Re: Writing to disk using filter scheme driver

6 Apr 2005

      site_archiver@lists.apple.com
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Hi Parav,

I get the error at compile time itself.
But there is declaration and definition of the function in my driver
class as follows:

MyDriver.h includes-
class com_MySoftwareCompany_driver_MyFilterScheme : public IOStorage {
OSDeclareDefaultStructors(com_MySoftwareCompany_driver_MyFilterScheme)

virtual void DoDriverWrite(IOMemoryDescriptor *inBuffer);
};

MyDriver.cpp includes -
// kMyScalarIStructImethod
void
com_MySoftwareCompany_driver_MyFilterScheme::DoDriverWrite(IOMemoryDescriptor * inBuffer)
{
	IOStorageCompletion completion;

     // If the user client's 'open' method was never called, return
kIOReturnNotOpen.
    if (!isOpen())
    {
        return kIOReturnNotOpen;
    }

    IOByteCount readBytes;
    UInt64 byteStart = 512;
    IOByteCount bufLength = inBuffer->getLength();
    char *myBuff = new char[bufLength];

    readBytes = inBuffer->readBytes(0, myBuff, bufLength);

    IOLog("MyFilterScheme::read BEFORE **** readBytes = %lu byteStart =
%lu \ bufLength = %lu buffer = %s \n", (long)readBytes, (long)byteStart,
(long)bufLength, myBuff);

    getProvider()->write(this, byteStart, inBuffer, completion);

    IOLog("MyFilterScheme::read AFTER **** readBytes = %lu byteStart =
%lu \ bufLength = %lu buffer = %s \n", (long)readBytes, (long)byteStart,
(long)bufLength, myBuff);

    delete[] myBuff;
}

Its a strange thing that even when the function is declared and define
in my driver class compiler gives me the compile time error that there
is no matching function IOSerive::DoDriverWrite().

Is there that i am mistaking in mapping of calls from userclient to
driver???

Thanks,
Yogesh Pahilwan

On Tue, 2005-04-05 at 02:06, Parav Pandit wrote:
...
Hi Yogesh,
ffProvider =
OSDynamicCast(com_MySoftwareCompany_driver_MyFilterScheme,
fProvider);
// is this a correct way of casting???
Yes, but you don't need to type cast because fPRovider
is already of type
com_MySoftwareCompany_driver_MyFilterScheme.
...
But i am still facing the same problem that "no
matching function
IOService::DoDriverWrite()"
//com_MySoftwareCompany_driver_MyFilterScheme*
fProvider;
If this is compilation error, it looks to me that your
driver class
com_MySoftwareCompany_driver_MyFilterScheme ( NOT
com_MySoftwareCompany_MyUserClient) doesn't have
declaration and definition of DoDriverWrite()
function.
and the compiler asking to it's top base class
IOServive whether it has the function or not.
Regards,
Parav Pandit
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Yogesh P

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