1.问题，项目中上传文件使用插件时，windows上支持函数exif_imagetype（），而在linux上不支持。
2.PHP exif_imagetype的本质
PHP exif_imagetype note #1Windows users: If you get the fatal error "Fatal error: Call to undefined function exif_imagetype()", and you have enabled php_exif.dll, make sure you enable php_mbstring.dll.
You must put mbstring before exif in the php.ini, i.e.:extension=php_mbstring.dllextension=php_exif.dllYou can check whether this has worked by calling phpinfo() and searching for exif.PHP exif_imagetype note #2If the function exif_imagetype() is not available,you can try the following workaround:if ( ! function_exists( 'exif_imagetype' ) ) {function exif_imagetype ( $filename ) {if ( ( list($width, $height, $type, $attr) = getimagesize( $filename ) ) !== false ) {return $type;}return false;}}PHP exif_imagetype note #3By trial and error, it seems that a file has to be 12 bytes or larger in order to avoid a "Read error!". Here's a work-around to avoid an error being thrown:// exif_imagetype throws "Read error!" if file is too smallif (filesize($uploadfile) > 11)$mimetype = exif_imagetype($uploadfile);else$mimetype = false;PHP exif_imagetype note #4Seems to give a 'Read error' warning if the size of the file is very small (2 bytes). I think this is because it needs a min 3 bytes to determine the file typePHP exif_imagetype note #5libexif can also be used to parse image info out of id3 tags:exif_read_data("mp3_with_2.4ID3TAGS, '', true, false);PHP exif_imagetype note #6After looking for hours, I found a very good source for exif related programs here: /code/exif/index.htmlIt lists exif specifications (pdf), a few good links to exif related stuff. The best source I have found in my quest to understand exif better for use in php based exif tools.
3.解决方案：
if ( ! function_exists( 'exif_imagetype' ) ) {
// $currFile = $file['tmp_name'];
list($width, $height, $type2, $attr) = getimagesize($file['tmp_name']);
$type = $type2;
// function exif_imagetype ($currFile) {
// if ( ( list($width, $height, $type2, $attr) = getimagesize($currFile) ) !== false ) {
// // return $type;
// $type = $type2;
// }
// return false;
// }
}else{
// $type = exif_imagetype($src);
$type = exif_imagetype($file['tmp_name']);
}
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