csope/src/compath.c

/*===========================================================================
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 IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
 THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
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/*
 *    compath(pathname)
 *
 *    This compresses pathnames.  All strings of multiple slashes are
 *    changed to a single slash.  All occurrences of "./" are removed.
 *    Whenever possible, strings of "/.." are removed together with
 *    the directory names that they follow.
 *
 *    WARNING: since pathname is altered by this function, it should
 *         be located in a temporary buffer. This avoids the problem
 *         of accidently changing strings obtained from makefiles
 *         and stored in global structures.
 */

#include "global.h"

#ifndef NULL
#define    NULL    0
#endif

char *
compath(char *pathname)        	/*FDEF*/
{
    char    *nextchar;
    char    *lastchar;
    char    *sofar;
    char    *pnend;

    int    pnlen;

        /*
         *	do not change the path if it has no "/"
         */

    if (strchr(pathname, '/') == NULL)
        return(pathname);

        /*
         *	find all strings consisting of more than one '/'
         */

    for (lastchar = pathname + 1; *lastchar != '\0'; lastchar++)
        if ((*lastchar == '/') && (*(lastchar - 1) == '/'))
        {

        	/*
        	 *	find the character after the last slash
        	 */

        	nextchar = lastchar;
        	while (*++lastchar == '/')
        	{
        	}

        	/*
        	 *	eliminate the extra slashes by copying
        	 *	everything after the slashes over the slashes
        	 */

        	sofar = nextchar;
        	while ((*nextchar++ = *lastchar++) != '\0')
        		;
        	lastchar = sofar;
        }

        /*
         *	find all strings of "./"
         */

    for (lastchar = pathname + 1; *lastchar != '\0'; lastchar++)
        if ((*lastchar == '/') && (*(lastchar - 1) == '.') &&
            ((lastchar - 1 == pathname) || (*(lastchar - 2) == '/')))
        {

        	/*
        	 *	copy everything after the "./" over the "./"
        	 */

        	nextchar = lastchar - 1;
        	sofar = nextchar;
        	while ((*nextchar++ = *++lastchar) != '\0')
        		;
        	lastchar = sofar;
        }

        /*
         *	find each occurrence of "/.."
         */

    for (lastchar = pathname + 1; *lastchar != '\0'; lastchar++)
        if ((lastchar != pathname) && (*lastchar == '/') &&
            (*(lastchar + 1) == '.') && (*(lastchar + 2) == '.') &&
            ((*(lastchar + 3) == '/') || (*(lastchar + 3) == '\0')))
        {

        	/*
        	 *	find the directory name preceding the "/.."
        	 */

        	nextchar = lastchar - 1;
        	while ((nextchar != pathname) &&
        	    (*(nextchar - 1) != '/'))
        		--nextchar;

        	/*
        	 *	make sure the preceding directory's name
        	 *	is not "." or ".."
        	 */

        	if ((*nextchar == '.') &&
        	    ((*(nextchar + 1) == '/') ||
        	     ((*(nextchar + 1) == '.') && (*(nextchar + 2) == '/'))))
        		/* EMPTY */;
        	else
        	{

        		/*
        		 * 	prepare to eliminate either
        		 *	"dir_name/../" or "dir_name/.."
        		 */

        		if (*(lastchar + 3) == '/')
        			lastchar += 4;
        		else
        			lastchar += 3;

        		/*
        		 *	copy everything after the "/.." to
        		 *	before the preceding directory name
        		 */

        		sofar = nextchar - 1;
        		while ((*nextchar++ = *lastchar++) != '\0');
        			
        		lastchar = sofar;

        		/*
        		 *	if the character before what was taken
        		 *	out is '/', set up to check if the
        		 *	slash is part of "/.."
        		 */

        		if ((sofar + 1 != pathname) && (*sofar == '/'))
        			--lastchar;
        	}
        }

    /*
      *    if the string is more than a character long and ends
     *    in '/', eliminate the '/'.
     */

    pnlen = strlen(pathname);
    pnend = strchr(pathname, '\0') - 1;

    if ((pnlen > 1) && (*pnend == '/'))
    {
        *pnend-- = '\0';
        pnlen--;
    }

    /*
     *    if the string has more than two characters and ends in
     *    "/.", remove the "/.".
     */

    if ((pnlen > 2) && (*(pnend - 1) == '/') && (*pnend == '.'))
        *--pnend = '\0';

    /*
     *    if all characters were deleted, return ".";
     *    otherwise return pathname
     */

    if (*pathname == '\0')
        (void) strcpy(pathname, ".");

    return(pathname);
}