darcs-2.11.0: a distributed, interactive, smart revision control system

Safe HaskellNone





data FileName

FileName is an abstract type intended to facilitate the input and output of unicode filenames.

encodeWhite :: FilePath -> String

encodeWhite translates whitespace in filenames to a darcs-specific format (numerical representation according to ord surrounded by backslashes). Note that backslashes are also escaped since they are used in the encoding.

 encodeWhite "hello there" == "hello\32\there"
 encodeWhite "hello\there" == "hello\92\there"

decodeWhite :: String -> FilePath

decodeWhite interprets the Darcs-specific "encoded" filenames produced by encodeWhite

 decodeWhite "hello\32\there"  == "hello there"
 decodeWhite "hello\92\there"  == "hello\there"
 decodeWhite "hello\there"   == error "malformed filename"


makeAbsolute :: AbsolutePath -> FilePath -> AbsolutePath

Take an absolute path and a string representing a (possibly relative) path and combine them into an absolute path. If the second argument is already absolute, then the first argument gets ignored. This function also takes care that the result is converted to Posix convention and normalized. Also, parent directories ("..") at the front of the string argument get canceled out against trailing directory parts of the absolute path argument.

Regarding the last point, someone more familiar with how these functions are used should verify that this is indeed necessary or at least useful.

ioAbsolute :: FilePath -> IO AbsolutePath

Interpret a possibly relative path wrt the current working directory.

rootDirectory :: AbsolutePath

The root directory as an absolute path.


data AbsolutePathOrStd

This is for situations where a string (e.g. a command line argument) may take the value "-" to mean stdin or stdout (which one depends on context) instead of a normal file path.

useAbsoluteOrStd :: (AbsolutePath -> a) -> a -> AbsolutePathOrStd -> a

Execute either the first or the second argument action, depending on whether the given path is an AbsolutePath or stdin/stdout.



data SubPath

Paths which are relative to the local darcs repository and normalized. Note: These are understood not to have the dot in front.

makeSubPathOf :: AbsolutePath -> AbsolutePath -> Maybe SubPath

Make the second path relative to the first, if possible

floatSubPath :: SubPath -> AnchoredPath

Transform a SubPath into an AnchoredPath.


getUniquePathName :: Bool -> (FilePath -> String) -> (Int -> FilePath) -> IO FilePath

Iteratively tries find first non-existing path generated by buildName, it feeds to buildName the number starting with -1. When it generates non-existing path and it isn't first, it displays the message created with buildMsg. Usually used for generation of the name like path_number when path already exist (e.g. darcs.net_0).

Check for malicious paths

isMaliciousPath :: String -> Bool

What is a malicious path?

A spoofed path is a malicious path.

  1. Darcs only creates explicitly relative paths (beginning with "./"), so any not explicitly relative path is surely spoofed.
  2. Darcs normalizes paths so they never contain "/../", so paths with "/../" are surely spoofed.

A path to a darcs repository's meta data can modify "trusted" patches or change safety defaults in that repository, so we check for paths containing "/_darcs/" which is the entry to darcs meta data.

To do?

  • How about get repositories?
  • Would it be worth adding a --semi-safe-paths option for allowing changes to certain preference files (_darcs/prefs/) in sub repositories'?

isMaliciousSubPath :: String -> Bool

Warning : this is less rigorous than isMaliciousPath but it's to allow for subpath representations that don't start with ./

Tree filtering.

filterFilePaths :: [FilePath] -> AnchoredPath -> t -> Bool

Same as filterPath, but for ordinary FilePaths (as opposed to AnchoredPath).

filterPaths :: [AnchoredPath] -> AnchoredPath -> t -> Bool

Construct a filter from a list of AnchoredPaths, that will accept any path that is either a parent or a child of any of the listed paths, and discard everything else.

AnchoredPaths: relative paths within a Tree. All paths are

newtype Name


Name ByteString 


newtype AnchoredPath

This is a type of sane file paths. These are always canonic in the sense that there are no stray slashes, no .. components and similar. They are usually used to refer to a location within a Tree, but a relative filesystem path works just as well. These are either constructed from individual name components (using appendPath, catPaths and makeName), or converted from a FilePath (floatPath -- but take care when doing that) or .


AnchoredPath [Name] 

appendPath :: AnchoredPath -> Name -> AnchoredPath

Append an element to the end of a path.

anchorPath :: FilePath -> AnchoredPath -> FilePath

Take a root directory and an anchored path and produce a full FilePath. Moreover, you can use anchorPath "" to get a relative FilePath.

isPrefix :: AnchoredPath -> AnchoredPath -> Bool

Check whether a path is a prefix of another path.

parent :: AnchoredPath -> AnchoredPath

Get parent (path) of a given path. foobarbaz -> foo/bar

parents :: AnchoredPath -> [AnchoredPath]

List all parents of a given path. foobarbaz -> [foo, foo/bar]

catPaths :: AnchoredPath -> AnchoredPath -> AnchoredPath

Catenate two paths together. Not very safe, but sometimes useful (e.g. when you are representing paths relative to a different point than a Tree root).

appendToName :: AnchoredPath -> String -> AnchoredPath

Append a ByteString to the last Name of an AnchoredPath.

Unsafe AnchoredPath functions.

floatBS :: ByteString -> AnchoredPath

Unsafe. Only ever use on bytestrings that came from flatten on a pre-existing AnchoredPath.

floatPath :: FilePath -> AnchoredPath

Take a relative FilePath and turn it into an AnchoredPath. The operation is (relatively) unsafe. Basically, by using floatPath, you are testifying that the argument is a path relative to some common root -- i.e. the root of the associated Tree object. Also, there are certain invariants about AnchoredPath that this function tries hard to preserve, but probably cannot guarantee (i.e. this is a best-effort thing). You should sanitize any FilePaths before you declare them good by converting into AnchoredPath (using this function).

replacePrefixPath :: AnchoredPath -> AnchoredPath -> AnchoredPath -> AnchoredPath

Take a prefix path, the changed prefix path, and a path to change. Assumes the prefix path is a valid prefix. If prefix is wrong return AnchoredPath [].