struct passwd *getpwnam();

/*----------------------------------------------------------------------
       Expand the ~ in a file ala the csh (as home directory)

   Args: buf --  The filename to expand (nothing happens unless begins with ~)
         len --  The length of the buffer passed in (expansion is in place)

 Result: Expanded string is returned using same storage as passed in.
         If expansion fails, NULL is returned
 ----*/
char *
fnexpand(buf, len)
    char *buf;
    int len;
{
    struct passwd *pw;
    register char *x,*y;
    char name[20];
    
    if(*buf == '~') {
        for(x = buf+1, y = name; *x != '/' && *x != '\0'; *y++ = *x++);
        *y = '\0';
        if(x == buf + 1) 
          pw = getpwuid(getuid());
        else
          pw = getpwnam(name);
        if(pw == NULL)
          return((char *)NULL);
        if(strlen(pw->pw_dir) + strlen(buf) > len) {
          return((char *)NULL);
        }
        rplstr(buf, x - buf, pw->pw_dir);
    }
    return(len ? buf : (char *)NULL);
}


