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Merge pull request #746 from cgwalters/block-cmd-cleanup
A few misc cleanups
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,156 @@ | ||
| use std::{ | ||
| io::{Read, Seek}, | ||
| process::Command, | ||
| }; | ||
|
|
||
| use anyhow::{Context, Result}; | ||
|
|
||
| /// Helpers intended for [`std::process::Command`]. | ||
| pub(crate) trait CommandRunExt { | ||
| fn run(&mut self) -> Result<()>; | ||
| /// Execute the child process, parsing its stdout as JSON. | ||
| fn run_and_parse_json<T: serde::de::DeserializeOwned>(&mut self) -> Result<T>; | ||
| } | ||
|
|
||
| /// Helpers intended for [`std::process::ExitStatus`]. | ||
| pub(crate) trait ExitStatusExt { | ||
| /// If the exit status signals it was not successful, return an error. | ||
| /// Note that we intentionally *don't* include the command string | ||
| /// in the output; we leave it to the caller to add that if they want, | ||
| /// as it may be verbose. | ||
| fn check_status(&mut self, stderr: std::fs::File) -> Result<()>; | ||
| } | ||
|
|
||
| /// Parse the last chunk (e.g. 1024 bytes) from the provided file, | ||
| /// ensure it's UTF-8, and return that value. This function is infallible; | ||
| /// if the file cannot be read for some reason, a copy of a static string | ||
| /// is returned. | ||
| fn last_utf8_content_from_file(mut f: std::fs::File) -> String { | ||
| // u16 since we truncate to just the trailing bytes here | ||
| // to avoid pathological error messages | ||
| const MAX_STDERR_BYTES: u16 = 1024; | ||
| let size = f | ||
| .metadata() | ||
| .map_err(|e| { | ||
| tracing::warn!("failed to fstat: {e}"); | ||
| }) | ||
| .map(|m| m.len().try_into().unwrap_or(u16::MAX)) | ||
| .unwrap_or(0); | ||
| let size = size.min(MAX_STDERR_BYTES); | ||
| let seek_offset = -(size as i32); | ||
| let mut stderr_buf = Vec::with_capacity(size.into()); | ||
| // We should never fail to seek()+read() really, but let's be conservative | ||
| let r = match f | ||
| .seek(std::io::SeekFrom::End(seek_offset.into())) | ||
| .and_then(|_| f.read_to_end(&mut stderr_buf)) | ||
| { | ||
| Ok(_) => String::from_utf8_lossy(&stderr_buf), | ||
| Err(e) => { | ||
| tracing::warn!("failed seek+read: {e}"); | ||
| "<failed to read stderr>".into() | ||
| } | ||
| }; | ||
| (&*r).to_owned() | ||
| } | ||
|
|
||
| impl ExitStatusExt for std::process::ExitStatus { | ||
| fn check_status(&mut self, stderr: std::fs::File) -> Result<()> { | ||
| let stderr_buf = last_utf8_content_from_file(stderr); | ||
| if self.success() { | ||
| return Ok(()); | ||
| } | ||
| anyhow::bail!(format!("Subprocess failed: {self:?}\n{stderr_buf}")) | ||
| } | ||
| } | ||
|
|
||
| impl CommandRunExt for Command { | ||
| /// Synchronously execute the child, and return an error if the child exited unsuccessfully. | ||
| fn run(&mut self) -> Result<()> { | ||
| let stderr = tempfile::tempfile()?; | ||
| self.stderr(stderr.try_clone()?); | ||
| self.status()?.check_status(stderr) | ||
| } | ||
|
|
||
| fn run_and_parse_json<T: serde::de::DeserializeOwned>(&mut self) -> Result<T> { | ||
| let mut stdout = tempfile::tempfile()?; | ||
| self.stdout(stdout.try_clone()?); | ||
| self.run()?; | ||
| stdout.seek(std::io::SeekFrom::Start(0)).context("seek")?; | ||
| let stdout = std::io::BufReader::new(stdout); | ||
| serde_json::from_reader(stdout).map_err(Into::into) | ||
| } | ||
| } | ||
|
|
||
| /// Helpers intended for [`tokio::process::Command`]. | ||
| #[allow(dead_code)] | ||
| pub(crate) trait AsyncCommandRunExt { | ||
| async fn run(&mut self) -> Result<()>; | ||
| } | ||
|
|
||
| impl AsyncCommandRunExt for tokio::process::Command { | ||
| /// Asynchronously execute the child, and return an error if the child exited unsuccessfully. | ||
| /// | ||
| async fn run(&mut self) -> Result<()> { | ||
| let stderr = tempfile::tempfile()?; | ||
| self.stderr(stderr.try_clone()?); | ||
| self.status().await?.check_status(stderr) | ||
| } | ||
| } | ||
|
|
||
| #[test] | ||
| fn command_run_ext() { | ||
| // The basics | ||
| Command::new("true").run().unwrap(); | ||
| assert!(Command::new("false").run().is_err()); | ||
|
|
||
| // Verify we capture stderr | ||
| let e = Command::new("/bin/sh") | ||
| .args(["-c", "echo expected-this-oops-message 1>&2; exit 1"]) | ||
| .run() | ||
| .err() | ||
| .unwrap(); | ||
| similar_asserts::assert_eq!( | ||
| e.to_string(), | ||
| "Subprocess failed: ExitStatus(unix_wait_status(256))\nexpected-this-oops-message\n" | ||
| ); | ||
|
|
||
| // Ignoring invalid UTF-8 | ||
| let e = Command::new("/bin/sh") | ||
| .args([ | ||
| "-c", | ||
| r"echo -e 'expected\xf5\x80\x80\x80\x80-foo\xc0bar\xc0\xc0' 1>&2; exit 1", | ||
| ]) | ||
| .run() | ||
| .err() | ||
| .unwrap(); | ||
| similar_asserts::assert_eq!( | ||
| e.to_string(), | ||
| "Subprocess failed: ExitStatus(unix_wait_status(256))\nexpected�����-foo�bar��\n" | ||
| ); | ||
| } | ||
|
|
||
| #[test] | ||
| fn command_run_ext_json() { | ||
| #[derive(serde::Deserialize)] | ||
| struct Foo { | ||
| a: String, | ||
| b: u32, | ||
| } | ||
| let v: Foo = Command::new("echo") | ||
| .arg(r##"{"a": "somevalue", "b": 42}"##) | ||
| .run_and_parse_json() | ||
| .unwrap(); | ||
| assert_eq!(v.a, "somevalue"); | ||
| assert_eq!(v.b, 42); | ||
| } | ||
|
|
||
| #[tokio::test] | ||
| async fn async_command_run_ext() { | ||
| use tokio::process::Command as AsyncCommand; | ||
| let mut success = AsyncCommand::new("true"); | ||
| let mut fail = AsyncCommand::new("false"); | ||
| // Run these in parallel just because we can | ||
| let (success, fail) = tokio::join!(success.run(), fail.run(),); | ||
| success.unwrap(); | ||
| assert!(fail.is_err()); | ||
| } |
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