From: "Tom Demmer" <DEMMER AT brain1 DOT lstm DOT ruhr-uni-bochum DOT de>
Organization:  Lehrstuhl Stroemungsmechanik, RUB
To: djgpp-workers AT delorie DOT com
Date:          Fri, 16 Aug 1996 17:31:09 GMT-1
MIME-Version:  1.0
Content-type: text/plain; charset=US-ASCII
Content-transfer-encoding: 7BIT
Subject:       UNC to drv:/path
Reply-to: Demmer AT LStM DOT Ruhr-Uni-Bochum DOT De
Message-ID: <7F7F143BAE@brain1.lstm.ruhr-uni-bochum.de>

Eli asked me a while ago for a function that
converts UNC to a drv:/path representation.

For what it's worth, here is one. It requires ioctl.c to 
check if a device is remote or not. The strategy is to 
check all possible drive values if they point to a remote drive, then 
do a _truename on the root of that drive and see if it matches to the 
given UNC. The longest match is taken as the result.

I have tested it under NW3.11 with VLM. Maybe someone here has 
another network redirector to check if it works there. XFS drives do 
not use UNCs.
Have a nice weekend.

>----------------------------------------------------------------
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <sys/stat.h>
#include <string.h>
#include <sys/ioctl.h>

#define DEBUG

/*
** tn2dr: Try to convert a UNC to drv:/path
** INPUT:
**   truename : The UNC
** OUTPUT:
**   drv_path : well, drive:/path/to/it
** RETURNS
**    0       : Success
**    -1      : Could not map
**    -2      : _truename failed.
**    -3      : Not called with a UNC specifier.
** errno remains untouched.
**
*/
int tn2dr(const char *truename,char *drv_path)
{   char drv;
    char template[16];
    char realname[256];
    char canon_path[128];
    char found = 0;
    int longest_match = -1;

    if(!(*truename =='\\' && truename[1]=='\\'))
      return -3;
    if(!_truename(truename,realname))
       return -2;
#ifdef DEBUG
    printf("Got <%s>, will check <%s>\n",truename, realname);
#endif
    strcpy(template,"x:\\");

    for(drv='A'; drv <='Z'; drv++){
        /* UNCs can only happen on remote drives? */
        /* I doubt it.                            */
        int t = ioctl(drv-'A'+1, _DOS_ISREDIRBLK);
        template[0]=drv;

        if(( t != -1) && (t & 0x1000 ) &&  
_truename(template,canon_path)){
#ifdef DEBUG
            printf("Truename<%s> == canonpath<%s>\n", 
template,canon_path);
#endif
            if(strstr(realname,canon_path)){
                char *c= realname;
                char *d= canon_path;
                int i=0;
                while(*c && *c++ == *d++) ++i;
                if(i>longest_match){
                    longest_match = i;
                    found         = drv;
                }
#ifdef DEBUG
                printf("Maybe it is %c, matches %d chars\n",drv,i);
#endif
            }
        }
    }
#ifdef DEBUG
    if(found)
      printf("Best match is drive %c:, %d 
chars\n",found,longest_match);
#endif
    if(found){
        printf("Realname = <%s>\nLongest 
Match:%d\n",realname,longest_match);
        sprintf(drv_path,"%c:%s",found,
                  longest_match< strlen(realname) ?
                  realname+longest_match : "/");
#ifdef DEBUG
        printf("%s\n",drv_path);
       getch();
#endif
        return 0;
    }
    return -1;
}
int main(int argc, char **argv){
    char drv_path[256];
    int i;
    for(; *argv; argv++){
        if(!tn2dr(*argv,drv_path))
          printf("%s really is %s\n",*argv,drv_path);
    }
    return 0;
}
<---------------------------------------------------------------------

Ciao
Tom

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