jpmschweitzerandClaude Opus 4.7
8074bf4201
`forkpty` calls `fork()` underneath. `fork()` in a multithreaded process is unsafe: only the calling thread survives in the child, but libc locks held by other threads remain "locked forever." With the multi-threaded Dart VM as parent, ~5% of spawns deadlocked in the child before `execve` (forensic probe: child stuck in S state with comm=`DartWorker`, master fd never sees POLLIN). `posix_spawn` uses `vfork` on glibc/musl/macOS, keeping the parent suspended until execve completes — no Dart code runs in the child. Pty pair built via the POSIX-standard `posix_openpt` / `grantpt` / `unlockpt` / `ptsname` sequence. Probed: zero hangs in 300 sequential spawns vs ~5% before. Behavior change: missing executable / missing workingDirectory now surface as a `PtyException` thrown by `NativePty.start` rather than a diagnostic written from the child to the slave PTY. Cleaner error path for callers. Side benefit: drops the `libutil.so.1` dynamic-library dependency. PTY now resolves entirely against libc via `DynamicLibrary.process()`. Splits the library-level `@Tags(['forkpty'])` on session_test.dart into a per-test tag, so the now-runnable-under-flutter-test cases contribute to coverage. `dart_test.yaml` declares the tag so the exclude-tags filters honor it. Drops the `retry: 2` workaround from the formerly-flaky registry test. D-5 amended. Trims session-introduced CHANGELOG entries that were over-verbose for the Keep-a-Changelog format. Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
24 lines
840 B
Dart
24 lines
840 B
Dart
/// Error type for the PTY subsystem. Flutter-free — `dart:io`'s
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/// `OSError` + `ProcessException` don't quite fit (we're a mix of
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/// syscall-level and subprocess-level failures), and we can't pull
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/// `PlatformException` from `package:flutter/services.dart` since the
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/// core library stays Flutter-free per D-005.
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library;
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/// A PTY operation failed. [op] identifies the step (`posix_openpt`,
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/// `posix_spawn`, `read`, `ioctl`, etc.); [errno] is POSIX errno when
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/// the failure came from a syscall, otherwise `null`.
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class PtyException implements Exception {
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const PtyException(this.op, this.message, {this.errno});
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final String op;
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final String message;
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final int? errno;
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@override
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String toString() {
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final suffix = errno != null ? ' (errno=$errno)' : '';
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return 'PtyException($op): $message$suffix';
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}
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}
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