How to debug browser hang during upload - codeigniter

Question

I am writing a simple file uploader in CodeIgniter 2.0.2. Pasting code below.
Under certain conditions the browser hangs during this upload and I get "waiting for localhost" in the browser status bar (identical behavior in FF and Chrome).
I have verified that the file is being uploaded to the Windows temporary folder (the complete file), but the process gets stuck after that.
It appears that the condition for the bug is file size. But my php.ini has all the right settings for uploading files, and I still get the hang with a 700k file.
This bug occurs only when I run it on Windows 7 Apache, not on an Ubuntu box.
The suggested to me that some paths in the php.ini may be incorrectly set.
Apache log files have not been much help here because there is no error thrown.
I have tried using Chrome developer panel to debug but haven't turned up anything useful.
I am currently trying to get XDebug working, but since no error is thrown and the process doesn't complete, my expectations are low.
Any suggestions for how to trace this bug?
If there are specific php.ini settings you'd like to see, let me know, don't want to do the big dump.
Controller:
function do_upload_sql(){
// create directory
if (! is_dir(BACKUP_DIR)) {
mkdir(BACKUP_DIR, 0777);
}
// or if it exists and has restricted file permissions, change them
elseif(fileperms(BACKUP_DIR)!=0777){
chmod(BACKUP_DIR, 0777);
}
$config['upload_path'] = BACKUP_DIR;
$config['allowed_types'] = 'backup'; // an SQL backup file type
$config['overwrite'] = TRUE;
$this->load->library('upload', $config);
if ( ! $this->upload->do_upload()) // this is the native CI function, probably where the problem is. I can provide some of that code if anyone wants.
{
$data['action'] = 'c_backup_restore/do_upload_sql';
$tab_error = array('error' => $this->upload->display_errors());
$data['error'] = $tab_error['error'];
$this->load->view('common/header');
$this->load->view('v_upload_sql', $data);
}
else
{
echo "success"; // yes it's getting here, but i get no file!
$data = array('upload_data' => $this->upload->data());
$file_upload = $data["upload_data"];
$this->restore_backup($file_upload); // go do something useful with the file
}
}
View:
<p>Select the backup file</p>
<div class="not_success"><?php echo $error;?></div>
<?php echo form_open_multipart($action);?>
<input type="file" name="userfile" size="30" />
<input type="submit" value="Upload" />
</form>

Answer 1

If your error only occurs on windows 7 apache, I think that your issue may be with the "is_dir()" "mkdir()" and "chmod()" commands -- these terminal commands are linux specific and will not work so great on a windows system.
I looked up the documentation on the mkdir() function in the PHP.net Manual at:
http://us.php.net/manual/en/function.mkdir.php
I found this in the comments section:
kendsnyder at gmail dot com 04-May-2007 08:17
When creating directories in Windows, trailing periods (".") are ignored. for example:
<?php
mkdir('c:/Buck Jr.',0755); // on Windows creates "c:/Buck Jr"
mkdir('c:/Elipses...',0755); // on Windows creates "c:/Elipses"
mkdir('c:/php.com',0755); // on Windows creates "c:/php.com"
?>
This is a Window's quirk, not a php shortcoming--meaning that you get the same results from a Window's command prompt.
So it seems it will work... but you are likely to have to futz with it to find the flavor that Windows systems prefer. Also it seems that you must specify the root drive on which to make the directory, e.g.: 'c:\somedir'
Also of interest, I did a quick google search and discovered that PHP has published a bug around the functionality you are using, specifically related to forward vs. back slashes of the windows vs. linux systems:
https://bugs.php.net/bug.php?id=29797
Here is a StackOverflow post related to your question:
PHP mkdir(), chmod() and Windows
So to summarize:
On a windows based web server, include the drive that the directory will be placed on
File Permissions on Windows are different from Linux (Windows doesn't have a chmod or file permissions structure like Linux!) Although from what I can tell Windows is supposed give a folder the equivalent of a 777 permissions level -- but this functionality seems buggy and error prone. But this also means that using the chmod() function on a windows system, you will get unpredictable results. For more info consult the PHP Manual: http://php.net/manual/en/function.chmod.php
Remember to use backslashes rather than forward slashes for the directory path, as Windows systems use back slashes, whereas Linux uses forward slashes.
When PHP creates a directory it uses the permissions that were granted to the user account that PHP is running under, which means that you may have to dig into windows to find what user permissions level your windows 7 Apache/PHP is running under and make that change there. I know, what a pain, right?
One final thing: mkdir() function returns true if the directory creation was successful and false if not -- you may want to be testing for that condition before proceeding with the rest of your code, because if the directory doesn't properly get created, all the rest of your code that relies on that directory existing is going to fail. Ultimately I think your browser is hanging upon submit because it is trying to access a function through PHP which there is no support for on Windows (chmod). Perform the function calls within a "Try/Catch" block to catch any exceptions that occur so that you can print them to screen or a log file if necessary:
$proceed = false;
try
{
// create directory
if (! is_dir(BACKUP_DIR)) {
$proceed = mkdir(BACKUP_DIR, 0777);
}
// or if it exists and has restricted file permissions, change them
elseif(fileperms(BACKUP_DIR)!=0777){
$proceed = chmod(BACKUP_DIR, 0777);
}
}
catch(Exception $e)
{
echo $e->message;
}
if($proceed == TRUE)
{
/*Proceed with your code*/
}
else
{
/*Gracefully fail*/
}
Good luck man, this is why I prefer Linux Boxes for web servers!
Cheers!