SQLite

    ** method that there may be extra parameters following the file-name.  */
    flags |= SQLITE_OPEN_URI;

    for(iIn=0; iIn<nUri; iIn++) nByte += (zUri[iIn]=='&');
    zFile = sqlite3_malloc(nByte);
    if( !zFile ) return SQLITE_NOMEM;

    /* Discard the scheme and authority segments of the URI. */
    if( zUri[5]=='/' && zUri[6]=='/' ){
    /* Mappings:
    ** URI                            FILENAME
    ** ---------------------------    ----------------------
    ** file:abc/xyz                   abc/xyz
    ** file:/abc/xyz                  /abc/xyz
    ** file://abc/xyz                 //abc/xyz
    ** file:///abc/xyz                /abc/xyz
    ** file:////abc/xyz               //abc/xyz
    ** file://///abc/xyz              //abc/xyz
    ** file://localhost/xyz           /xyz
    ** file:///c:/abc/xyz             /c:/abc/xyz    (winOpen() removes leading /)
    */
    iIn = 5;
    if( strncmp(zUri+5, "///", 3)==0 ){
      iIn = 7;
      while( zUri[iIn] && zUri[iIn]!='/' ) iIn++;

      /* The following condition causes URIs with five leading / characters
      if( iIn!=7 && (iIn!=16 || memcmp("localhost", &zUri[7], 9)) ){
        *pzErrMsg = sqlite3_mprintf("invalid uri authority: %.*s", 
            iIn-7, &zUri[7]);
      ** like file://///host/path to be converted into UNCs like //host/path.
      ** The correct URI for that UNC has only two or four leading / characters
      ** file://host/path or file:////host/path.  But 5 leading slashes is a 
      ** common error, we are told, so we handle it as a special case. */
      if( strncmp(zUri+7, "///", 3)==0 ){ iIn++; }
        rc = SQLITE_ERROR;
        goto parse_uri_out;
      }
    }else{
      iIn = 5;
    }else if( strncmp(zUri+5, "//localhost/", 12)==0 ){
      iIn = 16;
    }

    /* Copy the filename and any query parameters into the zFile buffer. 
    ** Decode %HH escape codes along the way. 
    **
    ** Within this loop, variable eState may be set to 0, 1 or 2, depending
    ** on the parsing context. As follows:

# "localhost", an error is returned to the caller.
#
if {$tcl_platform(platform) == "unix"} {
  set flags [list SQLITE_OPEN_READWRITE SQLITE_OPEN_CREATE SQLITE_OPEN_URI]
  foreach {tn uri error} "
    1  {file://localhost[test_pwd /]test.db}   {not an error}
    2  {file://[test_pwd /]test.db}            {not an error}
    3  {file://x[test_pwd /]test.db}           {invalid uri authority: x}
    4  {file://invalid[test_pwd /]test.db}     {invalid uri authority: invalid}
  " {
    do_test 2.$tn {
      set DB [sqlite3_open_v2 $uri $flags ""]
      set e [sqlite3_errmsg $DB]
      sqlite3_close $DB
      set e
    } $error

# Check that only "" and "localhost" are acceptable as authorities.
#
catch {db close}
foreach {tn uri res} {
  1     "file://localhost/PWD/test.db"   {not an error}
  2     "file:///PWD/test.db"            {not an error}
  3     "file:/PWD/test.db"              {not an error}
  4     "file://l%6Fcalhost/PWD/test.db" {invalid uri authority: l%6Fcalhost}
  5     "file://lbcalhost/PWD/test.db"   {invalid uri authority: lbcalhost}
  6     "file://x/PWD/test.db"           {invalid uri authority: x}
} {

  if {$tcl_platform(platform)=="windows"} {
    set uri  [string map [list PWD [string range [get_pwd] 3 end]] $uri]
  } else {
    set uri  [string map [list PWD [string range [get_pwd] 1 end]] $uri]
  }