Fossil

  /* The design of the checkout database changed on 2019-01-19, adding the mhash
  ** column to vfile and vmerge and changing the UNIQUE index on vmerge into
  ** a PRIMARY KEY that includes the new mhash column.  However, we must have
  ** the repository database at hand in order to do the migration, so that
  ** step is deferred. */
  return 1;
}

/*
** Returns true if the given filename ends with any of fossil's
** checkout database filenames: _FOSSIL_ or .fslckout. Specifically,
** it returns 1 if it's an exact match and 2 if it's the tail match
** on a longer input.
**
** zFilename must, for efficiency's sake, be a
** canonicalized/normalized name, e.g. using only '/' as directory
** separators.
**
** nFilename must be the strlen of zFilename. If it is negative,
** strlen() is used to calculate it.
*/
int is_fossil_ckout_db_name(const char *zFilename, int nFilename){
  const char *zEnd;

  if(nFilename>=0 && nFilename<8/*strlen _FOSSIL_*/) return 0;
  else if(nFilename<0) nFilename = (int)strlen(zFilename);
  if(nFilename<8) return 0;
  zEnd = zFilename + nFilename;
  switch(zEnd[-1]){
    case '_':
      return fossil_strcmp("_FOSSIL_", &zEnd[-8])
        ? 0 : (8==nFilename ? 1 : ('/'==zEnd[-9] ? 2 : 0));
    case 't':
      return (nFilename<9
              || '.'!=zEnd[-9]
              || fossil_strcmp(".fslckout", &zEnd[-9]))
        ? 0 : (9==nFilename ? 1 : ('/'==zEnd[-10] ? 2 : 0));
    default:
      return 0;
  }
}

/*
** COMMAND: test-is-ckout-db
**
** Usage: %fossil test-is-ckout-db FILENAMES...
**
** Passes each given name to is_fossil_ckout_db_name() and outputs one
** line per file: the result value of that function followed by the
** name.
*/
void test_is_ckout_name_cmd(void){
  int i;

  if(g.argc<3){
    usage("FILENAME_1 [...FILENAME_N]");
  }
  for( i = 2; i < g.argc; ++i ){
    const int check = is_fossil_ckout_db_name(g.argv[i], -1);
    fossil_print("%d %s\n", check, g.argv[i]);
  }
}

/*
** Locate the root directory of the local repository tree.  The root
** directory is found by searching for a file named "_FOSSIL_" or ".fslckout"
** that contains a valid repository database.
**
** For legacy, also look for ".fos".  The use of ".fos" is deprecated