micropython / micropython/micropython
struct.pack doesn't check for value bounds
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Description
Setup: MicroPython v1.11-555-g80df377e9 on 2019-11-04; PYBv1.1 with STM32F405RG
struct.pack('B', 256) # returns b'\x00'
CPython errors out with struct.error: ubyte format requires 0 <= number <= 255
Contributor guide
First steps
- Read the whole issue, then the project's contributing guide.
- Comment on the issue to say you are picking it up — it saves two people doing the same work.
- Fork the repository and make your change on a branch.
- Open a pull request that references the issue number.
Research direction
Start at the struct.pack entry point and reproduce the shown B format case on the listed MicroPython setup. Compare its handling of 256 with the CPython behavior described in the issue; done means out-of-range values are rejected instead of wrapped.
Written by the indexing model from the issue text.
Assessment
- Tech stack
- c, python
- Domain
- embedded-iot
- Issue type
- Bug
- Difficulty
- 3/5
- Estimated time
- 1-2 days
- Activity status
- Stale
- Clarity
- Mostly clear
- Newbie friendliness
- 35/100