String::toInt() and atol() behave different on different platforms with a number that is too large.
Nobody has claimed this yet.
Assessment
- Difficulty
- 3/5
- Estimated time
- 1-2 days
- Newbie friendliness
- 48/100
- Issue type
- Bug
- Clarity
- Mostly clear
- Activity status
- Stale
- Tech stack
- cpp
- Domain
- embedded-iot
Research direction
Start in String.cpp at String::toInt() and review how atol() behaves for values outside the platform's long range. Compare the proposed strtol() and errno handling across 8-bit and 32-bit platforms; the issue is done when oversized inputs produce consistent documented results without mishandling LONG_MAX or LONG_MIN.
Written by the indexing model from the issue text.
Description
User axemaster found strange behavior when using String::toInt() with a number that is too large. See the topic in the Arduino forum: https://forum.arduino.cc/t/toint-bug-how-unfortunate/1041669.
The result is different for 8-bit and 32-bit platforms.
It was narrowed down to the undefined behaviour of atol() when a number is too large to fit in a long.
The atol() in String::toInt() in String.cpp could be replaced by strtol() followed by a check for LONG_MAX or LONG_MIN and return zero if that happens. The documentation can stay as it is, because it will return a long, and zero if something is wrong.
To allow LONG_MAX and LONG_MIN as valid input numbers, the errno has to be used. I don't know how that will hold up in a multitasking environment.
- Dominant language
- C++
- Stars
- 306
- Forks
- 150
- PR merge metrics
- No merged PRs in 30d
Contributor guide
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First steps
- Read the whole issue, then the project's contributing guide.
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- Open a pull request that references the issue number.
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