Re: [PATCH 1/1] string: Add stpecpy(3)

[Sam James <sam@gentoo.org>]

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> On 23 Dec 2022, at 12:26, Alejandro Colomar via Libc-alpha <libc-alpha@sourceware.org> wrote:
> 
> Hi Sam!
> 
> On 12/23/22 08:02, Sam James wrote:
>>> On 22 Dec 2022, at 21:42, Alejandro Colomar via Libc-alpha <libc-alpha@sourceware.org> wrote:
>>> 
>>> Glibc didn't provide any function that copies a string with truncation.
>>> 
>>> It only provided strncpy(3) and stpncpy(3), which copy from a string
>>> into a null-padded character sequence at the destination fixed-width
>>> buffer, with truncation.
>>> 
>>> Those old functions, which don't produce a string, have been misused for
>>> a long time as a poor-man's replacement for strlcpy(3), but doing that
>>> is a source of bugs, since it's hard to calculate the right size that
>>> should be passed to the function, and it's also necessary to explicitly
>>> terminate the buffer with a null byte.  Detecting truncation is yet
>>> another problem.
>>> 
>>> stpecpy(3), described in the new string_copying(7) manual page, is
>>> similar to OpenBSD's strlcpy(3)/strlcat(3), but:
>>> 
>>> -  It's simpler to implement.
>>> -  It's faster.
>>> -  It's simpler to detect truncation.
>> Given strlcpy and strlcat are in POSIX next and therefore bar
>> some extraordinary event will be in glibc, I think we should
>> probably wait until those two land, then see if there's still
>> an appetite for stpecpy in glibc.
> 
> I disagree for the following reasons.
[snip]

Hi Alex,

Thanks for your detailed and thoughtful reply. I'll reflect on your comments here
and in the rest of the thread(s) - but there's some intriguing pointers you've made.

I wasn't trying to be dismissive at all so I hope it didn't come across like that.

Thank you again!

Best,
sam


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