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 #
Windows 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.dll
extension=php_exif.dll
You can check whether this has worked by calling phpinfo() and searching for exif.
PHP exif_imagetype note #
If 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 $type;
}
return false;
}
}
PHP exif_imagetype note #
By trial and error, it seems that a file has to be 12 bytes or larger in order to avoid a "Read error!". Here's a work-around to avoid an error being thrown: // exif_imagetype throws "Read error!" if file is too small
if (filesize($uploadfile) > 11)
$mimetype = exif_imagetype($uploadfile);
else
$mimetype = false;
PHP exif_imagetype note #4
Seems 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 type
PHP exif_imagetype note #5
libexif 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 #6
After looking for hours, I found a very good source for exif related programs here: http://drewnoakes.com/code/exif/index.html
It 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']);
}