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2. A C Refresher, Part 1: The Basics

Page 17

myShort was not declared. It should be an unsigned short.

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4. The Compiler

Page 68

In the compile-line comment in multilineMacro.m, the -i flag should be a -o flag.

Page 77

The packed structure indicator has an extra underscore in it. It also has extra underscores after it. It should be __attribute((packed))

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5. Libraries

Page 79

The instructions for making the source files for the library samples aren't clear. You should create (or download) files named src0.c, src1.c, src2.c, src3.c, and src4.c. Inside of those files is a function named like the file, like add_0, add_1, add_2, add_3, and add_4.

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6. Command Line Programs

Page 112

Panther has adopted getopt_long() from the GNU project. It is similar to getopt, but allows you to use the long argument names, such as something like
% ./build-hut --type=yurt --height=12

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8. Debugging With GDB

Page 164

The rebuilding command should be
% cc -g -i memerror memerror.m

Otherwise debugging symbols won't be included (which makes subsequent debugging steps more difficult)

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9. Exceptions, Error Handling, and Signals

Pages 194 - 198

Objective-C now has first-class exception handling. Documentation at Apple.

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10. Files, Part 1: I/O and Permissions

Page 213

For most file system types, using open (O_CREAT | O_EXCL) works ok for locking a file. This does not work for NFS volumes since you could find yourself in a race condition. For doing atomic locking for a lockfile is to make a unique file (such as using the hostname and pid of the process) and use link() to make a link to the lockfile. If link() succeeds, you have the lock. Otherwise use stat() on your unique file to see if its link count has increased to two, in which case the lock is successful. Otherwise you were not able to get the lock.

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12. NSFileManager

Page 274

In the -components method, the @"" string should be @"/" to represent the root of the filesystem.

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13. Network Programming With Sockets

Page 305

In the readMessage function, the loop that looks for complete messages has a signed/unsigned error in it. The line of code that reads
user->currentMessageSize = *scan++;
should read
user->currentMessageSize = (unsigned char)*scan++;
Otherwise, messages over 126 bytes in length cause the server to stop sending messages. (Thanks to Randy Antler for finding and fixing this one)

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14. CFRunLoop

Page 335

Towards the end of -consoleUser, the appendString needs a colon:

[consoleUser appendString:[consoleUserDict objectForKey: @"Name"]];

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16. Using NSTask

Page 375

There is an instruction "Open MainMenu.nib and drag AppController.h to it." This is unnecessary because you created all the actions and outlets in Interface Builder. You can do this step or skip it. It has no effect.

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20. Rendezvous

Page 437

The line that says:

[aNetService resolve];

On a large network, resolving every server found can create a lot of unnecessary network traffic.

A better solution would be to move resolving to the subscribe: method:

currentService = [services objectAtIndex:
                                  [hostField indexOfSelectedItem]];
[currentService resolve];

Then the rest of the method should be in the delegate's call back:

- (void)netServiceDidResolveAddress:(NSNetService *)sender

(Thanks to Jeremy Wyld for this suggestion.)

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21. Directory Services

Page 455

In DoNodeNativeAuth() sample, the declaration

tContextData aContinueData;

should be

tContextData aContinueData = NULL

. Without the initialization, you'll get error code = -14097 (invalid continuation data)

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23. Using Distributed Objects Between Threads

Pages 485 - 498

The Mandelbrotter sample code uses the old Pre-C99 _complex data type. The source code for the chapter has been updated, so download it for the latest version.

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