Forum PHP 2017

Common Pitfalls

La voce MAX_FILE_SIZE non può specificare una dimensione del file maggiore di quella impostata dal parametro upload_max_filesize del file php.ini. L'impostazione di default è 2 megabytes.

Se si è impostato un limite di memoria memory_limit può essere necessario ampliarlo. Occorre essere certi di impostare memory_limit alle dimensioni appropriate.

Se max_execution_time è impostato ad un valore basso, l'esecuzione dello script può eccedere tale valore. Ampliare max_execution_time ad un tempo sufficiente per l'upload.

Nota: max_execution_time influisce solo sul tempo di esecuzione dello script. Il tempo utilizzato per attività esterno allo script, tipo le chiamate di sistema system(), o la funzione sleep(), le query nei database, il tempo inpiegato nell'upload del file non è considerato nel computo del tempo di esecuzione dello script.


max_input_time imposta il tempo massimo, in secondi, in cui lo script può ricevere dati; questo comprende l'upload di file. Per file di grandi dimensioni o molteplici file, o su connessioni lente, il valore di default 60 seconds può essere sforato.

Se post_max_size è impostato ad un valore troppo piccolo, non si può inviare file di grosse dimensioni. Impostare post_max_size alle dimensioni appropriate.

Da PHP 5.2.12, il parametro di configurazione max_file_uploads controlla il numeo massimo di file che possono essere caricati in una singola richiesta. Se sono caricati più file del limite fissato, allora $_FILES smetterà di processare i file una volta che il limite è raggiunto. Per esempio, se max_file_uploads è impostato a 10, allora $_FILES non conterrà mai più di 10 elementi.

Non controllare il file su cui si sta operando potrebbe dare agli utenti accesso a informazioni sensibili contenute in altre directory.

Si noti che che il server CERN httpd sembra eliminare qualsiasi cosa a partire dal primo spazio nell'header mime content-type che riceve dal client. Fino a che questo si verificherà, il server CERN httpd non supporterà la possibilità di caricare file.

A causa della varietà di formati di directory, non si è in grado di garantire che nomi di file strani (ad esempio contenenti spazi) siano gestiti correttamente.

Un sviluppatore non può mischiare normali campi di input con campi di upload di file con lo stesso nome di campo (utilizzando nomi tipo foo[]).

add a note add a note

User Contributed Notes 11 notes

amalcon _a_t_ eudoramail _d_o_t_ com
12 years ago
Note that, when you want to upload VERY large files (or you want to set the limiters VERY high for test purposes), all of the upload file size limiters are stored in signed 32-bit ints.  This means that setting a limit higher than about 2.1 GB will result in PHP seeing a large negative number.  I have not found any way around this.
adrien.nizon+phpnet at gmail dot com
9 months ago
[Editor's note: to be more precise, MAX_FILE_SIZE can't exceed PHP_INT_MAX before PHP 7.1.]

Please note that the field MAX_FILE_SIZE cannot exceed 2147483647. Any greater value will lead to an upload error that will be displayed at the end of the upload

This is explained by the related C code :
if (!strcasecmp(param, "MAX_FILE_SIZE")) {
    max_file_size = atol(value);

The string is converted into a long int, which max value is... 2147483647

Seems to be corrected since php-7.1.0beta3 (
admin at creationfarm dot com
14 years ago
The macintosh OS (not sure about OSx) uses a dual forked file system, unlike the rest of the world ;-). Every macintosh file has a data fork and a resource fork. When a dual forked file hits a single forked file system, something has to go, and it is the resource fork. This was recognized as a problem (bad idea to begin with) and apple started recomending that developers avoid sticking vital file info in the resource fork portion of a file, but some files are still very sensitive to this. The main ones to watch out for are macintosh font files and executables, once the resource fork is gone from a mac font or an executable it is useless. To protect the files they should be stuffed or zipped prior to upload to protect the resource fork.

Most mac ftp clients (like fetch) allow files to be uploaded in Macbinhex, which will also protect the resource fork when transfering files via ftp. I have not seen this equivilent in any mac browser (but I haven't done too much digging either).

FYI, apple does have an old utility called ResEdit that lets you manipulate the resource fork portion of a file.
Nirmal Natarajan
7 years ago
If using IIS 7.0 or above, the Request Filtering is enabled by default and the max allowed content length is set to 30 MB.

One must change this value if they want to allow file uploads of more than 30 MB.

Sample web.config entry:

                <requestLimits maxAllowedContentLength="314572800"/>

The above setting will allow 300 MB of data to be sent as a request. Hope this helps someone.
sebastian at drozdz dot ch
14 years ago
It's important that the variable 'open_basedir' in php.ini isn't  set to a directory that doesn't not includes tempupload directory
dg at artegic dot de
7 years ago
In case of non-deterministic occurence of the UPLOAD_ERR_PARTIAL error:  The HTTPD (e.g. Apache) should respond with a 'Accept-Ranges: none' header field.
tjaart at siam-data-services dot com
12 years ago
Took me a while to figure this one out...

I think this is actually a header problem, but it only
happens when doing a file upload.

If you attept a header("location:http://...) redirect after
processing a $_POST[''] from a form doing a file upload
(i.e. having enctype="multipart/form-data"), the redirect
doesn't work in IE if you don't have a space between
location: & http, i.e.
header("location:http://...)  vs
header("location: http://...)

if ($_POST['submit']=='Upload') {
// Process File and the redirect...
header("location: http://"..."/somewhere.php");
<form enctype="multipart/form-data" action="upload.php" method="POST">
    <input type="hidden" name="MAX_FILE_SIZE" value="20000">
    Your file: <input name="filename" type="file">
    <input name="submit" type="submit" value="Upload">

This only happens if all of the following are true:
header("location:http://...) with no space
Form being processed has enctype="multipart/form-data"

To fix the problem, simply add the space.

Hope this helps someone else.
morganaj at coleggwent dot ac dot uk
13 years ago
Here is another that may make your upload fall over.  If you are using Squid or similar proxy server make sure that this is not limiting the size of the HTTP headers. This took me weeks to figure out!
anders jenbo pc dk
9 years ago
A responce to admin at creationfarm dot com, Mac OS X and Windows running on a NTFS disk also uses a multi stream file system. Still only the data stream in transfared on http upload. It is preferable to pack Mac OS X files in .dmg files rathere then zip but the avarage user will find zip much easir and they are supported on more platforms.
tomcashman at unitekgroup dot com
14 years ago
For apache, also check the LimitRequestBody directive.
If you're running a Red Hat install, this might be set in /etc/httpd/conf.d/php.conf.
By default, mine was set to 512 KB.
oliver dot schmidt at drehsinn dot de
10 years ago
If you want to use open_basedir for securing your server (which is highly recommended!!!) remember to add your tmp dir to the open_basedir value in php.ini.

Example: open_basedir = <your htdocs root, etc...>:/tmp

(Tested on gentoo Linux, Apache 2.2, PHP 5.1.6)
To Top