usr.sbin/sup/source/path.c

   1 /*      $NetBSD: path.c,v 1.3 1997/06/17 18:56:27 christos Exp $        */
   2
   3 /*
   4  * Copyright (c) 1991 Carnegie Mellon University
   5  * All Rights Reserved.
   6  *
   7  * Permission to use, copy, modify and distribute this software and its
   8  * documentation is hereby granted, provided that both the copyright
   9  * notice and this permission notice appear in all copies of the
  10  * software, derivative works or modified versions, and any portions
  11  * thereof, and that both notices appear in supporting documentation.
  12  *
  13  * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS"
  14  * CONDITION.  CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND FOR
  15  * ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
  16  *
  17  * Carnegie Mellon requests users of this software to return to
  18  *
  19  *  Software Distribution Coordinator   or   Software.Distribution@CS.CMU.EDU
  20  *  School of Computer Science
  21  *  Carnegie Mellon University
  22  *  Pittsburgh PA 15213-3890
  23  *
  24  * any improvements or extensions that they make and grant Carnegie the rights
  25  * to redistribute these changes.
  26  */
  27 /*  path  --  break filename into directory and file
  28  *
  29  *  path (filename,direc,file);
  30  *  char *filename,*direc,*file;
  31  *  filename is input; direc and file are output (user-supplied).
  32  *  file will not have any trailing /; direc might.
  33  *
  34  *  Note these rules:
  35  *  1.  trailing / are ignored (except as first character)
  36  *  2.  x/y is x;y where y contains no / (x may contain /)
  37  *  3.  /y  is /;y where y contains no /
  38  *  4.  y   is .;y where y contains no /
  39  *  5.      is .;. (null filename)
  40  *  6.  /   is /;. (the root directory)
  41  *
  42  * Algorithm is this:
  43  *  1.  delete trailing / except in first position
  44  *  2.  if any /, find last one; change to null; y++
  45  *      else y = x;             (x is direc; y is file)
  46  *  3.  if y is null, y = .
  47  *  4.  if x equals y, x = .
  48  *      else if x is null, x = /
  49  *
  50  *  HISTORY
  51  * 20-Nov-79  Steven Shafer (sas) at Carnegie-Mellon University
  52  *      Copied verbatim from PDP-11.  Still as messy as ever.
  53  *      Some people have asked for a modification (I think that's a better
  54  *      idea than a new routine) which will change the directory name
  55  *      into an absolute pathname if it isn't one already.  The change
  56  *      involves doing a getwd() and prepending that if appropriate, with
  57  *      a "/" in between that and the directory part of the path.
  58  *      If you want to be cute, you can also resolve ".."s at that time.
  59  *
  60  */
  61 #include "supcdefs.h"
  62 #include "supextern.h"
  63
  64 void
  65 path(char *original, char *direc, char *file)
  66 {
  67         char *y;
  68         /* x is direc */
  69         char *p;
  70
  71         /* copy and note the end */
  72         p = original;
  73         y = direc;
  74         while ((*y++ = *p++) != '\0');  /* copy string */
  75         /* y now points to first char after null */
  76         --y;                    /* y now points to null */
  77         --y;                    /* y now points to last char of string before
  78                                  * null */
  79
  80         /* chop off trailing / except as first character */
  81         while (y > direc && *y == '/')
  82                 --y;            /* backpedal past / */
  83         /* y now points to char before first trailing / or null */
  84         *(++y) = 0;             /* chop off end of string */
  85         /* y now points to null */
  86
  87         /* find last /, if any.  If found, change to null and bump y */
  88         while (y > direc && *y != '/')
  89                 --y;
  90         /* y now points to / or direc.  Note *direc may be / */
  91         if (*y == '/') {
  92                 *y++ = 0;
  93         }
  94         /* find file name part */
  95         if (*y)
  96                 strcpy(file, y);
  97         else
  98                 strcpy(file, ".");
  99
 100         /* find directory part */
 101         if (direc == y)
 102                 strcpy(direc, ".");
 103         else if (*direc == 0)
 104                 strcpy(direc, "/");
 105         /* else direc already has proper value */
 106 }