tempdrive

tempdrive is a Python library defining functions and context managers to create and remove Windows disk drive substitutions, i.e. virtual disk drives that act as an alias to a directory. (Just like the classic subst.exe does.)

This functionality can be useful to get around the 260-character path length limit present in many Windows applications.

Class tempdrive.DriveLetter

This class represents a Windows disk drive letter. It can be both initialized and queryied in a variety of formats. (See DriveLetter.is_drive_string().)

Properties:

• letter: str: Just the uppercase drive letter, eg. C
• device: str: The uppercase drive letter, plus a colon, eg. C:
• path: pathlib.Path: Path of the root folder of the drive, eg. C:\

Static methods:

• is_drive_string(s: str): Returns whether s is a valid drive string, i.e. one of the following (X can be any lower or upper case English letter): "X", "X:", "X:\", "X:/".

Context manager tempdrive.temporary_drive()

Context manager to create a new drive substitution (using tempdrive.subst()) for the specified path with an automatically chosen drive letter. Remove drive substitution on exit.

When used in a with statement, the target of the as clause will be set to a pathlib.Path pointing to the newly created drive's root folder.

This function can be useful if a script needs to work within a deeply nested folder, and it starts hitting the 260-character path length limit.

Arguments:

• path: pathlib.Path: Path the newly created drive substitution should point to.
• log: Callable[[str], None]: Logging function to use for informational messages upon adding and removing the drive substitution. If unspecified or set to None, no messages are emitted.

Raises tempdrive.TempDriveError if there is no available drive letter to use. Raises OSError if it runs into an error while calling WinAPI functions.

Function tempdrive.subst()

Creates new drive substitution, similarly to subst.exe.

For example, tempdrive.subst(tempdrive.DriveLetter("w:"), Path(r'c:\Windows')) creates a virtual W: drive that acts as an alias to the Windows folder.

Substituted drives can be useful if an application starts hitting the 260-character path length limit.

Arguments:

• drive: tempdrive.DriveLetter: Drive letter to use for newly created drive substitution.
• path: pathlib.Path: Path the newly created drive substitution should point to.

Raises tempdrive.TempDriveError if drive is already in use. Raises OSError if it runs into an error while calling WinAPI functions.

Function tempdrive.unsubst()

Removes a drive substitution created by tempdrive.subst().

Arguments:

• drive: tempdrive.DriveLetter: Drive letter of substitution to remove.

Raises tempdrive.TempDriveError if the drive does not exist, or is not a substitution. Raises OSError if it runs into an error while calling WinAPI functions.

Function get_used_drive_letters()

Returns the list of tempdrive.DriveLetter objects that represent all disk drives currently present in the system. This includes:

• Physical drives
• Virtual/substituted disk drives
• Connected network drives
• Disconnected but registered network drives
• ...

Raises OSError if it runs into an error while calling WinAPI functions.

Function get_free_drive_letters()

Returns the list of tempdrive.DriveLetter objects that represent the unassigned drive letters of the system, available for drive substitution using tempdrive.subst().

Note that this list never includes A: and B: because they were historically used for floppy disk drives, and Windows handles them specially, so it's ill-advised to use them for other purposes.

Raises OSError if it runs into an error while calling WinAPI functions.

Licensing

This library is licensed under the MIT license.