FileChunkIO

1.8 verified Mon Apr 27 auth: no python maintenance

FileChunkIO provides a file-like object representing a chunk of an OS-level file, supporting reading, writing, and random access within a byte range. Version 1.8 is the latest (2014), with no recent updates; stable but unmaintained.

pip install filechunkio

Common errors

error FileChunkIO requires integer offset and bytes ↓

cause Passing non-integer types (e.g., strings) for offset or bytes raises TypeError.

fix

Convert offset and bytes to int explicitly: int(offset).

error ValueError: I/O operation on closed file ↓

cause Attempting to read/write after closing the FileChunkIO object.

fix

Ensure all operations are done within a context manager or before calling close().

Warnings

gotcha FileChunkIO does not support 'w' mode for writing arbitrarily; only 'r', 'r+', 'a', 'a+', 'w', 'w+'. Opening with 'w' truncates the entire file, not just the chunk range. ↓

fix Use 'r+' mode and write only within the intended byte range; avoid 'w' mode unless you intend to truncate the whole file.

deprecated This library is effectively unmaintained since 2014. No Python 3 support beyond basic compatibility; may have issues with newer Python versions (e.g., file descriptor handling). ↓

fix Consider alternatives like 'io.BytesIO' or 'mmap' if possible.

gotcha The 'bytes' parameter specifies the number of bytes in the chunk, not the end offset. The actual accessible region is [offset, offset+bytes). If 'bytes' is None, the chunk extends to end of file. ↓

fix Ensure you compute the correct byte count; do not mistake 'bytes' for end offset.

Imports

FileChunkIO
```
from filechunkio import FileChunkIO
```
Standard import path

Quickstart

Opens a chunk of 'test.bin' from offset 0 for 512 bytes and reads it.

from filechunkio import FileChunkIO

with open('test.bin', 'wb') as f:
    f.write(b'a' * 1024)

with FileChunkIO('test.bin', 'r', offset=0, bytes=512) as chunk:
    data = chunk.read()
    print(len(data))  # 512