errorlog.c

unix环境高级编程的源代码

/* Error routines for programs that can run as a daemon. */

#include    <errno.h>        /* for definition of errno */
#include    <stdarg.h>        /* ANSI C header file */
#include    <syslog.h>
#include    "ourhdr.h"

static void    log_doit(int, int, const char *, va_list ap);

extern int    debug;        /* caller must define and set this:
                           nonzero if interactive, zero if daemon */

/* Initialize syslog(), if running as daemon. */

void
log_open(const char *ident, int option, int facility)
{
    if (debug == 0)
        openlog(ident, option, facility);
}

/* Nonfatal error related to a system call.
 * Print a message with the system's errno value and return. */

void
log_ret(const char *fmt, ...)
{
    va_list        ap;

    va_start(ap, fmt);
    log_doit(1, LOG_ERR, fmt, ap);
    va_end(ap);
    return;
}

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

void
log_sys(const char *fmt, ...)
{
    va_list        ap;

    va_start(ap, fmt);
    log_doit(1, LOG_ERR, fmt, ap);
    va_end(ap);
    exit(2);
}

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

void
log_msg(const char *fmt, ...)
{
    va_list        ap;

    va_start(ap, fmt);
    log_doit(0, LOG_ERR, fmt, ap);
    va_end(ap);
    return;
}

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

void
log_quit(const char *fmt, ...)
{
    va_list        ap;

    va_start(ap, fmt);
    log_doit(0, LOG_ERR, fmt, ap);
    va_end(ap);
    exit(2);
}

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

static void
log_doit(int errnoflag, int priority, const char *fmt, va_list ap)
{
    int        errno_save;
    char    buf[MAXLINE];

    errno_save = errno;        /* value caller might want printed */
    vsprintf(buf, fmt, ap);
    if (errnoflag)
        sprintf(buf+strlen(buf), ": %s", strerror(errno_save));
    strcat(buf, "\n");
    if (debug) {
        fflush(stdout);
        fputs(buf, stderr);
        fflush(stderr);
    } else
        syslog(priority, buf);
    return;
}