On 05/11/2023 23:31, Alejandro Colomar wrote: > Hi Jonny, > > On Sun, Nov 05, 2023 at 09:16:25PM +0000, Jonny Grant wrote: >> Michael, what do you think about this documentation suggestion I have made. Interested to hear your opinion. >> >> Should the man page follow the C spec description of the strncpy function and how when it copies the arrays, it may leave the resulting array of characters not terminated, and warn about this pitfall. >> >> C99 had this, and it is still there in latest C23 draft - worth clarifying on strncpy(3)? >> >> "7.21.2.4 The strncpy function" >> >> "269) Thus, if there is no null character in the first n characters of the array pointed to by s2, the result will >> not be null-terminated." > > What ISO C has said and continues to say about strncpy(3) is the actual > harmful stuff, which has led many programmers to believe strncpy(3) was > useful at all for producing strings. > > The problem I see with what ISO C says about strncpy(3) is that it > treats it as a string-copying function. If you treat strncpy(3) as a > string-copying function, then it is really broken and should be removed > from libc. > > However, its functionality is still useful for those cases where you > don't want a string, which is the only reason I didn't mark the function > as [[deprecated]]. > >> >> Note, I'm not using strncpy myself, it's a documentation clarification proposal. > > I think it could be useful to add a note that one should first read the > CAVEATS section and string_copying(7) and only then read this page. > > > diff --git a/man3/stpncpy.3 b/man3/stpncpy.3 > index 239a2eb7e..c7bb79028 100644 > --- a/man3/stpncpy.3 > +++ b/man3/stpncpy.3 > @@ -37,6 +37,12 @@ .SH SYNOPSIS > _GNU_SOURCE > .fi > .SH DESCRIPTION > +.IR Note : > +These functions are probably not what you want. > +Read CAVEATS below, > +and > +.BR string_copying (7). > +.PP > These functions copy the string pointed to by > .I src > into a null-padded character sequence at the fixed-width buffer pointed to by > > > Is this scary enough? Do you think this would tell readers to never use > this function unless they know what they're doing (and even when they > think they do, they probably don't)? > > Cheers, > Alex > >> >> Kind regards >> Jonny > Alejandro, We see things differently, I'm on the C standard side on this one. Would any information change your mind? With kind regards, Jonny
