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Error Handler Reference

Overview

In Mac OS 9, Error Handler provides a system service that displays system alerts seen during startup, and assumes control when certain low-level errors occur. For detailed information, see the chapter “System Error Handler” in Inside Macintosh: Operating System Utilities. A PDF version of this chapter is available at http://developer.apple.com/documentation/mac/pdf/Operating_System_Utilities/pdf.html.

The header MacErrors.h defines result codes that are used by many Carbon functions to indicate their return status. Developers can also define custom result codes for their own applications, using the range 1000 through 9999 inclusive (Apple reserves all values outside of this range for internal use.) For more information, see Technical Q&A OV02 at http://developer.apple.com/qa/ov/ov02.html.

Functions

SysError

In Mac OS 9, displays a low-level system alert or dialog. The appearance and semantics of the alert or dialog can vary, depending on the error code passed in.

Not recommended

void SysError (
   short errorCode
);

Parameters

errorCode

A value or code that indicates a specific condition.

Discussion

A Carbon application running in Mac OS 9 can use this function to simulate a low-level system error. To exit in a more graceful manner when a serious error occurs, your application should call ExitToShell instead.

In Mac OS X, this function:

1. Prints a message containing the value of errorCode in the console log. Does not display a system alert or dialog.

2. If the variable USERBREAK is defined in the process environment, raises a SIGINT signal. Otherwise, returns control to the caller.

If a signal is raised and the caller does not handle the signal, the calling process is automatically terminated.

Availability

• Not recommended in Carbon. Available in CarbonLib 1.0 and later when running Mac OS 8.1 or later.
• Available in Mac OS X 10.0 and later.

Declared In

MacErrors.h

Data Types

OSErr

A numeric code used in Carbon to indicate the return status of a function.

typedef SInt16 OSErr;

Discussion

The system software sometimes uses error codes to inform an application that a requested service is not possible. Many functions return a result code of type OSErr that indicates whether the function completed successfully, and if not, what the reason for failure was.

Availability

• Available in Mac OS X v10.0 and later.

Declared In

IOMacOSTypes.h

OSStatus

A numeric code used in Carbon to indicate the return status of a function.

typedef SInt32 OSStatus;

Discussion

The system software sometimes uses error codes to inform an application that a requested service is not possible. Many functions return a result code of type OSStatus that indicates whether the function completed successfully, and if not, what the reason for failure was.

If you want to use OSStatus to define error codes for your application, Apple recommends that you use values in the range 1000 through 9999 inclusive. Values outside of this range are reserved by Apple for internal use.

Availability

• Available in Mac OS X v10.0 and later.

Declared In

OSTypes.h

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