From 5996ed9c69c3436119ae41cce34f6d4ee28cd3e8 Mon Sep 17 00:00:00 2001
From: katelyn martin <kmartin@fastly.com>
Date: Thu, 10 Feb 2022 15:33:34 -0500
Subject: [PATCH] =?UTF-8?q?=F0=9D=9F=8E=20only=20log=20non-zero=20exit=20s?=
 =?UTF-8?q?tatus=20codes?=
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if a program invokes e.g., `std::process:exit(0)`, this should not cause
confusing diagnostic messages as reported in #127:

```
  Jan 1 00:00:00.123 ERROR viceroy_lib::execute: WebAssembly trapped: Exited with i32 exit status 0
wasm backtrace:
    0: 0x280ea - <unknown>!__wasi_proc_exit
    1: 0x280f6 - <unknown>!_Exit
```

this is unfortunately difficult to test, because the
`Result<(), ExecutionError>` of `ExecuteCtx::run_guest` is spawned in a
task that we do not join on later. (note: that is intentional)

the alternative of a test that checks for a particular log message felt
brittle, and this is a relatively straightfoward change.
---
 lib/src/execute.rs | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/lib/src/execute.rs b/lib/src/execute.rs
index fe969fae..e01971aa 100644
--- a/lib/src/execute.rs
+++ b/lib/src/execute.rs
@@ -264,7 +264,10 @@ impl ExecuteCtx {
             .await
             .map(|_| ())
             .map_err(|trap| {
-                event!(Level::ERROR, "WebAssembly trapped: {}", trap);
+                // Be sure that we only log non-zero status codes.
+                if trap.i32_exit_status() != Some(0) {
+                    event!(Level::ERROR, "WebAssembly trapped: {}", trap);
+                }
                 ExecutionError::WasmTrap(trap)
             });