source: trunk/minix/commands/cawf/getopt.c@ 12

/*
Newsgroups: mod.std.unix
Subject: public domain AT&T getopt source
Date: 3 Nov 85 19:34:15 GMT

Here's something you've all been waiting for:  the AT&T public domain
source for getopt(3).  It is the code which was given out at the 1985
UNIFORUM conference in Dallas.  I obtained it by electronic mail
directly from AT&T.  The people there assure me that it is indeed
in the public domain.
*/


/*LINTLIBRARY*/
#define NULL    0
#define EOF     (-1)
#define ERR(s, c)       if(opterr){\
        extern int strlen(), write();\
        char errbuf[2];\
        errbuf[0] = c; errbuf[1] = '\n';\
        (void) write(2, argv[0], (unsigned)strlen(argv[0]));\
        (void) write(2, s, (unsigned)strlen(s));\
        (void) write(2, errbuf, 2);}

extern int strcmp();
extern char *strchr();

int     opterr = 1;
int     optind = 1;
int     optopt;
char    *optarg;

int
getopt(argc, argv, opts)
int     argc;
char    **argv, *opts;
{
        static int sp = 1;
        register int c;
        register char *cp;

        if(sp == 1)
                if(optind >= argc ||
                   argv[optind][0] != '-' || argv[optind][1] == '\0')
                        return(EOF);
                else if(strcmp(argv[optind], "--") == NULL) {
                        optind++;
                        return(EOF);
                }
        optopt = c = argv[optind][sp];
        if(c == ':' || (cp=strchr(opts, c)) == NULL) {
                ERR(": illegal option -- ", c);
                if(argv[optind][++sp] == '\0') {
                        optind++;
                        sp = 1;
                }
                return('?');
        }
        if(*++cp == ':') {
                if(argv[optind][sp+1] != '\0')
                        optarg = &argv[optind++][sp+1];
                else if(++optind >= argc) {
                        ERR(": option requires an argument -- ", c);
                        sp = 1;
                        return('?');
                } else
                        optarg = argv[optind++];
                sp = 1;
        } else {
                if(argv[optind][++sp] == '\0') {
                        sp = 1;
                        optind++;
                }
                optarg = NULL;
        }
        return(c);
}