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86 lines
3.8 KiB
Rust
86 lines
3.8 KiB
Rust
//! Sandboxed WebAssembly plug-ins for VectorCraft.
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//!
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//! A plug-in is a WebAssembly module that implements the VectorCraft plug-in ABI (v1, documented
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//! in `docs/plugins.md`). It runs in [`wasmi`], a pure-Rust interpreter, with:
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//!
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//! - **no host imports but those of API level 2** ([`host`]: progress, Cancel and log lines with
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//! the `progress` permission, and settings and a cache of its own with the `settings` and `cache`
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//! permissions, [`storage`]): no WASI, file system, network, clock or randomness. A module that
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//! imports anything else is rejected;
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//! - an **instruction budget** (fuel) per call, metered in slices so a wall-clock deadline is
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//! also enforced (native builds), so infinite loops end with an error. A filter may ask for a
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//! larger one ([`Budget::Heavy`]), which the host lets the user allow before installing it;
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//! - a **linear-memory cap**, a **recursion-depth cap** and wasmi's strict module limits;
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//! - a **fresh instance per run**, so no state leaks between calls; what a plug-in keeps is only
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//! what it writes to its settings and cache.
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//!
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//! Every failure (malformed module, trap, exhausted budget, bad output) is an [`Error`]; nothing
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//! a module does can panic or hang the host.
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//!
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//! Plug-ins see the document as JSON ([`objects`]): the selected paths and compound paths with
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//! their geometry, fills, strokes (gradients included) and opacity. An **object filter** returns
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//! the objects to keep, change or add, applied to the document as one edit
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//! ([`objects::apply_output`]); a **live effect** ([`effect`]) rewrites one object's geometry each
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//! time it is drawn, from an appearance stack; an **exporter** ([`export`]) writes the whole
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//! document in a file format of its own. The process-wide [`registry`] holds the installed
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//! plug-ins; in [`safe_mode`] none of them loads or runs. A plug-in's parameters ([`manifest`]) come with what the host's dialogs need to show
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//! them well: labels, units, groups, help and conditions ([`dialog`]). What a plug-in may do is
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//! the set of [`permissions`] its manifest lists, which the user approves when it is installed.
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#![forbid(unsafe_code)]
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pub mod dialog;
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pub mod effect;
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pub mod export;
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pub mod host;
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pub mod manifest;
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pub mod objects;
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pub mod permissions;
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pub mod registry;
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mod runtime;
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pub mod safe_mode;
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pub mod storage;
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pub mod wat;
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pub use dialog::ParamUi;
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pub use host::{LogLevel, LogLine, Report};
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pub use manifest::{Budget, Kind, Manifest, Param, ParamSpec};
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pub use runtime::{ABI_VERSION, HEAVY_FUEL, HEAVY_WALL_TIME_MS, Limits, Plugin, heavy_terms};
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/// What the host puts before a plug-in's id to name what it adds: its live effect
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/// (`plugin.<id>`, [`effect`]) or its file format ([`export`]).
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pub const PREFIX: &str = "plugin.";
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/// A plug-in error. Every way a module can misbehave ends here, never in a panic.
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#[derive(Debug, Clone, PartialEq, Eq, thiserror::Error)]
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pub enum Error {
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#[error("not a valid plug-in module: {0}")]
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Module(String),
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#[error("plug-in ABI: {0}")]
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Abi(String),
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#[error("plug-in manifest: {0}")]
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Manifest(String),
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#[error("plug-in trapped: {0}")]
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Trap(String),
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#[error("plug-in exceeded its {0}")]
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Limit(String),
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#[error("plug-in parameters: {0}")]
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Params(String),
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#[error("plug-in output: {0}")]
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Output(String),
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#[error("plug-in failed: {0}")]
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Failed(String),
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#[error("no plug-in {0:?} is installed")]
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NotFound(String),
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/// The caller asked the run to stop ([`vectorcraft_doc::cancel`]), between two slices of
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/// its instruction budget.
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#[error("cancelled")]
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Cancelled,
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/// Safe Mode is on ([`safe_mode`]): no plug-in loads or runs.
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#[error("Safe Mode is on: plug-ins don't load or run until VectorCraft starts normally")]
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SafeMode,
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#[error("{0}")]
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Io(String),
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}
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pub type Result<T> = std::result::Result<T, Error>;
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