efl_net_dialer_http: fix interaction with CURL on receiving data.

When CURLOPT_WRITEFUNCTION returns less then the requested amount,
CURL will fail, not call us back with the remaining data.

Then in such cases we must pause CURL and read nothing.

When unpausing we need to kick curl with timeout action so FD handlers
will be re-arranged.

Last but not least, sync our buffer limit with CURL, otherwise it may
always fail if we're smaller than CURL.

src/lib/ecore_con/ecore_con_url_curl.h

@@ -253,6 +253,7 @@ typedef enum
    CINIT(DEBUGFUNCTION, FUNCTIONPOINT, 94),
    CINIT(DEBUGDATA, OBJECTPOINT, 95),
    CINIT(COOKIESESSION, LONG, 96),
+   CINIT(BUFFERSIZE, LONG, 98),
    CINIT(PROXYTYPE, LONG, 101),
    CINIT(ACCEPT_ENCODING, OBJECTPOINT, 102),
    CINIT(PRIVATE, OBJECTPOINT, 103),

src/lib/ecore_con/efl_net_dialer_http.c

@@ -942,8 +942,12 @@ _efl_net_dialer_http_receive_data_safe(Eo *o, Efl_Net_Dialer_Http_Data *pd, Eina
         return ro_slice.len;
      }
 
-   if (rw_slice.len == 0)
+   if (rw_slice.len < ro_slice.len)
      {
+        /* throttle CURL and let users read */
+        DBG("dialer=%p in=%zd, available %zd (limit=%zd)",
+            o, ro_slice.len, pd->recv.limit - pd->recv.used, pd->recv.limit);
+        efl_io_reader_can_read_set(o, EINA_TRUE);
         pd->pause |= CURLPAUSE_RECV;
         return CURL_WRITEFUNC_PAUSE;
       }
@@ -955,12 +959,6 @@ _efl_net_dialer_http_receive_data_safe(Eo *o, Efl_Net_Dialer_Http_Data *pd, Eina
    // pd->buf.recv inside _efl_io_reader_read()
    efl_io_reader_can_read_set(o, EINA_TRUE);
 
-   if (rw_slice.len == 0)
-     {
-        pd->pause |= CURLPAUSE_RECV;
-        return CURL_WRITEFUNC_PAUSE;
-     }
-
    return rw_slice.len;
 }
 
@@ -982,7 +980,10 @@ _efl_net_dialer_http_receive_data(const void *buffer, size_t count, size_t nitem
    ret = _efl_net_dialer_http_receive_data_safe(o, pd, ro_slice);
 
    _efl_net_dialer_http_curl_safe_end(o, pd, easy);
-   DBG("dialer=%p in=%zd used=%zd", o, ro_slice.len, ret);
+   if (ret == CURL_WRITEFUNC_PAUSE)
+     DBG("dialer=%p in=%zd is now paused", o, ro_slice.len);
+   else
+     DBG("dialer=%p in=%zd used=%zd", o, ro_slice.len, ret);
 
    return ret;
 }
@@ -1136,6 +1137,7 @@ _efl_net_dialer_http_efl_object_constructor(Eo *o, Efl_Net_Dialer_Http_Data *pd)
    curl_easy_setopt(pd->easy, CURLOPT_HEADERDATA, o);
    curl_easy_setopt(pd->easy, CURLOPT_WRITEFUNCTION, _efl_net_dialer_http_receive_data);
    curl_easy_setopt(pd->easy, CURLOPT_WRITEDATA, o);
+   curl_easy_setopt(pd->easy, CURLOPT_BUFFERSIZE, (long)pd->recv.limit);
    curl_easy_setopt(pd->easy, CURLOPT_READFUNCTION, _efl_net_dialer_http_send_data);
    curl_easy_setopt(pd->easy, CURLOPT_READDATA, o);
 
@@ -1368,6 +1370,34 @@ _efl_net_dialer_http_efl_net_socket_address_remote_get(Eo *o EINA_UNUSED, Efl_Ne
    return pd->address_remote;
 }
 
+static Eina_Error
+_efl_net_dialer_http_pause_reset(Eo *o, Efl_Net_Dialer_Http_Data *pd)
+{
+   CURLcode re;
+   CURLMcode rm;
+   Eina_Error err;
+
+   re = curl_easy_pause(pd->easy, pd->pause);
+   if (re != CURLE_OK)
+     {
+        err = _curlcode_to_eina_error(re);
+        ERR("dialer=%p could not unpause receive (flags=%#x): %s",
+            o, pd->pause, eina_error_msg_get(err));
+        return err;
+     }
+
+   rm = curl_multi_socket_action(pd->cm->multi, CURL_SOCKET_TIMEOUT, 0, &pd->cm->running);
+   if (rm != CURLM_OK)
+     {
+        err = _curlmcode_to_eina_error(rm);
+        ERR("dialer=%p could trigger timeout action: %s",
+            o, eina_error_msg_get(err));
+        return err;
+     }
+
+   return 0;
+}
+
 EOLIAN static Eina_Error
 _efl_net_dialer_http_efl_io_reader_read(Eo *o, Efl_Net_Dialer_Http_Data *pd, Eina_Rw_Slice *rw_slice)
 {
@@ -1395,16 +1425,11 @@ _efl_net_dialer_http_efl_io_reader_read(Eo *o, Efl_Net_Dialer_Http_Data *pd, Ein
 
    if ((pd->pause & CURLPAUSE_RECV) && (pd->recv.used < pd->recv.limit))
      {
-        CURLcode r;
+        Eina_Error err;
         pd->pause &= ~CURLPAUSE_RECV;
-        r = curl_easy_pause(pd->easy, pd->pause);
-        if (r != CURLE_OK)
-          {
-             Eina_Error err = _curlcode_to_eina_error(r);
-             ERR("dialer=%p could not unpause receive (flags=%#x): %s",
-                 o, pd->pause, eina_error_msg_get(err));
-             return err;
-          }
+        err = _efl_net_dialer_http_pause_reset(o, pd);
+        if (err)
+          return err;
      }
 
    return 0;
@@ -1447,7 +1472,6 @@ _efl_net_dialer_http_efl_io_writer_write(Eo *o, Efl_Net_Dialer_Http_Data *pd, Ei
 {
    Eina_Error err = EINVAL;
    CURLMcode rm;
-   CURLcode re;
 
    EINA_SAFETY_ON_NULL_RETURN_VAL(slice, EINVAL);
    EINA_SAFETY_ON_TRUE_GOTO(efl_io_closer_closed_get(o), error);
@@ -1457,14 +1481,8 @@ _efl_net_dialer_http_efl_io_writer_write(Eo *o, Efl_Net_Dialer_Http_Data *pd, Ei
    pd->send.slice = *slice;
    efl_io_writer_can_write_set(o, EINA_FALSE);
    pd->pause &= ~CURLPAUSE_SEND;
-   re = curl_easy_pause(pd->easy, pd->pause);
-   if (re != CURLE_OK)
-     {
-        err = _curlcode_to_eina_error(re);
-        ERR("dialer=%p could not unpause send (flags=%#x): %s",
-            o, pd->pause, eina_error_msg_get(err));
-        goto error;
-     }
+   err = _efl_net_dialer_http_pause_reset(o, pd);
+   if (err) goto error;
 
    pd->error = 0;
    rm = curl_multi_socket_action(pd->cm->multi,