Adds support for truncating files after write operations, enabling proper
HTTP PUT semantics where the entire file content should be replaced.
Implementation:
- Added TOASTY_WRITE_TRUNCATE_AFTER flag (0x02) to ToastyFS API
- Updated file_tree_write() to accept truncate_after parameter:
* When true, sets file size to exactly offset+length
* Removes chunks beyond the new file size
* Marks removed chunks for garbage collection
- Metadata server extracts and passes truncate flag to file_tree_write()
- WAL replay passes false for truncate_after (already handled in original write)
- Web proxy PUT now uses both CREATE_IF_MISSING and TRUNCATE_AFTER flags
- Updated documentation in PROTOCOL.txt, DESIGN.txt, and web/DESIGN.txt
Benefits:
- Proper HTTP PUT semantics (replace entire file content)
- Efficient: single write operation truncates and updates file
- Works with both sync and async APIs
- Garbage collection automatically removes orphaned chunks
Per PROTOCOL.txt specification, WRITE operations must provide a valid
generation counter and cannot use expect_gen=0 (unlike other operations).
This ensures the client has retrieved the file's metadata and knows the
correct chunk size before writing.
Changes:
- Added FILETREE_BADGEN error code (-8)
- Modified file_tree_write() to reject expect_gen=0
- Added error message for FILETREE_BADGEN
Previously, file_size was calculated as num_chunks * chunk_size, which
incorrectly treated the file size as the full capacity of all allocated
chunks. The actual file size should be the offset of the last byte
written plus 1.
Changes:
- Added file_size field to File structure to track actual file extent
- Initialize file_size to 0 when creating new files
- Update file_size in file_tree_write() based on write offset + length
- Modified file_tree_read() to use file_size instead of num_chunks * chunk_size
- Updated serialization/deserialization to handle file_size field
This ensures that actual_bytes calculations correctly reflect the true
file size, not just the allocated chunk capacity.
Add functionality to determine the actual number of bytes read during
read operations, making it possible to detect when a read was truncated
because it went past the end of the file.
Changes:
- Modified file_tree_read() to calculate and return actual_bytes via
new output parameter
- Updated metadata server to send actual_bytes in READ_SUCCESS messages
- Added bytes_read field to ToastyResult structure
- Modified client to parse, store, and report actual bytes read
- Updated toasty_read() to return the actual number of bytes read
instead of always returning 0
- Fixed web server to use bytes_read field instead of non-existent
count field
This allows clients to distinguish between:
- Reading zeros because the file is sparse (has holes)
- Reading past the end of the file (truncated read)
Claude
cozis