MQX 4.2.0 _io_write vs const data

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MQX 4.2.0 _io_write vs const data

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Contributor II

Hi,

We are using MQX 4.2.0 and I was quite surprised that _io_write is defined to take a non-const buffer for the data:

extern _mqx_int    _io_write(MQX_FILE_PTR, void *, _mqx_int);

I would have expected the second parameter to be something like const void*, furthermore that it is used in the inline definition of fwrite:

#define  fwrite(ptr,so,no,f) (_io_write(f,ptr,(so)*(no))/(so))

My question is: is it safe to assume that neither fwrite nor _io_write will modify the pointer that is given to them?

Can there be a problem to remove the const (using a cast) of an array we want to write using fwrite?

Thanks!

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NXP TechSupport
NXP TechSupport

Hi Ruby:

Thank you for your feedback. Yes, this is an issue. and it is fixed in MQX v5. 

Your can fixed it by yourself.

 For MQX v5 we did a full clean up of the code and we made things more consitent and up to date.

Regards

Daniel

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NXP TechSupport
NXP TechSupport

Hi Ruby:

Thank you for your feedback. Yes, this is an issue. and it is fixed in MQX v5. 

Your can fixed it by yourself.

 For MQX v5 we did a full clean up of the code and we made things more consitent and up to date.

Regards

Daniel

View solution in original post

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Contributor II

Hi Daniel,

Thank you for your answer.

Just to be clear, the issue here is only that the parameter is not declared as const?

I mean, it is used as const (i.e. not modified) by the _io_write implementation right?

If so, I guess that _strnlen is the same (i.e. the first parameter is not modified and can be considered as const char*). I stumbled upon it yesterday after my question.

Thanks!

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NXP TechSupport
NXP TechSupport

Yes, you are right.

Regards

Daniel