/2010/11/xv-894-yukino-hotaru-luscious-kissing-and-fucking/";,
"http://adult-movdl.blogspot.com/2010/09/annd-066-tsubomi-rui-saotome-lesbian.html";,
"http://popularhub.com/rin-sakuragi-lewd-lips-adz082";,
"http://goianh.com/index.php?/archives/438-C0930-Lewd-Wives-Wakana-Matsushita.html";,
"http://goianh.com/index.php?/archives/2456-Pavillon-Yua-Hagiwara.html";,
"http://goianh.com/index.php?/archives/2313-Mondo64-no122-Megu-Japanese-BDSM.html";,
"http://forun.8cyber.com/archiver/tid-14735921-page-5.html";,
"http://www.dadesiforum.com/index.php?/topic/24760887-asian-movie-star-jav9-update-dialy/page__st__525";,
"http://www.dadesiforum.com/Gokkun-and-Bukkake-Movies-collection-t24681069.html&mode=threaded&pid=2450632&tst=400";,
"http://gallows-jav.blogspot.com/2010/11/xv883-rin-fujisawa-set-loose-right-from.html";,
"http://www.zehrax.com/onanie-paranoia-ddk025";,
"http://laksasa.net/2010/07/20/fouls-on-a-beautiful-referee-yui-hatano-071510-427/";,
"http://laksasa.net/tag/%%E6%%B3%%A2%%E5%%A4%%9A%%E9%%87%%8E%%E7%%B5%%90%%E8%%A1%%A3/";,
"http://laksasa.net/2010/07/20/kamikaze-street-vol-8-arisa-kumada-kst-008/";,
"http://www.avcollectors.com/board/index.php?topic=12700.4270";,
"http://www.avun.com/Mediafire.com/one-piece-avi-364.html";,
"http://funkycavemen.com/forums/showthread.php?tid=18424&page=34";
};
timeout=3;
multi_handle = curl_multi_init();
for(i=0;i<27;i++)
{
printf("url=%s\n", urls[i]);
http_handles[i] = curl_easy_init();
if( !http_handles[i] )
{
fprintf( stderr, "curl_easy_init failed\n" );
continue;
}
curl_easy_setopt(http_handles[i], CURLOPT_URL, urls[i]);
curl_easy_setopt(http_handles[i], CURLOPT_WRITEFUNCTION, WriteMemoryCallback);
curl_easy_setopt(http_handles[i], CURLOPT_WRITEDATA, NULL ); // NULL is ok
curl_easy_setopt(http_handles[i], CURLOPT_USERAGENT, "Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.9.2.12) Gecko/20101026 Firefox/3.6.11" );
curl_easy_setopt(http_handles[i], CURLOPT_ENCODING, "gzip,deflate");
curl_easy_setopt(http_handles[i], CURLOPT_TIMEOUT, timeout );
curl_easy_setopt(http_handles[i], CURLOPT_NOSIGNAL, 1 ); // disable signal timout! not corrected bug ...
curl_easy_setopt(http_handles[i], CURLOPT_CONNECTTIMEOUT, timeout ); // seconds
/* add the individual transfers */
curl_multi_add_handle(multi_handle, http_handles[i]);
}
/* we start some action by calling perform right away */
curl_multi_perform(multi_handle, &still_running);
while(still_running) {
struct timeval timeout_tv;
int rc; /* select() return code */
fd_set fdread;
fd_set fdwrite;
fd_set fdexcep;
int maxfd = -1;
long curl_timeo = -1;
FD_ZERO(&fdread);
FD_ZERO(&fdwrite);
FD_ZERO(&fdexcep);
/* set a suitable timeout to play around with */
timeout_tv.tv_sec = 1;
timeout_tv.tv_usec = 0;
curl_multi_timeout(multi_handle, &curl_timeo);
if(curl_timeo >= 0)
{
timeout_tv.tv_sec = curl_timeo / 1000;
if(timeout_tv.tv_sec > 1) timeout_tv.tv_sec = 1;
else timeout_tv.tv_usec = (curl_timeo % 1000) * 1000;
}
/* get file descriptors from the transfers */
curl_multi_fdset(multi_handle, &fdread, &fdwrite, &fdexcep, &maxfd);
if( maxfd < -1 )
{
fprintf( stderr, "maxfd=%i\n", maxfd );
break;
}
rc = select(maxfd+1, &fdread, &fdwrite, &fdexcep, &timeout_tv);
switch(rc) {
case -1:
/* select error */
break;
case 0: /* timeout */
default:
/* readable/writable sockets */
curl_multi_perform(multi_handle, &still_running);
break;
}
printf("still_running=%i\n", still_running );
}
printf("Done, bug missed..\n");
return 0;
}
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