Add wrappers around boost::filesystem methods that handle the

required mangling of long filenames on Windows.

Also wrap lots of missing places (e.g. calls to asdcplib, libxml++,
libcxml etc.) in dcp::filesystem::fix_long_path().

The idea is to keep paths un-mangled until they we call some
filesystem-related API and mangle them at that point.  Otherwise
we end up serialising mangled names, which seems like it will
not end well.

Should fix DoM #2623.

1 files changed, 329 insertions, 0 deletions

diff --git a/src/filesystem.cc b/src/filesystem.cc
new file mode 100644
index 00000000..0dd89228
--- /dev/null
+++ b/src/filesystem.cc
@@ -0,0 +1,329 @@
+/*
+    Copyright (C) 2012-2021 Carl Hetherington <cth@carlh.net>
+
+    This file is part of libdcp.
+
+    libdcp is free software; you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation; either version 2 of the License, or
+    (at your option) any later version.
+
+    libdcp is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with libdcp.  If not, see <http://www.gnu.org/licenses/>.
+
+    In addition, as a special exception, the copyright holders give
+    permission to link the code of portions of this program with the
+    OpenSSL library under certain conditions as described in each
+    individual source file, and distribute linked combinations
+    including the two.
+
+    You must obey the GNU General Public License in all respects
+    for all of the code used other than OpenSSL.  If you modify
+    file(s) with this exception, you may extend this exception to your
+    version of the file(s), but you are not obligated to do so.  If you
+    do not wish to do so, delete this exception statement from your
+    version.  If you delete this exception statement from all source
+    files in the program, then also delete it here.
+*/
+
+
+#include "filesystem.h"
+#include <boost/algorithm/string.hpp>
+
+
+bool
+dcp::filesystem::exists(boost::filesystem::path const& path)
+{
+	return boost::filesystem::exists(dcp::filesystem::fix_long_path(path));
+}
+
+
+bool
+dcp::filesystem::is_regular_file(boost::filesystem::path const& path)
+{
+	return boost::filesystem::is_regular_file(dcp::filesystem::fix_long_path(path));
+}
+
+
+bool
+dcp::filesystem::create_directory(boost::filesystem::path const& path)
+{
+	return boost::filesystem::create_directory(dcp::filesystem::fix_long_path(path));
+}
+
+
+void
+dcp::filesystem::copy(boost::filesystem::path const& from, boost::filesystem::path const& to)
+{
+	boost::filesystem::copy(dcp::filesystem::fix_long_path(from), dcp::filesystem::fix_long_path(to));
+}
+
+
+void
+dcp::filesystem::copy_file(boost::filesystem::path const& from, boost::filesystem::path const& to)
+{
+	boost::filesystem::copy_file(dcp::filesystem::fix_long_path(from), dcp::filesystem::fix_long_path(to));
+}
+
+
+bool
+dcp::filesystem::create_directories(boost::filesystem::path const& path)
+{
+	return boost::filesystem::create_directories(dcp::filesystem::fix_long_path(path));
+}
+
+
+boost::filesystem::path
+dcp::filesystem::absolute(boost::filesystem::path const& path)
+{
+	return dcp::filesystem::unfix_long_path(boost::filesystem::absolute(dcp::filesystem::fix_long_path(path)));
+}
+
+
+boost::filesystem::path
+dcp::filesystem::canonical(boost::filesystem::path const& path)
+{
+	return dcp::filesystem::unfix_long_path(boost::filesystem::canonical(dcp::filesystem::fix_long_path(path)));
+}
+
+
+uintmax_t
+dcp::filesystem::remove_all(boost::filesystem::path const& path)
+{
+	return boost::filesystem::remove_all(dcp::filesystem::fix_long_path(path));
+}
+
+
+uintmax_t
+dcp::filesystem::file_size(boost::filesystem::path const& path)
+{
+	return boost::filesystem::file_size(dcp::filesystem::fix_long_path(path));
+}
+
+
+boost::filesystem::path
+dcp::filesystem::current_path()
+{
+	return dcp::filesystem::unfix_long_path(boost::filesystem::current_path());
+}
+
+
+void
+dcp::filesystem::current_path(boost::filesystem::path const& path)
+{
+	boost::filesystem::current_path(dcp::filesystem::fix_long_path(path));
+}
+
+
+void
+dcp::filesystem::create_hard_link(boost::filesystem::path const& from, boost::filesystem::path const& to)
+{
+	boost::filesystem::create_hard_link(dcp::filesystem::fix_long_path(from), dcp::filesystem::fix_long_path(to));
+}
+
+
+#ifdef DCPOMATIC_WINDOWS
+
+dcp::filesystem::directory_iterator::directory_iterator(boost::filesystem::path const& path)
+	: _wrapped(dcp::filesystem::fix_long_path(path))
+{
+
+}
+
+
+boost::filesystem::path
+dcp::filesystem::directory_entry::path() const
+{
+	return dcp::filesystem::unfix_long_path(_path);
+}
+
+
+dcp::filesystem::directory_entry::operator boost::filesystem::path const &() const
+{
+	return dcp::filesystem::unfix_long_path(_path);
+}
+
+
+dcp::filesystem::recursive_directory_iterator::recursive_directory_iterator(boost::filesystem::path const& path)
+	: _wrapped(dcp::filesystem::fix_long_path(path))
+{
+
+}
+
+#else
+
+dcp::filesystem::directory_iterator::directory_iterator(boost::filesystem::path const& path)
+	: _wrapped(path)
+{
+
+}
+
+
+boost::filesystem::path
+dcp::filesystem::directory_entry::path() const
+{
+	return _path;
+}
+
+
+dcp::filesystem::directory_entry::operator boost::filesystem::path const &() const
+{
+	return _path;
+}
+
+
+dcp::filesystem::recursive_directory_iterator::recursive_directory_iterator(boost::filesystem::path const& path)
+	: _wrapped(path)
+{
+
+}
+
+#endif
+
+
+dcp::filesystem::directory_entry::directory_entry(boost::filesystem::path const& path)
+	: _path(path)
+{
+
+}
+
+
+dcp::filesystem::directory_iterator&
+dcp::filesystem::directory_iterator::operator++()
+{
+	++_wrapped;
+	return *this;
+}
+
+
+dcp::filesystem::directory_entry
+dcp::filesystem::directory_iterator::operator*() const
+{
+	return dcp::filesystem::directory_entry(*_wrapped);
+}
+
+
+bool
+dcp::filesystem::directory_iterator::operator!=(dcp::filesystem::directory_iterator const& other) const
+{
+	return _wrapped != other._wrapped;
+}
+
+
+dcp::filesystem::directory_iterator const&
+dcp::filesystem::begin(dcp::filesystem::directory_iterator const& iter)
+{
+	return iter;
+}
+
+
+dcp::filesystem::directory_iterator
+dcp::filesystem::end(dcp::filesystem::directory_iterator const&)
+{
+	return dcp::filesystem::directory_iterator();
+}
+
+
+dcp::filesystem::recursive_directory_iterator&
+dcp::filesystem::recursive_directory_iterator::operator++()
+{
+	++_wrapped;
+	return *this;
+}
+
+
+bool
+dcp::filesystem::recursive_directory_iterator::operator!=(dcp::filesystem::recursive_directory_iterator const& other) const
+{
+	return _wrapped != other._wrapped;
+}
+
+
+dcp::filesystem::directory_entry
+dcp::filesystem::recursive_directory_iterator::operator*() const
+{
+	_entry = dcp::filesystem::directory_entry(_wrapped->path());
+	return _entry;
+}
+
+
+dcp::filesystem::directory_entry*
+dcp::filesystem::recursive_directory_iterator::operator->() const
+{
+	_entry = dcp::filesystem::directory_entry(_wrapped->path());
+	return &_entry;
+}
+
+
+dcp::filesystem::recursive_directory_iterator const&
+dcp::filesystem::begin(dcp::filesystem::recursive_directory_iterator const& iter)
+{
+	return iter;
+}
+
+
+dcp::filesystem::recursive_directory_iterator
+dcp::filesystem::end(dcp::filesystem::recursive_directory_iterator const&)
+{
+	return dcp::filesystem::recursive_directory_iterator();
+}
+
+
+/** Windows can't "by default" cope with paths longer than 260 characters, so if you pass such a path to
+ *  any boost::filesystem method it will fail.  There is a "fix" for this, which is to prepend
+ *  the string \\?\ to the path.  This will make it work, so long as:
+ *  - the path is absolute.
+ *  - the path contains no .. parts.
+ *  - the path only uses backslashes.
+ *  - individual path components are "short enough" (probably less than 255 characters)
+ *
+ *  See https://www.boost.org/doc/libs/1_57_0/libs/filesystem/doc/reference.html under
+ *  "Warning: Long paths on Windows" for some details.
+ *
+ *  Our fopen_boost uses this method to get this fix, but any other calls to boost::filesystem
+ *  will not unless this method is explicitly called to pre-process the pathname.
+ */
+boost::filesystem::path
+dcp::filesystem::fix_long_path(boost::filesystem::path long_path)
+{
+#ifdef LIBDCP_WINDOWS
+	using namespace boost::filesystem;
+
+	if (boost::algorithm::starts_with(long_path.string(), "\\\\")) {
+		/* This could mean it starts with \\ (i.e. a SMB path) or \\?\ (a long path)
+		 * or a variety of other things... anyway, we'll leave it alone.
+		 */
+		return long_path;
+	}
+
+	/* We have to make the path canonical but we can't call canonical() on the long path
+	 * as it will fail.  So we'll sort of do it ourselves (possibly badly).
+	 */
+	path fixed = "\\\\?\\";
+	if (long_path.is_absolute()) {
+		fixed += long_path.make_preferred();
+	} else {
+		fixed += filesystem::current_path() / long_path.make_preferred();
+	}
+	return fixed;
+#else
+	return long_path;
+#endif
+}
+
+
+boost::filesystem::path
+dcp::filesystem::unfix_long_path(boost::filesystem::path long_path)
+{
+#ifdef LIBDCP_WINDOWS
+	if (boost::algorithm::starts_with(long_path.string(), "\\\\?\\")) {
+		return long_path.string().substr(4);
+	}
+#endif
+	return long_path;
+}