How use CURLOPT_WRITEFUNCTION when download a file by CURL - php

Question

My Class for download file direct from a link:
MyClass{
function download($link){
......
$ch = curl_init($link);
curl_setopt($ch, CURLOPT_FILE, $File->handle);
curl_setopt($ch,CURLOPT_WRITEFUNCTION , array($this,'__writeFunction'));
curl_exec($ch);
curl_close($ch);
$File->close();
......
}
function __writeFunction($curl, $data) {
return strlen($data);
}
}
I want know how to use CRULOPT_WRITEFUNCTION when download file.
Above code if i remove line:
curl_setopt($ch,CURLOPT_WRITEFUNCTION , array($this,'__writeFunction'));
Then it will run good, i can download that file.But if i use CURL_WRITEFUNCTION option i can't download file.

Answer 1

I know this is an old question, but maybe my answer will be of some help for you or someone else. Try this:
function get_write_function(){
return function($curl, $data){
return strlen($data);
}
}
I don't know exactly what you want to do, but with PHP 5.3, you can do a lot with the callback. What's really great about generating a function in this way is that the values passed through the 'use' keyword remain with the function afterward, kind of like constants.
function get_write_function($var){
$obj = $this;//access variables or functions within your class with the object variable
return function($curl, $data) use ($var, $obj) {
$len = strlen($data);
//just an example - you can come up with something better than this:
if ($len > $var){
return -1;//abort the download
} else {
$obj->do_something();//call a class function
return $len;
}
}
}
You can retrieve the function as a variable as follows:
function download($link){
......
$var = 5000;
$write_function = $this->get_write_function($var);
$ch = curl_init($link);
curl_setopt($ch, CURLOPT_FILE, $File->handle);
curl_setopt($ch, CURLOPT_WRITEFUNCTION , $write_function);
curl_exec($ch);
curl_close($ch);
$File->close();
......
}
That was just an example. You can see how I used it here: Parallel cURL Request with WRITEFUNCTION Callback. I didn't actually test all of this code, so there may be minor errors. Let me know if you have problems, and I'll fix it.

Answer 2

<?php
$ch = curl_init();
curl_setopt($ch, CURLOPT_BUFFERSIZE, 8096);
curl_setopt($ch, CURLOPT_BINARYTRANSFER, true);
curl_setopt ($ch, CURLOPT_RETURNTRANSFER, 1);
curl_setopt($ch, CURLOPT_URL, 'http://blog.ronnyristau.de/wp-content/uploads/2008/12/php.jpg');
$content = curl_exec($ch);
curl_close($ch);
$out = fopen('/tmp/out.png','w');
if($out){
fwrite($out, $content);
fclose($out);
}

Answer 3

Why do you use curl to download a file? Is there a special reason? You can simply use fopen and fread
I have written a small class for it.
<?php
class Utils_FileDownload {
private $source;
private $dest;
private $buffer;
private $overwrite;
public function __construct($source,$dest,$buffer=4096,$overwrite=false){
$this->source = $source;
$this->dest = $dest;
$this->buffer = $buffer;
$this->overwrite = $overwrite;
}
public function download(){
if($this->overwrite||!file_exists($this->dest)){
if(!is_dir(dirname($this->dest))){mkdir(dirname($this->dest),0755,true);}
if($this->source==""){
$resource = false;
Utils_Logging_Logger::getLogger()->log("source must not be empty.",Utils_Logging_Logger::TYPE_ERROR);
}
else{ $resource = fopen($this->source,"rb"); }
if($this->source==""){
$dest = false;
Utils_Logging_Logger::getLogger()->log("destination must not be empty.",Utils_Logging_Logger::TYPE_ERROR);
}
else{ $dest = fopen($this->dest,"wb"); }
if($resource!==false&&$dest!==false){
while(!feof($resource)){
$read = fread($resource,$this->buffer);
fwrite($dest,$read,$this->buffer);
}
chmod($this->dest,0644);
fclose($dest); fclose($resource);
return true;
}else{
return false;
}
}else{
return false;
}
}
}

Answer 4

It seems like cURL uses your function instead of writing to the request once CURLOPT_WRITEFUNCTION is specified.
So the correct solution would be :
MyClass{
function download($link){
......
$ch = curl_init($link);
curl_setopt($ch, CURLOPT_FILE, $File->handle);
curl_setopt($ch,CURLOPT_WRITEFUNCTION , array($this,'__writeFunction'));
curl_exec($ch);
curl_close($ch);
$File->close();
......
}
function __writeFunction($curl, $data) {
echo $data;
return strlen($data);
}
}
This can also handle binary files as well.