getopt.c

ReactOS是一些高手根据Windows XP的内核编写出的类XP。内核实现机理和API函数调用几乎相同。甚至可以兼容XP的程序。喜欢研究系统内核的人可以看一看。

/* getopt.c
 *
 * Copyright (c) 1992-2001 by Mike Gleason.
 * All rights reserved.
 *
 */

#include <stdio.h>
#include <string.h>

#include "getopt.h"

int gOptErr = 1;					/* if error message should be printed */
int gOptInd = 1;					/* index into parent argv vector */
int gOptOpt;						/* character checked for validity */
const char *gOptArg;						/* argument associated with option */
const char *gOptPlace = kGetoptErrMsg;	/* saved position in an arg */

/* This must be called before each Getopt. */
void
GetoptReset(void)
{
	gOptInd = 1;
	gOptPlace = kGetoptErrMsg;
}	/* GetoptReset */




static char *
NextOption(const char *const ostr)
{
	if ((gOptOpt = (int) *gOptPlace++) == (int) ':')
		return 0;
	return strchr(ostr, gOptOpt);
}	/* NextOption */




int
Getopt(int nargc, const char **const nargv, const char *const ostr)
{
	const char *oli;				   /* Option letter list index */

	if (!*gOptPlace) {					   /* update scanning pointer */
		if (gOptInd >= nargc || *(gOptPlace = nargv[gOptInd]) != '-')
			return (EOF);
		if (gOptPlace[1] && *++gOptPlace == '-') {	/* found "--" */
			++gOptInd;
			return (EOF);
		}
	}								   /* Option letter okay? */
	oli = NextOption(ostr);
	if (oli == NULL) {
		if (!*gOptPlace)
			++gOptInd;
		if (gOptErr)
			(void) fprintf(stderr, "%s%s%c\n", *nargv, ": illegal option -- ", gOptOpt);
		return(kGetoptBadChar);
	}
	if (*++oli != ':') {			   /* don't need argument */
		gOptArg = NULL;
		if (!*gOptPlace)
			++gOptInd;
	} else {						   /* need an argument */
		if (*gOptPlace)					   /* no white space */
			gOptArg = gOptPlace;
		else if (nargc <= ++gOptInd) {  /* no arg */
			gOptPlace = kGetoptErrMsg;
			if (gOptErr)
				(void) fprintf(stderr, "%s%s%c\n", *nargv, ": option requires an argument -- ", gOptOpt);
			return(kGetoptBadChar);
		} else						   /* white space */
			gOptArg = nargv[gOptInd];
		gOptPlace = kGetoptErrMsg;
		++gOptInd;
	}
	return (gOptOpt);				   /* dump back Option letter */
}									   /* Getopt */

/* eof */