The Linux Programming Interface

52 Chapter 3

Listing 3-2: Declarations for common error-handling functions

––––––––––––––––––––––––––––––––––––––––––––––––––––– lib/error_functions.h

#ifndef ERROR_FUNCTIONS_H

#define ERROR_FUNCTIONS_H

void errMsg(const char *format, ...);

#ifdef __GNUC__

/* This macro stops 'gcc -Wall' complaining that "control reaches

end of non-void function" if we use the following functions to

terminate main() or some other non-void function. */

#define NORETURN __attribute__ ((__noreturn__))

#else

#define NORETURN

#endif

void errExit(const char *format, ...) NORETURN ;

void err_exit(const char *format, ...) NORETURN ;

void errExitEN(int errnum, const char *format, ...) NORETURN ;

void fatal(const char *format, ...) NORETURN ;

void usageErr(const char *format, ...) NORETURN ;

void cmdLineErr(const char *format, ...) NORETURN ;

#endif

––––––––––––––––––––––––––––––––––––––––––––––––––––– lib/error_functions.h

To diagnose errors from system calls and library functions, we use errMsg(),

errExit(), err_exit(), and errExitEN().

The errMsg() function prints a message on standard error. Its argument list is the

same as for printf(), except that a terminating newline character is automatically

appended to the output string. The errMsg() function prints the error text corre-

sponding to the current value of errno—this consists of the error name, such as

EPERM, plus the error description as returned by strerror()—followed by the formatted

output specified in the argument list.

The errExit() function operates like errMsg(), but also terminates the program,

either by calling exit() or, if the environment variable EF_DUMPCORE is defined with a

#include "tlpi_hdr.h"

void errMsg(const char *format, ...);

void errExit(const char *format, ...);

void err_exit(const char *format, ...);

void errExitEN(int errnum, const char *format, ...);