Jeff King [off-list ref] writes:
On Tue, Jun 30, 2015 at 09:22:18AM -0700, Junio C Hamano wrote:
quoted
Jeff King [off-list ref] writes:
quoted
quoted
strbuf_addf(&f, "%s ", fmt);
Basically I was trying to avoid making any assumptions about exactly how
strftime works. But presumably "stick a space in the format" is a
universally reasonable thing to do. It's a hack, but it's contained to
the function.
Why can't I shake this feeling that (" %s", fmt), i.e. prepend not
append, is the safer thing to do than to append?
Because then removing the extra space involves `memmove` of the buffer,
rather than just shortening the length by one.
That does not explain why I feel the other way is safer, though ;-)
In any case, responding myself to my other question, strftime(3)
does not define any useful error information even for a case where
you feed nonsense format to it, so it is even not possible to
protect ourselves by checking errno or doing something similar X-<.
On Tue, Jun 30, 2015 at 12:23:08PM -0700, Junio C Hamano wrote:
quoted
quoted
Why can't I shake this feeling that (" %s", fmt), i.e. prepend not
append, is the safer thing to do than to append?
Because then removing the extra space involves `memmove` of the buffer,
rather than just shortening the length by one.
That does not explain why I feel the other way is safer, though ;-)
Sorry, I think I read it as "saner". ;)
In any case, responding myself to my other question, strftime(3)
does not define any useful error information even for a case where
you feed nonsense format to it, so it is even not possible to
protect ourselves by checking errno or doing something similar X-<.
I do think " %" is probably safer than "% " in that it is less likely to
cause weird output from strftime (e.g., I could see an implementation
treat "%X", where "X" is unknown, as just "X", but treat a trailing "%"
as a raw "%"). But I doubt there is an implementation that would return
"0" for one but not the other (anything's possible of course, but we are
deep in the realm of guessing how systems might implement the
standard, so it's really our best guess until somebody can present a
particular data point; I've looked only at glibc and it is sane).
-Peff