Our server is saving EXIF data to every file saved with imagejpeg(). As far as I know, this is not the default behavior (or even possible, from what I've read). But, it is occurring, and due to the FileDateTime information being included (and using the time of save), it is breaking functionality in our upload/approval system (md5_file() returns a different value for the exact same image due to FileDateTime always being different).
Is there a way to prevent imagejpeg() from saving EXIF data for images by default?
<?php
public function upload_book_cover($book, $cover, $filename = NULL, $approved = NULL){
global $c_consummo, $user;
$approved = bool($approved, true, true);
if(filesize($cover)>5242880){
return false; // Too large;
}
$max_width = 450;
$cover_info = getimagesize($cover);
if(!$this->is_valid_book_cover_type($cover_info['mime'])){
return false; // Invalid image type
}
$width = $cover_info[0];
$height = $cover_info[1];
if($width<200){
return false; // Too small
} elseif($width>1500){
return false; // Too wide
}
$original_cover = false;
switch($cover_info[2]){
case IMAGETYPE_GIF:
$original_cover = imagecreatefromgif($cover);
break;
case IMAGETYPE_JPEG:
$original_cover = imagecreatefromjpeg($cover);
break;
case IMAGETYPE_PNG:
$original_cover = imagecreatefrompng($cover);
break;
case IMAGETYPE_BMP:
$original_cover = imagecreatefrombmp($cover);
break;
}
if(!$original_cover){
return false; // Unsupported type
}
if($width>$max_width){
$new_width = $max_width;
} else {
$new_width = $width;
}
$new_height = round($height*($new_width/$width));
$new_cover = imagecreatetruecolor($new_width, $new_height);
if(!$new_cover){
return false; // Could not create true color image
}
if(!imagecopyresampled($new_cover, $original_cover, 0, 0, 0, 0, $new_width, $new_height, $width, $height)){
return false; // Could not copy image
}
if(!imagejpeg($new_cover, $cover, 100)){
return false; // Image could not be saved to tmp file
// This is adding *new* EXIF data to images by itself
}
$file_hash = md5_file($cover);
$duplicate_book_cover = $this->find_duplicate_book_cover($book, $file_hash);
if($duplicate_book_cover){
return $duplicate_book_cover;
}
$file_id = $c_consummo->upload_file($cover, $filename);
...
}
Apparently, GD doesn't like when the path to the input / output file is the same, but the credit isn't mine. To fix, use a new (tmp) file to save the newly created image to:
<?php
...
if(!imagecopyresampled($new_cover, $original_cover, 0, 0, 0, 0, $new_width, $new_height, $width, $height)){
return false; // Could not copy image
}
// Create a tmp file.
$cover_new = tempnam('/tmp', 'cover-');
// Use $cover_new instead of $cover
if(!imagejpeg($new_cover, $cover_new, 100)){
return false; // Image could not be saved to tmp file
}
// Use $cover_new instead of $cover
$file_hash = md5_file($cover_new);
$duplicate_book_cover = $this->find_duplicate_book_cover($book, $file_hash);
if($duplicate_book_cover){
return $duplicate_book_cover;
}
// Use $cover_new instead of $cover
$file_id = $c_consummo->upload_file($cover_new, $filename);
...