Thanks a ton!! Sorry for forgetting to free the allocated memory in
mapping_data.

It works great now without any errors or memory leakage.

Thanks!!

On Tue, Aug 5, 2014 at 12:33 PM, David Chapman <dcchapman_at_acm.org> wrote:

> On 8/5/2014 10:09 AM, you wrote:
>
> Hi David,
>
> Thanks a lot for the reply.
>
> I have made the following changes as per your suggestions, but still get
> one error and memory leakage in Valgrind. Please suggest where am I doing
> it wrong..
>
>
> It appears that you are not releasing the memory allocated by
> write_function(). It is stored in data.data and is then returned from
> handle_url_followup(), but I do not see in the fragment of main() where it
> is released.
>
>
>
> char *handle_url_followup(char* url)
> {
> CURL *curl;
> char *url_new=NULL;
>
> struct url_data data;
> data.size = 0;
> data.data = malloc(4096); /* reasonable size initial buffer */
> if(NULL == data.data)
> {
> fprintf(stderr, "Failed to allocate memory.\n");
> return NULL;
> }
>
> data.data[0] = '\0';
>
> CURLcode res;
>
> curl = curl_easy_init();
> FILE *TEMP_url=fopen("new_url.txt","w");
> if (curl)
> {
> curl_easy_setopt(curl, CURLOPT_URL, url);
> curl_easy_setopt(curl, CURLOPT_FOLLOWLOCATION, 1L);
> curl_easy_setopt(curl, CURLOPT_WRITEFUNCTION, write_data);
> curl_easy_setopt(curl, CURLOPT_WRITEDATA, &data);
> curl_easy_perform(curl);
> curl_easy_getinfo(curl,CURLINFO_EFFECTIVE_URL,&url_new);
> fprintf(TEMP_url,"%s",url_new);
> res = curl_easy_perform(curl);
> if(res != CURLE_OK)
> {
> fprintf(stderr, "curl_easy_perform() failed: %s\n",
> curl_easy_strerror(res));
> }
> }
> curl_easy_cleanup(curl);
> return data.data;
> fclose(TEMP_url);
> }
>
>
> int main(int argc,char *argv[])
> {
> char *mapping_data="NULL";
> char url_new[100]="NULL";
>
> //FIRST URL printf("URL: %s\n", url);
> mapping_data=handle_url_followup(url);
> printf("%s\n",mapping_data);
> //SECOND URL is in the file new_url.txt
>
>
> It looks like you should now call free(mapping_data) here.
>
>
>
>
> The Valgrind errors are:
>
> ==2860== HEAP SUMMARY:
> ==2860== in use at exit: 357,525 bytes in 3,045 blocks
> ==2860== total heap usage: 5,033 allocs, 1,988 frees, 962,456 bytes
> allocated
> ==2860==
> ==2860== 403 bytes in 9 blocks are definitely lost in loss record 827 of
> 898
> ==2860== at 0x10001155D: realloc (vg_replace_malloc.c:525)
> ==2860== by 0x100000C71: write_data (Gwidd_uniprot_map2.c:23)
> ==2860== by 0x10002DD9A: Curl_client_write (in /usr/lib/libcurl.4.dylib)
> ==2860== by 0x1000431F9: Curl_readwrite (in /usr/lib/libcurl.4.dylib)
> ==2860== by 0x1000439C1: Curl_perform (in /usr/lib/libcurl.4.dylib)
> ==2860== by 0x100000FBF: handle_url_followup (Gwidd_uniprot_map2.c:109)
> ==2860== by 0x100001998: main (Gwidd_uniprot_map2.c:248)
> ==2860==
> ==2860== LEAK SUMMARY:
> ==2860== definitely lost: 403 bytes in 9 blocks
> ==2860== indirectly lost: 0 bytes in 0 blocks
> ==2860== possibly lost: 0 bytes in 0 blocks
> ==2860== still reachable: 357,122 bytes in 3,036 blocks
> ==2860== suppressed: 0 bytes in 0 blocks
> ==2860== Reachable blocks (those to which a pointer was found) are not
> shown.
> ==2860== To see them, rerun with: --leak-check=full --show-reachable=yes
> ==2860==
> ==2860== For counts of detected and suppressed errors, rerun with: -v
> ==2860== ERROR SUMMARY: 1 errors from 1 contexts (suppressed: 0 from 0)
>
> Thanks!
>
>
>
> On Mon, Aug 4, 2014 at 6:36 PM, David Chapman <dcchapman_at_acm.org> wrote:
>
>> On 8/4/2014 4:16 PM, Madhurima Das wrote:
>>
>> I want to retrieve the information data of a particular website (url) and
>> also find its follow-up url (url_new) but getting too many errors after
>> running Valgrind along with memory leakage.
>>
>> The function and part of the main program is as follows:
>>
>> void handle_url_followup(char* url, char** mapping_data, char** url_n)
>> {
>> CURL *curl;
>> char *url_new="NULL";
>>
>>
>> Don't put quote marks here; you would be assigning a constant string to
>> a non-const pointer. Even though you are not writing into the buffer, it
>> is a risky practice. Just use NULL without quotes.
>>
>>
>>
>> struct url_data data;
>> data.size = 0;
>> data.data = malloc(4096); /* reasonable size initial buffer */
>> if(NULL == data.data)
>> {
>> fprintf(stderr, "Failed to allocate memory.\n");
>> return NULL;
>> }
>>
>> data.data[0] = '\0';
>>
>> CURLcode res;
>>
>> curl = curl_easy_init();
>> if (curl)
>> {
>> curl_easy_setopt(curl, CURLOPT_URL, url);
>> curl_easy_setopt(curl, CURLOPT_FOLLOWLOCATION, 1L);
>> curl_easy_setopt(curl, CURLOPT_WRITEFUNCTION, write_data);
>> curl_easy_setopt(curl, CURLOPT_WRITEDATA, &data);
>> curl_easy_perform(curl);
>> curl_easy_getinfo(curl,CURLINFO_EFFECTIVE_URL,&url_new);
>>
>>
>> You need to copy the effective URL to a safe place; this call returns a
>> pointer to an internal cURL data structure. I would not expect cURL to
>> guarantee that this pointer would survive another call to
>> curl_easy_perform().
>>
>>
>> res = curl_easy_perform(curl);
>> if(res != CURLE_OK)
>> {
>> fprintf(stderr, "curl_easy_perform() failed: %s\n",
>> curl_easy_strerror(res));
>> }
>> }
>> curl_easy_cleanup(curl);
>>
>>
>> And now the effective URL has been freed.
>>
>> *mapping_data=data.data;
>> *url_n=url_new;
>>
>>
>> The returned string url_new needs to be freed by the caller.
>>
>> Fix this, then see if you still have valgrind errors.
>>
>> }
>>
>> int main(int argc,char *argv[])
>> {
>> char url[100]="NULL";
>> char *mapping_data="NULL";
>> char *url_new="NULL";
>>
>> //FIRST URL printf("URL: %s\n", url);
>> handle_url_followup(url,&mapping_data,&url_new);
>> //SECOND URL
>> printf("%s\n",url_new);
>>
>>
>> I get both the urls but in addition get 973 errors with Valgrind and
>> memory leakage of 403 bytes in 9 blocks. A few errors are:
>>
>> ==6599== Invalid read of size 1
>> ==6599== at 0x1000124F6: strlen (mc_replace_strmem.c:282)
>> ==6599== by 0x10010AEF4: puts (in /usr/lib/libSystem.B.dylib)
>> ==6599== by 0x1000019F9: main (prog.c:247)
>> ==6599== Address 0x1011db5d0 is 0 bytes inside a block of size 51 free'd
>> ==6599== at 0x100010E9F: free (vg_replace_malloc.c:366)
>> ==6599== by 0x100037C6B: Curl_close (in /usr/lib/libcurl.4.dylib)
>> ==6599== by 0x100001055: handle_url_followup (prog.c:113)
>> ==6599== by 0x1000019ED: main (prog.c:245)
>>
>> ==6599== Invalid read of size 8
>> ==6599== at 0x100013C30: memcpy (mc_replace_strmem.c:635)
>> ==6599== by 0x100096E74: __sfvwrite (in /usr/lib/libSystem.B.dylib)
>> ==6599== by 0x10010AF66: puts (in /usr/lib/libSystem.B.dylib)
>> ==6599== by 0x1000019F9: main (prog.c:247)
>> ==6599== Address 0x1011db5d0 is 0 bytes inside a block of size 51 free'd
>> ==6599== at 0x100010E9F: free (vg_replace_malloc.c:366)
>> ==6599== by 0x100037C6B: Curl_close (in /usr/lib/libcurl.4.dylib)
>> ==6599== by 0x100001055: handle_url_followup (prog.c:113)
>> ==6599== by 0x1000019ED: main (prog.c:245)
>> ==6599==
>>
>> ==6599==
>> ==6599== HEAP SUMMARY:
>> ==6599== in use at exit: 320,629 bytes in 3,035 blocks
>> ==6599== total heap usage: 5,023 allocs, 1,988 frees, 925,560 bytes
>> allocated
>> ==6599==
>> ==6599== 403 bytes in 9 blocks are definitely lost in loss record 827 of
>> 897
>> ==6599== at 0x10001155D: realloc (vg_replace_malloc.c:525)
>> ==6599== by 0x100000D05: write_data (Gwidd_uniprot_map2.c:23)
>> ==6599== by 0x10002DD9A: Curl_client_write (in
>> /usr/lib/libcurl.4.dylib)
>> ==6599== by 0x1000431F9: Curl_readwrite (in /usr/lib/libcurl.4.dylib)
>> ==6599== by 0x1000439C1: Curl_perform (in /usr/lib/libcurl.4.dylib)
>> ==6599== by 0x10000101D: handle_url_followup (Gwidd_uniprot_map2.c:106)
>> ==6599== by 0x1000019ED: main (Gwidd_uniprot_map2.c:245)
>> ==6599==
>> ==6599== LEAK SUMMARY:
>> ==6599== definitely lost: 403 bytes in 9 blocks
>>
>>
>> Any suggestion would be highly appreciated.
>>
>> Thanks!
>>
>> N.B. The other functions are:
>>
>> struct url_data
>> {
>> size_t size;
>> char* data;
>> };
>>
>> size_t write_data(void *ptr, size_t size, size_t nmemb, struct url_data
>> *data)
>> {
>> size_t index = data->size;
>> size_t n = (size * nmemb);
>> char* tmp;
>>
>> data->size += (size * nmemb);
>>
>> #ifdef DEBUG
>> fprintf(stderr, "data at %p size=%ld nmemb=%ld\n", ptr, size, nmemb);
>> #endif
>> tmp = realloc(data->data, data->size + 1); /* +1 for '\0' */
>>
>> if(tmp)
>> {
>> data->data = tmp;
>> }
>> else
>> {
>> if(data->data)
>> {
>> free(data->data);
>> }
>> fprintf(stderr, "Failed to allocate memory.\n");
>> return 0;
>> }
>> memcpy((data->data + index), ptr, n);
>> data->data[data->size] = '\0';
>>
>> return size * nmemb;
>> }
>>
>>
>>
>> -------------------------------------------------------------------
>> List admin: http://cool.haxx.se/list/listinfo/curl-library
>> Etiquette: http://curl.haxx.se/mail/etiquette.html
>>
>>
>>
>> --
>> David Chapman dcchapman_at_acm.org
>> Chapman Consulting -- San Jose, CA
>> Software Development Done Right.
>> www.chapman-consulting-sj.com
>>
>>
>
>
> --
> David Chapman dcchapman_at_acm.org
> Chapman Consulting -- San Jose, CA
> Software Development Done Right.
> www.chapman-consulting-sj.com
>
>

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Received on 2014-08-05