Public: Handles all operations for resolving, cleaning and joining paths. This class includes operations for handling both web paths (request URIs) and system paths.
The main emphasis of the class is on creating clean and secure paths. Clean paths are void of duplicate parent and current directory references in the path name. Secure paths are paths which are restricted from accessing directories outside of a jail root, if specified.
Since joining two paths can result in an insecure path, this class also handles the task of joining a parent (start) and child (target) path.
This class makes no use of path utilities from the Ruby libraries. Instead, it handles all aspects of path manipulation. The main benefit of internalizing these operations is that the class is able to handle both posix and windows paths independent of the operating system on which it runs. This makes the class both deterministic and easier to test.
Examples
resolver = PathResolver.new # Web Paths resolver.web_path('images') => 'images' resolver.web_path('./images') => './images' resolver.web_path('/images') => '/images' resolver.web_path('./images/../assets/images') => './assets/images' resolver.web_path('/../images') => '/images' resolver.web_path('images', 'assets') => 'assets/images' resolver.web_path('tiger.png', '../assets/images') => '../assets/images/tiger.png' # System Paths resolver.working_dir => '/path/to/docs' resolver.system_path('images') => '/path/to/docs/images' resolver.system_path('../images') => '/path/to/images' resolver.system_path('/etc/images') => '/etc/images' resolver.system_path('images', '/etc') => '/etc/images' resolver.system_path('', '/etc/images') => '/etc/images' resolver.system_path(nil, nil, '/path/to/docs') => '/path/to/docs' resolver.system_path('..', nil, '/path/to/docs') => '/path/to/docs' resolver.system_path('../../../css', nil, '/path/to/docs') => '/path/to/docs/css' resolver.system_path('../../../css', '../../..', '/path/to/docs') => '/path/to/docs/css' resolver.system_path('..', 'C:\data\docs\assets', 'C:\data\docs') => 'C:/data/docs' resolver.system_path('..\..\css', 'C:\data\docs\assets', 'C:\data\docs') => 'C:/data/docs/css' begin resolver.system_path('../../../css', '../../..', '/path/to/docs', :recover => false) rescue SecurityError => e puts e.message end => 'path ../../../../../../css refers to location outside jail: /path/to/docs (disallowed in safe mode)' resolver.system_path('/path/to/docs/images', nil, '/path/to/docs') => '/path/to/docs/images' begin resolver.system_path('images', '/etc', '/path/to/docs') rescue SecurityError => e puts e.message end => Start path /etc is outside of jail: /path/to/docs'
Public: Construct a new instance of PathResolver, optionally specifying the file separator (to override the system default) and the working directory (to override the present working directory). The working directory will be expanded to an absolute path inside the constructor.
#file_separator - the String file separator to use for path operations
(optional, default: File::FILE_SEPARATOR)
#working_dir - the String working directory (optional, default: Dir.pwd)
# File lib/asciidoctor/path_resolver.rb, line 121 def initialize(file_separator = nil, working_dir = nil) @file_separator = file_separator.nil? ? (File::ALT_SEPARATOR || File::SEPARATOR) : file_separator if working_dir.nil? @working_dir = File.expand_path(Dir.pwd) else @working_dir = is_root?(working_dir) ? working_dir : File.expand_path(working_dir) end end
Public: Expand the path by resolving any parent references (..) and cleaning self references (.).
The result will be relative if the path is relative and absolute if the path is absolute. The file separator used in the expanded path is the one specified when the class was constructed.
path - the String path to expand
returns a String path with any parent or self references resolved.
# File lib/asciidoctor/path_resolver.rb, line 176 def expand_path(path) path_segments, path_root, _ = partition_path(path) join_path path_segments, path_root end
Public: Check if the specified path is an absolute root path This operation correctly handles both posix and windows paths.
path - the String path to check
returns a Boolean indicating whether the path is an absolute root path
# File lib/asciidoctor/path_resolver.rb, line 136 def is_root?(path) if @file_separator == BACKSLASH && path.match(WIN_ROOT_RE) true elsif path.start_with? SLASH true else false end end
Public: Determine if the path is an absolute (root) web path
path - the String path to check
returns a Boolean indicating whether the path is an absolute (root) web path
# File lib/asciidoctor/path_resolver.rb, line 151 def is_web_root?(path) path.start_with? SLASH end
Public: Join the segments using the posix file separator (since Ruby knows how to work with paths specified this way, regardless of OS). Use the root, if specified, to construct an absolute path. Otherwise join the segments as a relative path.
segments - a String Array of path segments root - a String path root (optional, default: nil)
returns a String path formed by joining the segments using the posix file separator and prepending the root, if specified
# File lib/asciidoctor/path_resolver.rb, line 214 def join_path(segments, root = nil) if root "#{root}#{SLASH}#{segments * SLASH}" else segments * SLASH end end
Public: Partition the path into path segments and remove any empty segments or segments that are self references (.). The path is split on either posix or windows file separators.
path - the String path to partition #web_path - a Boolean indicating whether the path should be handled
as a web path (optional, default: false)
returns a 3-item Array containing the Array of String path segments, the path root, if the path is absolute, and the posix version of the path.
# File lib/asciidoctor/path_resolver.rb, line 191 def partition_path(path, web_path = false) posix_path = posixfy path is_root = web_path ? is_web_root?(posix_path) : is_root?(posix_path) path_segments = posix_path.tr_s(SLASH, SLASH).split(SLASH) # capture relative root root = path_segments.first == DOT ? DOT : nil path_segments.delete(DOT) # capture absolute root, preserving relative root if set root = is_root ? path_segments.shift : root [path_segments, root, posix_path] end
Public: Normalize path by converting any backslashes to forward slashes
path - the String path to normalize
returns a String path with any backslashes replaced with forward slashes
# File lib/asciidoctor/path_resolver.rb, line 160 def posixfy(path) return '' if path.to_s.empty? path.include?(BACKSLASH) ? path.tr(BACKSLASH, SLASH) : path end
Public: Calculate the relative path to this absolute filename from the specified base directory
If either the filename or the base_directory are not absolute paths, no work is done.
filename - An absolute file name as a String base_directory - An absolute base directory as a String
Return the relative path String of the filename calculated from the base directory
# File lib/asciidoctor/path_resolver.rb, line 383 def relative_path(filename, base_directory) if (is_root? filename) && (is_root? base_directory) offset = base_directory.chomp(@file_separator).length + 1 filename[offset..-1] else filename end end
Public: Resolve a system path from the target and start paths. If a jail path is specified, enforce that the resolved directory is contained within the jail path. If a jail path is not provided, the resolved path may be any location on the system. If the resolved path is absolute, use it as is. If the resolved path is relative, resolve it relative to the #working_dir specified in the constructor.
target - the String target path start - the String start (i.e., parent) path jail - the String jail path to confine the resolved path opts - an optional Hash of options to control processing (default: {}):
* :recover is used to control whether the processor should auto-recover when an illegal path is encountered * :target_name is used in messages to refer to the path being resolved
returns a String path that joins the target path with the start path with any parent references resolved and self references removed and enforces that the resolved path be contained within the jail, if provided
# File lib/asciidoctor/path_resolver.rb, line 240 def system_path(target, start, jail = nil, opts = {}) recover = opts.fetch(:recover, true) unless jail.nil? unless is_root? jail raise SecurityError, "Jail is not an absolute path: #{jail}" end jail = posixfy jail end if target.to_s.empty? target_segments = [] else target_segments, target_root, _ = partition_path(target) end if target_segments.empty? if start.to_s.empty? return jail.nil? ? @working_dir : jail elsif is_root? start if jail.nil? return expand_path start end else return system_path(start, jail, jail) end end if target_root && target_root != DOT resolved_target = join_path target_segments, target_root # if target is absolute and a sub-directory of jail, or # a jail is not in place, let it slide if jail.nil? || resolved_target.start_with?(jail) return resolved_target end end if start.to_s.empty? start = jail.nil? ? @working_dir : jail elsif is_root? start start = posixfy start else start = system_path(start, jail, jail) end # both jail and start have been posixfied at this point if jail == start jail_segments, jail_root, _ = partition_path(jail) start_segments = jail_segments.dup elsif !jail.nil? if !start.start_with?(jail) raise SecurityError, "#{opts[:target_name] || 'Start path'} #{start} is outside of jail: #{jail} (disallowed in safe mode)" end start_segments, start_root, _ = partition_path(start) jail_segments, jail_root, _ = partition_path(jail) # Already checked for this condition #if start_root != jail_root # raise SecurityError, "Jail root #{jail_root} does not match root of #{opts[:target_name] || 'start path'}: #{start_root}" #end else start_segments, start_root, _ = partition_path(start) jail_root = start_root end resolved_segments = start_segments.dup warned = false target_segments.each do |segment| if segment == DOT_DOT if !jail.nil? if resolved_segments.length > jail_segments.length resolved_segments.pop elsif !recover raise SecurityError, "#{opts[:target_name] || 'path'} #{target} refers to location outside jail: #{jail} (disallowed in safe mode)" elsif !warned warn "asciidoctor: WARNING: #{opts[:target_name] || 'path'} has illegal reference to ancestor of jail, auto-recovering" warned = true end else resolved_segments.pop end else resolved_segments.push segment end end join_path resolved_segments, jail_root end
Public: Resolve a web path from the target and start paths. The main function of this operation is to resolve any parent references and remove any self references.
target - the String target path start - the String start (i.e., parent) path
returns a String path that joins the target path with the start path with any parent references resolved and self references removed
# File lib/asciidoctor/path_resolver.rb, line 339 def web_path(target, start = nil) target = posixfy(target) start = posixfy(start) uri_prefix = nil unless is_web_root?(target) || start.empty? target = "#{start}#{SLASH}#{target}" if target.include?(':') && target.match(Asciidoctor::REGEXP[:uri_sniff]) uri_prefix = $~[0] target = target[uri_prefix.length..-1] end end target_segments, target_root, _ = partition_path(target, true) resolved_segments = target_segments.inject([]) do |accum, segment| if segment == DOT_DOT if accum.empty? accum.push segment unless target_root && target_root != DOT elsif accum[-1] == DOT_DOT accum.push segment else accum.pop end else accum.push segment end accum end if uri_prefix.nil? join_path resolved_segments, target_root else "#{uri_prefix}#{join_path resolved_segments, target_root}" end end