Not a question about a different OS. It is a question about your code. You change one single little variable assign somewhere, and then your assumption suddenly fails. Software Engineering it not just about getting something that works, but something that can continue to work and that can be maintained and extended with limited costs and risks.

Why do the society have to loose millions of dollars every hour? Because more developers than you have thougt the same thing - that they knew the input parameters and that they made informed decisions.

printf() is not intended for producing fixed-size data for binary storage in flash sectors. If you need fixed-size output, you roll your own packing code. Then you can control what happens if a value is <= -1000 or >= 10000.

Maybe you would even decide to store the information in a binary format - with binary storage, a 16-bit integer can always be stored in 16 bits. If building a data logger, you would be able to store two or three times as much data into the flash if using a binary format.

Another thing to think about - pad your output with a suitable number of space characters and truncate the output. The disadvantage is that you will not get any line ending, making a normal text editor unable to open the log.

But are you sure that you can't build a temporary buffer before sending it out? If the RTL has it, the traditional "safe" way of producing a text buffer for further processing is to use snprintf().