wasmer_wasix/bin_factory/
exec.rs

1#![allow(clippy::result_large_err)]
2use super::{BinaryPackage, BinaryPackageCommand};
3use crate::{
4    RewindState, SpawnError, WasiError, WasiRuntimeError,
5    os::task::{
6        TaskJoinHandle,
7        thread::{RewindResultType, WasiThreadRunGuard},
8    },
9    runtime::{
10        ModuleInput, TaintReason,
11        module_cache::HashedModuleData,
12        task_manager::{
13            TaskWasm, TaskWasmRecycle, TaskWasmRecycleProperties, TaskWasmRunProperties,
14        },
15    },
16    state::context_switching::ContextSwitchingEnvironment,
17    syscalls::rewind_ext,
18};
19use crate::{Runtime, WasiEnv, WasiFunctionEnv};
20use std::{borrow::Cow, sync::Arc};
21use tracing::*;
22use virtual_mio::block_on;
23use wasmer::{Function, Memory32, Memory64, Module, RuntimeError, Store, Value};
24use wasmer_wasix_types::wasi::Errno;
25
26#[tracing::instrument(level = "trace", skip_all, fields(%name, package_id=%binary.id))]
27pub async fn spawn_exec(
28    binary: BinaryPackage,
29    name: &str,
30    env: WasiEnv,
31    runtime: &Arc<dyn Runtime + Send + Sync + 'static>,
32) -> Result<TaskJoinHandle, SpawnError> {
33    spawn_union_fs(&env, &binary).await?;
34
35    let cmd = package_command_by_name(&binary, name)?;
36    let input = ModuleInput::Command(Cow::Borrowed(cmd));
37    let module = runtime.resolve_module(input, None, None).await?;
38
39    // Free the space used by the binary, since we don't need it
40    // any longer
41    drop(binary);
42
43    spawn_exec_module(module, env, runtime)
44}
45
46#[tracing::instrument(level = "trace", skip_all, fields(%name))]
47pub async fn spawn_exec_wasm(
48    wasm: HashedModuleData,
49    name: &str,
50    env: WasiEnv,
51    runtime: &Arc<dyn Runtime + Send + Sync + 'static>,
52) -> Result<TaskJoinHandle, SpawnError> {
53    let module = spawn_load_module(name, wasm, runtime).await?;
54
55    spawn_exec_module(module, env, runtime)
56}
57
58pub fn package_command_by_name<'a>(
59    pkg: &'a BinaryPackage,
60    name: &str,
61) -> Result<&'a BinaryPackageCommand, SpawnError> {
62    // If an explicit command is provided, use it.
63    // Otherwise, use the entrypoint.
64    // If no entrypoint exists, and the package has a single
65    // command, then use it. This is done for backwards
66    // compatibility.
67    let cmd = if let Some(cmd) = pkg.get_command(name) {
68        cmd
69    } else if let Some(cmd) = pkg.get_entrypoint_command() {
70        cmd
71    } else {
72        match pkg.commands.as_slice() {
73            // Package only has a single command, so use it.
74            [first] => first,
75            // Package either has no command, or has multiple commands, which
76            // would make the choice ambiguous, so fail.
77            _ => {
78                return Err(SpawnError::MissingEntrypoint {
79                    package_id: pkg.id.clone(),
80                });
81            }
82        }
83    };
84
85    Ok(cmd)
86}
87
88pub async fn spawn_load_module(
89    name: &str,
90    wasm: HashedModuleData,
91    runtime: &Arc<dyn Runtime + Send + Sync + 'static>,
92) -> Result<Module, SpawnError> {
93    match runtime.load_hashed_module(wasm, None).await {
94        Ok(module) => Ok(module),
95        Err(err) => {
96            tracing::error!(
97                command = name,
98                error = &err as &dyn std::error::Error,
99                "Failed to compile the module",
100            );
101            Err(err)
102        }
103    }
104}
105
106pub async fn spawn_union_fs(env: &WasiEnv, binary: &BinaryPackage) -> Result<(), SpawnError> {
107    // If the file system has not already been union'ed then do so
108    env.state
109        .fs
110        .conditional_union(binary)
111        .await
112        .map_err(|err| {
113            tracing::warn!("failed to union file system - {err}");
114            SpawnError::FileSystemError(crate::ExtendedFsError::with_msg(
115                err,
116                "could not union filesystems",
117            ))
118        })?;
119    tracing::debug!("{:?}", env.state.fs);
120    Ok(())
121}
122
123pub fn spawn_exec_module(
124    module: Module,
125    env: WasiEnv,
126    runtime: &Arc<dyn Runtime + Send + Sync + 'static>,
127) -> Result<TaskJoinHandle, SpawnError> {
128    // Create a new task manager
129    let tasks = runtime.task_manager();
130
131    // Create the signaler
132    let pid = env.pid();
133
134    let join_handle = env.thread.join_handle();
135    {
136        // Create a thread that will run this process
137        let tasks_outer = tasks.clone();
138
139        tasks_outer
140            .task_wasm(
141                TaskWasm::new(Box::new(run_exec), env, module, true, true).with_pre_run(Box::new(
142                    |ctx, store| {
143                        Box::pin(async move {
144                            ctx.data(store).state.fs.close_cloexec_fds().await;
145                        })
146                    },
147                )),
148            )
149            .map_err(|err| {
150                error!("wasi[{}]::failed to launch module - {}", pid, err);
151                SpawnError::Other(Box::new(err))
152            })?
153    };
154
155    Ok(join_handle)
156}
157
158/// # SAFETY
159/// This must be executed from the same thread that owns the instance as
160/// otherwise it will cause a panic
161unsafe fn run_recycle(
162    callback: Option<Box<TaskWasmRecycle>>,
163    ctx: WasiFunctionEnv,
164    mut store: Store,
165) {
166    if let Some(callback) = callback {
167        let env = ctx.data_mut(&mut store);
168        let memory = unsafe { env.memory() }.clone();
169
170        let props = TaskWasmRecycleProperties {
171            env: env.clone(),
172            memory,
173            store,
174        };
175        callback(props);
176    }
177}
178
179pub fn run_exec(props: TaskWasmRunProperties) {
180    let ctx = props.ctx;
181    let mut store = props.store;
182
183    // Create the WasiFunctionEnv
184    let thread = WasiThreadRunGuard::new(ctx.data(&store).thread.clone());
185    let recycle = props.recycle;
186
187    // Perform the initialization
188    // If this module exports an _initialize function, run that first.
189    if let Ok(initialize) = ctx
190        .data(&store)
191        .inner()
192        .main_module_instance_handles()
193        .instance
194        .exports
195        .get_function("_initialize")
196        .cloned()
197    {
198        // This does not need a context switching environment as the documentation
199        // states that that is only available after the first call to main
200        let result = initialize.call(&mut store, &[]);
201
202        if let Err(err) = result {
203            thread.thread.set_status_finished(Err(err.into()));
204            ctx.data(&store)
205                .blocking_on_exit(Some(Errno::Noexec.into()));
206            unsafe { run_recycle(recycle, ctx, store) };
207            return;
208        }
209    }
210
211    // Bootstrap the process
212    // Unsafe: The bootstrap must be executed in the same thread that runs the
213    //         actual WASM code
214    let rewind_state = match unsafe { ctx.bootstrap(&mut store) } {
215        Ok(r) => r,
216        Err(err) => {
217            tracing::warn!("failed to bootstrap - {}", err);
218            thread.thread.set_status_finished(Err(err));
219            ctx.data(&store)
220                .blocking_on_exit(Some(Errno::Noexec.into()));
221            unsafe { run_recycle(recycle, ctx, store) };
222            return;
223        }
224    };
225
226    // If there is a start function
227    debug!("wasi[{}]::called main()", ctx.data(&store).pid());
228    // TODO: rewrite to use crate::run_wasi_func
229
230    // Call the module
231    call_module(ctx, store, thread, rewind_state, recycle);
232}
233
234fn get_start(ctx: &WasiFunctionEnv, store: &Store) -> Option<Function> {
235    ctx.data(store)
236        .inner()
237        .main_module_instance_handles()
238        .instance
239        .exports
240        .get_function("_start")
241        .cloned()
242        .ok()
243}
244
245/// Calls the module
246fn call_module(
247    ctx: WasiFunctionEnv,
248    mut store: Store,
249    handle: WasiThreadRunGuard,
250    rewind_state: Option<(RewindState, RewindResultType)>,
251    recycle: Option<Box<TaskWasmRecycle>>,
252) {
253    let env = ctx.data(&store);
254    let pid = env.pid();
255    let tasks = env.tasks().clone();
256    handle.thread.set_status_running();
257    let runtime = env.runtime.clone();
258
259    // If we need to rewind then do so
260    if let Some((rewind_state, rewind_result)) = rewind_state {
261        let mut ctx = ctx.env.clone().into_mut(&mut store);
262        if rewind_state.is_64bit {
263            let res = rewind_ext::<Memory64>(
264                &mut ctx,
265                Some(rewind_state.memory_stack),
266                rewind_state.rewind_stack,
267                rewind_state.store_data,
268                rewind_result,
269            );
270            if res != Errno::Success {
271                ctx.data().blocking_on_exit(Some(res.into()));
272                unsafe { run_recycle(recycle, WasiFunctionEnv { env: ctx.as_ref() }, store) };
273                return;
274            }
275        } else {
276            let res = rewind_ext::<Memory32>(
277                &mut ctx,
278                Some(rewind_state.memory_stack),
279                rewind_state.rewind_stack,
280                rewind_state.store_data,
281                rewind_result,
282            );
283            if res != Errno::Success {
284                ctx.data().blocking_on_exit(Some(res.into()));
285                unsafe { run_recycle(recycle, WasiFunctionEnv { env: ctx.as_ref() }, store) };
286                return;
287            }
288        };
289    }
290
291    // Invoke the start function
292    // Call the module
293    let Some(start) = get_start(&ctx, &store) else {
294        debug!("wasi[{}]::exec-failed: missing _start function", pid);
295        ctx.data(&store)
296            .blocking_on_exit(Some(Errno::Noexec.into()));
297        unsafe { run_recycle(recycle, ctx, store) };
298        return;
299    };
300
301    let (mut store, mut call_ret) =
302        ContextSwitchingEnvironment::run_main_context(&ctx, store, start.clone(), vec![]);
303
304    let mut store = loop {
305        // Technically, it's an error for a vfork to return from main, but anyway...
306        store = match resume_vfork(&ctx, store, &start, &call_ret) {
307            // A vfork was resumed, there may be another, so loop back
308            (store, Ok(Some(ret))) => {
309                call_ret = ret;
310                store
311            }
312
313            // An error was encountered when restoring from the vfork, report it
314            (store, Err(e)) => {
315                call_ret = Err(RuntimeError::user(Box::new(WasiError::Exit(e.into()))));
316                break store;
317            }
318
319            // No vfork, keep the call_ret value
320            (store, Ok(None)) => break store,
321        };
322    };
323
324    let ret = if let Err(err) = call_ret {
325        match err.downcast::<WasiError>() {
326            Ok(WasiError::Exit(code)) if code.is_success() => Ok(Errno::Success),
327            Ok(WasiError::ThreadExit) => Ok(Errno::Success),
328            Ok(WasiError::Exit(code)) => {
329                runtime.on_taint(TaintReason::NonZeroExitCode(code));
330                Err(WasiError::Exit(code).into())
331            }
332            Ok(WasiError::DeepSleep(deep)) => {
333                // Create the callback that will be invoked when the thread respawns after a deep sleep
334                let rewind = deep.rewind;
335                let respawn = {
336                    move |ctx, store, rewind_result| {
337                        // Call the thread
338                        call_module(
339                            ctx,
340                            store,
341                            handle,
342                            Some((rewind, RewindResultType::RewindWithResult(rewind_result))),
343                            recycle,
344                        );
345                    }
346                };
347
348                // Spawns the WASM process after a trigger
349                if let Err(err) = unsafe {
350                    tasks.resume_wasm_after_poller(Box::new(respawn), ctx, store, deep.trigger)
351                } {
352                    debug!("failed to go into deep sleep - {}", err);
353                }
354                return;
355            }
356            Ok(WasiError::UnknownWasiVersion) => {
357                debug!("failed as wasi version is unknown");
358                runtime.on_taint(TaintReason::UnknownWasiVersion);
359                Ok(Errno::Noexec)
360            }
361            Ok(WasiError::DlSymbolResolutionFailed(symbol)) => {
362                debug!("failed as a needed DL symbol could not be resolved");
363                runtime.on_taint(TaintReason::DlSymbolResolutionFailed(symbol.clone()));
364                Err(WasiError::DlSymbolResolutionFailed(symbol).into())
365            }
366            Err(err) => {
367                runtime.on_taint(TaintReason::RuntimeError(err.clone()));
368                Err(WasiRuntimeError::from(err))
369            }
370        }
371    } else {
372        Ok(Errno::Success)
373    };
374
375    let code = if let Err(err) = &ret {
376        match err.as_exit_code() {
377            Some(s) => s,
378            None => {
379                let err_display = err.display(&mut store);
380                error!("{err_display}");
381                eprintln!("{err_display}");
382                Errno::Noexec.into()
383            }
384        }
385    } else {
386        Errno::Success.into()
387    };
388
389    // Cleanup the environment
390    ctx.data(&store).blocking_on_exit(Some(code));
391    unsafe { run_recycle(recycle, ctx, store) };
392
393    debug!("wasi[{pid}]::main() has exited with {code}");
394    handle.thread.set_status_finished(ret.map(|a| a.into()));
395}
396
397#[allow(clippy::type_complexity)]
398fn resume_vfork(
399    ctx: &WasiFunctionEnv,
400    mut store: Store,
401    start: &Function,
402    call_ret: &Result<Box<[Value]>, RuntimeError>,
403) -> (
404    Store,
405    Result<Option<Result<Box<[Value]>, RuntimeError>>, Errno>,
406) {
407    let (err, code) = match call_ret {
408        Ok(_) => (None, wasmer_wasix_types::wasi::ExitCode::from(0u16)),
409        Err(err) => match err.downcast_ref::<WasiError>() {
410            // If the child process is just deep sleeping, we don't restore the vfork
411            Some(WasiError::DeepSleep(..)) => return (store, Ok(None)),
412
413            Some(WasiError::Exit(code)) => (None, *code),
414            Some(WasiError::ThreadExit) => (None, wasmer_wasix_types::wasi::ExitCode::from(0u16)),
415            Some(WasiError::UnknownWasiVersion) => (None, Errno::Noexec.into()),
416            Some(WasiError::DlSymbolResolutionFailed(_)) => (None, Errno::Nolink.into()),
417            None => (
418                Some(WasiRuntimeError::from(err.clone())),
419                Errno::Unknown.into(),
420            ),
421        },
422    };
423
424    if let Some(mut vfork) = ctx.data_mut(&mut store).vfork.take() {
425        if let Some(err) = err {
426            error!(%err, "Error from child process");
427            eprintln!("{err}");
428        }
429
430        block_on(
431            unsafe { ctx.data(&store).get_memory_and_wasi_state(&store, 0) }
432                .1
433                .fs
434                .close_all(),
435        );
436
437        tracing::debug!(
438            pid = %ctx.data_mut(&mut store).process.pid(),
439            vfork_pid = %vfork.env.process.pid(),
440            "Resuming from vfork after child process was terminated"
441        );
442
443        // Restore the WasiEnv to the point when we vforked
444        vfork.env.swap_inner(ctx.data_mut(&mut store));
445        std::mem::swap(vfork.env.as_mut(), ctx.data_mut(&mut store));
446        let mut child_env = *vfork.env;
447        child_env.owned_handles.push(vfork.handle);
448
449        // Terminate the child process
450        child_env.process.terminate(code);
451
452        // If the vfork contained a context-switching environment, exit now
453        if ctx.data(&store).context_switching_environment.is_some() {
454            // We cannot recover from this situation when using context switching
455            tracing::error!(
456                "Terminated a vfork in another way than exit or exec which is undefined behaviour. In this case the parent process will be terminated."
457            );
458            return (store, Err(code.into()));
459        }
460        let Some(asyncify_info) = vfork.asyncify else {
461            // We can only recover from this situation when using asyncify-based vforking; since asyncify is not in use here, we cannot recover and must terminate the parent process
462            tracing::error!(
463                "Terminated a vfork in another way than exit or exec which is undefined behaviour. In this case the parent process will be terminated."
464            );
465            return (store, Err(code.into()));
466        };
467        // TODO: We can also only safely recover if we are not using nested calling
468        // TODO: Just delete this branch
469
470        // Jump back to the vfork point and continue execution
471        let child_pid = child_env.process.pid();
472        let rewind_stack = asyncify_info.rewind_stack.freeze();
473        let store_data = asyncify_info.store_data;
474
475        let ctx_cloned = ctx.env.clone().into_mut(&mut store);
476        // Now rewind the previous stack and carry on from where we did the vfork
477        let rewind_result = if asyncify_info.is_64bit {
478            crate::syscalls::rewind::<Memory64, _>(
479                ctx_cloned,
480                None,
481                rewind_stack,
482                store_data,
483                crate::syscalls::ForkResult {
484                    pid: child_pid.raw() as wasmer_wasix_types::wasi::Pid,
485                    ret: Errno::Success,
486                },
487            )
488        } else {
489            crate::syscalls::rewind::<Memory32, _>(
490                ctx_cloned,
491                None,
492                rewind_stack,
493                store_data,
494                crate::syscalls::ForkResult {
495                    pid: child_pid.raw() as wasmer_wasix_types::wasi::Pid,
496                    ret: Errno::Success,
497                },
498            )
499        };
500
501        match rewind_result {
502            Errno::Success => {
503                // We should only get here, if the engine does not support context switching
504                // If the engine supports it, we should exit in the check a few lines above
505                let (store, result) = ContextSwitchingEnvironment::run_main_context(
506                    ctx,
507                    store,
508                    start.clone(),
509                    vec![],
510                );
511                (store, Ok(Some(result)))
512            }
513            err => {
514                warn!("fork failed - could not rewind the stack - errno={}", err);
515                (store, Err(err))
516            }
517        }
518    } else {
519        (store, Ok(None))
520    }
521}
wasmer_wasix/bin_factory/exec.rs

wasmer_wasix/bin_factory/
exec.rs
