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POHow do detect if the selected image for upload is a valid image?
 

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  1. POHow do detect if the selected image for upload is a valid image?
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    <p>I'm implementing a script which to validate an image for upload using php. Actually, the php script is working well with gif, png, and jpg image file, but when i have one condition that:</p> <ol> <li>I took an image <code>theFileName.bmp</code> and renamed its extension to <code>theFileName.jpg</code>.</li> <li>Then I select the renamed one to upload.</li> </ol> <p>I renamed the image file name manually on my computer and then I selected the file to upload.</p> <p>The uploading process tooks around 2 or 3 seconds then nothing showed up (not even an error), only the default message from browser displayed: </p> <blockquote> <p>The connection to localhost was interrupted.</p> </blockquote> <p>How can I prevent the user from selecting an image file (and any other file for that matter) which is not an actual valid image?</p> <h2>Solutions here</h2> <p>Finally, I managed to come up with my own solutions. It's a bit long but at least it can get the work done! Hope it might help someone.</p> <ol> <li>It helps prevent from user upload not wanted mime-type</li> <li>Prevent from user uses text file and renamed its extension and so on.</li> <li>Prevent from user uses text file and changes its mime-type</li> <li>Prevent from the file is unreadale</li> <li>Prevent from the file contains error</li> <li>Prevent from upload not an http</li> <li>Prevent from the image file size width: 0, height: 0</li> <li><p>There are still more things to validate and check in order to make sure it's safe by this means.</p> <pre><code># CHECK &amp; TRY READ IMAGE FILE function is_readable_image( $theTmpFileloc ){ try { if ( !getimagesize( $theTmpFileloc ) ){ # THE IMAGE IS UNREADABLE return false; } # THE IMAGE IS READABLE return true; }catch( Exception $e ){ # THE IMAGE IS OTHER FILE return false; } } # READ AND RETURN AN ARRAY OF IMAGE SIZES function get_image_size( $theTmpFileloc ){ $imageSizes = array(); $tmpResults = getimagesize( $theTmpFileloc ); $imageSizes['width'] = $tmpResults[0]; $imageSizes['height'] = $tmpResults[1]; # IF EITHER WIDTH OR HEIGHT = 0, RETURN FALSE if ( $tmpResults[0] == 0 || $tmpResults[1] == 0 ) { return false; } return $imageSizes; } # READ AND RETURN AN IMAGE ACTUAL MIMETYPE function get_image_mime( $theTmpFileloc ){ $imageMime = ''; $tmpResults = getimagesize( $theTmpFileloc ); $imageMime = $tmpResults['mime']; return $imageMime; } # START OF PHP TO VALIDATE IMAGE FILE if ( isset($_FILES['postImage']) &amp;&amp; !empty($_FILES['postImage']['name']) ) { $tmpFileLoc = $_FILES['postImage']['tmp_name']; $array_file_type = array('image/gif', 'image/png', 'image/x-png', 'image/jpeg', 'image/pjpeg'); if ( $_FILES['postImage']['error'] == 1 ) { # THE IMAGE FILE CONTAINS ERROR $resMessage['Error'] = true; }elseif ( !is_uploaded_file( $tmpFileLoc ) ) { # PREVENT FROM UPLOADING FROM EXTERNAL SOURCE NOT HTTP $resMessage['Error'] = true; }elseif ( !is_readable_image( $tmpFileLoc ) ) { # PREVENT FROM IMAGE IS INVALID OR OTHER MIMETYPE $resMessage['Error'] = true; }elseif ( !get_image_size( $tmpFileLoc ) ) { # PREVENT FROM IMAGE SIZE 0, 0 OR INVALID ACTUAL MIMETYPE $resMessage['Error'] = true; }elseif ( !in_array( get_image_mime( $tmpFileLoc ), $array_file_type) ) { # LEVEL 2 OF CHECKING AN IMAGE MIMETYPE $resMessage['Error'] = true; }else { # other checks with file extension, max_size, # dir is_writable and so on then move to move_uploaded_file } } </code></pre></li> </ol>
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    1. PTQuestion
    1. USNathan
    1. USThavarith
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    1. COYou can't, because you (the PHP script) don't have the image data yet. If the user is dumb enough to change the extension on an image, then they deserve to wait before being told it wont work.
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      1. POHow do detect if the selected image for upload is a valid image?
      1. USJonathon Reinhart
    2. COcheck image mime type
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      1. POHow do detect if the selected image for upload is a valid image?
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    3. CO@Jonathon Reinhart: thanks for info. I can't really believe that the PHP cannot do that for image file.
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      1. POHow do detect if the selected image for upload is a valid image?
      1. USThavarith
 

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