src/Composer/Util/Filesystem.php
public function relativeSymlink($target, $link)
    {
        $cwd = getcwd();

        $relativePath = $this->findShortestPath($link, $target);
        chdir(dirname($link));
        $result = @symlink($relativePath, $link);

        chdir($cwd);

        return $result;
    }
public function relativeSymlink($target, $link)
    {
        $cwd = getcwd();

        $relativePath = $this->findShortestPath($link, $target);
        chdir(dirname($link));
        $result = @symlink($relativePath, $link);

        chdir($cwd);

        return $result;
    }
Creates a relative symlink from $link to $target

@param  string $target The path of the binary file to be symlinked
@param  string $link   The path where the symlink should be created
@return bool