您可能需要提供更多的相关信息。
例如：你没有明确说，无论你是使用multi interface或easy interface ..＆也许提到你的工作是什么平台和什么libcurl您正在使用等。
下面是最小的卷曲easy和multi对考试libcurl/7.21.6 。
我愉快地猛拉出来的网线，停止HTTP服务器和等等〜这似乎应付OK。
这些可以帮助你：
curl_easy_setopt(curl, CURLOPT_LOW_SPEED_LIMIT, dl_lowspeed_bytes); //bytes/sec
curl_easy_setopt(curl, CURLOPT_LOW_SPEED_TIME, dl_lowspeed_time); //seconds
curl_easy_setopt(curl, CURLOPT_VERBOSE, 1L);
注意：你必须工作非常努力， 使 curl秋天，当连接掉线了。 这是由设计。 但让人惊奇一些。
[编辑：]
我怀疑你会想使用CURLOPT_TIMEOUT 。 这将超时转移。 如果你的d / l为大，那么它几乎肯定会需要更长的时间比你可能愿意等待，看看是否有什么东西了您的网络连接〜>超时会被击中。 相比之下， CURLOPT_LOW_SPEED_TIME超时可能永远不会打，甚至atfter的经过传输时间小时。
curltest_easy.c：
/*----------------------------------------------------
curltest_easy.c
WARNING: for test purposes only ~
*/
#include <stdio.h>
#include <unistd.h>
#include <curl/curl.h>
#include <curl/types.h>
#include <curl/easy.h>
#include <sys/stat.h>
static int dl_progress(void *clientp,double dltotal,double dlnow,double ultotal,double ulnow)
{
if (dlnow && dltotal)
printf("dl:%3.0f%%\r",100*dlnow/dltotal); //shenzi prog-mon
fflush(stdout);
return 0;
}
static size_t dl_write(void *buffer, size_t size, size_t nmemb, void *stream)
{
return fwrite(buffer, size, nmemb, (FILE*)stream);
}
int do_dl(void)
{
CURL *curl;
FILE *fp;
CURLcode curl_retval;
long http_response;
double dl_size;
int retval=0;
long dl_lowspeed_bytes=1000; //1K
long dl_lowspeed_time=10; //sec
/*put something biG here, preferably on a server that you can switch off at will ;) */
char url[] = {"http://fc00.deviantart.net/fs26/f/2008/134/1/a/Dragon_VII_by_NegativeFeedback.swf"};
char filename[]={"blah.dl"};
struct stat st={0};
if (!stat(filename, &st));
printf("st.st_size:[%ld]\n", st.st_size);
if(!(fp=fopen(filename, "ab"))) /*append binary*/
return 1;
curl_global_init(CURL_GLOBAL_DEFAULT);
curl = curl_easy_init();
if (curl)
{
//http://linux.die.net/man/3/curl_easy_setopt
curl_easy_setopt(curl, CURLOPT_URL, url);
/*callbacks*/
curl_easy_setopt(curl, CURLOPT_WRITEFUNCTION, dl_write);
curl_easy_setopt(curl, CURLOPT_PROGRESSFUNCTION, dl_progress);
curl_easy_setopt(curl, CURLOPT_NOPROGRESS, 0);
/*curl will keep running -so you have the freedom to recover
from network disconnects etc in your own way without
distrubing the curl task in hand. ** this is by design :p ** */
//curl_easy_setopt(curl, CURLOPT_TIMEOUT, 60);
//curl_easy_setopt(curl, CURLOPT_CONNECTTIMEOUT, 30);
/*set up min download speed threshold & time endured before aborting*/
curl_easy_setopt(curl, CURLOPT_LOW_SPEED_LIMIT, dl_lowspeed_bytes); //bytes/sec
curl_easy_setopt(curl, CURLOPT_LOW_SPEED_TIME, dl_lowspeed_time); //seconds while below low spped limit before aborting
curl_easy_setopt(curl, CURLOPT_WRITEDATA, fp);
curl_easy_setopt(curl, CURLOPT_RESUME_FROM,st.st_size);
/*uncomment this to get curl to tell you what its up to*/
//curl_easy_setopt(curl, CURLOPT_VERBOSE, 1L);
if(CURLE_OK != (curl_retval=curl_easy_perform(curl)))
{
printf("curl_retval:[%d]\n", curl_retval);
switch(curl_retval)
{
//Transferred a partial file
case CURLE_WRITE_ERROR: //can be due to a dropped connection
break;
//all defined in curl/curl.h
default: //suggest quitting on unhandled error
retval=0;
};
curl_easy_getinfo(curl, CURLINFO_CONTENT_LENGTH_DOWNLOAD, &dl_size);
printf("CURLINFO_CONTENT_LENGTH_DOWNLOAD:%f\n", dl_size);
curl_retval=curl_easy_getinfo(curl, CURLINFO_RESPONSE_CODE, &http_response);
//see: http://www.w3.org/Protocols/rfc2616/rfc2616-sec10.html
printf("CURLINFO_RESPONSE_CODE:%ld\n", http_response);
switch(http_response)
{
case 0: //eg connection down from kick-off ~suggest retrying till some max limit
break;
case 200: //yay we at least got to our url
break;
case 206:
case 416: //http://www.checkupdown.com/status/E416.html
printf("ouch! you might want to handle this & others\n");
default: //suggest quitting on an unhandled error
retval=0;
};
}
else
{
printf("our work here is done ;)\n");
retval=2;
}
if (fp)
fclose(fp);
if (curl)
curl_easy_cleanup(curl);
}
printf("retval [%d]\n", retval);
return retval;
}
int main(void)
{
while (!do_dl())
{
usleep(5000);
}
return 0;
}
/* notes ----
$sudo apt-get install libcurl4-gnutls-dev
$ curl-config --libs
-L/usr/lib/i386-linux-gnu -lcurl -Wl,-Bsymbolic-functions
#oook. lets do it:
$ gcc -o curltest_easy curltest_easy.c -L/usr/lib/i386-linux-gnu -lcurl -Wl,-Bsymbolic-functions
$ ./curltest
*/
curltest_multi.c：
/*----------------------------------------------------
curltest_mult1.c
WARNING: for test purposes only ~
*/
#include <stdio.h>
#include <unistd.h>
#include <curl/curl.h>
#include <curl/types.h>
#include <curl/easy.h>
#include <sys/stat.h>
typedef struct S_dl_byte_data
{
double new_bytes_received; //from the latest request
double existing_filesize;
} dl_byte_data, *pdl_byte_data;
static int dl_progress(pdl_byte_data pdata,double dltotal,double dlnow,double ultotal,double ulnow)
{
/*dltotal := hacky way of getting the Content-Length ~ less hacky would be to first
do a HEAD request & then curl_easy_getinfo with CURLINFO_CONTENT_LENGTH_DOWNLOAD*/
if (dltotal && dlnow)
{
pdata->new_bytes_received=dlnow;
dltotal+=pdata->existing_filesize;
dlnow+=pdata->existing_filesize;
printf(" dl:%3.0f%% total:%.0f received:%.0f\r",100*dlnow/dltotal, dltotal, dlnow); //shenzi prog-mon
fflush(stdout);
}
return 0;
}
static size_t dl_write(void *buffer, size_t size, size_t nmemb, void *stream)
{
return fwrite(buffer, size, nmemb, (FILE*)stream);
}
////////////////////////
int do_dl(void)
{
CURLM *multi_handle;
CURL *curl;
FILE *fp;
CURLcode curl_retval;
int retval=0;
int handle_count=0;
double dl_bytes_remaining, dl_bytes_received;
dl_byte_data st_dldata={0};
char curl_error_buf[CURL_ERROR_SIZE]={"meh"};
long dl_lowspeed_bytes=1000, dl_lowspeed_time=10; /* 1KBs for 10 secs*/
/*put something biG here, preferably on a server that you can switch off at will ;) */
char url[] = {"http://fc00.deviantart.net/fs26/f/2008/134/1/a/Dragon_VII_by_NegativeFeedback.swf"};
char outfilename[]={"blah.swf"}, filename[]={"blah.dl"};
struct stat st={0};
if (!(fp=fopen(filename, "ab")) || -1==fstat(fileno(fp), &st)) //append binary
return -1;
if (curl_global_init(CURL_GLOBAL_DEFAULT))
return -2;
if (!(multi_handle = curl_multi_init()))
return -3;
if (!(curl = curl_easy_init()))
return -4;
st_dldata.new_bytes_received=st_dldata.existing_filesize=st.st_size;
//http://curl.haxx.se/libcurl/c/curl_easy_setopt.html
curl_easy_setopt(curl, CURLOPT_URL, url);
/*callbacks*/
curl_easy_setopt(curl, CURLOPT_WRITEFUNCTION, dl_write);
curl_easy_setopt(curl, CURLOPT_PROGRESSFUNCTION, dl_progress);
curl_easy_setopt(curl, CURLOPT_PROGRESSDATA, &st_dldata);
curl_easy_setopt(curl, CURLOPT_NOPROGRESS, 0);
/*curl will keep running -so you have the freedom to recover from network disconnects etc
in your own way without distrubing the curl task in hand. ** this is by design :p **
The follwoing sets up min download speed threshold & time endured before aborting*/
curl_easy_setopt(curl, CURLOPT_LOW_SPEED_LIMIT, dl_lowspeed_bytes); //bytes/sec
curl_easy_setopt(curl, CURLOPT_LOW_SPEED_TIME, dl_lowspeed_time); //seconds while below low spped limit before aborting
//alternatively these are available in libcurl 7.25
//curl_easy_setopt(curl, CURLOPT_TCP_KEEPALIVE,1L);
//curl_easy_setopt(curl, CURLOPT_TCP_KEEPIDLE,10);
//curl_easy_setopt(curl, CURLOPT_TCP_KEEPINTVL,10);
curl_easy_setopt(curl, CURLOPT_WRITEDATA, fp);
/*uncomment this to get curl to tell you what its up to*/
//curl_easy_setopt(curl, CURLOPT_VERBOSE, 1L);
curl_easy_setopt(curl, CURLOPT_ERRORBUFFER, curl_error_buf);
do
{
if (st_dldata.new_bytes_received) //set the new range for the partial transfer if we have previously received some bytes
{
printf("resuming d/l..\n");
fflush(fp);
//get the new filesize & sanity check for file; on error quit outer do-loop & return to main
if (-1==(retval=fstat(fileno(fp), &st)) || !(st_dldata.existing_filesize=st.st_size)) break;
//see also: CURLOPT_RANGE for passing a string with our own X-Y range
curl_easy_setopt(curl, CURLOPT_RESUME_FROM, st.st_size);
st_dldata.new_bytes_received=0;
}
printf("\n\nbytes already received:[%.0f]\n", st_dldata.existing_filesize);
//re-use the curl handle again & again & again & again... lol
curl_multi_add_handle(multi_handle, curl);
do //curl_multi_perform event-loop
{
CURLMsg *pMsg;
int msgs_in_queue;
while (CURLM_CALL_MULTI_PERFORM == curl_multi_perform(multi_handle, &handle_count));
//check for any mesages regardless of handle count
while(pMsg=curl_multi_info_read(multi_handle, &msgs_in_queue))
{
long http_response;
printf("\nmsgs_in_queue:[%d]\n",msgs_in_queue);
if (CURLMSG_DONE != pMsg->msg)
{
fprintf(stderr,"CURLMSG_DONE != pMsg->msg:[%d]\n", pMsg->msg);
}
else
{
printf("pMsg->data.result:[%d] meaning:[%s]\n",pMsg->data.result,curl_easy_strerror(pMsg->data.result));
if (CURLE_OK != pMsg->data.result) printf("curl_error_buf:[%s]\n", curl_error_buf);
switch(pMsg->data.result)
{
case CURLE_OK: ///////////////////////////////////////////////////////////////////////////////////////
printf("CURLE_OK: ");
curl_easy_getinfo(pMsg->easy_handle, CURLINFO_CONTENT_LENGTH_DOWNLOAD, &dl_bytes_remaining);
curl_easy_getinfo(pMsg->easy_handle, CURLINFO_SIZE_DOWNLOAD, &dl_bytes_received);
if (dl_bytes_remaining == dl_bytes_received)
{
printf("our work here is done ;)\n");
rename(filename, outfilename);
retval=1;
}
else
{
printf("ouch! st_dldata.new_bytes_received[%f]\n",st_dldata.new_bytes_received);
printf("ouch! dl_bytes_received[%f] dl_bytes_remaining[%f]\n",dl_bytes_received,dl_bytes_remaining);
retval=dl_bytes_received < dl_bytes_remaining ? 0 : -5;
}
break; /////////////////////////////////////////////////////////////////////////////////////////////////
case CURLE_COULDNT_CONNECT: //no network connectivity ?
case CURLE_OPERATION_TIMEDOUT: //cos of CURLOPT_LOW_SPEED_TIME
case CURLE_COULDNT_RESOLVE_HOST: //host/DNS down ?
printf("CURMESSAGE switch handle_count:[%d]\n",handle_count);
break; //we'll keep trying
default://see: http://curl.haxx.se/libcurl/c/libcurl-errors.html
handle_count=0;
retval=-5;
};
//see: http://www.w3.org/Protocols/rfc2616/rfc2616-sec10.html
curl_retval=curl_easy_getinfo(pMsg->easy_handle, CURLINFO_RESPONSE_CODE, &http_response);
printf("CURLINFO_RESPONSE_CODE HTTP:[%ld]\n", http_response);
switch(http_response)
{
case 0: //eg connection down from kick-off ~suggest retrying till some max limit
case 200: //yay we at least got to our url
case 206: //Partial Content
break;
case 416:
//cannot d/l range ~ either cos no server support
//or cos we're asking for an invalid range ~ie: we already d/ld the file
printf("HTTP416: either the d/l is already complete or the http server cannot d/l a range\n");
retval=2;
default: //suggest quitting on an unhandled error
handle_count=0;
retval=-6;
};
}
}
if (handle_count) //select on any active handles
{
fd_set fd_read={0}, fd_write={0}, fd_excep={0};
struct timeval timeout={5,0};
int select_retval;
int fd_max;
curl_multi_fdset(multi_handle, &fd_read, &fd_write, &fd_excep, &fd_max);
if (-1 == (select_retval=select(fd_max+1, &fd_read, &fd_write, &fd_excep, &timeout)))
{
//errno shall be set to indicate the error
fprintf(stderr, "yikes! select error :(\n");
handle_count=0;
retval=-7;
break;
}
else{/*check whatever*/}
}
} while (handle_count);
curl_multi_remove_handle(multi_handle,curl);
printf("continue from here?");
getchar();
}
while(retval==0);
curl_multi_cleanup(multi_handle);
curl_easy_cleanup(curl);
curl_global_cleanup();
if (fp) fclose(fp);
return retval;
}
////////////////////////
int main(void)
{
int retval;
printf("\n\ncurl_multi d/l test ~curl version:[%s]\n", curl_version());
while (1!=(retval=do_dl()))
{
printf("retval [%d] continue?\n\n", retval);
printf("continue?");
getchar();
}
printf("\nend of test!\n\n", retval);
return retval;
}
/* notes ----
$sudo apt-get install libcurl4-gnutls-dev
$curl-config --libs
-L/usr/lib/i386-linux-gnu -lcurl -Wl,-Bsymbolic-functions
#oook. lets do it:
$gcc -o curltest_multi curltest_multi.c -L/usr/lib/i386-linux-gnu -lcurl -Wl,-Bsymbolic-functions
$./curltest_multi
*/
呃，你可能要记得删除blah.dl开始一个全新的测试之前的文件。 在PROG故意没有，所以你可以事先截断现有的文件进行测试;）
注意：这样的事情，你也许应该*不能仅仅依靠CURLE_COULDNT_CONNECT 〜你的代码应该大部分错误处理洛尔（;可能更少，如果你的前卫是严格供个人使用;）
[编辑：]我已经更新了curtest_multi.c证明easy_handle再利用。
而做注意从以下引用的文件建立 ：
当完成一个转移，易手柄仍留有加入到多堆叠。 你需要先用curl_multi_remove_handle（3）取出容易手柄，然后用curl_easy_cleanup（3），或者可能设置新的选项，它关闭，并与curl_multi_add_handle再次添加（3）启动另一个转移。
希望这可以帮助 ;）
