Hello
I'm using libcurl with C++ classes in a single threaded application by setting
up the curl env in the constructor and invoking cleanup operation in the
destructor, but I'm having trouble freeing the allocated memory. I read the
curl documentation and tutorial. What is the correct method of freeing
resources?
Making the following curl function calls In the constructor:
=======================================================
Ctor()
{
curl_global_init(CURL_GLOBAL_ALL);
_cURLHandle = curl_easy_init();
curl_easy_setopt(_cURLHandle, CURLOPT_ERRORBUFFER,_cURLMessages);
}
According to the curl documentation:
curl_easy_init initializes curl and this call MUST have a corresponding call
to curl_easy_cleanup(3)<http://curl.haxx.se/libcurl/c/curl_easy_cleanup.html>
when the operation is complete.
According to the curl documentation:
You should call
curl_global_cleanup(3)<http://curl.haxx.se/libcurl/c/curl_global_cleanup.html>
once for each call you make to
curl_global_init(3)<http://curl.haxx.se/libcurl/c/curl_global_init.html>, after
you are done using libcurl.
I tried 4 scenarios for cleanup in the destructor
dtor scenario_1
{
/*Call curl_global_cleanup() immediately before the program exits, when
the program is again only one thread
*and after its last use of libcurl. It isn't actually required that
the functions be called at the beginning
*and end of the program -- that's just usually the easiest way to do
it. It is required that the functions
*be called when no other thread in the program is running.
*/
curl_global_cleanup();
/*This function must be the last function to call for an easy session.
It is the opposite of
* the curl_easy_init(3) function and must be called with the same
handle as input that the
* curl_easy_init call returned.
*/
curl_easy_cleanup(_cURLFileHandle);
}
Results:Program received signal SIGSEGV, Segmentation fault.
=================================================
#0 0x63912920 in Curl_cookie_loadfiles+0x9c ()
#1 0x63933c74 in flush_cookies+0x8c ()
#2 0x639341ac in Curl_close+0x2ac
#3 0x639624e8 in curl_easy_cleanup+0x3c ()
dtor scenario_2
{
/*This function must be the last function to call for an easy session.
It is the opposite of
* the curl_easy_init(3) function and must be called with the same
handle as input that the
* curl_easy_init call returned.
*/
curl_easy_cleanup(_cURLFileHandle);
/*Call curl_global_cleanup() immediately before the program exits, when
the program is again only one thread
*and after its last use of libcurl. It isn't actually required that
the functions be called at the beginning
*and end of the program -- that's just usually the easiest way to do
it. It is required that the functions
*be called when no other thread in the program is running.
*/
curl_global_cleanup();
}
Results:Program received signal SIGSEGV, Segmentation fault.
=================================================
#0 0x6388d920 in Curl_cookie_loadfiles+0x9c ()
#1 0x638aec74 in flush_cookies+0x8c
#2 0x638af1ac in Curl_close+0x2ac
#3 0x638dd4e8 in curl_easy_cleanup+0x3c ()
dtor scenario_3
{
/*Call curl_global_cleanup() immediately before the program exits, when
the program is again only one thread
*and after its last use of libcurl. It isn't actually required that
the functions be called at the beginning
*and end of the program -- that's just usually the easiest way to do
it. It is required that the functions
*be called when no other thread in the program is running.
*/
curl_global_cleanup();
}
Results:Memory Leak.
=================================================
Memory leaked: 37013 bytes (60.9%); potentially leaked: 0 bytes (0%)
MLK: 34256 bytes leaked at 0x401c49d0
This memory was allocated from:
malloc [rtlib.o]
calloc [rtlib.o]
Curl_open [libcurl.sl.5.1]
curl_easy_init [libcurl.sl.5.1]
csCtkXmlEntityResolver::setUpCurlEnvironment()
[csCtkXmlEntityResolver.C:286]
* for transferring. You must never share the same
handle in multiple threads. curl_easy_init initializes
* curl and this call MUST have a corresponding call
to curl_easy_cleanup() when the operation is complete.
*/
=> _cURLHandle = curl_easy_init();
//If this function returns NULL, something went wrong
and you cannot use the other curl functions.
if(_cURLHandle)
csCtkXmlEntityResolver::csCtkXmlEntityResolver(const char
*,bool)%2 [csCtkXmlEntityResolver.C:56]
csCtkXmlDOMParser::parseDocumentUseExternalDTD(char *,char *)
[csCtkXmlDOMParser.C:907]
csCtkXmlDOMParser::isXmlValidUseExternalDTD(char *,const char *)
[csCtkXmlDOMParser.C:661]
csCtkXmlDOMParser::doValidateAgainstExternalDtd(char *,char *)
[csCtkXmlDOMParser.C:291]
csCtkXmlDOMParser::doValidateAgainstExternalDtd(char *)
[csCtkXmlDOMParser.C:298]
doXmlParserSelfTest(int,char **) [testMe.C:109]
main [testMe.C:59]
dtor scenario_4
{
/*This function must be the last function to call for an easy session.
It is the opposite of
* the curl_easy_init(3) function and must be called with the same
handle as input that the
* curl_easy_init call returned.
*/
curl_easy_cleanup(_cURLFileHandle);
}
Results:Program received signal SIGSEGV, Segmentation fault.
=================================================
#0 0x6388d920 in Curl_cookie_loadfiles+0x9c
#1 0x638aec74 in flush_cookies+0x8c ()
#2 0x638af1ac in Curl_close+0x2ac
#3 0x638dd4e8 in curl_easy_cleanup+0x3c ()
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