errors.h

#ifndef __errors_h
#define __errors_h

#include <unistd.h>
#include <errno.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

/*
 * Define a macro that can be used for diagnostic output from
 * examples. When compiled -DDEBUG, it results in calling printf
 * with the specified argument list. When DEBUG is not defined, it
 * expands to nothing.
 */
#ifdef DEBUG
# define DPRINTF(arg) printf arg
#else
# define DPRINTF(arg)
#endif

/*
 * NOTE: the "do {" ... "} while (0);" bracketing around the macros
 * allows the err_abort and errno_abort macros to be used as if they
 * were function calls, even in contexts where a trailing ";" would
 * generate a null statement. For example,
 *
 *      if (status != 0)
 *          err_abort (status, "message");
 *      else
 *          return status;
 *
 * will not compile if err_abort is a macro ending with "}", because
 * C does not expect a ";" to follow the "}". Because C does expect
 * a ";" following the ")" in the do...while construct, err_abort and
 * errno_abort can be used as if they were function calls.
 */
#define err_abort(code,text) do { \
    fprintf (stderr, "%s at \"%s\":%d: %s\n", \
        text, __FILE__, __LINE__, strerror (code)); \
    abort (); \
    } while (0)
#define errno_abort(text) do { \
    fprintf (stderr, "%s at \"%s\":%d: %s\n", \
        text, __FILE__, __LINE__, strerror (errno)); \
    abort (); \
    } while (0)

#endif