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 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"

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.

Interpret a possibly relative path wrt the current working directory.

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.

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

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

Make the second path relative to the first, if possible

Transform a SubPath into an AnchoredPath.

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).

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'?

TODO: Properly review the way we handle paths on Windows - it's not enough to just use the OS native concept of path separator. Windows often accepts both path separators, and repositories always use the UNIX separator anyway.

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.

Make a Name from a String. If the input String is invalid, that is, "", ".", "..", or contains a /, return Left with an error message.

Make a Name from a ByteString.

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).

Append an element to the end of a path.

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

Check whether a path is a prefix of another path.

If the patch is under a directory, split into Right of the first component (which must be a directory name) and the rest of teh path. Otherwise return Left of the single component. This function is *undefined* on the root path (which has no components).

The effect of renaming on paths. The first argument is the old path, the second is the new path, and the third is the possibly affected path we are interested in.

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

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

Replace the second arg's parent with the first arg.

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).

Is the given path in (or equal to) the _darcs metadata directory?

For displaying paths to the user. It should never be used for on-disk patch storage. This adds the "./" for consistency with how repo paths are displayed by showPatch and friends, except for the root path which is displayed as plain ".".

Interpret an AnchoredPath as relative the current working directory. Intended for IO operations in the file system. Use with care!

Take a relative FilePath and turn it into an AnchoredPath. This is a partial function. 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. In particular, the input path may not contain any ocurrences of "." or ".." after normalising. You should sanitize any FilePaths before you declare them "good" by converting into AnchoredPath (using this function), especially if the FilePath come from any external source (command line, file, environment, network, etc)