unix环境高级编程 err文件

#include "apue.h"
#include <errno.h>    /*for definition of errno*/
#include <stdarg.h>    /*ISO C varialbe aruments*/
static void err_doit(int,int,const char*,va_list);

/*
*Nonfatal error related to a system call.
*Print a message and return
*/
void
err_ret(const char *fmt, ...)
{
va_list ap;
va_start(ap,fmt);
err_doit(1,errno,fmt,ap);
va_end(ap);
}

/*
*Fatal error related to a system call
*Print a message and terminate.
*/
void
err_sys(const char *fmt, ...)
{
va_list ap;
err_doit(1,errno,fmt,ap);
va_end(ap);
exit(1);
}

/*
*Fatal error unrelated to a system call.
*Error code passed as explict parameter
*Print a message and terminate
*/
void err_exit(int error,const char *fmt, ...)
{
va_list ap;
va_start(ap,fmt);
err_doit(1,error,fmt,ap);
va_end(ap);
exit(1);
}

/*
*Fatal error related to a system call.
*Print a message,dump core,and terminate.
*/
void
err_dump(const char *fmt, ...)
{
va_list ap;
va_start(ap,fmt);
err_doit(1,errno,fmt,ap);
va_end(ap);
abort();    /*dump core and terminate*/
exit(1);    /*shouldn't get here*/
}

/*
*Nonfatal error unrelated to a system call.
*Pirnt a message and return
*/
void
err_msg(const char *fmt, ...)
{
va_list ap;
va_start(ap,fmt);
err_doit(0,0,fmt,ap);
va_end(ap);
}

/*
*Fatal error unrelated to a system call
*Print a message and terminate
*/
void
err_quit(const char *fmt, ...)
{
va_list ap;
va_start(ap,fmt);
err_doit(0,0,fmt,ap);
va_end(ap);
exit(1);
}

/*
*Print a message and return to caller
*Caller specifies "errnoflag"
*/
static void
err_doit(int errnoflag,int error,const char *fmt,va_list ap)
{
char buf[MAXLINE];
vsnprintf(buf,MAXLINE,fmt,ap);
if(errnoflag)
snprintf(buf+strlen(buf),MAXLINE-strlen(buf), ": %s",
strerror(error));
strcat(buf,"\n");
fflush(stdout);    /*in case stdout and stderr are the same*/
fputs(buf,stderr);
fflush(NULL);    /*flushes all stdio output streams*/
}