How to get the mime type of a file after using fil

问题:

i'm reading a file from php from Alfresco and then outputting it to the browser. The only ptoblem is the mimetype or the extension of the file. This is the code i'm using:

<?php
ob_start();
//require_once("libs/FirePHPCore/fb.php");
require_once("libs/AlfrescoConnect.php");

$nomeFile = rawurldecode($_GET['nomeFile']);    
$urlDownload = $_GET['urlDownload'];
$fileDownloadUrl = AlfrescoConnect::$serverPath. $urlDownload . "&attach=true&alf_ticket=".AlfrescoConnect::getTiket();
fb($fileDownloadUrl);


$cnt = file_get_contents($fileDownloadUrl);


header("Content-type: Application/octet-stream");
header('Cache-Control: must-revalidate');
header('Content-disposition: attachment; filename=' .$nomeFile);
echo($cnt);
exit();

echo("Impossibile trovare il file");

I receive the name of the file from the get becausa i don't know how to get the name from alfresco, but i have to guess the mimetype somehow. if i "echo" $cnt in the firsat caracters there are references to the fact that it is a PDF (for example on screen i see "%PDF-1.3 %âãÏÓ 2 0 obj << /Length 3 0 R /Filter /CCITTFaxDecode /DecodeParms << /K 0 /Columns 2480 /Rows 3508 >> /Type /XObject /Subtype /Image /Width 2480 /Height 3508 /BitsPerComponent 1 /ColorSpace /DeviceGray >> stream" so there must be a way to get the mime_tipe from it with a function.

Any help is apprecieted!

Edit. If anyone is intereste here is a class that you can use to get the extension from the mime-type. http://www.ustrem.org/en/articles/mime-type-by-extension-en/

回答1:

Use cURL instead of file_get_contents, then you can see the response header, which will hopefully have the mime type.

Or you could try using this http://www.php.net/manual/en/ref.fileinfo.php or this deprecated function http://php.net/manual/en/function.mime-content-type.php

回答2:

You can use the finfo::buffer() method: http://php.net/finfo_buffer.

<?php
$finfo = new finfo(FILEINFO_MIME);
echo $finfo->buffer($cnt) . PHP_EOL;

NOTE: You could optionally use the finfo_buffer procedural function if that suites you better than using the object-oriented methodology.

回答3:

You do not have to guess (aka autodetect) the MIME type.

Use $http_response_header to retrieve headers of the last file_get_contents call (or any call with http:// wrapper).

$contents = file_get_contents("https://www.example.com/");
$pattern = "/^content-type\s*:\s*(.*)$/i";
if (($header = preg_grep($pattern, $http_response_header)) &&
    (preg_match($pattern, array_shift(array_values($header)), $match) !== false))
{
    $content_type = $match[1];
    echo "Content-Type is '$content_type'\n";
}

回答4:

Here is a curl implementation from the filefield_sources module in Drupal. It can probably work anywhere:

<?php
  // Inspect the remote image
  // Check the headers to make sure it exists and is within the allowed size.
  $ch = curl_init();
  curl_setopt($ch, CURLOPT_URL, $url);
  curl_setopt($ch, CURLOPT_HEADER, TRUE);
  curl_setopt($ch, CURLOPT_NOBODY, TRUE);
  curl_setopt($ch, CURLOPT_RETURNTRANSFER, TRUE);
  curl_setopt($ch, CURLOPT_HEADERFUNCTION, '_filefield_source_remote_parse_header');
  // Causes a warning if PHP safe mode is on.
  @curl_setopt($ch, CURLOPT_FOLLOWLOCATION, TRUE);
  curl_exec($ch);
  $info = curl_getinfo($ch);
  curl_close($ch);

/**
 * Parse cURL header and record the filename specified in Content-Disposition.
 */
function _filefield_source_remote_parse_header(&$ch, $header) {
  if (preg_match('/Content-Disposition:.*?filename="(.+?)"/', $header, $matches)) {
    // Content-Disposition: attachment; filename="FILE NAME HERE"
    _filefield_source_remote_filename($matches[1]);
  }
  elseif (preg_match('/Content-Disposition:.*?filename=([^; ]+)/', $header, $matches)) {
    // Content-Disposition: attachment; filename=file.ext
    _filefield_source_remote_filename($matches[1]);
  }

  // This is required by cURL.
  return strlen($header);
}

/**
 * Get/set the remote file name in a static variable.
 */
function _filefield_source_remote_filename($curl_filename = NULL) {
  static $filename = NULL;
  if (isset($curl_filename)) {
    $filename = $curl_filename;
  }
  return $filename;
}

 ?>

To get the mime:

<?php
echo $info['content_type'];
?>

Code is here: http://drupal.org/project/filefield_sources

回答5:

Put this in a class:

/**
 * Given a string ($data) with a file's contents, guess and return the mime type
 *
 * Uses the standard unix program /usr/bin/file to handle the magic (pun intended)
 *
 * @param string $data
 */
public static function get_string_mime_type($data) {
    $file_cmd = '/usr/bin/file --brief --mime-type --no-buffer -';
    return rtrim(self::exec_write_read($file_cmd, $data));
}

/**
 * Executes $cmd, writes to $cmd's stdin, then returns what $cmd wrote to stdout
 */
private static function exec_write_read($cmd, $write, $log_errors = false) {
    $descriptorspec = array(
        0 => array("pipe", "r"),  // stdin is a pipe that $cmd will read from
        1 => array("pipe", "w"),  // stdout is a pipe that $cmd will write to
        2 => array("pipe", "w"),  // stderr is a pipe that $cmd will write to
    );

    $process = proc_open($cmd, $descriptorspec, $pipes);
    if (is_resource($process)) {
        // $pipes now looks like this:
        // 0 => writeable handle connected to child stdin
        // 1 => readable handle connected to child stdout
        // 2 => readable handle connected to child stderr

        fwrite($pipes[0], $write);
        fclose($pipes[0]);

        $output = stream_get_contents($pipes[1]);
        fclose($pipes[1]);

        if( $log_errors ){
            error_log(stream_get_contents($pipes[2]));
        }
        fclose($pipes[2]);

        // It is important that you close any pipes before calling
        // proc_close in order to avoid a deadlock
        $exit_code = proc_close($process);

        return $output;
    }
    else {
        throw new Exception("Couldn't open $cmd");
    }
}

回答6:

BE CAREFULL ! NOT ONLY CHECK the mimetype, but check it for malicious code !!!!!!!!!

details: PHP: How to get mimeType of a image with file_get_contents