84 lines
2.8 KiB
Go
84 lines
2.8 KiB
Go
// Package sys includes constants and types used by both public and internal APIs.
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package sys
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import (
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"context"
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"fmt"
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)
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// These two special exit codes are reserved by wazero for context Cancel and Timeout integrations.
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// The assumption here is that well-behaving Wasm programs won't use these two exit codes.
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const (
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// ExitCodeContextCanceled corresponds to context.Canceled and returned by ExitError.ExitCode in that case.
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ExitCodeContextCanceled uint32 = 0xffffffff
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// ExitCodeDeadlineExceeded corresponds to context.DeadlineExceeded and returned by ExitError.ExitCode in that case.
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ExitCodeDeadlineExceeded uint32 = 0xefffffff
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)
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// ExitError is returned to a caller of api.Function when api.Module CloseWithExitCode was invoked,
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// or context.Context passed to api.Function Call was canceled or reached the Timeout.
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//
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// ExitCode zero value means success while any other value is an error.
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//
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// Here's an example of how to get the exit code:
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//
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// main := module.ExportedFunction("main")
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// if err := main(ctx); err != nil {
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// if exitErr, ok := err.(*sys.ExitError); ok {
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// // This means your module exited with non-zero code!
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// }
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// --snip--
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//
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// Note: While possible the reason of this was "proc_exit" from "wasi_snapshot_preview1", it could be from other host
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// functions, for example an AssemblyScript's abort handler, or any arbitrary caller of CloseWithExitCode.
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//
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// See https://github.com/WebAssembly/WASI/blob/main/phases/snapshot/docs.md#proc_exit and
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// https://www.assemblyscript.org/concepts.html#special-imports
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//
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// Note: In the case of context cancellation or timeout, the api.Module from which the api.Function created is closed.
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type ExitError struct {
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// Note: this is a struct not a uint32 type as it was originally one and
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// we don't want to break call-sites that cast into it.
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exitCode uint32
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}
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var exitZero = &ExitError{}
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func NewExitError(exitCode uint32) *ExitError {
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if exitCode == 0 {
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return exitZero
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}
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return &ExitError{exitCode: exitCode}
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}
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// ExitCode returns zero on success, and an arbitrary value otherwise.
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func (e *ExitError) ExitCode() uint32 {
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return e.exitCode
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}
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// Error implements the error interface.
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func (e *ExitError) Error() string {
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switch e.exitCode {
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case ExitCodeContextCanceled:
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return fmt.Sprintf("module closed with %s", context.Canceled)
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case ExitCodeDeadlineExceeded:
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return fmt.Sprintf("module closed with %s", context.DeadlineExceeded)
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default:
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return fmt.Sprintf("module closed with exit_code(%d)", e.exitCode)
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}
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}
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// Is allows use via errors.Is
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func (e *ExitError) Is(err error) bool {
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if target, ok := err.(*ExitError); ok {
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return e.exitCode == target.exitCode
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}
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if e.exitCode == ExitCodeContextCanceled && err == context.Canceled {
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return true
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}
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if e.exitCode == ExitCodeDeadlineExceeded && err == context.DeadlineExceeded {
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return true
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}
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return false
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}
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