Improve CI_Upload::_file_mime_type()
diff --git a/system/libraries/Upload.php b/system/libraries/Upload.php
index 506d158..564d600 100644
--- a/system/libraries/Upload.php
+++ b/system/libraries/Upload.php
@@ -1018,50 +1018,104 @@
*/
protected function _file_mime_type($file)
{
- // Use if the Fileinfo extension, if available (only versions above 5.3 support the FILEINFO_MIME_TYPE flag)
- if ( (float) substr(phpversion(), 0, 3) >= 5.3 && function_exists('finfo_file'))
+ // We'll need this to validate the MIME info string (e.g. text/plain; charset=us-ascii)
+ $regexp = '/^([a-z\-]+\/[a-z0-9\-]+);\s.+$/';
+
+ /* Fileinfo extension - most reliable method
+ *
+ * Unfortunately, prior to PHP 5.3 - it's only available as a PECL extension and the
+ * more convenient FILEINFO_MIME_TYPE flag doesn't exist.
+ */
+ if (function_exists('finfo_file'))
{
- $finfo = new finfo(FILEINFO_MIME_TYPE);
- if ($finfo !== FALSE) // This is possible, if there is no magic MIME database file found on the system
+ $finfo = finfo_open(FILEINFO_MIME);
+ if (is_resource($finfo)) // It is possible that a FALSE value is returned, if there is no magic MIME database file found on the system
{
- $file_type = $finfo->file($file['tmp_name']);
+ $mime = @finfo_file($finfo, $file['tmp_name']);
+ finfo_close($finfo);
/* According to the comments section of the PHP manual page,
* it is possible that this function returns an empty string
* for some files (e.g. if they don't exist in the magic MIME database)
*/
- if (strlen($file_type) > 1)
+ if (is_string($mime) && preg_match($regexp, $mime, $matches))
{
- $this->file_type = $file_type;
+ $this->file_type = $matches[1];
return;
}
}
}
- // Fall back to the deprecated mime_content_type(), if available
- if (function_exists('mime_content_type'))
- {
- $this->file_type = @mime_content_type($file['tmp_name']);
- if (strlen($this->file_type) > 0) // Turns out it's possible that mime_content_type() returns FALSE or an empty string
- {
- return;
- }
- }
-
- /* This is an ugly hack, but UNIX-type systems provide a native way to detect the file type,
- * which is still more secure than depending on the value of $_FILES[$field]['type'].
+ /* This is an ugly hack, but UNIX-type systems provide a "native" way to detect the file type,
+ * which is still more secure than depending on the value of $_FILES[$field]['type'], and as it
+ * was reported in issue #750 (https://github.com/EllisLab/CodeIgniter/issues/750) - it's better
+ * than mime_content_type() as well, hence the attempts to try calling the command line with
+ * three different functions.
*
* Notes:
* - the DIRECTORY_SEPARATOR comparison ensures that we're not on a Windows system
- * - many system admins would disable the exec() function due to security concerns, hence the function_exists() check
+ * - many system admins would disable the exec(), shell_exec(), popen() and similar functions
+ * due to security concerns, hence the function_exists() checks
*/
- if (DIRECTORY_SEPARATOR !== '\\' && function_exists('exec'))
+ if (DIRECTORY_SEPARATOR !== '\\')
{
- $output = array();
- @exec('file --brief --mime-type ' . escapeshellarg($file['tmp_name']), $output, $return_code);
- if ($return_code === 0 && strlen($output[0]) > 0) // A return status code != 0 would mean failed execution
+ $cmd = 'file --brief --mime ' . escapeshellarg($file['tmp_name']) . ' 2>&1';
+
+ if (function_exists('exec'))
{
- $this->file_type = rtrim($output[0]);
+ /* This might look confusing, as $mime is being populated with all of the output when set in the second parameter.
+ * However, we only neeed the last line, which is the actual return value of exec(), and as such - it overwrites
+ * anything that could already be set for $mime previously. This effectively makes the second parameter a dummy
+ * value, which is only put to allow us to get the return status code.
+ */
+ $mime = @exec($cmd, $mime, $return_status);
+ if ($return_status === 0 && is_string($mime) && preg_match($regexp, $mime, $matches))
+ {
+ $this->file_type = $matches[1];
+ return;
+ }
+ }
+
+ if ( (bool) @ini_get('safe_mode') === FALSE && function_exists('shell_exec'))
+ {
+ $mime = @shell_exec($cmd);
+ if (strlen($mime) > 0)
+ {
+ $mime = explode("\n", trim($mime));
+ if (preg_match($regexp, $mime[(count($mime) - 1)], $matches))
+ {
+ $this->file_type = $matches[1];
+ return;
+ }
+ }
+ }
+
+ if (function_exists('popen'))
+ {
+ $proc = @popen($cmd, 'r');
+ if (is_resource($proc))
+ {
+ $mime = @fread($test, 512);
+ @pclose($proc);
+ if ($mime !== FALSE)
+ {
+ $mime = explode("\n", trim($mime));
+ if (preg_match($regexp, $mime[(count($mime) - 1)], $matches))
+ {
+ $this->file_type = $matches[1];
+ return;
+ }
+ }
+ }
+ }
+ }
+
+ // Fall back to the deprecated mime_content_type(), if available (still better than $_FILES[$field]['type'])
+ if (function_exists('mime_content_type'))
+ {
+ $this->file_type = @mime_content_type($file['tmp_name']);
+ if (strlen($this->file_type) > 0) // It's possible that mime_content_type() returns FALSE or an empty string
+ {
return;
}
}