It looks like you're missing a call to curl_slist_free_all().
See: https://curl.se/libcurl/c/curl_slist_append.html
-Kerry
On Fri, Apr 22, 2022 at 9:25 AM Iku_ex Diaz via curl-library
<curl-library@lists.haxx.se> wrote:
>
> System
> x86 with Linux Ubuntu 22.04
>
> Problem
> I'm running a program that uses libcurl to perform 3 requests, one GET, and
> two PUT. Using Valgrind outputs several memory leaks originated at the
> curl_slist_append() calls for the two PUT requests.
>
> TRACE:
> ==15078== HEAP SUMMARY:
>
> ==15078== in use at exit: 1,428 bytes in 72 blocks
> ==15078== total heap usage: 8,310 allocs, 8,238 frees, 1,512,884 bytes
> allocated
> ==15078==
> ==15078== 124 (64 direct, 60 indirect) bytes in 4 blocks are definitely lost
> in loss record 5 of 12
> ==15078== at 0x483B7F3: malloc (in
> /usr/lib/x86_64-linux-gnu/valgrind/vgpreload_memcheck-amd64-linux.so)
> ==15078== by 0x48A034D: ??? (in /usr/lib/x86_64-linux-gnu/libcurl.so.4.6.0)
> ==15078== by 0x48A03BC: curl_slist_append (in
> /usr/lib/x86_64-linux-gnu/libcurl.so.4.6.0)
> ==15078== by 0x1149CD:
> DLMController::liberateClient(std::__cxx11::basic_string<char,
> std::char_traits<char>, std::allocator<char> >,
> std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char>
> >) (dlmController.cpp:598)
> ==15078== by 0x113F82: DLMController::stopDLM() (dlmController.cpp:466)
> ==15078== by 0x160259: main (in
> /home/ikerdiaz/Desktop/dlm/embedded_load_manager/dlm)
> ==15078==
> ==15078== 164 (64 direct, 100 indirect) bytes in 4 blocks are definitely lost
> in loss record 6 of 12
> ==15078== at 0x483B7F3: malloc (in
> /usr/lib/x86_64-linux-gnu/valgrind/vgpreload_memcheck-amd64-linux.so)
> ==15078== by 0x48A034D: ??? (in /usr/lib/x86_64-linux-gnu/libcurl.so.4.6.0)
> ==15078== by 0x48A03BC: curl_slist_append (in
> /usr/lib/x86_64-linux-gnu/libcurl.so.4.6.0)
> ==15078== by 0x1149A1:
> DLMController::liberateClient(std::__cxx11::basic_string<char,
> std::char_traits<char>, std::allocator<char> >,
> std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char>
> >) (dlmController.cpp:596)
> ==15078== by 0x113F82: DLMController::stopDLM() (dlmController.cpp:466)
> ==15078== by 0x160259: main (in
> /home/ikerdiaz/Desktop/dlm/embedded_load_manager/dlm)
> ==15078==
> ==15078== 188 (64 direct, 124 indirect) bytes in 4 blocks are definitely lost
> in loss record 7 of 12
> ==15078== at 0x483B7F3: malloc (in
> /usr/lib/x86_64-linux-gnu/valgrind/vgpreload_memcheck-amd64-linux.so)
> ==15078== by 0x48A034D: ??? (in /usr/lib/x86_64-linux-gnu/libcurl.so.4.6.0)
> ==15078== by 0x48A03BC: curl_slist_append (in
> /usr/lib/x86_64-linux-gnu/libcurl.so.4.6.0)
> ==15078== by 0x1149B7:
> DLMController::liberateClient(std::__cxx11::basic_string<char,
> std::char_traits<char>, std::allocator<char> >,
> std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char>
> >) (dlmController.cpp:597)
> ==15078== by 0x113F82: DLMController::stopDLM() (dlmController.cpp:466)
> ==15078== by 0x160259: main (in
> /home/ikerdiaz/Desktop/dlm/embedded_load_manager/dlm)
>
>
> The trace is larger. There is always this same leak whenever there is a call
> to curl_slist_append(). The code generating the trace above is the following
> one (where the lines in orange in the Valgrind trace are the calls to
> curl_slist_append).
>
>
> CODE:
>
> void DLMController::liberateClient(std::string dev_id, std::string ip)
> {
> // Payload
> nlohmann::json free_payload = {
> {"device",
> {
> {"id", dev_id}
> }
> }
> };
>
>
> std::string tmp_str = free_payload.dump(4);
> const char* put_data = tmp_str.c_str();
>
> CURL* curl;
> CURLcode res;
>
> std::string route = ip + "/services/cpi/dlmLimitReset.json";
> const char* ip_dir = route.c_str();
>
> curl = curl_easy_init();
>
> struct curl_slist* headers = NULL;
> curl_slist_append(headers, "Accept: application/json"); // MEMORY LEAK
> curl_slist_append(headers, "Content-Type: application/json"); //MEMORY LEAK
> curl_slist_append(headers, "charset: utf-8"); //MEMORY LEAK
>
> curl_easy_setopt(curl, CURLOPT_URL, ip_dir);
>
> curl_easy_setopt(curl, CURLOPT_CUSTOMREQUEST, "PUT");
> curl_easy_setopt(curl, CURLOPT_HTTPHEADER, headers);
> curl_easy_setopt(curl, CURLOPT_POSTFIELDS, put_data);
>
> // CALL
> res = curl_easy_perform(curl);
> // Check for errors.
> if (res != CURLE_OK) {
> std::cout << curl_easy_strerror(res) << std::endl;
> }
>
> // Check return code
> long httpCode(0);
> curl_easy_getinfo(curl, CURLINFO_RESPONSE_CODE, &httpCode);
> curl_easy_cleanup(curl);
>
> if (httpCode != 204 && httpCode != 200) {
> std::cout << "Fail, returned code: " << httpCode << std::endl;
> }
> }
>
>
> Please note that even if curl_global_init(0) and curl_global_cleanup() don't
> appear in the function, they are called in another part of the code before
> this function is called. This is done once as explained in the documentation.
> The code does work, meaning that the request is successful and works just
> fine, although there is this memory leak.
>
> I would highly appreciate it if someone could help me figure this out.
>
>
> Thank you!
>
> Iker
>
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