CURLOPT_XFERINFOFUNCTION: introducing a new progress callback

CURLOPT_XFERINFOFUNCTION is now the preferred progress callback function
and CURLOPT_PROGRESSFUNCTION is considered deprecated.

This new callback uses pure 'curl_off_t' arguments to pass on full
resolution sizes. It otherwise retains the same characteristics: the
same call rate, the same meanings for the arguments and the return code
is used the same way.

The progressfunc.c example is updated to show how to use the new
callback for newer libcurls while supporting the older one if built with
an older libcurl or even built with a newer libcurl while running with
an older.

1 files changed, 41 insertions, 6 deletions

diff --git a/docs/examples/progressfunc.c b/docs/examples/progressfunc.c
index 51a9c9b5e..b2635bc8a 100644
--- a/docs/examples/progressfunc.c
+++ b/docs/examples/progressfunc.c
@@ -5,7 +5,7 @@
  *                            | (__| |_| |  _ <| |___
  *                             \___|\___/|_| \_\_____|
  *
- * Copyright (C) 1998 - 2011, Daniel Stenberg, <daniel@haxx.se>, et al.
+ * Copyright (C) 1998 - 2013, Daniel Stenberg, <daniel@haxx.se>, et al.
  *
  * This software is licensed as described in the file COPYING, which
  * you should have received as part of this distribution. The terms
@@ -30,9 +30,10 @@ struct myprogress {
   CURL *curl;
 };
 
-static int progress(void *p,
-                    double dltotal, double dlnow,
-                    double ultotal, double ulnow)
+/* this is how the CURLOPT_XFERINFOFUNCTION callback works */
+static int xferinfo(void *p,
+                    curl_off_t dltotal, curl_off_t dlnow,
+                    curl_off_t ultotal, curl_off_t ulnow)
 {
   struct myprogress *myp = (struct myprogress *)p;
   CURL *curl = myp->curl;
@@ -48,7 +49,9 @@ static int progress(void *p,
     fprintf(stderr, "TOTAL TIME: %f \r\n", curtime);
   }
 
-  fprintf(stderr, "UP: %g of %g  DOWN: %g of %g\r\n",
+  fprintf(stderr, "UP: %" CURL_FORMAT_CURL_OFF_T " of %" CURL_FORMAT_CURL_OFF_T
+          "  DOWN: %" CURL_FORMAT_CURL_OFF_T " of %" CURL_FORMAT_CURL_OFF_T
+          "\r\n",
           ulnow, ultotal, dlnow, dltotal);
 
   if(dlnow > STOP_DOWNLOAD_AFTER_THIS_MANY_BYTES)
@@ -56,6 +59,19 @@ static int progress(void *p,
   return 0;
 }
 
+/* for libcurl older than 7.32.0 (CURLOPT_PROGRESSFUNCTION) */
+static int older_progress(void *p,
+                          double dltotal, double dlnow,
+                          double ultotal, double ulnow)
+{
+  return xferinfo(p,
+                  (curl_off_t)dltotal,
+                  (curl_off_t)dlnow,
+                  (curl_off_t)ultotal,
+                  (curl_off_t)ulnow);
+}
+
+
 int main(void)
 {
   CURL *curl;
@@ -68,9 +84,28 @@ int main(void)
     prog.curl = curl;
 
     curl_easy_setopt(curl, CURLOPT_URL, "http://example.com/");
-    curl_easy_setopt(curl, CURLOPT_PROGRESSFUNCTION, progress);
+
+    curl_easy_setopt(curl, CURLOPT_PROGRESSFUNCTION, older_progress);
     /* pass the struct pointer into the progress function */
     curl_easy_setopt(curl, CURLOPT_PROGRESSDATA, &prog);
+
+#if LIBCURL_VERSION_NUM >= 0x072000
+    /* xferinfo was introduced in 7.32.0, no earlier libcurl versions will
+       compile as they won't have the symbols around.
+
+       If built with a newer libcurl, but running with an older libcurl:
+       curl_easy_setopt() will fail in run-time trying to set the new
+       callback, making the older callback get used.
+
+       New libcurls will prefer the new callback and instead use that one even
+       if both callbacks are set. */
+
+    curl_easy_setopt(curl, CURLOPT_XFERINFOFUNCTION, xferinfo);
+    /* pass the struct pointer into the xferinfo function, note that this is
+       an alias to CURLOPT_PROGRESSDATA */
+    curl_easy_setopt(curl, CURLOPT_XFERINFODATA, &prog);
+#endif
+
     curl_easy_setopt(curl, CURLOPT_NOPROGRESS, 0L);
     res = curl_easy_perform(curl);