GeezerVison is showing github.com — impl preexec_fn by youknowone · Pull Request #6479 · RustPython/RustPython
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youknowone
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Dec 24, 2025
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edited by coderabbitai
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Summary by CodeRabbit
Bug Fixes
- preexec_fn is now supported in subprocess execution (previously blocked)
- Enhanced error reporting for preexec_fn failures with clearer, more descriptive error messages distinguishing subprocess-level errors from OS-level errors
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coderabbitai
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Dec 24, 2025
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edited
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The pull request is closed.
📝 Walkthrough
Walkthrough
The changes enable preexec_fn support in subprocess execution by removing a not-implemented guard, threading the VM reference through function signatures from fork_exec to exec_inner, adding a new PreExec variant to ExecErrorContext for error distinction, and implementing preexec_fn invocation in the child process after setup but before file descriptor closing.
Changes
| Cohort / File(s) |
Summary |
preexec_fn invocation and error context
crates/stdlib/src/posixsubprocess.rs |
Removed preexec_fn guard allowing its execution; added PreExec variant to ExecErrorContext enum with corresponding message "Exception occurred in preexec_fn."; enhanced error reporting to distinguish PreExec errors (SubprocessError:0:) from OS errors (OSError:<errno_hex>:) |
Function signature updates for VM threading
crates/stdlib/src/posixsubprocess.rs |
Updated exec() signature to accept vm: &VirtualMachine parameter; updated exec_inner() signature to accept vm: &VirtualMachine parameter; updated call site in fork_exec() to pass vm to exec() and all exec_inner() call sites to forward the VM reference |
preexec_fn execution logic
crates/stdlib/src/posixsubprocess.rs |
Implemented preexec_fn invocation in child process after setup steps but before file descriptor closing; on failure, sets error context to PreExec and returns UnknownErrno; on success, execution continues to execve/execv |
Estimated code review effort
🎯 2 (Simple) | ⏱️ ~12 minutes
Poem
🐰 A preexec hop through code we go,
With VMs passed where children flow,
Callbacks bloom before execve's call,
Error messages catch one and all—
Subprocess magic, clean and bright!
✨ Finishing touches
🧪 Generate unit tests (beta)
- Create PR with unit tests
- Post copyable unit tests in a comment
📜 Recent review details
Configuration used: Path: .coderabbit.yml
Review profile: CHILL
Plan: Pro
📥 Commits
Reviewing files that changed from the base of the PR and between 309b2ad and c7fcd56.
⛔ Files ignored due to path filters (1)
Lib/test/test_subprocess.py is excluded by !Lib/**
📒 Files selected for processing (1)
crates/stdlib/src/posixsubprocess.rs
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This was referenced Dec 30, 2025
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