Posix Error 14 (bad address) on open read stream in Cocoa. Hints?

Question

I'm following the sample code in CFNetwork Programming Guide, specifically the section on Preventing Blocking When Working with Streams. my code is nearly identical to theirs (below) but, when I connect to my server, I get posix error 14 (bad address -- is that bad IP address (except it's not)? Bad memory address for some call I made? or what?!.

I have no idea how to go about debugging this. I'm really pretty new to the whole CFNetworking thing, and was never particularly expert at networks in the first place (the one thing I really loved about Java: easy networks! :D)

Anyway, log follows, with code below. Any hints would be greatly appreciated.

Log:

[6824:20b] [DEBUG] Compat version: 30000011
[6824:20b] [DEBUG] resovled host.
[6824:20b] [DEBUG] writestream opened.
[6824:20b] [DEBUG] readstream client assigned.
[6824:20b] [DEBUG] readstream opened.
[6824:20b] [DEBUG] *** Read stream reported kCFStreamEventErrorOccurred
[6824:20b] [DEBUG] *** POSIX error: 14 - Bad address
[6824:20b] Error closing readstream
[6824:20b] [DEBUG] Writing int: 0x09000000 (0x00000009)

Code:

+ (BOOL) connectToServerNamed:(NSString*)name atPort:(int)port {
    CFHostRef theHost = CFHostCreateWithName (NULL, (CFStringRef)name);
    CFStreamError error;

    if (CFHostStartInfoResolution (theHost, kCFHostReachability, &error))
    {
        NSLog (@"[DEBUG] resovled host.");
        CFStreamCreatePairWithSocketToCFHost (NULL, theHost, port, &readStream, &writeStream);
        if (CFWriteStreamOpen(writeStream))
        {
            NSLog (@"[DEBUG] writestream opened.");

            CFStreamClientContext myContext = { 0, self, NULL, NULL, NULL };
            CFOptionFlags registeredEvents = kCFStreamEventHasBytesAvailable |
                    kCFStreamEventErrorOccurred | kCFStreamEventEndEncountered;
            if (CFReadStreamSetClient (readStream, registeredEvents, readCallBack, &myContext))
            {
                NSLog (@"[DEBUG] readstream client assigned.");
                CFReadStreamScheduleWithRunLoop(readStream, CFRunLoopGetCurrent(),
                                                kCFRunLoopCommonModes);
                if (CFReadStreamOpen(readStream))
                {
                    NSLog (@"[DEBUG] readstream opened.");
                    CFRunLoopRun();
         // Lots of error condition handling snipped.
        [...]
    return YES;
}


void readCallBack (CFReadStreamRef stream, CFStreamEventType event, void *myPtr)
{
    switch (event)
    {
        case kCFStreamEventHasBytesAvailable:
        {
            CFIndex bytesRead = CFReadStreamRead(stream, buffer, kNetworkyBitsBufferSize); // won't block
            if (bytesRead > 0)                                                  // <= 0 leads to additional events
            {
                if (listener)
                {
                    UInt8 *tmpBuffer = malloc (sizeof (UInt8) * bytesRead);
                    memcpy (buffer, tmpBuffer, bytesRead);
                    NSLog(@"[DEBUG] reveived %d bytes", bytesRead);
                    [listener networkDataArrived:tmpBuffer count:bytesRead];
                }
                NSLog(@"[DEBUG] reveived %d bytes; no listener", bytesRead);
            }
        }
            break;

        case kCFStreamEventErrorOccurred:
            NSLog(@"[DEBUG] *** Read stream reported kCFStreamEventErrorOccurred");
            CFStreamError error = CFReadStreamGetError(stream);
            logError(error);
            [NetworkyBits shutDownRead];
            break;

        case kCFStreamEventEndEncountered:
            NSLog(@"[DEBUG] *** Read stream reported kCFStreamEventEndEncountered");
            [NetworkyBits shutDownRead];
            break;
    }
}

void logError (CFStreamError error)
{
    if (error.domain == kCFStreamErrorDomainPOSIX)                              // Interpret error.error as a UNIX errno.
    {
        NSLog (@"[DEBUG] *** POSIX error: %d - %s", (int) error.error, strerror(error.error));
    }
    else if (error.domain == kCFStreamErrorDomainMacOSStatus)
    {
        NSLog (@"[DEBUG] *** MacOS error: %d", (int) error.error);
    }
    else
    {
        NSLog (@"[DEBUG] *** Stream error domain: %d, error: %d", (int) error.error);
    }
}

Answer 1

I'm not familiar with Cocoa or Objective-C, but I can tell you that POSIX error code 14 is called EFAULT, and it means you made a system call with an invalid pointer value. This is almost certainly some user-supplied buffer pointer to a read or write system call of some sort. Check all of the buffer pointers and make sure they're not NULL. Check the return value from malloc() - you might be failing to allocate a buffer.

Answer 2

Olie, where does

buffer

that you supply to

CFReadStreamRead()

come from? EFAULT is a bad buffer address... are you sure you've actually initialized this buffer to point to something valid? It's obviously a global or sometime... which itself is a pretty bad idea. You should allocate it in your function or it should be an ivar (if you're using Obj-C).