add context to command failures (#466)

Fixes #465

src/agent/debugger/src/debugger.rs

@@ -238,7 +238,10 @@ impl Debugger {
         mut command: Command,
         callbacks: &mut impl DebugEventHandler,
     ) -> Result<(Self, Child)> {
-        let child = command.creation_flags(DEBUG_ONLY_THIS_PROCESS).spawn()?;
+        let child = command
+            .creation_flags(DEBUG_ONLY_THIS_PROCESS)
+            .spawn()
+            .context("debugee failed to start")?;
 
         check_winapi(|| unsafe { DebugSetProcessKillOnExit(TRUE) })
             .context("Setting DebugSetProcessKillOnExit to TRUE")?;

src/agent/onefuzz-agent/src/tasks/coverage/recorder.rs

@@ -126,7 +126,7 @@ impl CoverageRecorder {
             cmd.env(k, v);
         }
 
-        let child = cmd.spawn()?;
+        let child = cmd.spawn().context("gdb failed to start")?;
 
         Ok(child)
     }
@@ -163,7 +163,7 @@ impl CoverageRecorder {
             cmd.env(k, v);
         }
 
-        let child = cmd.spawn()?;
+        let child = cmd.spawn().context("cdb.exe failed to start")?;
 
         Ok(child)
     }

src/agent/onefuzz-agent/src/tasks/fuzz/generator.rs

@@ -6,7 +6,7 @@ use crate::tasks::{
     heartbeat::*,
     utils::{self, default_bool_true},
 };
-use anyhow::Result;
+use anyhow::{Context, Result};
 use futures::stream::StreamExt;
 use onefuzz::{
     expand::Expand,
@@ -150,7 +150,7 @@ impl GeneratorTask {
         output_dir: impl AsRef<Path>,
     ) -> Result<()> {
         utils::reset_tmp_dir(&output_dir).await?;
-        let mut generator = {
+        let (mut generator, generator_path) = {
             let mut expand = Expand::new();
             expand
                 .generated_inputs(&output_dir)
@@ -179,11 +179,13 @@ impl GeneratorTask {
             for (k, v) in &self.config.generator_env {
                 generator.env(k, expand.evaluate_value(v)?);
             }
-            generator
+            (generator, generator_path)
         };
 
         info!("Generating test cases with {:?}", generator);
-        let output = generator.spawn()?;
+        let output = generator
+            .spawn()
+            .with_context(|| format!("generator failed to start: {}", generator_path))?;
         monitor_process(output, "generator".to_string(), true, None).await?;
 
         Ok(())

src/agent/onefuzz-agent/src/tasks/fuzz/supervisor.rs

@@ -9,7 +9,7 @@ use crate::tasks::{
     stats::common::{monitor_stats, StatsFormat},
     utils::CheckNotify,
 };
-use anyhow::{Error, Result};
+use anyhow::{Context, Error, Result};
 use onefuzz::{
     expand::Expand,
     fs::{has_files, set_executable, OwnedDir},
@@ -213,7 +213,9 @@ async fn start_supervisor(
     }
 
     info!("starting supervisor '{:?}'", cmd);
-    let child = cmd.spawn()?;
+    let child = cmd
+        .spawn()
+        .with_context(|| format!("supervisor failed to start: {:?}", cmd))?;
     Ok(child)
 }
 

src/agent/onefuzz-supervisor/src/commands.rs

@@ -2,7 +2,7 @@
 // Licensed under the MIT License.
 
 use crate::auth::Secret;
-use anyhow::Result;
+use anyhow::{Context, Result};
 use onefuzz::machine_id::get_scaleset_name;
 use std::process::Stdio;
 use tokio::{fs, io::AsyncWriteExt, process::Command};
@@ -52,9 +52,11 @@ pub async fn add_ssh_key(key_info: SshKeyInfo) -> Result<()> {
         .stdin(Stdio::null())
         .stdout(Stdio::piped())
         .stderr(Stdio::piped())
-        .spawn()?
+        .spawn()
+        .context("icacls failed to start")?
         .wait_with_output()
-        .await?;
+        .await
+        .context("icalcs failed to run")?;
     if !result.status.success() {
         bail!(
             "set authorized_keys ({}) permissions failed: {:?}",
@@ -70,9 +72,11 @@ pub async fn add_ssh_key(key_info: SshKeyInfo) -> Result<()> {
         .stdin(Stdio::null())
         .stdout(Stdio::piped())
         .stderr(Stdio::piped())
-        .spawn()?
+        .spawn()
+        .context("icacls failed to start")?
         .wait_with_output()
-        .await?;
+        .await
+        .context("icacls failed to run")?;
     if !result.status.success() {
         bail!(
             "set authorized_keys ({}) permissions failed: {:?}",
@@ -92,9 +96,11 @@ pub async fn add_ssh_key(key_info: SshKeyInfo) -> Result<()> {
         .stdin(Stdio::null())
         .stdout(Stdio::piped())
         .stderr(Stdio::piped())
-        .spawn()?
+        .spawn()
+        .context("Powershell Get-ACL | Set-ACL failed to start")?
         .wait_with_output()
-        .await?;
+        .await
+        .context("Powershell Get-ACL | Set-ACL failed to run")?;
     if !result.status.success() {
         bail!(
             "set authorized_keys ({}) permissions failed: {:?}",
@@ -137,9 +143,11 @@ pub async fn add_ssh_key(key_info: SshKeyInfo) -> Result<()> {
         .stdin(Stdio::null())
         .stdout(Stdio::piped())
         .stderr(Stdio::piped())
-        .spawn()?
+        .spawn()
+        .context("chmod failed to start")?
         .wait_with_output()
-        .await?;
+        .await
+        .context("chmod failed to run")?;
     if !result.status.success() {
         bail!("set $HOME/.ssh permissions failed: {:?}", result);
     }
@@ -159,9 +167,11 @@ pub async fn add_ssh_key(key_info: SshKeyInfo) -> Result<()> {
         .stdin(Stdio::null())
         .stdout(Stdio::piped())
         .stderr(Stdio::piped())
-        .spawn()?
+        .spawn()
+        .context("chmod failed to start")?
         .wait_with_output()
-        .await?;
+        .await
+        .context("chmod failed to run")?;
     if !result.status.success() {
         bail!(
             "set authorized_keys ({}) permissions failed: {:?}",

src/agent/onefuzz-supervisor/src/worker.rs

@@ -231,7 +231,7 @@ impl IWorkerRunner for WorkerRunner {
         cmd.stderr(Stdio::piped());
         cmd.stdout(Stdio::piped());
 
-        let child = cmd.spawn()?;
+        let child = cmd.spawn().context("onefuzz-agent failed to start")?;
         let child = Box::new(child);
 
         Ok(child)

src/agent/onefuzz/src/az_copy.rs

@@ -1,7 +1,7 @@
 // Copyright (c) Microsoft Corporation.
 // Licensed under the MIT License.
 
-use anyhow::Result;
+use anyhow::{Context, Result};
 use std::ffi::OsStr;
 use tokio::process::Command;
 
@@ -21,7 +21,12 @@ pub async fn sync(src: impl AsRef<OsStr>, dst: impl AsRef<OsStr>, delete_dst: bo
         cmd.arg("--delete-destination");
     }
 
-    let output = cmd.spawn()?.wait_with_output().await?;
+    let output = cmd
+        .spawn()
+        .context("azcopy failed to start")?
+        .wait_with_output()
+        .await
+        .context("azcopy failed to run")?;
     if !output.status.success() {
         let stdout = String::from_utf8_lossy(&output.stdout);
         let stderr = String::from_utf8_lossy(&output.stderr);
@@ -53,7 +58,12 @@ pub async fn copy(src: impl AsRef<OsStr>, dst: impl AsRef<OsStr>, recursive: boo
         cmd.arg("--recursive=true");
     }
 
-    let output = cmd.spawn()?.wait_with_output().await?;
+    let output = cmd
+        .spawn()
+        .context("azcopy failed to start")?
+        .wait_with_output()
+        .await
+        .context("azcopy failed to run")?;
     if !output.status.success() {
         let stdout = String::from_utf8_lossy(&output.stdout);
         let stderr = String::from_utf8_lossy(&output.stderr);

src/agent/onefuzz/src/fs.rs

@@ -74,9 +74,11 @@ pub async fn set_executable(path: impl AsRef<Path>) -> Result<()> {
         .stdin(Stdio::null())
         .stdout(Stdio::null())
         .stderr(Stdio::piped())
-        .spawn()?
+        .spawn()
+        .with_context(|| format!("command failed to start: chmod -R +x {}", path.display()))?
         .wait_with_output()
-        .await?;
+        .await
+        .with_context(|| format!("command failed to run: chmod -R +x {}", path.display()))?;
 
     if !output.status.success() {
         bail!("'chmod -R +x' of {:?} failed: {}", path, output.status);

src/agent/onefuzz/src/libfuzzer.rs

@@ -5,7 +5,7 @@ use crate::{
     expand::Expand,
     input_tester::{TestResult, Tester},
 };
-use anyhow::Result;
+use anyhow::{Context, Result};
 use std::{
     collections::HashMap,
     ffi::OsString,
@@ -71,7 +71,12 @@ impl<'a> LibFuzzer<'a> {
             cmd.arg(o);
         }
 
-        let result = cmd.spawn()?.wait_with_output().await?;
+        let result = cmd
+            .spawn()
+            .with_context(|| format_err!("libfuzzer failed to start: {}", self.exe.display()))?
+            .wait_with_output()
+            .await
+            .with_context(|| format_err!("libfuzzer failed to run: {}", self.exe.display()))?;
         if !result.status.success() {
             bail!("fuzzer does not respond to '-help=1'. output:{:?}", result);
         }
@@ -141,7 +146,9 @@ impl<'a> LibFuzzer<'a> {
             cmd.arg(dir.as_ref());
         }
 
-        let child = cmd.spawn()?;
+        let child = cmd
+            .spawn()
+            .with_context(|| format_err!("libfuzzer failed to start: {}", self.exe.display()))?;
 
         Ok(child)
     }
@@ -204,7 +211,12 @@ impl<'a> LibFuzzer<'a> {
             cmd.arg(o);
         }
 
-        let output = cmd.spawn()?.wait_with_output().await?;
+        let output = cmd
+            .spawn()
+            .with_context(|| format_err!("libfuzzer failed to start: {}", self.exe.display()))?
+            .wait_with_output()
+            .await
+            .with_context(|| format_err!("libfuzzer failed to run: {}", self.exe.display()))?;
 
         let output_text = String::from_utf8_lossy(&output.stderr);
         let pat = r"MERGE-OUTER: (\d+) new files with (\d+) new features added";

src/agent/onefuzz/src/process.rs

@@ -1,7 +1,7 @@
 // Copyright (c) Microsoft Corporation.
 // Licensed under the MIT License.
 
-use anyhow::Result;
+use anyhow::{Context, Result};
 use process_control::{self, ChildExt, Timeout};
 use std::path::Path;
 use std::process::Command;
@@ -122,8 +122,13 @@ pub async fn run_cmd<S: ::std::hash::BuildHasher>(
         .args(argv)
         .envs(env);
 
+    // make a stringified version to save in the context of spawn_blocking
+    let program_name = program.display().to_string();
+
     let runner = tokio::task::spawn_blocking(move || {
-        let child = cmd.spawn()?;
+        let child = cmd
+            .spawn()
+            .with_context(|| format!("process failed to start: {}", program_name))?;
         child
             .with_output_timeout(timeout)
             .terminating()