Alejandro Colomar 225530b7e1 lib/strncpy.h: Add STRNCPY() wrapper for strncpy(3) ...

This wrapper calculates the destination buffer's size, to avoid errors
in the size calculation.

A curious fact: this macro did exist in Version 7 Unix (with a slightly
different name).  I found it by chance, investigating the origins of
strncpy(3) and strncat(3) in V7, after Branden suggested me to do so,
related to recent discussions about string_copying(7).

	alx@debian:~/src/unix/unix/Research-V7$ grepc SCPYN .
	./usr/src/cmd/login.c:#define SCPYN(a, b)	strncpy(a, b, sizeof(a))

Our implementation is slightly better, because using nitems() we're
protected against passing a pointer instead of an array, and it's also
conceptually more appropriate: for wide characters, it would be

	#define WCSNCPY(dst, src)  wcsncpy(dst, src, NITEMS(dst))

Cc: "G. Branden Robinson" <branden@debian.org>
Signed-off-by: Alejandro Colomar <alx@kernel.org>

2023-11-26 06:48:18 -06:00

2.9 KiB

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