有个小需求，批量分析一批pdf文件的总页数，写（找）了个小函数，如下：

function getPageTotal($path){
    if (!$fp = @fopen($path, 'r')) {
        return false;
    }
    $max=0;
    while(!feof($fp)) {
        $line = fgets($fp,255);
        if (preg_match('/\/Count [0-9]+/', $line, $matches)){
            preg_match('/[0-9]+/',$matches[0], $matches2);
            if ($max<$matches2[0]) $max=$matches2[0];
        }
    }
    fclose($fp);
    return $max;
}

实际使用中，发现有极个别文件识别失败，取样分析后，发现出问题的文件都是mac格式的，那自然就是fgets对mac换行符的识别问题了

查了下手册: fgets

Note: If PHP is not properly recognizing the line endings when reading files either on or created by a Macintosh computer, enabling the auto_detect_line_endings run-time configuration option may help resolve the problem.

auto_detect_line_endings 这个运行时配置到是从没注意过，ok、稍作修改

function getPageTotal($path){
    ini_set("auto_detect_line_endings",true);

    if (!$fp = @fopen($path, 'r')) {
        return false;
    }
    $max=0;
    while(!feof($fp)) {
        $line = fgets($fp,255);
        if (preg_match('/\/Count [0-9]+/', $line, $matches)){
            preg_match('/[0-9]+/',$matches[0], $matches2);
            if ($max<$matches2[0]) $max=$matches2[0];
        }
    }
    fclose($fp);
    return $max;
}

问题解决！

关于auto-detect-line-endings的解释：

When turned on, PHP will examine the data read by fgets() and file() to see if it is using Unix, MS-Dos or Macintosh line-ending conventions.

This enables PHP to interoperate with Macintosh systems, but defaults to Off, as there is a very small performance penalty when detecting the EOL conventions for the first line, and also because people using carriage-returns as item separators under Unix systems would experience non-backwards-compatible behaviour.

Note: This configuration option was introduced in PHP 4.3.0