lurongjiang commented on PR #1044:
URL: https://github.com/apache/poi/pull/1044#issuecomment-4210591787
### Key Changes:
1. **Added Configurable Tolerance Mode**
(`org.apache.poi.poifs.allowCorruptBlocks`)
- Modified `ByteArrayBackedDataSource.java` and
`FileBackedDataSource.java`
- Default behavior: **Strict mode** - throws `IndexOutOfBoundsException`
when encountering blocks beyond EOF
- Optional tolerant mode: Set system property to `true` to allow reading
corrupt files with missing blocks
- System property is checked dynamically at runtime, allowing flexible
configuration
2. **Improved Test Coverage**
- Updated `TestHWPFParser.java` with comprehensive tests:
- `testDocRead()`: Verifies file can be read in tolerant mode with
actual text content validation
- `testDocReadStrictMode()`: Verifies strict mode properly rejects
corrupt files
- `testWpsDocByFs()`: Tests file system-based reading with content
validation
- `testOffice97_2003DocRead()`: Validates normal document reading
- All tests now verify actual text content (not just non-null), checking:
- Text is not null
- Text is not empty
- Text is not blank (after trimming)
- Added `getRootCause()` helper method with depth limit (20 levels) for
robust exception chain analysis
3. **Clear Error Messages**
- Exception messages guide users on how to enable tolerant mode if needed
- Example: "Position X is beyond EOF (Y). Set system property
'org.apache.poi.poifs.allowCorruptBlocks' to true to allow reading corrupt
files with missing blocks."
### Design Rationale:
- **Fail-fast by default**: Aligns with Apache POI's principle of strict
validation
- **Opt-in tolerance**: Users who need to handle damaged documents can
enable it via system property
- **No API changes**: Backward compatible, uses standard Java system
properties
- **Follows existing patterns**: Similar to other POI configuration options
like `org.apache.poi.ss.ignoreMissingFontSystem`
### Testing:
All tests pass successfully, verifying both strict and tolerant modes work
as expected. The implementation has been tested with the problematic
`issue_1041.doc` file that was previously causing issues.
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