[neomutt-devel] strfcpy() improvement

Fabian Groffen grobian at gentoo.org
Tue Oct 4 15:07:09 CEST 2016

On 04-10-2016 13:23:09 +0100, Richard Russon wrote:
> Next, Mutt created a macro strfcpy() based on the BSD function.  It
> guarantees a length limit AND a NULL termination.
>     #define strfcpy(DST,SRC,LEN) strncpy(DST,SRC,LEN), *(DST+(LEN)-1)=0
> Because of the way it works, it triggers a warning in Coverity (a static
> analysis tool).  It fills DST (without NULL), then writes the NULL.
> Why have I told you all of this?  Because I'm changing the macro.
>     dotlock.c lib.h rfc822.c
> My testing shows it works correctly, but I may missed something.
>     #define strfcpy(DST,SRC,LEN) do { if ((LEN) > 0) { *(DST+(LEN)-1)=0; strncpy(DST,SRC,(LEN)-1); } } while (0)

Why not:

#define strfcpy(DST,SRC,LEN) snprintf(DST,LEN,"%s",SRC)

It simplifies the macro considerably, not sure about the performance
effect though.


Fabian Groffen
Gentoo on a different level
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