types

WASI filesystem is a filesystem API primarily intended to let users run WASI programs that access their files on their existing filesystems, without significant overhead. Paths are passed as interface-type `string`s, meaning they must consist of a sequence of Unicode Scalar Values (USVs). Some filesystems may contain paths which are not accessible by this API. The directory separator in WASI is always the forward-slash (`/`). All paths in WASI are relative paths, and are interpreted relative to a `descriptor` referring to a base directory. If a `path` argument to any WASI function starts with `/`, or if any step of resolving a `path`, including `..` and symbolic link steps, reaches a directory outside of the base directory, or reaches a symlink to an absolute or rooted path in the underlying filesystem, the function fails with `error-code::not-permitted`. For more information about WASI path resolution and sandboxing, see [WASI filesystem path resolution]. Though this package presents a portable interface modelled on POSIX, it prioritizes compatibility over portability: allowing users to access their files on their machine is more important than exposing a single semantics across all platforms. Notably, depending on the underlying operating system and file system: * Paths may be case-folded or not. * Deleting (unlinking) a file may fail if there are other file descriptors open. * Durability and atomicity of changes to underlying files when there are concurrent writers. Users that need well-defined, portable semantics should use a key-value store or a database instead. [WASI filesystem path resolution]: https://github.com/WebAssembly/wasi-filesystem/blob/main/path-resolution.md