[vox-tech] strerror deprecated?

[Jeff Newmiller]

Peter Jay Salzman wrote:
> Hi all,
> 
> Trying to write portable/correct code between Linux and MS Visual C++.
> 
> The cl.exe compiler is telling me that "strerror() is deprecated".  Is that
> true?  I never heard such a thing.  Tried Googling and couldn't find any
> mention of strerror() being deprecated.
> 
> The compiler also told me that strerror() was unsafe.  After thinking about
> it for a second, I'm guessing it meant "thread unsafe".
> 
> Lastly, the compiler told me that I should use strerror_s() which is more
> safe.  I looked at the prototype for this function and it requires a buffer,
> the buffer's length, and the errno.  Passing a char * to be filled by a
> function when you don't know how large of a buffer that function wants
> hardly sounds like a good idea.  How should this function be used safely?
> Keep allocating memory until the buffer isn't filled all the way?  Sounds
> like I would need to write my own strerror function just to make sure the
> buffer is large enough.  Why would a standards committee do such a thing?
> 
> Lastly, strerror_s doesn't appear in any man pages on my Linux system.
> However, it does appear to be similar to strerror_r() which my man pages say
> is POSIX compliant (under a suitable #define).
> 
> What's the quickest fastest way of using strerror_r if on Linux and
> strerror_s if on Windows?
> 
> Thanks,
> Peter
> 

One solution I have not heard mentioned today: don't use strerror at all.

The few times I have used it in twenty years of programming, it
has been for programs I did not plan on distributing anyway.
Normally, I try to handle all defined errors in a manner appropriate
to the context.  For example, in an embedded system errors may be
reported through LEDs, and ENOMEM is pretty useless information
to the typical user of such a tool.  In reality, errno is pretty
useless information to users in most contexts... it is really
debugging information, and incomplete for that purpose as well.

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