gotosocial/vendor/github.com/tetratelabs/wazero/config.go

901 lines
34 KiB
Go

package wazero
import (
"context"
"errors"
"fmt"
"io"
"io/fs"
"math"
"net"
"time"
"github.com/tetratelabs/wazero/api"
experimentalsys "github.com/tetratelabs/wazero/experimental/sys"
"github.com/tetratelabs/wazero/internal/engine/interpreter"
"github.com/tetratelabs/wazero/internal/engine/wazevo"
"github.com/tetratelabs/wazero/internal/filecache"
"github.com/tetratelabs/wazero/internal/internalapi"
"github.com/tetratelabs/wazero/internal/platform"
internalsock "github.com/tetratelabs/wazero/internal/sock"
internalsys "github.com/tetratelabs/wazero/internal/sys"
"github.com/tetratelabs/wazero/internal/wasm"
"github.com/tetratelabs/wazero/sys"
)
// RuntimeConfig controls runtime behavior, with the default implementation as
// NewRuntimeConfig
//
// The example below explicitly limits to Wasm Core 1.0 features as opposed to
// relying on defaults:
//
// rConfig = wazero.NewRuntimeConfig().WithCoreFeatures(api.CoreFeaturesV1)
//
// # Notes
//
// - This is an interface for decoupling, not third-party implementations.
// All implementations are in wazero.
// - RuntimeConfig is immutable. Each WithXXX function returns a new instance
// including the corresponding change.
type RuntimeConfig interface {
// WithCoreFeatures sets the WebAssembly Core specification features this
// runtime supports. Defaults to api.CoreFeaturesV2.
//
// Example of disabling a specific feature:
// features := api.CoreFeaturesV2.SetEnabled(api.CoreFeatureMutableGlobal, false)
// rConfig = wazero.NewRuntimeConfig().WithCoreFeatures(features)
//
// # Why default to version 2.0?
//
// Many compilers that target WebAssembly require features after
// api.CoreFeaturesV1 by default. For example, TinyGo v0.24+ requires
// api.CoreFeatureBulkMemoryOperations. To avoid runtime errors, wazero
// defaults to api.CoreFeaturesV2, even though it is not yet a Web
// Standard (REC).
WithCoreFeatures(api.CoreFeatures) RuntimeConfig
// WithMemoryLimitPages overrides the maximum pages allowed per memory. The
// default is 65536, allowing 4GB total memory per instance if the maximum is
// not encoded in a Wasm binary. Setting a value larger than default will panic.
//
// This example reduces the largest possible memory size from 4GB to 128KB:
// rConfig = wazero.NewRuntimeConfig().WithMemoryLimitPages(2)
//
// Note: Wasm has 32-bit memory and each page is 65536 (2^16) bytes. This
// implies a max of 65536 (2^16) addressable pages.
// See https://www.w3.org/TR/2019/REC-wasm-core-1-20191205/#grow-mem
WithMemoryLimitPages(memoryLimitPages uint32) RuntimeConfig
// WithMemoryCapacityFromMax eagerly allocates max memory, unless max is
// not defined. The default is false, which means minimum memory is
// allocated and any call to grow memory results in re-allocations.
//
// This example ensures any memory.grow instruction will never re-allocate:
// rConfig = wazero.NewRuntimeConfig().WithMemoryCapacityFromMax(true)
//
// See https://www.w3.org/TR/2019/REC-wasm-core-1-20191205/#grow-mem
//
// Note: if the memory maximum is not encoded in a Wasm binary, this
// results in allocating 4GB. See the doc on WithMemoryLimitPages for detail.
WithMemoryCapacityFromMax(memoryCapacityFromMax bool) RuntimeConfig
// WithDebugInfoEnabled toggles DWARF based stack traces in the face of
// runtime errors. Defaults to true.
//
// Those who wish to disable this, can like so:
//
// r := wazero.NewRuntimeWithConfig(wazero.NewRuntimeConfig().WithDebugInfoEnabled(false)
//
// When disabled, a stack trace message looks like:
//
// wasm stack trace:
// .runtime._panic(i32)
// .myFunc()
// .main.main()
// .runtime.run()
// ._start()
//
// When enabled, the stack trace includes source code information:
//
// wasm stack trace:
// .runtime._panic(i32)
// 0x16e2: /opt/homebrew/Cellar/tinygo/0.26.0/src/runtime/runtime_tinygowasm.go:73:6
// .myFunc()
// 0x190b: /Users/XXXXX/wazero/internal/testing/dwarftestdata/testdata/main.go:19:7
// .main.main()
// 0x18ed: /Users/XXXXX/wazero/internal/testing/dwarftestdata/testdata/main.go:4:3
// .runtime.run()
// 0x18cc: /opt/homebrew/Cellar/tinygo/0.26.0/src/runtime/scheduler_none.go:26:10
// ._start()
// 0x18b6: /opt/homebrew/Cellar/tinygo/0.26.0/src/runtime/runtime_wasm_wasi.go:22:5
//
// Note: This only takes into effect when the original Wasm binary has the
// DWARF "custom sections" that are often stripped, depending on
// optimization flags passed to the compiler.
WithDebugInfoEnabled(bool) RuntimeConfig
// WithCompilationCache configures how runtime caches the compiled modules. In the default configuration, compilation results are
// only in-memory until Runtime.Close is closed, and not shareable by multiple Runtime.
//
// Below defines the shared cache across multiple instances of Runtime:
//
// // Creates the new Cache and the runtime configuration with it.
// cache := wazero.NewCompilationCache()
// defer cache.Close()
// config := wazero.NewRuntimeConfig().WithCompilationCache(c)
//
// // Creates two runtimes while sharing compilation caches.
// foo := wazero.NewRuntimeWithConfig(context.Background(), config)
// bar := wazero.NewRuntimeWithConfig(context.Background(), config)
//
// # Cache Key
//
// Cached files are keyed on the version of wazero. This is obtained from go.mod of your application,
// and we use it to verify the compatibility of caches against the currently-running wazero.
// However, if you use this in tests of a package not named as `main`, then wazero cannot obtain the correct
// version of wazero due to the known issue of debug.BuildInfo function: https://github.com/golang/go/issues/33976.
// As a consequence, your cache won't contain the correct version information and always be treated as `dev` version.
// To avoid this issue, you can pass -ldflags "-X github.com/tetratelabs/wazero/internal/version.version=foo" when running tests.
WithCompilationCache(CompilationCache) RuntimeConfig
// WithCustomSections toggles parsing of "custom sections". Defaults to false.
//
// When enabled, it is possible to retrieve custom sections from a CompiledModule:
//
// config := wazero.NewRuntimeConfig().WithCustomSections(true)
// r := wazero.NewRuntimeWithConfig(ctx, config)
// c, err := r.CompileModule(ctx, wasm)
// customSections := c.CustomSections()
WithCustomSections(bool) RuntimeConfig
// WithCloseOnContextDone ensures the executions of functions to be terminated under one of the following circumstances:
//
// - context.Context passed to the Call method of api.Function is canceled during execution. (i.e. ctx by context.WithCancel)
// - context.Context passed to the Call method of api.Function reaches timeout during execution. (i.e. ctx by context.WithTimeout or context.WithDeadline)
// - Close or CloseWithExitCode of api.Module is explicitly called during execution.
//
// This is especially useful when one wants to run untrusted Wasm binaries since otherwise, any invocation of
// api.Function can potentially block the corresponding Goroutine forever. Moreover, it might block the
// entire underlying OS thread which runs the api.Function call. See "Why it's safe to execute runtime-generated
// machine codes against async Goroutine preemption" section in RATIONALE.md for detail.
//
// Upon the termination of the function executions, api.Module is closed.
//
// Note that this comes with a bit of extra cost when enabled. The reason is that internally this forces
// interpreter and compiler runtimes to insert the periodical checks on the conditions above. For that reason,
// this is disabled by default.
//
// See examples in context_done_example_test.go for the end-to-end demonstrations.
//
// When the invocations of api.Function are closed due to this, sys.ExitError is raised to the callers and
// the api.Module from which the functions are derived is made closed.
WithCloseOnContextDone(bool) RuntimeConfig
}
// NewRuntimeConfig returns a RuntimeConfig using the compiler if it is supported in this environment,
// or the interpreter otherwise.
func NewRuntimeConfig() RuntimeConfig {
return newRuntimeConfig()
}
type newEngine func(context.Context, api.CoreFeatures, filecache.Cache) wasm.Engine
type runtimeConfig struct {
enabledFeatures api.CoreFeatures
memoryLimitPages uint32
memoryCapacityFromMax bool
engineKind engineKind
dwarfDisabled bool // negative as defaults to enabled
newEngine newEngine
cache CompilationCache
storeCustomSections bool
ensureTermination bool
}
// engineLessConfig helps avoid copy/pasting the wrong defaults.
var engineLessConfig = &runtimeConfig{
enabledFeatures: api.CoreFeaturesV2,
memoryLimitPages: wasm.MemoryLimitPages,
memoryCapacityFromMax: false,
dwarfDisabled: false,
}
type engineKind int
const (
engineKindCompiler engineKind = iota
engineKindInterpreter
engineKindCount
)
// NewRuntimeConfigCompiler compiles WebAssembly modules into
// runtime.GOARCH-specific assembly for optimal performance.
//
// The default implementation is AOT (Ahead of Time) compilation, applied at
// Runtime.CompileModule. This allows consistent runtime performance, as well
// the ability to reduce any first request penalty.
//
// Note: While this is technically AOT, this does not imply any action on your
// part. wazero automatically performs ahead-of-time compilation as needed when
// Runtime.CompileModule is invoked.
//
// # Warning
//
// - This panics at runtime if the runtime.GOOS or runtime.GOARCH does not
// support compiler. Use NewRuntimeConfig to safely detect and fallback to
// NewRuntimeConfigInterpreter if needed.
//
// - If you are using wazero in buildmode=c-archive or c-shared, make sure that you set up the alternate signal stack
// by using, e.g. `sigaltstack` combined with `SA_ONSTACK` flag on `sigaction` on Linux,
// before calling any api.Function. This is because the Go runtime does not set up the alternate signal stack
// for c-archive or c-shared modes, and wazero uses the different stack than the calling Goroutine.
// Hence, the signal handler might get invoked on the wazero's stack, which may cause a stack overflow.
// https://github.com/tetratelabs/wazero/blob/2092c0a879f30d49d7b37f333f4547574b8afe0d/internal/integration_test/fuzz/fuzz/tests/sigstack.rs#L19-L36
func NewRuntimeConfigCompiler() RuntimeConfig {
ret := engineLessConfig.clone()
ret.engineKind = engineKindCompiler
ret.newEngine = wazevo.NewEngine
return ret
}
// NewRuntimeConfigInterpreter interprets WebAssembly modules instead of compiling them into assembly.
func NewRuntimeConfigInterpreter() RuntimeConfig {
ret := engineLessConfig.clone()
ret.engineKind = engineKindInterpreter
ret.newEngine = interpreter.NewEngine
return ret
}
// clone makes a deep copy of this runtime config.
func (c *runtimeConfig) clone() *runtimeConfig {
ret := *c // copy except maps which share a ref
return &ret
}
// WithCoreFeatures implements RuntimeConfig.WithCoreFeatures
func (c *runtimeConfig) WithCoreFeatures(features api.CoreFeatures) RuntimeConfig {
ret := c.clone()
ret.enabledFeatures = features
return ret
}
// WithCloseOnContextDone implements RuntimeConfig.WithCloseOnContextDone
func (c *runtimeConfig) WithCloseOnContextDone(ensure bool) RuntimeConfig {
ret := c.clone()
ret.ensureTermination = ensure
return ret
}
// WithMemoryLimitPages implements RuntimeConfig.WithMemoryLimitPages
func (c *runtimeConfig) WithMemoryLimitPages(memoryLimitPages uint32) RuntimeConfig {
ret := c.clone()
// This panics instead of returning an error as it is unlikely.
if memoryLimitPages > wasm.MemoryLimitPages {
panic(fmt.Errorf("memoryLimitPages invalid: %d > %d", memoryLimitPages, wasm.MemoryLimitPages))
}
ret.memoryLimitPages = memoryLimitPages
return ret
}
// WithCompilationCache implements RuntimeConfig.WithCompilationCache
func (c *runtimeConfig) WithCompilationCache(ca CompilationCache) RuntimeConfig {
ret := c.clone()
ret.cache = ca
return ret
}
// WithMemoryCapacityFromMax implements RuntimeConfig.WithMemoryCapacityFromMax
func (c *runtimeConfig) WithMemoryCapacityFromMax(memoryCapacityFromMax bool) RuntimeConfig {
ret := c.clone()
ret.memoryCapacityFromMax = memoryCapacityFromMax
return ret
}
// WithDebugInfoEnabled implements RuntimeConfig.WithDebugInfoEnabled
func (c *runtimeConfig) WithDebugInfoEnabled(dwarfEnabled bool) RuntimeConfig {
ret := c.clone()
ret.dwarfDisabled = !dwarfEnabled
return ret
}
// WithCustomSections implements RuntimeConfig.WithCustomSections
func (c *runtimeConfig) WithCustomSections(storeCustomSections bool) RuntimeConfig {
ret := c.clone()
ret.storeCustomSections = storeCustomSections
return ret
}
// CompiledModule is a WebAssembly module ready to be instantiated (Runtime.InstantiateModule) as an api.Module.
//
// In WebAssembly terminology, this is a decoded, validated, and possibly also compiled module. wazero avoids using
// the name "Module" for both before and after instantiation as the name conflation has caused confusion.
// See https://www.w3.org/TR/2019/REC-wasm-core-1-20191205/#semantic-phases%E2%91%A0
//
// # Notes
//
// - This is an interface for decoupling, not third-party implementations.
// All implementations are in wazero.
// - Closing the wazero.Runtime closes any CompiledModule it compiled.
type CompiledModule interface {
// Name returns the module name encoded into the binary or empty if not.
Name() string
// ImportedFunctions returns all the imported functions
// (api.FunctionDefinition) in this module or nil if there are none.
//
// Note: Unlike ExportedFunctions, there is no unique constraint on
// imports.
ImportedFunctions() []api.FunctionDefinition
// ExportedFunctions returns all the exported functions
// (api.FunctionDefinition) in this module keyed on export name.
ExportedFunctions() map[string]api.FunctionDefinition
// ImportedMemories returns all the imported memories
// (api.MemoryDefinition) in this module or nil if there are none.
//
// ## Notes
// - As of WebAssembly Core Specification 2.0, there can be at most one
// memory.
// - Unlike ExportedMemories, there is no unique constraint on imports.
ImportedMemories() []api.MemoryDefinition
// ExportedMemories returns all the exported memories
// (api.MemoryDefinition) in this module keyed on export name.
//
// Note: As of WebAssembly Core Specification 2.0, there can be at most one
// memory.
ExportedMemories() map[string]api.MemoryDefinition
// CustomSections returns all the custom sections
// (api.CustomSection) in this module keyed on the section name.
CustomSections() []api.CustomSection
// Close releases all the allocated resources for this CompiledModule.
//
// Note: It is safe to call Close while having outstanding calls from an
// api.Module instantiated from this.
Close(context.Context) error
}
// compile-time check to ensure compiledModule implements CompiledModule
var _ CompiledModule = &compiledModule{}
type compiledModule struct {
module *wasm.Module
// compiledEngine holds an engine on which `module` is compiled.
compiledEngine wasm.Engine
// closeWithModule prevents leaking compiled code when a module is compiled implicitly.
closeWithModule bool
typeIDs []wasm.FunctionTypeID
}
// Name implements CompiledModule.Name
func (c *compiledModule) Name() (moduleName string) {
if ns := c.module.NameSection; ns != nil {
moduleName = ns.ModuleName
}
return
}
// Close implements CompiledModule.Close
func (c *compiledModule) Close(context.Context) error {
c.compiledEngine.DeleteCompiledModule(c.module)
// It is possible the underlying may need to return an error later, but in any case this matches api.Module.Close.
return nil
}
// ImportedFunctions implements CompiledModule.ImportedFunctions
func (c *compiledModule) ImportedFunctions() []api.FunctionDefinition {
return c.module.ImportedFunctions()
}
// ExportedFunctions implements CompiledModule.ExportedFunctions
func (c *compiledModule) ExportedFunctions() map[string]api.FunctionDefinition {
return c.module.ExportedFunctions()
}
// ImportedMemories implements CompiledModule.ImportedMemories
func (c *compiledModule) ImportedMemories() []api.MemoryDefinition {
return c.module.ImportedMemories()
}
// ExportedMemories implements CompiledModule.ExportedMemories
func (c *compiledModule) ExportedMemories() map[string]api.MemoryDefinition {
return c.module.ExportedMemories()
}
// CustomSections implements CompiledModule.CustomSections
func (c *compiledModule) CustomSections() []api.CustomSection {
ret := make([]api.CustomSection, len(c.module.CustomSections))
for i, d := range c.module.CustomSections {
ret[i] = &customSection{data: d.Data, name: d.Name}
}
return ret
}
// customSection implements wasm.CustomSection
type customSection struct {
internalapi.WazeroOnlyType
name string
data []byte
}
// Name implements wasm.CustomSection.Name
func (c *customSection) Name() string {
return c.name
}
// Data implements wasm.CustomSection.Data
func (c *customSection) Data() []byte {
return c.data
}
// ModuleConfig configures resources needed by functions that have low-level interactions with the host operating
// system. Using this, resources such as STDIN can be isolated, so that the same module can be safely instantiated
// multiple times.
//
// Here's an example:
//
// // Initialize base configuration:
// config := wazero.NewModuleConfig().WithStdout(buf).WithSysNanotime()
//
// // Assign different configuration on each instantiation
// mod, _ := r.InstantiateModule(ctx, compiled, config.WithName("rotate").WithArgs("rotate", "angle=90", "dir=cw"))
//
// While wazero supports Windows as a platform, host functions using ModuleConfig follow a UNIX dialect.
// See RATIONALE.md for design background and relationship to WebAssembly System Interfaces (WASI).
//
// # Notes
//
// - This is an interface for decoupling, not third-party implementations.
// All implementations are in wazero.
// - ModuleConfig is immutable. Each WithXXX function returns a new instance
// including the corresponding change.
type ModuleConfig interface {
// WithArgs assigns command-line arguments visible to an imported function that reads an arg vector (argv). Defaults to
// none. Runtime.InstantiateModule errs if any arg is empty.
//
// These values are commonly read by the functions like "args_get" in "wasi_snapshot_preview1" although they could be
// read by functions imported from other modules.
//
// Similar to os.Args and exec.Cmd Env, many implementations would expect a program name to be argv[0]. However, neither
// WebAssembly nor WebAssembly System Interfaces (WASI) define this. Regardless, you may choose to set the first
// argument to the same value set via WithName.
//
// Note: This does not default to os.Args as that violates sandboxing.
//
// See https://linux.die.net/man/3/argv and https://en.wikipedia.org/wiki/Null-terminated_string
WithArgs(...string) ModuleConfig
// WithEnv sets an environment variable visible to a Module that imports functions. Defaults to none.
// Runtime.InstantiateModule errs if the key is empty or contains a NULL(0) or equals("") character.
//
// Validation is the same as os.Setenv on Linux and replaces any existing value. Unlike exec.Cmd Env, this does not
// default to the current process environment as that would violate sandboxing. This also does not preserve order.
//
// Environment variables are commonly read by the functions like "environ_get" in "wasi_snapshot_preview1" although
// they could be read by functions imported from other modules.
//
// While similar to process configuration, there are no assumptions that can be made about anything OS-specific. For
// example, neither WebAssembly nor WebAssembly System Interfaces (WASI) define concerns processes have, such as
// case-sensitivity on environment keys. For portability, define entries with case-insensitively unique keys.
//
// See https://linux.die.net/man/3/environ and https://en.wikipedia.org/wiki/Null-terminated_string
WithEnv(key, value string) ModuleConfig
// WithFS is a convenience that calls WithFSConfig with an FSConfig of the
// input for the root ("/") guest path.
WithFS(fs.FS) ModuleConfig
// WithFSConfig configures the filesystem available to each guest
// instantiated with this configuration. By default, no file access is
// allowed, so functions like `path_open` result in unsupported errors
// (e.g. syscall.ENOSYS).
WithFSConfig(FSConfig) ModuleConfig
// WithName configures the module name. Defaults to what was decoded from
// the name section. Duplicate names are not allowed in a single Runtime.
//
// Calling this with the empty string "" makes the module anonymous.
// That is useful when you want to instantiate the same CompiledModule multiple times like below:
//
// for i := 0; i < N; i++ {
// // Instantiate a new Wasm module from the already compiled `compiledWasm` anonymously without a name.
// instance, err := r.InstantiateModule(ctx, compiledWasm, wazero.NewModuleConfig().WithName(""))
// // ....
// }
//
// See the `concurrent-instantiation` example for a complete usage.
//
// Non-empty named modules are available for other modules to import by name.
WithName(string) ModuleConfig
// WithStartFunctions configures the functions to call after the module is
// instantiated. Defaults to "_start".
//
// Clearing the default is supported, via `WithStartFunctions()`.
//
// # Notes
//
// - If a start function doesn't exist, it is skipped. However, any that
// do exist are called in order.
// - Start functions are not intended to be called multiple times.
// Functions that should be called multiple times should be invoked
// manually via api.Module's `ExportedFunction` method.
// - Start functions commonly exit the module during instantiation,
// preventing use of any functions later. This is the case in "wasip1",
// which defines the default value "_start".
// - See /RATIONALE.md for motivation of this feature.
WithStartFunctions(...string) ModuleConfig
// WithStderr configures where standard error (file descriptor 2) is written. Defaults to io.Discard.
//
// This writer is most commonly used by the functions like "fd_write" in "wasi_snapshot_preview1" although it could
// be used by functions imported from other modules.
//
// # Notes
//
// - The caller is responsible to close any io.Writer they supply: It is not closed on api.Module Close.
// - This does not default to os.Stderr as that both violates sandboxing and prevents concurrent modules.
//
// See https://linux.die.net/man/3/stderr
WithStderr(io.Writer) ModuleConfig
// WithStdin configures where standard input (file descriptor 0) is read. Defaults to return io.EOF.
//
// This reader is most commonly used by the functions like "fd_read" in "wasi_snapshot_preview1" although it could
// be used by functions imported from other modules.
//
// # Notes
//
// - The caller is responsible to close any io.Reader they supply: It is not closed on api.Module Close.
// - This does not default to os.Stdin as that both violates sandboxing and prevents concurrent modules.
//
// See https://linux.die.net/man/3/stdin
WithStdin(io.Reader) ModuleConfig
// WithStdout configures where standard output (file descriptor 1) is written. Defaults to io.Discard.
//
// This writer is most commonly used by the functions like "fd_write" in "wasi_snapshot_preview1" although it could
// be used by functions imported from other modules.
//
// # Notes
//
// - The caller is responsible to close any io.Writer they supply: It is not closed on api.Module Close.
// - This does not default to os.Stdout as that both violates sandboxing and prevents concurrent modules.
//
// See https://linux.die.net/man/3/stdout
WithStdout(io.Writer) ModuleConfig
// WithWalltime configures the wall clock, sometimes referred to as the
// real time clock. sys.Walltime returns the current unix/epoch time,
// seconds since midnight UTC 1 January 1970, with a nanosecond fraction.
// This defaults to a fake result that increases by 1ms on each reading.
//
// Here's an example that uses a custom clock:
// moduleConfig = moduleConfig.
// WithWalltime(func(context.Context) (sec int64, nsec int32) {
// return clock.walltime()
// }, sys.ClockResolution(time.Microsecond.Nanoseconds()))
//
// # Notes:
// - This does not default to time.Now as that violates sandboxing.
// - This is used to implement host functions such as WASI
// `clock_time_get` with the `realtime` clock ID.
// - Use WithSysWalltime for a usable implementation.
WithWalltime(sys.Walltime, sys.ClockResolution) ModuleConfig
// WithSysWalltime uses time.Now for sys.Walltime with a resolution of 1us
// (1000ns).
//
// See WithWalltime
WithSysWalltime() ModuleConfig
// WithNanotime configures the monotonic clock, used to measure elapsed
// time in nanoseconds. Defaults to a fake result that increases by 1ms
// on each reading.
//
// Here's an example that uses a custom clock:
// moduleConfig = moduleConfig.
// WithNanotime(func(context.Context) int64 {
// return clock.nanotime()
// }, sys.ClockResolution(time.Microsecond.Nanoseconds()))
//
// # Notes:
// - This does not default to time.Since as that violates sandboxing.
// - This is used to implement host functions such as WASI
// `clock_time_get` with the `monotonic` clock ID.
// - Some compilers implement sleep by looping on sys.Nanotime (e.g. Go).
// - If you set this, you should probably set WithNanosleep also.
// - Use WithSysNanotime for a usable implementation.
WithNanotime(sys.Nanotime, sys.ClockResolution) ModuleConfig
// WithSysNanotime uses time.Now for sys.Nanotime with a resolution of 1us.
//
// See WithNanotime
WithSysNanotime() ModuleConfig
// WithNanosleep configures the how to pause the current goroutine for at
// least the configured nanoseconds. Defaults to return immediately.
//
// This example uses a custom sleep function:
// moduleConfig = moduleConfig.
// WithNanosleep(func(ns int64) {
// rel := unix.NsecToTimespec(ns)
// remain := unix.Timespec{}
// for { // loop until no more time remaining
// err := unix.ClockNanosleep(unix.CLOCK_MONOTONIC, 0, &rel, &remain)
// --snip--
//
// # Notes:
// - This does not default to time.Sleep as that violates sandboxing.
// - This is used to implement host functions such as WASI `poll_oneoff`.
// - Some compilers implement sleep by looping on sys.Nanotime (e.g. Go).
// - If you set this, you should probably set WithNanotime also.
// - Use WithSysNanosleep for a usable implementation.
WithNanosleep(sys.Nanosleep) ModuleConfig
// WithOsyield yields the processor, typically to implement spin-wait
// loops. Defaults to return immediately.
//
// # Notes:
// - This primarily supports `sched_yield` in WASI
// - This does not default to runtime.osyield as that violates sandboxing.
WithOsyield(sys.Osyield) ModuleConfig
// WithSysNanosleep uses time.Sleep for sys.Nanosleep.
//
// See WithNanosleep
WithSysNanosleep() ModuleConfig
// WithRandSource configures a source of random bytes. Defaults to return a
// deterministic source. You might override this with crypto/rand.Reader
//
// This reader is most commonly used by the functions like "random_get" in
// "wasi_snapshot_preview1", "seed" in AssemblyScript standard "env", and
// "getRandomData" when runtime.GOOS is "js".
//
// Note: The caller is responsible to close any io.Reader they supply: It
// is not closed on api.Module Close.
WithRandSource(io.Reader) ModuleConfig
}
type moduleConfig struct {
name string
nameSet bool
startFunctions []string
stdin io.Reader
stdout io.Writer
stderr io.Writer
randSource io.Reader
walltime sys.Walltime
walltimeResolution sys.ClockResolution
nanotime sys.Nanotime
nanotimeResolution sys.ClockResolution
nanosleep sys.Nanosleep
osyield sys.Osyield
args [][]byte
// environ is pair-indexed to retain order similar to os.Environ.
environ [][]byte
// environKeys allow overwriting of existing values.
environKeys map[string]int
// fsConfig is the file system configuration for ABI like WASI.
fsConfig FSConfig
// sockConfig is the network listener configuration for ABI like WASI.
sockConfig *internalsock.Config
}
// NewModuleConfig returns a ModuleConfig that can be used for configuring module instantiation.
func NewModuleConfig() ModuleConfig {
return &moduleConfig{
startFunctions: []string{"_start"},
environKeys: map[string]int{},
}
}
// clone makes a deep copy of this module config.
func (c *moduleConfig) clone() *moduleConfig {
ret := *c // copy except maps which share a ref
ret.environKeys = make(map[string]int, len(c.environKeys))
for key, value := range c.environKeys {
ret.environKeys[key] = value
}
return &ret
}
// WithArgs implements ModuleConfig.WithArgs
func (c *moduleConfig) WithArgs(args ...string) ModuleConfig {
ret := c.clone()
ret.args = toByteSlices(args)
return ret
}
func toByteSlices(strings []string) (result [][]byte) {
if len(strings) == 0 {
return
}
result = make([][]byte, len(strings))
for i, a := range strings {
result[i] = []byte(a)
}
return
}
// WithEnv implements ModuleConfig.WithEnv
func (c *moduleConfig) WithEnv(key, value string) ModuleConfig {
ret := c.clone()
// Check to see if this key already exists and update it.
if i, ok := ret.environKeys[key]; ok {
ret.environ[i+1] = []byte(value) // environ is pair-indexed, so the value is 1 after the key.
} else {
ret.environKeys[key] = len(ret.environ)
ret.environ = append(ret.environ, []byte(key), []byte(value))
}
return ret
}
// WithFS implements ModuleConfig.WithFS
func (c *moduleConfig) WithFS(fs fs.FS) ModuleConfig {
var config FSConfig
if fs != nil {
config = NewFSConfig().WithFSMount(fs, "")
}
return c.WithFSConfig(config)
}
// WithFSConfig implements ModuleConfig.WithFSConfig
func (c *moduleConfig) WithFSConfig(config FSConfig) ModuleConfig {
ret := c.clone()
ret.fsConfig = config
return ret
}
// WithName implements ModuleConfig.WithName
func (c *moduleConfig) WithName(name string) ModuleConfig {
ret := c.clone()
ret.nameSet = true
ret.name = name
return ret
}
// WithStartFunctions implements ModuleConfig.WithStartFunctions
func (c *moduleConfig) WithStartFunctions(startFunctions ...string) ModuleConfig {
ret := c.clone()
ret.startFunctions = startFunctions
return ret
}
// WithStderr implements ModuleConfig.WithStderr
func (c *moduleConfig) WithStderr(stderr io.Writer) ModuleConfig {
ret := c.clone()
ret.stderr = stderr
return ret
}
// WithStdin implements ModuleConfig.WithStdin
func (c *moduleConfig) WithStdin(stdin io.Reader) ModuleConfig {
ret := c.clone()
ret.stdin = stdin
return ret
}
// WithStdout implements ModuleConfig.WithStdout
func (c *moduleConfig) WithStdout(stdout io.Writer) ModuleConfig {
ret := c.clone()
ret.stdout = stdout
return ret
}
// WithWalltime implements ModuleConfig.WithWalltime
func (c *moduleConfig) WithWalltime(walltime sys.Walltime, resolution sys.ClockResolution) ModuleConfig {
ret := c.clone()
ret.walltime = walltime
ret.walltimeResolution = resolution
return ret
}
// We choose arbitrary resolutions here because there's no perfect alternative. For example, according to the
// source in time.go, windows monotonic resolution can be 15ms. This chooses arbitrarily 1us for wall time and
// 1ns for monotonic. See RATIONALE.md for more context.
// WithSysWalltime implements ModuleConfig.WithSysWalltime
func (c *moduleConfig) WithSysWalltime() ModuleConfig {
return c.WithWalltime(platform.Walltime, sys.ClockResolution(time.Microsecond.Nanoseconds()))
}
// WithNanotime implements ModuleConfig.WithNanotime
func (c *moduleConfig) WithNanotime(nanotime sys.Nanotime, resolution sys.ClockResolution) ModuleConfig {
ret := c.clone()
ret.nanotime = nanotime
ret.nanotimeResolution = resolution
return ret
}
// WithSysNanotime implements ModuleConfig.WithSysNanotime
func (c *moduleConfig) WithSysNanotime() ModuleConfig {
return c.WithNanotime(platform.Nanotime, sys.ClockResolution(1))
}
// WithNanosleep implements ModuleConfig.WithNanosleep
func (c *moduleConfig) WithNanosleep(nanosleep sys.Nanosleep) ModuleConfig {
ret := *c // copy
ret.nanosleep = nanosleep
return &ret
}
// WithOsyield implements ModuleConfig.WithOsyield
func (c *moduleConfig) WithOsyield(osyield sys.Osyield) ModuleConfig {
ret := *c // copy
ret.osyield = osyield
return &ret
}
// WithSysNanosleep implements ModuleConfig.WithSysNanosleep
func (c *moduleConfig) WithSysNanosleep() ModuleConfig {
return c.WithNanosleep(platform.Nanosleep)
}
// WithRandSource implements ModuleConfig.WithRandSource
func (c *moduleConfig) WithRandSource(source io.Reader) ModuleConfig {
ret := c.clone()
ret.randSource = source
return ret
}
// toSysContext creates a baseline wasm.Context configured by ModuleConfig.
func (c *moduleConfig) toSysContext() (sysCtx *internalsys.Context, err error) {
var environ [][]byte // Intentionally doesn't pre-allocate to reduce logic to default to nil.
// Same validation as syscall.Setenv for Linux
for i := 0; i < len(c.environ); i += 2 {
key, value := c.environ[i], c.environ[i+1]
keyLen := len(key)
if keyLen == 0 {
err = errors.New("environ invalid: empty key")
return
}
valueLen := len(value)
result := make([]byte, keyLen+valueLen+1)
j := 0
for ; j < keyLen; j++ {
if k := key[j]; k == '=' { // NUL enforced in NewContext
err = errors.New("environ invalid: key contains '=' character")
return
} else {
result[j] = k
}
}
result[j] = '='
copy(result[j+1:], value)
environ = append(environ, result)
}
var fs []experimentalsys.FS
var guestPaths []string
if f, ok := c.fsConfig.(*fsConfig); ok {
fs, guestPaths = f.preopens()
}
var listeners []*net.TCPListener
if n := c.sockConfig; n != nil {
if listeners, err = n.BuildTCPListeners(); err != nil {
return
}
}
return internalsys.NewContext(
math.MaxUint32,
c.args,
environ,
c.stdin,
c.stdout,
c.stderr,
c.randSource,
c.walltime, c.walltimeResolution,
c.nanotime, c.nanotimeResolution,
c.nanosleep, c.osyield,
fs, guestPaths,
listeners,
)
}