Module fs 

Filesystem manipulation operations.

This module contains basic methods to manipulate the contents of the local filesystem. All methods in this module represent cross-platform filesystem operations. Extra platform-specific functionality can be found in the extension traits of std::os::$platform.

Time of Check to Time of Use (TOCTOU)

Many filesystem operations are subject to a race condition known as “Time of Check to Time of Use” (TOCTOU). This occurs when a program checks a condition (like file existence or permissions) and then uses the result of that check to make a decision, but the condition may have changed between the check and the use.

For example, checking if a file exists and then creating it if it doesn’t is vulnerable to TOCTOU - another process could create the file between your check and creation attempt.

Another example is with symbolic links: when removing a directory, if another process replaces the directory with a symbolic link between the check and the removal operation, the removal might affect the wrong location. This is why operations like remove_dir_all need to use atomic operations to prevent such race conditions.

To avoid TOCTOU issues:

• Be aware that metadata operations (like metadata or symlink_metadata) may be affected by changes made by other processes.
• Use atomic operations when possible (like File::create_new instead of checking existence then creating).
• Keep file open for the duration of operations.

Structs

DirBuilder

A builder used to create directories in various manners.

DirEntry

Entries returned by the ReadDir iterator.

File

An object providing access to an open file on the filesystem.

FileTimes

Representation of the various timestamps on a file.

FileType

A structure representing a type of file with accessors for each file type. It is returned by Metadata::file_type method.

Metadata

Metadata information about a file.

OpenOptions

Options and flags which can be used to configure how a file is opened.

Permissions

Representation of the various permissions on a file.

ReadDir

Iterator over the entries in a directory.

DirExperimental

An object providing access to a directory on the filesystem.

Enums

TryLockError

An enumeration of possible errors which can occur while trying to acquire a lock from the try_lock method and try_lock_shared method on a File.

Functions

canonicalize

Returns the canonical, absolute form of a path with all intermediate components normalized and symbolic links resolved.

copy

Copies the contents of one file to another. This function will also copy the permission bits of the original file to the destination file.

create_dir

Creates a new, empty directory at the provided path.

create_dir_all

Recursively create a directory and all of its parent components if they are missing.

exists

Returns Ok(true) if the path points at an existing entity.

hard_link

Creates a new hard link on the filesystem.

metadata

Given a path, queries the file system to get information about a file, directory, etc.

read

Reads the entire contents of a file into a bytes vector.

read_dir

Returns an iterator over the entries within a directory.

read_link

Reads a symbolic link, returning the file that the link points to.

read_to_string

Reads the entire contents of a file into a string.

remove_dir

Removes an empty directory.

remove_dir_all

Removes a directory at this path, after removing all its contents. Use carefully!

remove_file

Removes a file from the filesystem.

rename

Renames a file or directory to a new name, replacing the original file if to already exists.

set_permissions

Changes the permissions found on a file or a directory.

soft_linkDeprecated

Creates a new symbolic link on the filesystem.

symlink_metadata

Queries the metadata about a file without following symlinks.

write

Writes a slice as the entire contents of a file.

set_permissions_nofollowExperimental

Changes the permissions found on a file or a directory. On certain platforms, if the file is a symlink, it will change the permissions bits on the symlink itself rather than the target (e.g. Windows, BSD, MacOS). On other platforms, this results in an error when attempting to change permissions on a symlink (e.g. Linux).

set_timesExperimental

Changes the timestamps of the file or directory at the specified path.

set_times_nofollowExperimental

Changes the timestamps of the file or symlink at the specified path.