Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!csd4.milw.wisc.edu!leah!rpi!sun.soe.clarkson.edu!nelson
From: nelson@sun.soe.clarkson.edu (Russ Nelson)
Newsgroups: comp.sys.ibm.pc
Subject: Re: Full pathname of file wanted
Message-ID: <NELSON.89Apr12165025@sun.soe.clarkson.edu>
Date: 12 Apr 89 20:50:26 GMT
References: <883@syma.sussex.ac.uk>
Sender: news@sun.soe.clarkson.edu
Reply-To: nelson@clutx.clarkson.edu
Organization: Clarkson University, Postdam NY
Lines: 130
In-reply-to: leilabd@syma.sussex.ac.uk's message of 11 Apr 89 11:55:20 GMT

Written for Turbo C.  I can't remember if I wrote this or if it's based
on some anonymous code from the IBMPC-Digest.
-russ



#include <string.h>
#include <ctype.h>
#include <dos.h>
#include <dir.h>

/*** rootpath  --  convert a pathname argument to root based cannonical form
 *
 * rootpath determines the current directory, appends the path argument (which
 * may affect which disk the current directory is relative to), and qualifies
 * "." and ".." references.  The result is a complete, simple, path name with
 * drive specifier.
 *
 * If the relative path the user specifies does not include a drive spec., the
 * default drive will be used as the base.  (The default drive will never be
 * changed.)
 *
 *  entry: relpath  -- pointer to the pathname to be expanded
 *         fullpath -- must point to a working buffer, see warning
 *   exit: fullpath -- the full path which results
 * return: true if an error occurs, false otherwise
 *
 * calls: getcurdir getdisk
 *
 * warning: fullpath must point to a working buffer large enough to hold the
 *          longest possible relative path argument plus the longest possible
 *          current directory path.
 *
 */
int rootpath(char *relpath, char *fullpath)
{
	int drivenum ;
	char tempchar;
	register char *lead, *follow ;


	/* extract drive spec */
	if ((*relpath != '\0') && (relpath[1] == ':')) {
		drivenum = toupper(*relpath) - 'A' ;
		relpath += 2 ;
	} else drivenum = getdisk() ;
	fullpath[0] = (char) ('A' + drivenum) ;
	fullpath[1] = ':' ;

	/* append relpath to fullpath/base */
	if (*relpath == '\\' || *relpath == '/') {
		/* relpath starts at base */
		strcpy(fullpath+2, relpath) ;
	} else {
		/* must get base path first */
		fullpath[2] = '\\';
		if (getcurdir(drivenum+1, fullpath+3))
			return 1;			/* terrible error */
		if ((*relpath != '\0') && (strlen(fullpath) > 3))
			strcat(fullpath, "\\") ;
		strcat(fullpath, relpath) ;
	}


	/* convert path to cannonical form */
	lead = fullpath ;
	while(*lead != '\0') {
		/* mark next path segment */
		follow = lead ;
		if ((lead = strchr(follow+1, '\\')) != '\0') {
		  char *fslash;

		  tempchar = '\\';
		  if ((fslash = strchr(follow+1, '/')) != '\0') {
		    if (fslash < lead) lead = fslash;
		  }
		}
		else if ((lead = strchr(follow+1, '/')) != '\0') tempchar = '\\';
		else {
			lead = fullpath + strlen(fullpath) ;
			tempchar = '\0';
		}
		*lead = '\0';

		/* "." segment? */
		if (strcmp(follow+1, ".") == 0) {
			*lead = tempchar ;
			strcpy(follow, lead);	/* remove "." segment */
			lead = follow ;
		}

		/* ".." segment? */
		else if (strcmp(follow+1, "..") == 0) {
			*lead = tempchar ;
			do {
				if (--follow < fullpath)
					return 1;
			} while (*follow != '\\') ;
			strcpy(follow, lead);		/* remove ".." segment */
			lead = follow ;
		}

		/* normal segment */
		else
			*lead = tempchar ;
	}
	if (strlen(fullpath) == 2)	/* 'D:' or some such */
		strcat(fullpath, "\\") ;

	/* shift to upper case */
	strupr(fullpath) ;

	return 0;
}

#ifdef DEBUG
void main(int argc, char *argv[])
{
	char fullpath[64];
	if (argc != 2) cputs("usage: rootpath pathname");
	else {
		rootpath(argv[1], fullpath);
		cputs(fullpath);
	}
}
#endif
--
--russ (nelson@clutx [.bitnet | .clarkson.edu])
America -- Socialism for the rich people, Capitalism for the rest of us.
	- Michael Harrington, Co-Chair, Democratic Socialists of America