Hi Tim and Alexei,
Thanks your advices, I'll try the exception approach.
Alexei Fedotov wrote:
Technically, both approaches cross JNI-boundary twice. When we raise
an exception in JNI code, we return back to Java to run its
constructor, hence cross the boundary. It seems that Tim's approach is
just more compact which makes it eaiser to write the code without
bugs.
On Fri, Dec 5, 2008 at 7:42 PM, Tim Ellison <[EMAIL PROTECTED]> wrote:
Regis wrote:
Jim Yu wrote:
2008/12/5 Regis <[EMAIL PROTECTED]>
Kevin Zhou wrote:
The FileNotFoundException is being thrown by the constructor of
FileOutputStream when that constructor is attempting to open File f for
writing and it doesn't have permission to do so.
To open f the FileOutputStream class is calling
org.apache.harmony.luni.platform.OSFileSystem.open(). The
o.a.h.l.p.OSFileSystem.open() method invokes a native openImpl()
method.
The
native method can fail for several reasons. The problem lies in the
fact
that the reason behind the failure of the native method isn't being
propagated back to the FileOutputStream which is creating the
FileNotFoundException upon failure.
Yes, the native code just return -1 to indicate an error occurred,
while in
hyfile.c::hyfile_open, error messages are set by
portLibrary->error_set_last_error, but the caller never use them. So I
suggest to add a method in OSFileSystem.c to retrieve the error
messages.
The java could get the failure reasons when the native return -1, and
add
them to the exception message.
Agree to add a method for retrieving the error message from Port Library
which can be invoked by Java code. Maybe there are more cases which
have the
similar requirements of retrieving the error message.
Yes, we could supply the utility function first, and then use it when
needed. If no one object I would like to add this function.
How about raising the exception (with the right message) in the openImpl
native code rather than just returning -1 and crossing the JNI-boundary
again to find the reason?
There are other cases (i.e. other than FileNotFound) that you might want
to distinguish through IOExceptions too.
Regards,
Tim
Best Regards,
Regis.
