SimonSapin created this revision. Herald added a reviewer: hg-reviewers. Herald added a subscriber: mercurial-patches.
REPOSITORY rHG Mercurial BRANCH default REVISION DETAIL https://phab.mercurial-scm.org/D10093 AFFECTED FILES rust/rhg/src/main.rs tests/test-rhg.t CHANGE DETAILS diff --git a/tests/test-rhg.t b/tests/test-rhg.t --- a/tests/test-rhg.t +++ b/tests/test-rhg.t @@ -1,9 +1,10 @@ #require rust Define an rhg function that will only run if rhg exists + $ export RHG="$RUNTESTDIR/../rust/target/release/rhg" $ rhg() { - > if [ -f "$RUNTESTDIR/../rust/target/release/rhg" ]; then - > "$RUNTESTDIR/../rust/target/release/rhg" "$@" + > if [ -f "$RHG" ]; then + > "$RHG" "$@" > else > echo "skipped: Cannot find rhg. Try to run cargo build in rust/rhg." > exit 80 @@ -151,6 +152,27 @@ $ rhg cat -r 1 copy_of_original original content +Fallback to Python + $ rhg cat original + unsupported feature: `rhg cat` without `--rev` / `-r` + [252] + $ export FALLBACK="--config rhg.on-unsupported=fallback" + $ rhg cat original $FALLBACK + original content + + $ rhg cat original $FALLBACK --config rhg.fallback-executable=false + [1] + + $ rhg cat original $FALLBACK --config rhg.fallback-executable=hg-non-existent + tried to fall back to a 'hg-non-existent' sub-process but got error $ENOENT$ + unsupported feature: `rhg cat` without `--rev` / `-r` + [252] + + $ rhg cat original $FALLBACK --config rhg.fallback-executable="$RHG" + Blocking recursive fallback. The 'rhg.fallback-executable = /home/simon/projects/hg/tests/../rust/target/release/rhg' config points to `rhg` itself. + unsupported feature: `rhg cat` without `--rev` / `-r` + [252] + Requirements $ rhg debugrequirements dotencode diff --git a/rust/rhg/src/main.rs b/rust/rhg/src/main.rs --- a/rust/rhg/src/main.rs +++ b/rust/rhg/src/main.rs @@ -11,6 +11,7 @@ use hg::utils::SliceExt; use std::ffi::OsString; use std::path::PathBuf; +use std::process::Command; mod blackbox; mod error; @@ -138,9 +139,45 @@ fn exit( ui: &Ui, - on_unsupported: OnUnsupported, + mut on_unsupported: OnUnsupported, result: Result<(), CommandError>, ) -> ! { + if let ( + OnUnsupported::Fallback { executable }, + Err(CommandError::UnsupportedFeature { .. }), + ) = (&on_unsupported, &result) + { + let mut args = std::env::args_os(); + let executable_path = get_path_from_bytes(&executable); + let this_executable = args.next().expect("exepcted argv[0] to exist"); + if executable_path == &PathBuf::from(this_executable) { + // Avoid spawning infinitely many processes until resource + // exhaustion. + let _ = ui.write_stderr(&format_bytes!( + b"Blocking recursive fallback. The 'rhg.fallback-executable = {}' config \ + points to `rhg` itself.\n", + executable + )); + // TODO: warn about this to explain `rhg.fallback-executable` + // config + on_unsupported = OnUnsupported::Abort + } else { + // `args` is now `argv[1..]` since we’ve already consumed `argv[0]` + let result = Command::new(executable_path).args(args).status(); + match result { + Ok(status) => std::process::exit( + status.code().unwrap_or(exitcode::ABORT), + ), + Err(error) => { + let _ = ui.write_stderr(&format_bytes!( + b"tried to fall back to a '{}' sub-process but got error {}\n", + executable, format_bytes::Utf8(error) + )); + on_unsupported = OnUnsupported::Abort + } + } + } + } match &result { Ok(_) => {} Err(CommandError::Abort { message }) => { @@ -154,15 +191,13 @@ Err(CommandError::UnsupportedFeature { message }) => { match on_unsupported { OnUnsupported::Abort => { - // Ignore errors when writing to stderr, we’re already - // exiting with failure code so there’s - // not much more we can do. let _ = ui.write_stderr(&format_bytes!( b"unsupported feature: {}\n", message )); } OnUnsupported::AbortSilent => {} + OnUnsupported::Fallback { .. } => unreachable!(), } } } @@ -271,18 +306,32 @@ Abort, /// Silently exit with code 252. AbortSilent, + /// Try running a Python implementation + Fallback { executable: Vec<u8> }, } impl OnUnsupported { + const DEFAULT: Self = OnUnsupported::Abort; + const DEFAULT_FALLBACK_EXECUTABLE: &'static [u8] = b"hg"; + fn from_config(config: &Config) -> Self { - let default = OnUnsupported::Abort; - match config.get(b"rhg", b"on-unsupported") { + match config + .get(b"rhg", b"on-unsupported") + .map(|value| value.to_ascii_lowercase()) + .as_deref() + { Some(b"abort") => OnUnsupported::Abort, Some(b"abort-silent") => OnUnsupported::AbortSilent, - None => default, + Some(b"fallback") => OnUnsupported::Fallback { + executable: config + .get(b"rhg", b"fallback-executable") + .unwrap_or(Self::DEFAULT_FALLBACK_EXECUTABLE) + .to_owned(), + }, + None => Self::DEFAULT, Some(_) => { // TODO: warn about unknown config value - default + Self::DEFAULT } } } To: SimonSapin, #hg-reviewers Cc: mercurial-patches, mercurial-devel _______________________________________________ Mercurial-devel mailing list Mercurial-devel@mercurial-scm.org https://www.mercurial-scm.org/mailman/listinfo/mercurial-devel
