error.rs

use alloc::string::{String, ToString};
use alloc::vec::Vec;
use core::{fmt::Display, ops::ControlFlow};
use tinywasm_types::FuncType;

#[cfg(feature = "parser")]
pub use tinywasm_parser::ParseError;

#[cfg(feature = "async")]
use crate::coro::UnexpectedSuspendError;

use crate::interpreter;

/// Errors that can occur for `TinyWasm` operations
#[derive(Debug)]
pub enum Error {
    /// A WebAssembly trap occurred
    Trap(Trap),

    /// A linking error occurred
    Linker(LinkingError),

    /// A WebAssembly feature is not supported
    UnsupportedFeature(String),

    /// An unknown error occurred
    Other(String),

    /// A host function returned an invalid value
    InvalidHostFnReturn {
        /// The expected type
        expected: FuncType,
        /// The actual value
        actual: Vec<tinywasm_types::WasmValue>,
    },

    /// An invalid label type was encountered
    InvalidLabelType,

    /// The store is not the one that the module instance was instantiated in
    InvalidStore,

    /// ResumeArgument of wrong type was provided
    InvalidResumeArgument,

    /// Tried to resume on runtime when it's not suspended
    InvalidResume,

    /// Function unexpectedly yielded instead of returning
    /// (for backwards compatibility with old api)
    #[cfg(feature = "async")]
    UnexpectedSuspend(UnexpectedSuspendError),

    #[cfg(feature = "std")]
    /// An I/O error occurred
    Io(crate::std::io::Error),

    #[cfg(feature = "parser")]
    /// A parsing error occurred
    ParseError(ParseError),
}

#[derive(Debug)]
/// Errors that can occur when linking a WebAssembly module
pub enum LinkingError {
    /// An unknown import was encountered
    UnknownImport {
        /// The module name
        module: String,
        /// The import name
        name: String,
    },

    /// A mismatched import type was encountered
    IncompatibleImportType {
        /// The module name
        module: String,
        /// The import name
        name: String,
    },
}

impl LinkingError {
    pub(crate) fn incompatible_import_type(import: &tinywasm_types::Import) -> Self {
        Self::IncompatibleImportType { module: import.module.to_string(), name: import.name.to_string() }
    }

    pub(crate) fn unknown_import(import: &tinywasm_types::Import) -> Self {
        Self::UnknownImport { module: import.module.to_string(), name: import.name.to_string() }
    }
}

#[derive(Debug)]
/// A WebAssembly trap
///
/// See <https://webassembly.github.io/spec/core/intro/overview.html#trap>
pub enum Trap {
    /// An unreachable instruction was executed
    Unreachable,

    /// An out-of-bounds memory access occurred
    MemoryOutOfBounds {
        /// The offset of the access
        offset: usize,
        /// The size of the access
        len: usize,
        /// The maximum size of the memory
        max: usize,
    },

    /// An out-of-bounds table access occurred
    TableOutOfBounds {
        /// The offset of the access
        offset: usize,
        /// The size of the access
        len: usize,
        /// The maximum size of the memory
        max: usize,
    },

    /// A division by zero occurred
    DivisionByZero,

    /// Invalid Integer Conversion
    InvalidConversionToInt,

    /// Integer Overflow
    IntegerOverflow,

    /// Call stack overflow
    CallStackOverflow,

    /// An undefined element was encountered
    UndefinedElement {
        /// The element index
        index: usize,
    },

    /// An uninitialized element was encountered
    UninitializedElement {
        /// The element index
        index: usize,
    },

    /// Indirect call type mismatch
    IndirectCallTypeMismatch {
        /// The expected type
        expected: FuncType,
        /// The actual type
        actual: FuncType,
    },
}

impl Trap {
    /// Get the message of the trap
    pub fn message(&self) -> &'static str {
        match self {
            Self::Unreachable => "unreachable",
            Self::MemoryOutOfBounds { .. } => "out of bounds memory access",
            Self::TableOutOfBounds { .. } => "out of bounds table access",
            Self::DivisionByZero => "integer divide by zero",
            Self::InvalidConversionToInt => "invalid conversion to integer",
            Self::IntegerOverflow => "integer overflow",
            Self::CallStackOverflow => "call stack exhausted",
            Self::UndefinedElement { .. } => "undefined element",
            Self::UninitializedElement { .. } => "uninitialized element",
            Self::IndirectCallTypeMismatch { .. } => "indirect call type mismatch",
        }
    }
}

impl LinkingError {
    /// Get the message of the linking error
    pub fn message(&self) -> &'static str {
        match self {
            Self::UnknownImport { .. } => "unknown import",
            Self::IncompatibleImportType { .. } => "incompatible import type",
        }
    }
}

impl From<LinkingError> for Error {
    fn from(value: LinkingError) -> Self {
        Self::Linker(value)
    }
}

impl From<Trap> for Error {
    fn from(value: Trap) -> Self {
        Self::Trap(value)
    }
}

impl Display for Error {
    fn fmt(&self, f: &mut core::fmt::Formatter<'_>) -> core::fmt::Result {
        match self {
            #[cfg(feature = "parser")]
            Self::ParseError(err) => write!(f, "error parsing module: {err:?}"),

            #[cfg(feature = "std")]
            Self::Io(err) => write!(f, "I/O error: {err}"),

            #[cfg(feature = "async")]
            Self::UnexpectedSuspend(_) => write!(f, "funtion yielded instead of returning"),

            Self::Trap(trap) => write!(f, "trap: {trap}"),
            Self::Linker(err) => write!(f, "linking error: {err}"),
            Self::InvalidLabelType => write!(f, "invalid label type"),
            Self::Other(message) => write!(f, "unknown error: {message}"),
            Self::UnsupportedFeature(feature) => write!(f, "unsupported feature: {feature}"),
            Self::InvalidHostFnReturn { expected, actual } => {
                write!(f, "invalid host function return: expected={expected:?}, actual={actual:?}")
            }
            Self::InvalidStore => write!(f, "invalid store"),
            Self::InvalidResumeArgument => write!(f, "invalid resume argument supplied to suspended function"),
            Self::InvalidResume => write!(f, "attempt to resume coroutine that has already finished"),
        }
    }
}

impl Display for LinkingError {
    fn fmt(&self, f: &mut core::fmt::Formatter<'_>) -> core::fmt::Result {
        match self {
            Self::UnknownImport { module, name } => write!(f, "unknown import: {}.{}", module, name),
            Self::IncompatibleImportType { module, name } => {
                write!(f, "incompatible import type: {}.{}", module, name)
            }
        }
    }
}

impl Display for Trap {
    fn fmt(&self, f: &mut core::fmt::Formatter<'_>) -> core::fmt::Result {
        match self {
            Self::Unreachable => write!(f, "unreachable"),
            Self::MemoryOutOfBounds { offset, len, max } => {
                write!(f, "out of bounds memory access: offset={offset}, len={len}, max={max}")
            }
            Self::TableOutOfBounds { offset, len, max } => {
                write!(f, "out of bounds table access: offset={offset}, len={len}, max={max}")
            }
            Self::DivisionByZero => write!(f, "integer divide by zero"),
            Self::InvalidConversionToInt => write!(f, "invalid conversion to integer"),
            Self::IntegerOverflow => write!(f, "integer overflow"),
            Self::CallStackOverflow => write!(f, "call stack exhausted"),
            Self::UndefinedElement { index } => write!(f, "undefined element: index={index}"),
            Self::UninitializedElement { index } => {
                write!(f, "uninitialized element: index={index}")
            }
            Self::IndirectCallTypeMismatch { expected, actual } => {
                write!(f, "indirect call type mismatch: expected={expected:?}, actual={actual:?}")
            }
        }
    }
}

impl core::error::Error for Error {}

#[cfg(feature = "parser")]
impl From<tinywasm_parser::ParseError> for Error {
    fn from(value: tinywasm_parser::ParseError) -> Self {
        Self::ParseError(value)
    }
}

/// A wrapper around [`core::result::Result`] for tinywasm operations
pub type Result<T, E = Error> = crate::std::result::Result<T, E>;

pub(crate) trait Controlify<T> {
    fn to_cf(self) -> ControlFlow<interpreter::executor::ReasonToBreak, T>;
}

impl<T> Controlify<T> for Result<T, Error> {
    fn to_cf(self) -> ControlFlow<interpreter::executor::ReasonToBreak, T> {
        match self {
            Ok(value) => ControlFlow::Continue(value),
            Err(err) => ControlFlow::Break(interpreter::executor::ReasonToBreak::Errored(err)),
        }
    }
}