Fileinfo 函数
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finfo_file

finfo::file

(PHP >= 5.3.0, PECL fileinfo >= 0.1.0)

finfo_file -- finfo::file — Return information about a file

说明

过程化风格

string finfo_file ( resource $finfo , string $file_name = NULL [, int $options = FILEINFO_NONE [, resource $context = NULL ]] )

面向对象风格

string finfo::file ( string $file_name = NULL [, int $options = FILEINFO_NONE [, resource $context = NULL ]] )

This function is used to get information about a file.

参数

finfo

Fileinfo resource returned by finfo_open().

file_name

Name of a file to be checked.

options

One or disjunction of more Fileinfo constants.

context

For a description of contexts, refer to Stream 函数.

返回值

Returns a textual description of the contents of the filename argument, or FALSE if an error occurred.

范例

Example #1 A finfo_file() example

<?php
$finfo = finfo_open(FILEINFO_MIME_TYPE); // return mime type ala mimetype extension
foreach (glob("*") as $filename) {
    echo finfo_file($finfo, $filename) . "\n";
}
finfo_close($finfo);
?>

以上例程的输出类似于：

text/html
image/gif
application/vnd.ms-excel

参见

Fileinfo 函数
在线手册：中文 英文
PHP手册
PHP手册 - N: Return information about a file

用户评论:

contato at vfreitas dot com (02-Mar-2012 02:31)

Well, i have a great probleam with that, MS Office 2007 extensions (pptx, xlsx, docx) do not have a default Mime type, they have "application/zip" mime type, so, to fix that, i do one little function to verify the extension.
That function allow's you to be safe of fake extensions hack.

<?php

$arrayZips = array("application/zip", "application/x-zip", "application/x-zip-compressed");

$arrayExtensions = array(".pptx", ".docx", ".dotx", ".xlsx");

$file = 'path/to/file.xlsx';

$original_extension = (false === $pos = strrpos($file, '.')) ? '' : substr($file, $pos);

$finfo = new finfo(FILEINFO_MIME);

$type = $finfo->file($file);

if (in_array($type, $arrayZips) && in_array($original_extension, $arrayExtensions))
{
   return $original_extension;
}

?>

Zane MegaLab.it (13-Jun-2011 04:38)

I was getting application/octet-stream or "<= not supported" for all the files.

I found out that in PHP 5.3 the magic file is built-in into PHP and that is what should be used. The magic file found on the system may not always be what libmagic expects, hence the error.

info at tech dash bits dot net (13-Feb-2011 09:34)

While figuring out my problem using this new function, i had a brainwave in using the full path of the file instead of the relative path. For example:

<?php
$folder = "somefolder/";
$fileName "aFile.pdf";

$finfo = finfo_open(FILEINFO_MIME_TYPE);
finfo_file($finfo, $folder.$fileName);
?>

This will result in an error where it can't find the file specified.

This however fixxes that problem:

<?php
$folder = "somefolder/";
$fileName "aFile.pdf";

$finfo = finfo_open(FILEINFO_MIME_TYPE);
$mime = finfo_file($finfo, dirname(__FILE__)."/".$folder.$fileName);
?>

scott at thebrain dot ca (07-Jan-2009 05:29)

I thought to use fileinfo to check if a file was gzip or bzip2. However, the mime type of a compressed file is "data" because compression is an encoding rather than a type.

gzip files begin with binary 1f8b.
bzip2 files begin with magic bytes 'B'  'Z'  'h'.
e.g.

<?php
$s = file_get_contents("somefilepath");
if ( bin2hex(substr($s,0,2)) == '1f8b' ) {/* could be a gzip file */}
if( substr($s,0,3) == 'BZh' ){/* could be a bzip2 file */}
?>

I am not an encoding expert. My only testing was using a few of my own encoded files.

darko at uvcms dot com (01-Aug-2008 04:28)

OO (bit improved) version of the same thing

<?php
$file = '<somefile>';
$ftype = 'application/octet-stream';
$finfo = @new finfo(FILEINFO_MIME);
$fres = @$finfo->file($file);
if (is_string($fres) && !empty($fres)) {
   $ftype = $fres;
}
?>

darko at uvcms dot com (24-Apr-2008 05:53)

Another interresting feature of finfo_file on Windows.

This function can return empty string instead of FALSE for some file types (ppt for example). Therefore to be sure do a triple check of output result and provide default type just in case. Here is a sample code:

$ftype = 'application/octet-stream';
$finfo = @finfo_open(FILEINFO_MIME);
if ($finfo !== FALSE) {
   $fres = @finfo_file($finfo, $file);
   if ( ($fres !== FALSE)
        && is_string($fres)
        && (strlen($fres)>0)) {
            $ftype = $fres;
        }
   @finfo_close($finfo);
}

WebShowPro (25-Sep-2007 10:01)

Just an improvement on the sample Ryan Day posted - slightly off topic since this method does not use finfo_file but in some cases this method might be preferable.

The main change is the -format %m parameters given to the identify call.  I would suggest using the full system path to identify i.e. /usr/bin/identify to be a little safer (the location may change from server to server though).

<?php

function is_jpg($fullpathtoimage){
    if(file_exists($fullpathtoimage)){
        exec("/usr/bin/identify -format %m $fullpathtoimage",$out);
        //using system() echos STDOUT automatically
        if(!empty($out)){
            //identify returns an empty result to php
            //if the file is not an image
           
            if($out == 'JPEG'){
                return true;
            }
        }
    }
    return false;
}

?>

Ryan Day (31-Aug-2007 10:34)

to check images on unix based systems its much better to use the identify command provided by image magic as it provides accurate results about all files

<?php
function is_jpg($fullpathtoimage){
    if(file_exists($fullpathtoimage)){
        exec("identify $fullpathtoimage",$out);
        //using system() echos STDOUT automatically
        if(!empty($out)){
            //identify returns an empty result to php
            //if the file is not an image
            $info = $out[0];
            $info = explode(' ',$out[0]);
            //^IF THE FILENAME CONTAINS SPACES
            //^THIS WILL NOT WORK...be creative
            $type = $info[1];
            if($type == 'JPEG'){
                return true;
            }
        }
    }
    return false;
}
?>

identify can process all types of images that are web friendly
sample output:
./image/someimage.jpg JPEG 150x112 150x112+0+0 DirectClass 8-bit 4.54688kb
if you dont want to control the image name or want to support spaces use: escapeshellarg()
http://us2.php.net/manual/en/function.escapeshellarg.php

function links:
exec() -- http://us2.php.net/manual/en/function.exec.php
explode() -- http://us2.php.net/manual/en/function.explode.php

Schraalhans Keukenmeester (21-May-2007 11:20)

Tempting as it may seem to use finfo_file() to validate uploaded image files (Check whether a supposed imagefile really contains an image), the results cannot be trusted. It's not that hard to wrap harmful executable code in a file identified as a GIF for instance.

A better & safer option is to check the result of:

if (!$img = @imagecreatefromgif($uploadedfilename)) {
  trigger_error('Not a GIF image!',E_USER_WARNING);
  // do necessary stuff
}