I've got an application where I'm using cURL in a C program to post data
read out of a file to a server. The problem I'm having with it is, the
curl_slist_append call I'm using seems to be causing a segfault
intermittently, and seems to vary depending on the machine it is being used
on. To demonstrate, I've stripped the program down to the point that it
isn't actually posting anything anymore. It is just creating a form and an
slist, then cleaning it up, and reattempting the same thing. I've posted it
below.

I'm sure I'm doing something wrong here, I just don't know what it is.

Thanks,

-Tim

-----------------------------------------------
#include <stdio.h>
#include <stdlib.h>
#include <string.h> /* string manip */
#include <unistd.h> /* for usleep */

#include <curl/curl.h>
#include <curl/types.h>
#include <curl/easy.h>

int main()
{
 CURL *curl;

 struct curl_httppost *formpost=NULL;
 struct curl_httppost *lastptr=NULL;
 struct curl_slist *headerlist=NULL;
 static const char buf[] = "Expect:";

 char CharArray[] = "This is the text to post....or not.\0";
 int loop_count = 0;
 curl_global_init(CURL_GLOBAL_ALL);
 loop_count = 0;

 while (1)
 {
  {
   sleep(1);

   if (loop_count<86400)
   { loop_count++; }
   else
   { loop_count=0; }
  }
   printf("\n\nFill out a form to post: %s\n",CharArray);

   /* Fill in the operation field */
   curl_formadd(&formpost,
                &lastptr,
                CURLFORM_COPYNAME, "operation",
                CURLFORM_COPYCONTENTS, "PostData",
                CURLFORM_END);

   /* Fill in the file data field */
   curl_formadd(&formpost,
                &lastptr,
                CURLFORM_COPYNAME, "filedata",
                CURLFORM_COPYCONTENTS, CharArray,
                CURLFORM_END);

   /* Fill in the submit field too, even if this is rarely needed */
   curl_formadd(&formpost,
                &lastptr,
                CURLFORM_COPYNAME, "submit",
                CURLFORM_COPYCONTENTS, "send",
                CURLFORM_END);
   curl = curl_easy_init();

   /* initalize custom header list */
        printf("calling curl_slist_append......\n");
        headerlist = curl_slist_append(headerlist, buf); /******segfault
here 2nd time through******/
        printf("curl_slist_append complete.\n");

        if(curl)
   {
         /* Don't actually do anything with the data for this example */
         /* however act like we did and start cleanup */
    curl_easy_cleanup(curl);
    curl_formfree(formpost);

         printf("About to free slist....\n");
    curl_slist_free_all (headerlist);
         printf("slist freed\n\n\n");
        }
 }
}
---------------------------------

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Received on 2011-09-01