*/
const char * file_extension(const char *zFileName){
  const char * zExt = zFileName ? strrchr(zFileName, '.') : 0;
  return zExt ? &zExt[1] : 0;
}

/*
** Returns non-zero if the specified file name ends with any reserved name,
** e.g.: _FOSSIL_ or .fslckout.  Specifically, it returns 1 for exact match

** or 2 for a tail match on a longer file name.
**
** For the sake of efficiency, zFilename must be a canonical name, e.g. an
** absolute path using only forward slash ('/') as a directory separator.

**
** nFilename must be the length of zFilename.  When negative, strlen() will
** be used to calculate it.
*/
int file_is_reserved_name(const char *zFilename, int nFilename){
  const char *zEnd;  /* one-after-the-end of zFilename */
  int gotSuffix = 0; /* length of suffix (-wal, -shm, -journal) */

  assert( zFilename && "API misuse" );
  if( nFilename<0 ) nFilename = (int)strlen(zFilename);
  if( nFilename<8 ) return 0; /* strlen("_FOSSIL_") */
  zEnd = zFilename + nFilename;
  if( nFilename>=12 ){ /* strlen("_FOSSIL_-(shm|wal)") */
    /* Check for (-wal, -shm, -journal) suffixes, with an eye towards
    ** runtime speed. */
    if( zEnd[-4]=='-' ){
      if( fossil_strnicmp("wal", &zEnd[-3], 3)
       && fossil_strnicmp("shm", &zEnd[-3], 3) ){
        return 0;
      }
      gotSuffix = 4;
    }else if( nFilename>=16 && zEnd[-8]=='-' ){ /*strlen(_FOSSIL_-journal) */
      if( fossil_strnicmp("journal", &zEnd[-7], 7) ) return 0;


      gotSuffix = 8;
    }
    if( gotSuffix ){
      assert( 4==gotSuffix || 8==gotSuffix );
      zEnd -= gotSuffix;
      nFilename -= gotSuffix;
      gotSuffix = 1;
    }
    assert( nFilename>=8 && "strlen(_FOSSIL_)" );
    assert( gotSuffix==0 || gotSuffix==1 );
  }
  switch( zEnd[-1] ){
    case '_':{
      if( fossil_strnicmp("_FOSSIL_", &zEnd[-8], 8) ) return 0;
      if( 8==nFilename ) return 1;

      return zEnd[-9]=='/' ? 2 : gotSuffix;
    }
    case 'T':
    case 't':{
      if( nFilename<9 || zEnd[-9]!='.'

       || fossil_strnicmp(".fslckout", &zEnd[-9], 9) ){
        return 0; 
      }
      if( 9==nFilename ) return 1;

      return zEnd[-10]=='/' ? 2 : gotSuffix;
    }
    default:{
      return 0;
    }
  }
}

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

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