error.c

让你了解Unix进程间的通信是如何实现的

#include	"unpipc.h"

#include	<stdarg.h>		/* ANSI C header file */
#include	<syslog.h>		/* for syslog() */

int		daemon_proc;		/* set nonzero by daemon_init() */

static void	err_doit(int, int, const char *, va_list);

/* Nonfatal error related to a system call.
 * Print a message and return. */

/* $$.ix [err_ret]~function,~source~code$$ */
void
err_ret(const char *fmt, ...)
{
	va_list		ap;

	va_start(ap, fmt);
	err_doit(1, LOG_INFO, fmt, ap);
	va_end(ap);
	return;
}

/* Fatal error related to a system call.
 * Print a message and terminate. */

/* $$.ix [err_sys]~function,~source~code$$ */
void
err_sys(const char *fmt, ...)
{
	va_list		ap;

	va_start(ap, fmt);
	err_doit(1, LOG_ERR, fmt, ap);
	va_end(ap);
	exit(1);
}

/* Fatal error related to a system call.
 * Print a message, dump core, and terminate. */

/* $$.ix [err_dump]~function,~source~code$$ */
void
err_dump(const char *fmt, ...)
{
	va_list		ap;

	va_start(ap, fmt);
	err_doit(1, LOG_ERR, fmt, ap);
	va_end(ap);
	abort();		/* dump core and terminate */
	exit(1);		/* shouldn't get here */
}

/* Nonfatal error unrelated to a system call.
 * Print a message and return. */

/* $$.ix [err_msg]~function,~source~code$$ */
void
err_msg(const char *fmt, ...)
{
	va_list		ap;

	va_start(ap, fmt);
	err_doit(0, LOG_INFO, fmt, ap);
	va_end(ap);
	return;
}

/* Fatal error unrelated to a system call.
 * Print a message and terminate. */

/* $$.ix [err_quit]~function,~source~code$$ */
void
err_quit(const char *fmt, ...)
{
	va_list		ap;

	va_start(ap, fmt);
	err_doit(0, LOG_ERR, fmt, ap);
	va_end(ap);
	exit(1);
}

/* Print a message and return to caller.
 * Caller specifies "errnoflag" and "level". */

/* $$.ix [err_doit]~function,~source~code$$ */
static void
err_doit(int errnoflag, int level, const char *fmt, va_list ap)
{
	int		errno_save, n;
	char	buf[MAXLINE];

	errno_save = errno;		/* value caller might want printed */
#ifdef	HAVE_VSNPRINTF
	vsnprintf(buf, sizeof(buf), fmt, ap);	/* this is safe */
#else
	vsprintf(buf, fmt, ap);					/* this is not safe */
#endif
	n = strlen(buf);
	if (errnoflag)
		snprintf(buf+n, sizeof(buf)-n, ": %s", strerror(errno_save));
	strcat(buf, "\n");

	if (daemon_proc) {
		syslog(level, buf);
	} else {
		fflush(stdout);		/* in case stdout and stderr are the same */
		fputs(buf, stderr);
		fflush(stderr);
	}
	return;
}