src/lib/url/url_parse_file.cc

// Copyright 2013 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include <lib/syslog/cpp/macros.h>

#include "src/lib/url/third_party/mozilla/url_parse.h"
#include "src/lib/url/url_file.h"
#include "src/lib/url/url_parse_internal.h"

// Interesting IE file:isms...
//
//  INPUT                      OUTPUT
//  =========================  ==============================
//  file:/foo/bar              file:///foo/bar
//      The result here seems totally invalid!?!? This isn't UNC.
//
//  file:/
//  file:// or any other number of slashes
//      IE6 doesn't do anything at all if you click on this link. No error:
//      nothing. IE6's history system seems to always color this link, so I'm
//      guessing that it maps internally to the empty URL.
//
//  C:\                        file:///C:/
//      When on a file: URL source page, this link will work. When over HTTP,
//      the file: URL will appear in the status bar but the link will not work
//      (security restriction for all file URLs).
//
//  file:foo/                  file:foo/     (invalid?!?!?)
//  file:/foo/                 file:///foo/  (invalid?!?!?)
//  file://foo/                file://foo/   (UNC to server "foo")
//  file:///foo/               file:///foo/  (invalid, seems to be a file)
//  file:////foo/              file://foo/   (UNC to server "foo")
//      Any more than four slashes is also treated as UNC.
//
//  file:C:/                   file://C:/
//  file:/C:/                  file://C:/
//      The number of slashes after "file:" don't matter if the thing following
//      it looks like an absolute drive path. Also, slashes and backslashes are
//      equally valid here.

namespace url {

namespace {

// A subcomponent of DoInitFileURL, the input of this function should be a UNC
// path name, with the index of the first character after the slashes following
// the scheme given in |after_slashes|. This will initialize the host, path,
// query, and ref, and leave the other output components untouched
// (DoInitFileURL handles these for us).
void DoParseUNC(const char* spec, size_t after_slashes, size_t spec_len, Parsed* parsed) {
  size_t next_slash = FindNextSlash(spec, after_slashes, spec_len);
  if (next_slash == spec_len) {
    // No additional slash found, as in "file://foo", treat the text as the
    // host with no path (this will end up being UNC to server "foo").
    size_t host_len = spec_len - after_slashes;
    if (host_len)
      parsed->host = Component(after_slashes, host_len);
    else
      parsed->host.reset();
    parsed->path.reset();
    return;
  }

  // Otherwise, everything up until that first slash we found is the host name,
  // which will end up being the UNC host. For example "file://foo/bar.txt"
  // will get a server name of "foo" and a path of "/bar". Later, on Windows,
  // this should be treated as the filename "\\foo\bar.txt" in proper UNC
  // notation.
  size_t host_len = next_slash - after_slashes;
  if (host_len)
    parsed->host = MakeRange(after_slashes, next_slash);
  else
    parsed->host.reset();
  if (next_slash < spec_len) {
    ParsePathInternal(spec, MakeRange(next_slash, spec_len), &parsed->path, &parsed->query,
                      &parsed->ref);
  } else {
    parsed->path.reset();
  }
}

// A subcomponent of DoParseFileURL, the input should be a local file, with the
// beginning of the path indicated by the index in |path_begin|. This will
// initialize the host, path, query, and ref, and leave the other output
// components untouched (DoInitFileURL handles these for us).
void DoParseLocalFile(const char* spec, size_t path_begin, size_t spec_len, Parsed* parsed) {
  parsed->host.reset();
  ParsePathInternal(spec, MakeRange(path_begin, spec_len), &parsed->path, &parsed->query,
                    &parsed->ref);
}

}  // namespace

// Backend for the external functions that operates on either char type.
// Handles cases where there is a scheme, but also when handed the first
// character following the "file:" at the beginning of the spec. If so,
// this is usually a slash, but needn't be; we allow paths like "file:c:\foo".
void ParseFileURL(const char* spec, size_t spec_len, Parsed* parsed) {
  FX_DCHECK(spec_len >= 0);

  // Get the parts we never use for file URLs out of the way.
  parsed->username.reset();
  parsed->password.reset();
  parsed->port.reset();

  // Many of the code paths don't set these, so it's convenient to just clear
  // them. We'll write them in those cases we need them.
  parsed->query.reset();
  parsed->ref.reset();

  // Strip leading & trailing spaces and control characters.
  size_t begin = 0;
  TrimURL(spec, &begin, &spec_len);

  // Find the scheme, if any.
  size_t num_slashes = CountConsecutiveSlashes(spec, begin, spec_len);
  size_t after_scheme;
  size_t after_slashes;
  {
    // ExtractScheme doesn't understand the possibility of filenames with
    // colons in them, in which case it returns the entire spec up to the
    // colon as the scheme. So handle /foo.c:5 as a file but foo.c:5 as
    // the foo.c: scheme.
    if (!num_slashes && ExtractScheme(&spec[begin], spec_len - begin, &parsed->scheme)) {
      // Offset the results since we gave ExtractScheme a substring.
      parsed->scheme.begin += begin;
      after_scheme = parsed->scheme.end() + 1;
    } else {
      // No scheme found, remember that.
      parsed->scheme.reset();
      after_scheme = begin;
    }
  }

  // Handle empty specs ones that contain only whitespace or control chars,
  // or that are just the scheme (for example "file:").
  if (after_scheme == spec_len) {
    parsed->host.reset();
    parsed->path.reset();
    return;
  }

  num_slashes = CountConsecutiveSlashes(spec, after_scheme, spec_len);
  after_slashes = after_scheme + num_slashes;
  // file: URL with exactly 2 slashes is considered to have a host component.
  if (num_slashes == 2) {
    DoParseUNC(spec, after_slashes, spec_len, parsed);
    return;
  }

  // Easy and common case, the full path immediately follows the scheme
  // (modulo slashes), as in "file://c:/foo". Just treat everything from
  // there to the end as the path. Empty hosts have 0 length instead of -1.
  // We include the last slash as part of the path if there is one.
  DoParseLocalFile(spec, num_slashes > 0 ? after_scheme + num_slashes - 1 : after_scheme, spec_len,
                   parsed);
}

}  // namespace url