libcurl console progress bar for file download - c

Question

Here I implemented code for file download from server. its working fine.
Now I want to make my own progress bar function which calculates some data like remaining seconds data Rate per second etc.
So from here I found one way to use curl progress bar option. how we can enable this option.
I completely done with this.
I put my code below. here in this code my_progress_func calls frequently as per curl library time interval. I want to change this interval time and make it to 1 second. is it possible in curl library using to set some options for curl library?
I want to call this my_progress_func function after every 1 second.
Code :
#include <stdio.h>
#include <curl/curl.h>
long test =0;
struct FtpFile {
const char *filename;
FILE *stream;
long iAppend;
};
static size_t my_fwrite(void *buffer, size_t size, size_t nmemb, void *stream)
{
struct FtpFile *out=(struct FtpFile *)stream;
if(out && !out->stream) {
/* open file for writing */
out->stream=fopen(out->filename, out->iAppend ? "ab":"wb");
if(!out->stream)
return -1; /* failure, can't open file to write */
}
out->iAppend += nmemb;
return fwrite(buffer, size, nmemb, out->stream);
}
int my_progress_func(void *bar,
double t, /* dltotal */
double d, /* dlnow */
double ultotal,
double ulnow)
{
printf("%f : %f \n", d, t);
return 0;
}
int main(void)
{
CURL *curl;
CURLcode res;
int c;
struct FtpFile ftpfile={
"dev.zip", /* name to store the file as if succesful */
NULL,
};
curl_global_init(CURL_GLOBAL_DEFAULT);
curl = curl_easy_init();
if(curl) {
curl_easy_setopt(curl, CURLOPT_URL,
"sftp://root:xyz_#192.170.10.1/mnt/xyz.tar");
curl_easy_setopt(curl, CURLOPT_TIMEOUT, 120L);
/* Define our callback to get called when there's data to be written */
curl_easy_setopt(curl, CURLOPT_WRITEFUNCTION, my_fwrite);
/* Set a pointer to our struct to pass to the callback */
curl_easy_setopt(curl, CURLOPT_WRITEDATA, &ftpfile);
curl_easy_setopt(curl, CURLOPT_FTPPORT, "-");
/* Switch on full protocol/debug output */
curl_easy_setopt(curl, CURLOPT_VERBOSE, 1L);
curl_easy_setopt(curl, CURLOPT_NOPROGRESS, 0L);
curl_easy_setopt(curl, CURLOPT_PROGRESSFUNCTION, my_progress_func);
res = curl_easy_perform(curl);
printf("res is %d\n, data get %ld\n", res, ftpfile.iAppend);
///Retry upto 100 times it timeout or connection drop occur
for (c = 0; (res != CURLE_OK) && (c < 100); c++) {
curl_easy_setopt(curl, CURLOPT_RESUME_FROM , ftpfile.iAppend);
res = curl_easy_perform(curl);
if(res == CURLE_OK) c =0;
printf("%d res is %d\n, data get %ld\n",c, res, ftpfile.iAppend);
}
/* always cleanup */
curl_easy_cleanup(curl);
}
if(ftpfile.stream)
fclose(ftpfile.stream); /* close the local file */
curl_global_cleanup();
return 0;
}

Answer 1

According to the curl documentation:
http://curl.haxx.se/libcurl/c/curl_easy_setopt.html
Function pointer that should match the curl_progress_callback
prototype found in . This function gets called by libcurl
instead of its internal equivalent with a frequent interval during
operation (roughly once per second or sooner) no matter if data is
being transfered or not. Unknown/unused argument values passed to the
callback will be set to zero (like if you only download data, the
upload size will remain 0). Returning a non-zero value from this
callback will cause libcurl to abort the transfer and return
CURLE_ABORTED_BY_CALLBACK.
If it's calling too frequently then you can use time() and a static var to limit this, something like this:
static time_t prevtime;
time_t currtime;
double dif;
static int first = 1;
if(first) {
time(&prevtime);
first = 0;
}
time(&currtime);
dif = difftime(currtime, prevtime);
if(dif < 1.0)
return;
prevtime = currtime;
Obviously, you run the risk that curl might not call this function again for fully another second.