Hi everybody,
we've been struggling for a few days hunting a weird bug in
ImageInput::create, and the search raised one major concern about the
use of std::string in the API.
I don't know if the issue has been discussed before (in a sense, I hope
not).
We've had a crash when trying to open a specific JPEG file. To
understand its cause we built OIIO in debug, to find that the crash
occured in the geterror() function. Apparently it crashed in the
destruction of the std::string that is used in ImageInput::create
because it's been overwritten.
Recompiling with more debug flags we found that strangely the string is
already in a bad state before opening the file: we crashed in the boost
function that extracts the extension of the file. (called from the line
"std::string format = Filesystem::extension (filename)" in
ImageInput::create).
Which is quite weird because it does not relate very well with the crash
we had at the beginning, which was linked to the data in the file. And
it now crashes on every single file we try to open.
Trying to dig deeper we hit a bunch of issues, mainly related to
std::string and the way it's implemented.
Is there a reason for using "std::string" instead of a simple "char*"
(even const) in all interface functions ? As far as we're concerned,
it's heavy and raises many compatibility issues especially under windows
( libraries versions, debug/non debug MT option, etc...). So far we have
failed to build a full debug version of an application using OIIO that
does not crash at startup. Either we can't debug because libraries are
in release, either we crash in mainCRTStartup.
Our debug session uses the trunk of OIIO and boost 1.44 version.
We used boost 1.44 because of this bug
https://svn.boost.org/trac/boost/ticket/6320, which seems to have
appeared in 1.48 and was fixed only on boost trunk at this time. At
first we used the 1.49 version then tried the 1.53 and finally the 1.44.
Going back to the 1.44 did change things a bit: with OIIO in release
with debug info, no crash. But OIIO won't load any image.
------------------------------
Michel
Isotropix SAS
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