**  * removing /A/../
**
** Changes are made in-place.  Return the new name length.
** If the slash parameter is non-zero, the trailing slash, if any,
** is retained.
*/
int file_simplify_name(char *z, int n, int slash){
  int i = 1, j;
  if( n<0 ) n = strlen(z);

  /* On windows and cygwin convert all \ characters to /
   * and remove extended path prefix if present */
#if defined(_WIN32) || defined(__CYGWIN__)
  for(j=0; j<n; j++){
    if( z[j]=='\\' ) z[j] = '/';
  }
  if( n>3 && !memcmp(z, "//?/", 4) ){
    i += 4;
    z[0] = z[4];
  }
#endif

  /* Removing trailing "/" characters */
  if( !slash ){
    while( n>1 && z[n-1]=='/' ){ n--; }
  }

  /* Remove duplicate '/' characters.  Except, two // at the beginning
  ** of a pathname is allowed since this is important on windows. */
  for(j=1; i<n; i++){
    z[j++] = z[i];
    while( z[i]=='/' && i<n-1 && z[i+1]=='/' ) i++;
  }
  n = j;

  /* Skip over zero or more initial "./" sequences */
  for(i=0; i<n-1 && z[i]=='.' && z[i+1]=='/'; i+=2){}