Question

I am trying to upload a file to a ftp server using libcurl but I am getting an error.

Code:

#include <stdio.h>
#include <string.h>

#include <curl/curl.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <errno.h>
#ifdef WIN32
#include <io.h>
#else
#include <unistd.h>
#endif



#define LOCAL_FILE      "C:/AdobeRenderLog.txt"
#define UPLOAD_FILE_AS  "log.txt"
#define REMOTE_URL      "ftp://******:*******@*********.ccom"  UPLOAD_FILE_AS
#define RENAME_FILE_TO  "log.txt"


static size_t read_callback(void *ptr, size_t size, size_t nmemb, void *stream)
{

size_t retcode = fread(ptr, size, nmemb, stream);

nread = (curl_off_t)retcode;

fprintf(stderr, "*** We read %" CURL_FORMAT_CURL_OFF_T" bytes from file\n", nread);
return retcode;
}

int main(void)
{
CURL *curl;
CURLcode res;
FILE *hd_src;
struct stat file_info;
curl_off_t fsize;

struct curl_slist *headerlist=NULL;
static const char buf_1 [] = "RNFR " UPLOAD_FILE_AS;
static const char buf_2 [] = "RNTO " RENAME_FILE_TO;

/* get the file size of the local file */
if(stat(LOCAL_FILE, &file_info)) {
printf("Couldnt open '%s': %s\n", LOCAL_FILE, strerror(errno));
return 1;
}
fsize = (curl_off_t)file_info.st_size;

printf("Local file size: %" CURL_FORMAT_CURL_OFF_T " bytes.\n", fsize);

/* get a FILE * of the same file */
hd_src = fopen(LOCAL_FILE, "rb");

/* In windows, this will init the winsock stuff */
curl_global_init(CURL_GLOBAL_ALL);

/* get a curl handle */
curl = curl_easy_init();
if(curl) {
/* build a list of commands to pass to libcurl */
headerlist = curl_slist_append(headerlist, buf_1);
headerlist = curl_slist_append(headerlist, buf_2);

/* we want to use our own read function */
curl_easy_setopt(curl, CURLOPT_READFUNCTION, read_callback);

/* enable uploading */
curl_easy_setopt(curl, CURLOPT_UPLOAD, 1L);

/* specify target */
curl_easy_setopt(curl,CURLOPT_URL, REMOTE_URL);

/* pass in that last of FTP commands to run after the transfer */
curl_easy_setopt(curl, CURLOPT_POSTQUOTE, headerlist);

/* now specify which file to upload */
curl_easy_setopt(curl, CURLOPT_READDATA, hd_src);

/* Set the size of the file to upload (optional).  If you give a *_LARGE
   option you MUST make sure that the type of the passed-in argument is a
   curl_off_t. If you use CURLOPT_INFILESIZE (without _LARGE) you must
   make sure that to pass in a type 'long' argument. */
curl_easy_setopt(curl, CURLOPT_INFILESIZE_LARGE,
                 (curl_off_t)fsize);

/* Now run off and do what you've been told! */
res = curl_easy_perform(curl);

/* clean up the FTP commands list */
curl_slist_free_all (headerlist);

/* always cleanup */
curl_easy_cleanup(curl);
}
fclose(hd_src); /* close the local file */

curl_global_cleanup();
return 0;
}

Error:

main.cpp||In function 'size_t read_callback(void*, size_t, size_t, void*)':|

main.cpp|37|error: invalid conversion from 'void*' to 'FILE*'|

main.cpp|37|error:   initializing argument 4 of 'size_t fread(void*, size_t, size_t, FILE*)'|

Answer 1

You are having a casting issue at

main.cpp|37|error: invalid conversion from 'void*' to 'FILE*'|

could be resolved with casting as “C” stile

size_t retcode = fread(ptr, size, nmemb, (FILE*) stream);