Tim Ellison wrote:
Oliver Deakin wrote:
I've had a quick look around for the "right" way to do this, and it
seems there are 2 options:
1) Determine the max path length from a system macro, probably PATH_MAX
in limits.h.
2) Use the unix system call pathconf() to get the max path length.
I think using a build time constant, as in 1, is preferable, however
this macro is not defined on all platforms. On zOS, for example, only
_POSIX_PATH_MAX is defined, and that is set to a paltry 256 (which is
not the real max path length - pathconf() tells me it is 1024).
Perhaps to start with we can include /usr/include/linux/limits.h and use
PATH_MAX for linux platforms (I'm assuming that file exists for linux
distros in general here - perhaps someone can clarify this?) and on
non-linux platforms fall back to a default of 1024. We can add other
platforms in as we find the correct includes/macro definitions for them.
From the Harmony code I was looking at, the max path length is used to
allocate char buffers so we can do path manipulations before passing
through to OS calls. We fail early if the path is greater than the
expected max path length.
Would could, as you say try to set the max path length based on the OS
we are using, but even that is going to be a guess since who knows where
the file path points (e.g. network drives etc.)?
I wonder if we can be a bit lazier and set the Harmony max path length
to a large number for the path manipulations, then let the OS call fail
if the path is too long?
agree
(caveat: I've not looked at all uses of the HyMaxPath const to see if
that is a good idea or not)
Regards,
Tim
I guess we have max path length because we used char array as buffer. It's not
efficient and a kind of waste memory if the buffer size was the same as OS limit
(on Windows it's 32,767 characters).
So I wonder if we can set a threshold value, like 1024, if path length is
smaller than the value, we allocate char array as buffer, just like we have
done; otherwise dynamic malloc memory as buffer, and then let OS tell us if the
path is too long?
--
Best Regards,
Regis.
