手动检查php中文件标记ffd9(?)的jpeg结尾以捕获截断错误 [英] check manually for jpeg end of file marker ffd9 (?) in php to catch truncation errors

问题描述

基本上是尝试从集合中删除损坏的，过早结束的jpeg文件.我认为如果文件尾标记不存在，则意味着该图像被截断了，因此出于我的目的，我认为该图像无效. 这是检查声音的方法吗?如果可以的话，关于如何在php中实现它的任何想法?

basically trying to remove corrupt, prematurely ending jpeg files from a collection. i figured if the end of file marker was absent then that meant the image is truncated and therefore i would consider it invalid for my purposes. is this method of checking sound? if so any ideas of how i could implement this in php?

欢呼

推荐答案

尝试一下:

$jpgdata = file_get_contents('image.jpg');

if (substr($jpgdata,-2)!="\xFF\xD9") {
  echo 'Bad file';
}

这会将整个JPG文件加载到内存中，并且可能导致大文件出错.

This would load the entire JPG file into memory and can result into an error for big files.

替代:

$jpgdata = fopen('image.jpg', 'r'); // 'r' is for reading
fseek($jpgdata, -2, SEEK_END); // move to EOF -2
$eofdata = fread($jpgdata, 2);
fclose($jpgdata);

if ($eofdata!="\xFF\xD9") echo 'Bad file';

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