Module require 

Requirements: conditions on the player’s work that are always checked.

A level’s requirements run before its answer, unconditionally: a correct answer next to a failed requirement is still a failure. That is what makes an answer impossible to shortcut (submitting level-1 without having used pwd fails), and what lets a level with no answer at all (a pure chmod task) be graded on the filesystem alone.

Each constructor (at, file(), content, …) returns a small builder with the message overrides that make sense for it; every builder converts into a Requirement, which is what Level::require takes. A requirement’s success text is never shown, so none is kept.

All declared paths are relative to the level’s section root and go through the one containment function. A path that passes through a symlink fails with messages::PATH_ESCAPES_WORKSPACE rather than being followed.

Structs

At

See at.

FileContent

See content.

LineCount

See line_count.

ModeIs

See mode and dir_mode.

Moved

See moved.

PermBits

See perm_bits.

Presence

See file(), dir, no_file and no_dir.

Requirement

A condition on the player’s work. Build one with the free functions of this module.

Same

See same.

Functions

at

The player must be standing in this section-relative directory.

at_home

The player must be standing in $HOME (compared canonically).

cd_evidence

This level’s own cd drill must have been performed (Marker::Cd). Needs a cd policy on the level, which is what writes the marker.

check

An arbitrary check, for the rare condition nothing else expresses. Prefer the declarative requirements: they are checked by the catalog lint, this is not.

content

Conditions on a text file’s content.

dir

A directory must exist here.

dir_mode

A directory’s permission bits must be exactly mode.

evidence

The marker file must exist: the player did something only the shell could witness.

fd_evidence

This level’s own file-descriptor drill must have been performed (Marker::Fd). Needs an on_fd rule on the level.

file

A regular file must exist here.

line_count

The file must have exactly expected lines, counted like Python’s str.splitlines().

mode

A file’s permission bits must be exactly mode.

moved

source must be gone and destination must exist.

no_dir

Nothing may remain here (a leftover symlink, even a dangling one, counts as remaining). The messages talk about a directory.

no_file

Nothing may remain here (a leftover symlink, even a dangling one, counts as remaining). The messages talk about a file.

perm_bits

Permission bits a file must have and must not have.

same

destination must be an exact copy of source: same names, same bytes, dotfiles included, symlinks compared by their link target and never followed.