[unix-history] / usr / src / usr.bin / dirname / dirname.c

/*-
* Copyright (c) 1991, 1993
*      The Regents of the University of California.  All rights reserved.
*
* %sccs.include.redist.c%
*/

#ifndef lint
static char copyright[] =
"@(#) Copyright (c) 1991, 1993\n\
       The Regents of the University of California.  All rights reserved.\n";
#endif /* not lint */

#ifndef lint
static char sccsid[] = "@(#)dirname.c   8.1 (Berkeley) %G%";
#endif /* not lint */

#include <stdio.h>
#include <stdlib.h>

main(argc, argv)
       int argc;
       char **argv;
{
       extern int optind;
       register char *p;
       int ch;

       while ((ch = getopt(argc, argv, "")) != EOF)
               switch(ch) {
               case '?':
               default:
                       usage();
               }
       argc -= optind;
       argv += optind;

       if (argc != 1)
               usage();

       /*
        * (1) If string is //, skip steps (2) through (5).
        * (2) If string consists entirely of slash characters, string
        *     shall be set to a single slash character.  In this case,
        *     skip steps (3) through (8).
        */
       for (p = *argv;; ++p) {
               if (!*p) {
                       if (p > *argv)
                               (void)printf("/\n");
                       else
                               (void)printf(".\n");
                       exit(0);
               }
               if (*p != '/')
                       break;
       }

       /*
        * (3) If there are any trailing slash characters in string, they
        *     shall be removed.
        */
       for (; *p; ++p);
       while (*--p == '/');
       *++p = '\0';

       /*
        * (4) If there are no slash characters remaining in string,
        *     string shall be set to a single period character.  In this
        *     case skip steps (5) through (8).
        *
        * (5) If there are any trailing nonslash characters in string,
        *     they shall be removed.
        */
       while (--p >= *argv)
               if (*p == '/')
                       break;
       ++p;
       if (p == *argv) {
               (void)printf(".\n");
               exit(0);
       }

       /*
        * (6) If the remaining string is //, it is implementation defined
        *     whether steps (7) and (8) are skipped or processed.
        *
        * This case has already been handled, as part of steps (1) and (2).
        */
       
       /*
        * (7) If there are any trailing slash characters in string, they
        *     shall be removed.
        */
       while (--p >= *argv)
               if (*p != '/')
                       break;
       ++p;

       /*
        * (8) If the remaining string is empty, string shall be set to
        *     a single slash character.
        */
       *p = '\0';
       (void)printf("%s\n", p == *argv ? "/" : *argv);
       exit(0);
}

usage()
{
       (void)fprintf(stderr, "usage: dirname path\n");
       exit(1);
}