getimagesize（）vs finfo_file（）是否与检测mime类型完全相同？

Question

Are these functions doing the same checks to detect the mime type of a file? Are there any benefits in choosing one over the other (ie terms of reliability/security)?

Answer 1

They are for different purpose, so you may use in they specific scope. I'm prefer use finfo for the first check of the reliability of file if I don't know its origin

getimagesize — Get the size of an image

Which also can gather the meta segment for JPG APP and presume to detect the image mime

And

finfo_file — Return information about a file

Will get you the meta info from the file

A s you marked GD, you may be interacting with images only(?). So you may use getimagesize() , which seem to return the mime type of file independent of its extension, being a +1 on security, but probably limited by PHP supported images types.

My PHP 5.6.4 has:

    [IMAGETYPE_GIF] => 1
    [IMAGETYPE_JPEG] => 2
    [IMAGETYPE_PNG] => 3
    [IMAGETYPE_SWF] => 4
    [IMAGETYPE_PSD] => 5
    [IMAGETYPE_BMP] => 6
    [IMAGETYPE_TIFF_II] => 7
    [IMAGETYPE_TIFF_MM] => 8
    [IMAGETYPE_JPC] => 9
    [IMAGETYPE_JP2] => 10
    [IMAGETYPE_JPX] => 11
    [IMAGETYPE_JB2] => 12
    [IMAGETYPE_SWC] => 13
    [IMAGETYPE_IFF] => 14
    [IMAGETYPE_WBMP] => 15
    [IMAGETYPE_JPEG2000] => 9
    [IMAGETYPE_XBM] => 16
    [IMAGETYPE_ICO] => 17
    [IMAGETYPE_UNKNOWN] => 0
    [IMAGETYPE_COUNT] => 18

O n the other hand, I suggest you use finfo , to gatter real meta info of your file.

finfo do not read other thing than the headers, getimagesize can also return some markers and also extra info (extra computation), image specific info.

L ets check:

Having this simple non standar function:

function displayInfo($path, $info = FILEINFO_MIME_TYPE ) {

        $imageinfo = array();
        $getimagesize = array();

        $finfo = new finfo($info);
        $finfo_mt = $finfo->file($path);

        print_r(getimagesize($path, $imageinfo));
        print_r($imageinfo);
        print_r($finfo_mt);
    }

You may use $info=FILEINFO_MIME to return Type and Encoding for safe reading a file. So,

display('file.php'); will output

Array
(
)
text/x-php

display('image.png.hide'); and display('image.png'); will output

Array
(
    [0] => 31
    [1] => 31
    [2] => 3
    [3] => width="31" height="31"
    [bits] => 8
    [mime] => image/png
)
Array
(
)
image/png

and, display('image.jpg'); will output

Array
(
    [0] => 206
    [1] => 206
    [2] => 2
    [3] => width="206" height="206"
    [bits] => 8
    [channels] => 3
    [mime] => image/jpeg
)
Array
(
    [APP0] => JFIF
    [APP13] => Photoshop 3.08BIMgldeLs_Kr6L1Vvu73FGOs(bFBMD01000ac1030000b1060000ad0b00006f0c0000800d0000fe11000011180000bf180000c8190000ef1a0000d2240000
    [APP2] => [REMOVED UTF CHARS FOR stackoverflow]
)
image/jpeg

Hope to be pointed on your question.

Answer 2

well there are basically two ways of finding the mime types of the files... one is mime_content_type and the other is file info... you can refer the urls bellow :

http://php.net/manual/en/function.finfo-file.php

http://php.net/manual/en/function.mime-content-type.php

mime_content_type is now deprecated .. file info method is for latest php versions... file info requires fileinfo extension to be enabled on the server...