NetBSD/usr.sbin/sup/source/path.c

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1993-05-21 18:52:16 +04:00
/*
* Copyright (c) 1991 Carnegie Mellon University
* All Rights Reserved.
*
* Permission to use, copy, modify and distribute this software and its
* documentation is hereby granted, provided that both the copyright
* notice and this permission notice appear in all copies of the
* software, derivative works or modified versions, and any portions
* thereof, and that both notices appear in supporting documentation.
*
* CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS"
* CONDITION. CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND FOR
* ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
*
* Carnegie Mellon requests users of this software to return to
*
* Software Distribution Coordinator or Software.Distribution@CS.CMU.EDU
* School of Computer Science
* Carnegie Mellon University
* Pittsburgh PA 15213-3890
*
* any improvements or extensions that they make and grant Carnegie the rights
* to redistribute these changes.
*/
/* path -- break filename into directory and file
*
* path (filename,direc,file);
* char *filename,*direc,*file;
* filename is input; direc and file are output (user-supplied).
* file will not have any trailing /; direc might.
*
* Note these rules:
* 1. trailing / are ignored (except as first character)
* 2. x/y is x;y where y contains no / (x may contain /)
* 3. /y is /;y where y contains no /
* 4. y is .;y where y contains no /
* 5. is .;. (null filename)
* 6. / is /;. (the root directory)
*
* Algorithm is this:
* 1. delete trailing / except in first position
* 2. if any /, find last one; change to null; y++
* else y = x; (x is direc; y is file)
* 3. if y is null, y = .
* 4. if x equals y, x = .
* else if x is null, x = /
*
* HISTORY
* 20-Nov-79 Steven Shafer (sas) at Carnegie-Mellon University
* Copied verbatim from PDP-11. Still as messy as ever.
* Some people have asked for a modification (I think that's a better
* idea than a new routine) which will change the directory name
* into an absolute pathname if it isn't one already. The change
* involves doing a getwd() and prepending that if appropriate, with
* a "/" in between that and the directory part of the path.
* If you want to be cute, you can also resolve ".."s at that time.
*
*/
path (original,direc,file)
char *original,*direc,*file;
{
register char *y;
/* x is direc */
register char *p;
/* copy and note the end */
p = original;
y = direc;
while (*y++ = *p++) ; /* copy string */
/* y now points to first char after null */
--y; /* y now points to null */
--y; /* y now points to last char of string before null */
/* chop off trailing / except as first character */
while (y>direc && *y == '/') --y; /* backpedal past / */
/* y now points to char before first trailing / or null */
*(++y) = 0; /* chop off end of string */
/* y now points to null */
/* find last /, if any. If found, change to null and bump y */
while (y>direc && *y != '/') --y;
/* y now points to / or direc. Note *direc may be / */
if (*y == '/') {
*y++ = 0;
}
/* find file name part */
if (*y) strcpy (file,y);
else strcpy (file,".");
/* find directory part */
if (direc == y) strcpy (direc,".");
else if (*direc == 0) strcpy (direc,"/");
/* else direc already has proper value */
}