strlcpy [LWN.net]

strlcpy

Posted Jun 12, 2003 3:51 UTC (Thu) by JoeBuck (subscriber, #2330)
Parent article: strlcpy

If you don't have a document anywhere, explaining these relatively small functions clearly enough so that any competent programmer can produce a correct implementation, there's a problem. "Just use our code" is OK, but doesn't really suffice for good security analysis unless you want everyone to do duplicate work.

Also, many common uses of strcpy are completely safe and more efficient than strlcpy. Removing every use is just superstition.

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strlcpy

Posted Jun 12, 2003 7:46 UTC (Thu) by set (guest, #4788) [Link]

Linus claims to have maintained *BSD compatibility, though he
wrote the functions himself:

"Ok, I did my own versions, since (a) I had already started and your
patches wouldn't apply, and (b) I hate adding a zillion lines of extra
copyright notices for a 5-line function..."

(strlcat was added as well)

I dont think strcpy is the main target, as much as strncpy. Linus again:

"Yeah, "strncpy()" is a frigging disaster when it comes to '\0', in many
ways. We should probably disallow using strncpy(), and aim for a _sane_
implementation that does what we actually want (none of that zero-padding
crap, and _always_ put a NUL at the end). I bet that is what most current
strncpy() users actually would want."

A light grep of 2.5.70 shows many uses of strlcpy, strncpy, and strcpy
out there...

Paul