Path: utzoo!attcan!uunet!mailrus!umich!samsung!rex!uflorida!stat!sun13!gw.scri.fsu.edu!pepke
From: pepke@gw.scri.fsu.edu (Eric Pepke)
Newsgroups: comp.sys.mac.programmer
Subject: Speaking of Munger...
Message-ID: <233@sun13.scri.fsu.edu>
Date: 11 Jul 90 14:54:11 GMT
Sender: news@sun13.scri.fsu.edu
Organization: Florida State University, but I don't speak for them
Lines: 67

Speaking of Munger, it's a cute little routine, but what happens when it 
fails due to insufficient memory?

I run this little test program: 

#include <stdio.h>
#include <MacTypes.h>
#include <MemoryMgr.h>

main()
{
    unsigned char buffer[1000];
    Handle block;
    long beforeLength, afterLength;
    
    printf("Yahoo!\n");
    
    block = NewHandle(0L);
        
    for (;;)
    {
        beforeLength = GetHandleSize(block);
        Munger(block, GetHandleSize(block), (unsigned char *) 0, 
                0L, buffer, (long) sizeof(buffer));
        afterLength = GetHandleSize(block);
        
        if (beforeLength + sizeof(buffer) > afterLength || MemError())
        {
            printf("\nSize increased from %ld to %ld\n", 
                    beforeLength, afterLength);
            printf("MemError() == %d\n", MemError());
            exit(-1);
        }
        else
        {
            printf(".");
        }
    }
}

and I get

Yahoo!
...........................................................................
.....
...........................................................................
.....
...........................................................................
.....
.......................................................................
Size increased from 311000 to 311000
MemError() == 0

So, when Munger fails due to lack of memory, you cannot tell from looking 
at MemError.  In this case, at least, it left the handle unchanged.  Can 
somebody who knows about the internals of Munger tell me if that is 
guaranteed to be the case, or is there a possibility that the handle will 
be corrupted in any way, such as being left larger than it was but not as 
large as is needed?

Eric Pepke                                    INTERNET: pepke@gw.scri.fsu.edu
Supercomputer Computations Research Institute MFENET:   pepke@fsu
Florida State University                      SPAN:     scri::pepke
Tallahassee, FL 32306-4052                    BITNET:   pepke@fsu

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