CODEWITHSUNDEEP
c++curlcrashlibcurl
Albert
Albert

Reputation: 41

libcurl curl_easy_perform crash (Segmentation fault) c++

I am sorry for my bad English. I am trying to run the following code but it crashes when the progress run about one day or several hours， so this crash is come up by accident. By the way , The SecMonitor_Curl is a single Class, so curl_global_init() run only one time global. I can not resolve this question, so I don't know what wrong with my program . Please help me. thanks!

   SecMonitor_Curl::SecMonitor_Curl()
{
    curl_global_init(CURL_GLOBAL_ALL);
}

SecMonitor_Curl::~SecMonitor_Curl()
{
    curl_global_cleanup();
}


static size_t write_to_string(void *ptr, size_t size, size_t nmemb, void *stream) {
    ((std::string*)stream)->append((char*)ptr, 0, size*nmemb);
    return size * nmemb;
}


int SecMonitor_Curl::http_get(const std::string url, const std::string method, const std::map<std::string, std::string>& params, std::string post_data, std::string& response)
{
    int ret = 0;
    CURLcode res;
    curl_ = curl_easy_init();
    if (curl_ == NULL)
    {
        return -1;
    }
    if(curl_)
    {
        url_t = "www.google.com";
        method = "POST";
        post_body="{"test":"test"}";

        res = curl_easy_setopt(curl_, CURLOPT_URL, url_t.c_str());

        if (method == "POST" || method == "PUT" || method == "DELETE")
        {
            curl_easy_setopt(curl_, CURLOPT_CUSTOMREQUEST, method.c_str());
            curl_easy_setopt(curl_, CURLOPT_POSTFIELDS, post_body.c_str());
            curl_easy_setopt(curl_, CURLOPT_POSTFIELDSIZE, post_body.size());
        }

        res = curl_easy_setopt(curl_, CURLOPT_FOLLOWLOCATION, 1L);
        res = curl_easy_setopt(curl_, CURLOPT_NOSIGNAL, 1L); 
        res = curl_easy_setopt(curl_, CURLOPT_ACCEPT_ENCODING, "deflate");
        std::string out;
        res = curl_easy_setopt(curl_, CURLOPT_WRITEFUNCTION, write_to_string);
        res = curl_easy_setopt(curl_, CURLOPT_WRITEDATA, &out);

        //printf("curl_version : %s ",curl_version());
        res = curl_easy_perform(curl_);
        /* Check for errors */
        if (res != CURLE_OK) {
            srlog_error("SecMonitor_Curl | curl_easy_perform() failed: %s\n",
                    curl_easy_strerror(res));
            ret = -1;
        }
        response = out;
    }
    else
    {
        ret = -1;
    }
    curl_easy_cleanup(curl_);

    return ret;
}

This is the dump file :

Program terminated with signal 11, Segmentation fault.
#0  _IO_fwrite (buf=0x7f16a31dba70, size=2, count=1, fp=0x0) at iofwrite.c:43
43  iofwrite.c: No such file or directory.
    in iofwrite.c    
(gdb) bt
#0  _IO_fwrite (buf=0x7f16a31dba70, size=2, count=1, fp=0x0) at iofwrite.c:43
#1  0x00007f16a31aef93 in ?? () from /usr/lib64/libcurl.so.4
#2  0x00007f16a31af0c0 in Curl_debug () from /usr/lib64/libcurl.so.4
#3  0x00007f16a31afd69 in Curl_infof () from /usr/lib64/libcurl.so.4
#4  0x00007f16a31b55f4 in Curl_protocol_connect () from /usr/lib64/libcurl.so.4
#5  0x00007f16a31bbb0c in Curl_connect () from /usr/lib64/libcurl.so.4
#6  0x00007f16a31c3a90 in Curl_perform () from /usr/lib64/libcurl.so.4
#7  0x0000000000437a10 in SecMonitor_Curl::http_get (this=0x11e2db8, url=
    "http://dip.alibaba-inc.com/api/v2/services/schema/mock/61919?spm=a312q.7764190.0.0.40e80cf75fUogt", method="POST", params=std::map with 5 elements = {...}, post_data="", response="")
    at /home/albert.yb/secMonitorAgent/secMonitor/monitor/server/SecMonitor/SecMonitor_Curl.cpp:131
#8  0x0000000000435ab0 in SecMonitor_Cmd::run_cmd (this=0x11eeef8, cmd_name="update")

SecMonitor_Curl.cpp:131 : means curl_easy_perform().

Thanks

Upvotes: 1

Views: 2974

Answers (1)

Albert
Albert

Reputation: 41

I collected 3 write_to_string callback function: First :

static size_t write_to_string(void *ptr, size_t size, size_t nmemb, void *stream) {
    ((std::string*)stream)->append((const char*)ptr, size*nmemb);
    return size * nmemb;
}

Second: 

static size_t write_to_string(void *contents, size_t size, size_t nmemb, std::string *s)
{
    size_t newLength = size*nmemb;
    size_t oldLength = s->size();
    try
    {
        s->resize(oldLength + newLength);
    }
    catch(std::bad_alloc &e)
    {
        //handle memory problem
        return 0;
    }

    std::copy((char*)contents,(char*)contents+newLength,s->begin()+oldLength);
    return size*nmemb;
}

Third:

   struct MemoryStruct {
      char *memory;
      size_t size;
    };

    static size_t
    write_to_string(void *contents, size_t size, size_t nmemb, void *userp)
    {
      size_t realsize = size * nmemb;
      struct MemoryStruct *mem = (struct MemoryStruct *)userp;

      mem->memory = realloc(mem->memory, mem->size + realsize + 1);
      if(mem->memory == NULL) {
        /* out of memory! */
        printf("not enough memory (realloc returned NULL)\n");
        return 0;
      }

      memcpy(&(mem->memory[mem->size]), contents, realsize);
      mem->size += realsize;
      mem->memory[mem->size] = 0;

      return realsize;
    }

These callback method can deal with this thing of output the curl response to String . But this problem is no in here, all crash because "crul_" which is the member variable of this class. when the function of "http_get" is quoting by multi thread , the crash must be happend.

Upvotes: 2

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