# Refactoring Report: Robust Error Handling
## Overview
The `linux-procfs` library has been refactored to replace panic-prone logic with standard Rust `Result`-based error handling. This change ensures that applications using this library can gracefully handle unexpected system states or malformed `/proc` files without crashing.
## Key Changes
### 1. New Error System (`src/error.rs`)
- Introduced `ProcError` enum covering:
- `Io`: Standard I/O errors.
- `Utf8`: UTF-8 decoding errors.
- `ParseInt` / `ParseFloat`: Standard parsing errors.
- `UnexpectedFormat(String)`: Specific formatting issues.
- `PermissionDenied` / `NotFound`: Explicit variants for common file system issues.
- Added `ProcResult<T>` alias for `Result<T, ProcError>`.
### 2. Safer Utilities (`src/util.rs`)
- Replaced string-formatted path construction with `PathBuf::join` to prevent panics on non-UTF-8 paths.
- Added `try_update` methods that return `io::Result`, used by the main API to propagate errors.
- Fixed borrow checker issues in buffer management by separating mutable and immutable access scopes.
### 3. Fallible API (`src/lib.rs`)
- All `get_*` methods (e.g., `get_stat`, `get_loadavg`, `get_pidentries`) now return `ProcResult<T>`.
- Internal logic now uses the `?` operator to propagate errors up from the parsers.
### 4. Robust Parsers (`src/parser/*.rs`)
- Eliminated all occurrences of `.unwrap()` and `unreachable!()` during the scanning and parsing process.
- Introduced `try_scan!` macro (and similar logic) to return `ProcError::UnexpectedFormat` when delimiters or expected fields are missing.
- Ensured all parsers return `ProcResult`.
### 5. Verified Tests (`tests/*.rs`)
- Updated all integration tests to handle the new `Result` return types using `.unwrap()` where success is expected.
- Fixed several latent bugs in tests (e.g., variable naming mismatches in `more_test*.rs`).
- Updated documentation examples in `src/lib.rs` to ensure they are runnable and correct.
## Conclusion
The library is now significantly more "production-ready". While it remains high-performance, it no longer risks crashing the host process due to minor variations in the Linux `/proc` filesystem interface.
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Date: 2026-05-24
Status: Completed