/**
* Gets the relative path from a source directory to a target directory.
* The allowed TYPO3 path is checked as well, thus it's not possible to go to upper levels.
*
* @param string $sourcePath Absolute source path
* @param string $targetPath Absolute target path
* @return NULL|string
*/
public static function getRelativePath($sourcePath, $targetPath)
{
$relativePath = null;
$sourcePath = rtrim(GeneralUtility::fixWindowsFilePath($sourcePath), '/');
$targetPath = rtrim(GeneralUtility::fixWindowsFilePath($targetPath), '/');
if ($sourcePath !== $targetPath) {
$commonPrefix = self::getCommonPrefix(array($sourcePath, $targetPath));
if ($commonPrefix !== null && GeneralUtility::isAllowedAbsPath($commonPrefix)) {
$commonPrefixLength = strlen($commonPrefix);
$resolvedSourcePath = '';
$resolvedTargetPath = '';
$sourcePathSteps = 0;
if (strlen($sourcePath) > $commonPrefixLength) {
$resolvedSourcePath = (string) substr($sourcePath, $commonPrefixLength);
}
if (strlen($targetPath) > $commonPrefixLength) {
$resolvedTargetPath = (string) substr($targetPath, $commonPrefixLength);
}
if ($resolvedSourcePath !== '') {
$sourcePathSteps = count(explode('/', $resolvedSourcePath));
}
$relativePath = self::sanitizeTrailingSeparator(str_repeat('../', $sourcePathSteps) . $resolvedTargetPath);
}
}
return $relativePath;
}