scubainit: Restore the default SIGPIPE action

Rust pre-main code may change the SIGPIPE disposition to ignore: * rust-lang/rust#62569 * rust-lang/rust#97889 We could use the nightly compiler flag -Zon-broken-pipe=inherit to disable this behavior. Instead, we take the simpler route and restore the default disposition ourselves. Fixes #254
JonathonReinhart · May 22, 2024 · e15af52 · e15af52
1 parent 325fb58
commit e15af52
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diff --git a/scubainit/src/main.rs b/scubainit/src/main.rs
@@ -45,6  45,8 @@ fn run_scubainit() -> Result<()> {
     setup_logging()?;
     info!("Looking Rusty!");
 
     restore_sigpipe_default()?;
 
     let ctx = process_envvars()?;
 
     if let Some(ref user_info) = ctx.user_info {
@@ -368,3  370,34 @@ fn setup_logging() -> Result<()> {
         .verbosity(verbosity)
         .init()?)
 }
 
 // Restore the default SIGPIPE action.
 //
 // Rust pre-main code may change the SIGPIPE disposition to ignore:
 // * https://github.com/rust-lang/rust/issues/62569
 // * https://github.com/rust-lang/rust/issues/97889
 //
 // While scubainit doesn't rely on any specific SIGPIPE behavior, the dispositions of ignored
 // signals are inherited through execve and Rust's pre-main code shouldn't influence the process
 // executed by scuba.
 //
 // From man signal(7):
 //
 //   Signal dispositions ...  A child created via fork(2) inherits a copy of its parent's signal
 //   dispositions. During an execve(2), the dispositions of handled signals are reset to the
 //   default; the dispositions of ignored signals are left unchanged.
 //
 // This code may be unnecessary in the future if Rust's execve library function is changed to
 // restore SIGPIPE.
 fn restore_sigpipe_default() -> Result<()> {
     // Set the SIGPIPE disposition to default (terminate).
     // SAFETY: No signal handler is provided, only the default action,
     //         so no additional consideration is needed.
     unsafe {
         let result = libc::signal(libc::SIGPIPE, libc::SIG_DFL);
         if result == libc::SIG_ERR {
             return Err(std::io::Error::last_os_error().into());
         }
     }
     Ok(())
 }
diff --git a/tests/test_main.py b/tests/test_main.py
@@ -278,6  278,17 @@ def test_redirect_stdin(self) -> None:
         assert_str_equalish(out, test_str)
 
 
 class TestMainSignals(MainTest):
     def test_sigpipe(self) -> None:
         """Verify SIGPIPE is handled correctly"""
         # See https://github.com/JonathonReinhart/scuba/issues/254
         SCUBA_YML.write_text(f"image: {DOCKER_IMAGE}")
 
         out, err = run_scuba(["sh", "-c", "yes | echo abcd"])
         assert_str_equalish(out, "abcd")
         assert_str_equalish(err, "")
 
 
 class TestMainUser(MainTest):
     def _test_user(
         self,