My personal choice in things I write is to expect the caller to
strdup(). But I understand the reentrancy issue here. (though why
you'd be using popt in a thread is beyond me at this time.. and it does
have a poptContext handle anyway).
But yeah, I guess I'd opt for consistency as well. The thing that
surprised me was that while poptGetOptArg() expects the caller to free
it, it's still returning a const. I use 'const' not as memory
protection (we know it doesn't do that), but as a signifier that the
caller doesn't need to worry about freeing the contents. But whatever,
I just put a /* popt requires this to be freed */ comment every time I
use it.
If this is going to continue to be the behavior, I'd suggest a
poptFreeOptArg() call just to highlight the necessity (and deal with
type and NULL pointer checks).
If all Get's in popt allocate, that's fine (I actually hadn't noticed
that because I wasn't really expecting it). But if there's ever a time
when you have a mix, I'd also suggest function names containing "New"
(or "Dup" or "Alloc" or something of the sort) to drive home the point
that something's being allocated. "Get" to me typically means retrieve,
not allocate. But like I said, it's not a huge issue. Just add the
poptFreeOptArg() and I think it'll be clear for everyone.
On 6/7/2010 9:02 AM, Jeff Johnson wrote:
On Jun 7, 2010, at 11:50 AM, Mark Hatle wrote:
Jeff Johnson wrote:
On Jun 7, 2010, at 10:37 AM, Mark Hatle wrote:
The way I've usually addressed this is to either add an option to the library
that changes the default behavior from strdup to passing the address with the
expectation of const.
I'd rather _NOT_ go the "Have it your own way!" route in
a API/ABI becuase it adds yet another datum that needs to
be extracted from lusers doing POPT support.
Runtime not build time. For a library like popt, build time would be really
bad.
I was thinking "run-time" ...
For runtime, it should be a simple 'switch' for the strdup call.
... and there's nothing "simple" about insturmenting choice in POPT
underneath applications.
Its either Yet Another Arcane flag that noone uses or a goosey-loosey
envvar that makes debugging run-time dependent, see the tedium of
POSIX_ME_HARDER that is already in POPT since forever.
But sure I know the "Have it your own way!" run-time drill quite well too.
Just I'm hoping not to go there, I do like KISSy-poo.
Either by adding const style prototypes/functions, or by using some mechanism
to change the behavior of all of the functions.
(aside)
Well I've gone multiple ways with the C borkage of "const char **"
vs "char *const *" in POPT and RPM. These days there's so much spewage
from GCC that I don't believe that compilers or language hints solve
any "real world" issue. But I can/will go to PROT_READ mandatory hardware
enforcement using mmap(2) if that is what is desired. Its easier
to implement the code than it is to discuss the various religion's
coding fetishism's Yet Agin. But I digress ...
Note that it _WAS_ GCC's writable strings that forced the malloc
into POPT in the first place, where POPT sometimes returned
strings from RO memory, and sometimes from argv, and the morons were confused.
Adding the strdup() to POPT was 1 less issue to worry about. Another digression
...
Ya, I don't doubt it. I believe the issue comes down to consistency. Either
everything popt returns should be duplicated so that the user has to clear
them, or nothing should be so the user knows that it's expected to be
read-only. (Enforcing read-only is another issue entirely, and one that I don't
really think is popt's responsibility. Set the prototype properly on the
functions and if the user violates them so be it.. they live with the
consequences.)
What is currently implemented is the former, malloc everything returned,
and those with clue will figger it out. That's general, just surprising.
But I can/will make the audit's easier if that is what is desired. Its
a bleeping string, deal with it, stop fussing POPT "leaks" is MNSHO privately.
My biggest concern is the potential retrofit of existing apps that expect the
current behavior.. but I agree with many of the submitters.. popt really should
be sending const points and then the app needs to strdup.
And so "legacy compatibility" again again again. POPT 2.0 is a major change
with no "compatibility" implied or intended. Meanwhile I will strive to
make the change as painless as possible. But there are issues (aka "deep hacks")
that have been in POPT for a decade that aren't the right thing to do. And even
though I've overloaded just about everything possible in the 7-tuple of a
POPT table item, there are these issues:
If both popt 1 and popt 2 can live on the same machine and have different
sonames, then I vote for no strdup.. it's the users problem to duplicate what
they want.
Changing the soname or even (gasp!) using ELF symbol versioning
is quite doable, all the necessary precursor elements have been in place
for years.
IMHO libraries should not protect the user from themselves. If they are dumb
enough to modify memory or expect that memory will live beyond a certain
pre-defined lifecycle.. then it's their problem to fix... (Note of course
reentrancy and such could be an issue.. but thats only a problem if it's
allowed by popt.)
Hehe, so PROT_READ LART'ing is where you want to go ;-) That would
be fine with me except I'm also trying to avoid any POPT "support" headaches.
Note that C macros could be used to ease the pain of "long"<-> "void *"
punning. But I _REALLY_ need another pointer field somehow without overloading
the two i18n --help fields which are already way way way too complicated
for my taste.
73 de Jeff
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