>
> Hello, I basically did a copy-paste of the WRITEFUNCTION example found on
> this site and on other forums, but for some reason, it crashes every time.
> When I debugged, I found that the last variable going to the callback
> function (void* stream in the code below) is NULL thus causing a memory
> access violation. Can anybody help please? Here is the relevant code:
>
> struct MemoryStruct {
> char *memory;
> size_t size;
> };
>
> size_t callback_func(char *ptr, size_t size, size_t count, void *stream)
> {
> printf("Entered callback\n");
>
> size_t realsize = size * count;
> struct MemoryStruct *mem = (struct MemoryStruct *)stream;
>
> mem->memory = (char *)realloc(mem->memory, mem->size + realsize + 1);
> //explicitly changed to char * for compiler issues
> if (!mem->memory) {
> printf("Not enough memory (realloc returned NULL)\n");
> exit(EXIT_FAILURE);
> }
>
> memcpy(&(mem->memory[mem->size]), ptr, realsize);
> mem->size += realsize;
> mem->memory[mem->size] = 0;
>
> return realsize;
> }
>
>
> void SSHConnect(char *hostname,char *user,char *pass)
> {
> char strBuffer[1024];
> sprintf(strBuffer,"sftp://%s:%s@%s",user,pass,hostname);
> curl_easy_setopt(hCurl, CURLOPT_URL, strBuffer);
>
> struct MemoryStruct chunk;
> chunk.memory = (char *)malloc(1); //explicitly changed to char * for
> compiler issues
> chunk.size = 0;
>
> curl_easy_setopt(hCurl, CURLOPT_WRITEDATA, (void *)&chunk);
>
> curl_easy_perform(hCurl);
>
> printf("%lu bytes retrieved\n", (long)chunk.size);
>
> if(chunk.memory) {
> free(chunk.memory);
> }
> }
>

OK I simplified the code a bit, unfortunately I still get a crash, with
NULL values being passed to the callback function. (I realise I omitted the
call to the writefunction in the above example, but it WAS in my code.)

size_t callback_func(char *ptr, size_t size, size_t count, void *stream)
{
  printf("Entered callback\n");

size_t realsize = size * count;

return realsize;
}

void SSHConnect(char *hostname,char *user,char *pass)
{
char strBuffer[1024];
sprintf(strBuffer,"sftp://%s:%s@%s",user,pass,hostname);
 curl_easy_setopt(hCurl, CURLOPT_URL, strBuffer);

curl_easy_setopt(hCurl, CURLOPT_WRITEFUNCTION, &callback_func);

int chunk;

curl_easy_setopt(hCurl, CURLOPT_WRITEDATA, (void *)&chunk);

curl_easy_perform(hCurl);
}

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Received on 2013-01-23