I am making an online tool for identifying certain file types. I need to access some byte values from the file header to do this.
The user selects the file on the client machine. Somehow, I need to get the key byte values from the file, and then these are looked up in a server side database to categorize the file.
How can I read bytes from a client-side file?
I know I could have the user upload the file to the server, but these files are very large, and I only need a few bytes, so it would be slow and wasteful to upload the whole file.
Could I somehow upload part of the file? It seems it is difficult to cancel a html form upload and the file-part is not available after cancel. Is this correct?
Is it possible to read a file in javascript? I have googled this, but the answer is unclear. I have read that it is possible with a java applet, but only if the applet is signed.
Is there some other way?
You can use html5, but will need to fallback on flash or some other non-javascript method for older browsers.
http://www.html5rocks.com/en/tutorials/file/dndfiles/
So. as Said above you must use non-javascript methodds. But each of this methods has some minus.
FLASH - bad work with proxy. Really bad. Of course you can use flash obly for get base64 code of file and give it to js. In this case this will be work greate.
Java Applet - greate work but not many users have JVM or versions of JVM may not be sasme (but if you will use JDK1.4 or 1.5 thi is no problem).
ActiveX - work only in IE and on Windows
HTML5 File Api - not cross browsers solution. Will be work only on last browsers and not in all.
of course much better use server side - in php for example getmimetype and other functions.
But I can manually change headers of my file. For example i can add to php file headers from jpeg or png - and your script will be think that is image.
So this is bad solution : use headers. For check filetype maybe simple use mimetype of file of trust to user and generate icon through file extension
Related
As all of us know, PHP finishes the upload and the enables you to use move_uploaded_file(); before this, however, it creates a temp file and then does the job. I want to know is it possible to get the name of this uploaded file during the file upload and before populating it into $_FILES?
I want to get the upload progress, while $_SESSION and Javascript onprogress solution both suck..
$_FILES['file']['tmp_name']; is the filename. It is not possible in PHP (without using ugly tricks) to get the filename before the upload is finished.
To do this, you have to fallback on either Flash (uploadify) or CGI (Perl / Python / C++ / Other)
A "reliable" progress bar, which seems to be your goal, will always require some sort of server and client support. In its most general and portable instance, PHP will see only the completed upload and you'll get no progress bar, but only the filled $_FILES structure.
On some platforms the information can be garnered from the system itself. For example under Linux/Apache you can inspect what temporary files Apache has opened in the /proc pseudo-filesystem, where available; so you need to put in the requisites "Linux, Apache, php5_module, /proc".
You can use a dedicated POST endpoint that does not terminate on the Web server, but on a specially crafted uploader process (I worked on a Perl script doing this years ago; I recall it used POE, and the architecture):
POST (from browser) ==> (server, proxying) ==> UPLOADER
The uploader immediately echoes a crafted GET to the server, activating
a PHP "pre-upload" page, and then might call a progress GET URL periodically
to update the upload status. When completed, it would issue a pseudo POST
to PHP "almost" as if it came from the client, sending $_POST['_FILES']
instead of $_FILES.
The $_SESSION solution is a good compromise but relies on the server not doing buffering.
A better and more "modern" solution would be to leverage the chunked upload AJAX trick and get resumable uploads, reliable progress and large file support all in one nifty package. See for example this other answer. Now you get wider server support but the solution won't work on some older browsers.
You could offer the user the choice between old-style FILE upload, Flash uploader (which bypasses all problems as it doesn't rely on the browser but on Flash code), Java FTP upload control (same thing, but sometimes with some protocol and firewall issues since it doesn't use HTTP as the container web page does), and AJAX HTML5 chunking, possibly based on browser capabilities.
I.e., a user with IE6 would see a form saying
SORRY!
Your browser does not support large file uploads and progress bar.
To send a file of no more than XXX meg,
[ ] [Choose file...] [ >> BEGIN UPLOAD >>> ]
So far I've figured out HOW to upload files asynchronously with Ajax and PHP, no problem there. But I want to get the percentage of the file that's already been uploaded, as it's uploading, and, after hours of research, I can't find a good way to do this without cheating.
Some implementations I've seen used Flash to upload, and getting the percentage in Flash is apparently fairly common, but I'd like to avoid this if I can.
Any ideas?
The core problem is that RFC 1867, the specification for file uploads over HTTP via the multipart/form-data MIME type, does not provide any method for providing file upload progress.
A file upload is actually just a fancy form submit. CGI scripts, PHP, and all other web technologies that rely on a front-end web server to first accept the request might not actually begin executing until the entire upload has completed. This means that they generally can't even know when the upload has started, only when it's been completed.
New versions of PHP's APC extension include a workaround for this problem that performs some level of black magic that allows it to know about uploads earlier. It only works as part of mod_php, though. The devs don't seem to have plans to support it under FastCGI.
Another server-side option would be the "uploadprogress" PECL extension. I'm not entirely sure what kind of black magic it uses. The source suggests that it actually hooks into the processing of the multipart MIME parts. (This suggests that at least some SAPIs stream form data to PHP as the client uploads it. I know that at least some FastCGI servers buffer the entire request before passing it along, so this might not work for you. YMMV.)
Both of these options are for normal file uploads. Ajax -- or rather, XMLHttpRequest -- does not support file upload operations. Most of the workarounds in this area involve creating an iframe and submitting a form there, and that also implies someone else's client-side work. If you're going to go through that level of hoop jumping, you'd may as well use one of the modern file upload widgets.
Personally, I use Plupload, a Javascript widget that can work with everyone's favorite Javascript library, jQuery. Some others swear by Uploadify. Regardless, both of these widgets offer a high degree of user feedback as to upload progress. They are likely to be easier for you to implement than APC or uploadprogress and have the advantage of being built and tested thoroughly by other people.
Plupload supports multiple upload engines, including HTML5, Gears, Flash, Silverlight, oldschool HTML4 and more. Between HTML5, Flash and Silverlight, you've pretty much just covered 100% of your audience. It also allows you to subscribe to events and have your own code perform magic. For example, if you need server-side file upload progress information, you can have the client regularly send updates to a different script. This would be useful if you regularly have clients uploading huge files and you want to know about it in real time.
tl;dr: Uploading is hard, let's go client-side!
Yeah,I dont like that "cheating" method either, In my opinon, the best method is to use APC , and its method, apc_fetch
Using ajax to make a apc_fetch, with a unique key specifying the upload, will return what you need .. ie bytes uploaded / total bytes.
Then simply do a progress bar with javascript.
I have heard chrome and safari dont allow you to do ajax calls during post upload, the work arround includes using an iframe to do the calls with the apc identifier.
When the user selects a file to be uploaded, is there a way I can get the exact size of this file before the upload even begins? I'm guessing this needs to be done on the client side with jQuery or JavaScript. Any ideas how?
This cannot be done in pure Javascript in current browsers.
Instead, you can use Uploadify, which uses Flash.
In non-IE browsers, you can also use HTML5 to read files on the client.
$("#file_input_selector").bind('change', function(){
alert(this.files[0].size);
});
Not sure of all the compatibility issues, but this seems to be working just fine for me.
Take a look at this post:
http://forums.digitalpoint.com/showthread.php?t=6704
Javascript doesn't have the ability to check file sizes (or access the file system for that matter). You'll need to upload the file to get the size
I suggest you look at the HTML5 File API. This, combined with some JS might be able to help you. I only say might because I have not yet had a chance to browse at this part of the HTML5 standard.
http://www.w3.org/TR/FileAPI/#dfn-filereader
The way PHP file uploads work, it is very hard to check file details before, or during a file upload (since the file is uploaded before your code even gets loaded).
I know it is possible to do some fancy things in some other languages (possibly Perl or Python) that handle the file uploading directly with the script (where the script opens the socket and handles the whole transfer itself), however PHP does this for you and accepts any file on your script's behalf. The file gets discarded if it is not within PHP's acceptable limits, but only after the file is completely uploaded.
There have also been several file upload implementations made using Flash, but not being an ActionScript coder, I can't really help too much there either.
I code primarily in PHP and Perl. I have a client who is insisting on seeking video submissions (any encoding) from the public via one of their pages rather than letting YouTube do its job.
Server in question is a virtual machine and I can adjust ini settings for max post, max upload size etc as needed.
My initial thought is to use a Flash based uploader with PHP on the back end but I wondered if someone might have useful advice and experience on the subject?
Doing large file transfers of HTTP is not usually fun -- but sometimes it's necessary.
For large files, you'll definitely want to provide some kind of progress gauge for end-users.
There are flash-based tools that do this (swfUpload comes to mind).
If you want to avoid flash and do it with pretty html/javascript/css, you can leverage PHP's APC extension, which for some reason provides support for getting upload status from the server, as explained here
You can adjust the post size and use a normal html form. The big problem is not Apache, its http. If anything goes wrong in the transmission you will have no way to detect the error. Further more there is no way to resume the transfer. This is exactly why BitTorrent is so popular.
I don't know how against youtube your client is, but you can use their api to do the uploads from a page on your site.
http://code.google.com/apis/youtube/2.0/developers_guide_protocol.html#Uploading_Videos
See: browser based uploading.
For web-based uploads, there's not many options. Regardless of web platform, web server, etc. you're still transferring over HTTP. The transfer is all or nothing.
Your best option might be to find a Flash, Java, or other client side option that can chunk files and upload them piecemeal, then do a checksum to verify. That will allow for resuming uploads. Unfortunately, I don't know of any such open source component that does this.
Try to convince your client to change point of view.
Using http (and the browser, hell, the browser!) for this kind of issue is rarely a good deal; Will his users wait 40 minutes with the computer and the browser running until the upload is complete?
I dont think so.
Maybe, you could set up a public ftp account, where users can upload but not download and see the others user's files.. then, who want to use FTP software can, who like to do it via browser can too.
The big problem dealing using a browser is that, if something go wrong, you cant resume but have to restart from zero again.
the past year i had the same issue, i gave a look to ZUpload
, but i didnt use it so i can suggest (we wrote a small python script that we send to our customer; the python script create a torrent of the folder our costumer need to send to us, and we download it via utorrent ;)
p.s: again, sorry for my bad english ;)
I used jupload. Yes it looks horrible, but it just works.
With that said, it's still a better idea to convince the client that doing so is stupid.
I would agree with others stating that using HTML is a poor option. I believe there is a size limitation using Flash as well. I know of a script that uses a JavaScript Applet to perform an actual FTP transfer. It is called Simple2FTP and can be found at http://www.simple2ftp.com
Not sure but perhaps worth a try?
I need to stream an flv file.
Streaming should look like live streaming,
and I there should be a way to change the target file.
Sorry for my poor English.
If by "streaming" you mean "showing a flash-video clip", flv-streaming isn't really streaming, but it's a normal file transfer, with the flash player starting playback even if the file isn't completely downloaded to the client. Time seeking is implemented in a standard HTTP way, with a file download offset - if you scroll the video halfway on the timeline and it hasn't downloaded yet, the current download is (most often) aborted, and restarted with an offset of filesize/2 bytes.
So, you could be fine with just using plain old readfile() and fixing the HTTP mime-type headers appropriately with header(). But, since you'd need seeking, you need to parse the HTTP request and instead of readfile(), use fpassthru(), seeking the right place, instead.
tl;dr: Avoid handling this on the PHP side, and let Apache (or the httpd of your choice) handle this instead.
I'm not quite sure what you're asking about, but if you have a bunch of media files and want to play them with a Youtube-esque media player on your website, I suggest checking out Flowplayer - It has an amazing Javascript API that lets you do all kinds of cool stuff to the player, including handling stuff like playlists and programmatically changing the current video.
I recently used it on a project with great results.