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Fix bugs in filesystem::path::lexically_normal()

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Using path::_List::erase(const_iterator) to remove a non-final component
in path::lexically_normal() is a bug, because it leaves the following
component with an incorrect _M_pos value.

Instead of providing erase members that allow removing components from
the middle, replace them with pop_back() and
_M_erase_from(const_iterator) which only allow removing elements at the
end. Most uses of erase are unaffected, because they only remove
elements from the end anyway. The one use of erasure from the middle in
lexically_normal() is replaced by calls to pop_back() and/or clearing
the last component to leave it as an empty final filename.

Also replace the "???" comment in lexically_normal() to document when
that branch is taken.

	* include/bits/fs_path.h (path::_List::erase): Replace both overloads
	with ...
	(path::pop_back(), path::_M_erase_from(const_iterator)): New member
	functions that will only erase elements at the end.
	* src/filesystem/std-path.cc (path::_List::_Impl::pop_back()): Define.
	(path::_List::_Impl::_M_erase_from(const_iterator)): Define.
	(path::_List::operator=(const _List&)): Use _M_erase_from(p) instead
	of erase(p, end()).
	(path::_List::pop_back()): Define.
	(path::_List::_M_erase_from(const_iterator)): Define.
	(path::operator/=(const path&)): Use pop_back to remove last component
	and _M_erase_from to remove multiple components.
	(path::_M_append(basic_string_view<value_type>)): Likewise.
	(path::operator+=(const path&)): Likewise.
	(path::_M_concat(basic_string_view<value_type>)): Likewise.
	(path::remove_filename()): Likewise.
	(path::lexically_normal()): Use _List::_Impl iterators instead of
	path::iterator. Use pop_back to remove components from the end. Clear
	trailing filename, instead of using erase(const_iterator) to remove
	a non-final component.
	* testsuite/27_io/filesystem/path/generation/normal.cc: Test
	additional cases.
	* testsuite/27_io/filesystem/path/generation/normal2.cc: New test.

From-SVN: r267576
This commit is contained in:
Jonathan Wakely 2019-01-04 14:03:59 +00:00 committed by Jonathan Wakely
parent 2d4c371efa
commit 73d968d945
5 changed files with 121 additions and 34 deletions
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24
libstdc++-v3/ChangeLog
View File

@ -1,5 +1,29 @@
2019-01-04 Jonathan Wakely <jwakely@redhat.com>
* include/bits/fs_path.h (path::_List::erase): Replace both overloads
with ...
(path::pop_back(), path::_M_erase_from(const_iterator)): New member
functions that will only erase elements at the end.
* src/filesystem/std-path.cc (path::_List::_Impl::pop_back()): Define.
(path::_List::_Impl::_M_erase_from(const_iterator)): Define.
(path::_List::operator=(const _List&)): Use _M_erase_from(p) instead
of erase(p, end()).
(path::_List::pop_back()): Define.
(path::_List::_M_erase_from(const_iterator)): Define.
(path::operator/=(const path&)): Use pop_back to remove last component
and _M_erase_from to remove multiple components.
(path::_M_append(basic_string_view<value_type>)): Likewise.
(path::operator+=(const path&)): Likewise.
(path::_M_concat(basic_string_view<value_type>)): Likewise.
(path::remove_filename()): Likewise.
(path::lexically_normal()): Use _List::_Impl iterators instead of
path::iterator. Use pop_back to remove components from the end. Clear
trailing filename, instead of using erase(const_iterator) to remove
a non-final component.
* testsuite/27_io/filesystem/path/generation/normal.cc: Test
additional cases.
* testsuite/27_io/filesystem/path/generation/normal2.cc: New test.
* src/filesystem/std-path.cc (path::operator+=(const path&)): Fix
incorrect treatment of empty filename after trailing slash.
* testsuite/27_io/filesystem/path/concat/path.cc: Test problem case.

4
libstdc++-v3/include/bits/fs_path.h
View File

@ -544,8 +544,8 @@ _GLIBCXX_BEGIN_NAMESPACE_CXX11
const value_type& front() const noexcept;
const value_type& back() const noexcept;
void erase(const_iterator);
void erase(const_iterator, const_iterator);
void pop_back();
void _M_erase_from(const_iterator __pos); // erases [__pos,end())
struct _Impl;
struct _Impl_deleter

72
libstdc++-v3/src/filesystem/std-path.cc
View File

@ -207,22 +207,17 @@ struct path::_List::_Impl
void clear() { std::destroy_n(begin(), _M_size); _M_size = 0; }
void erase(const_iterator cpos)
void pop_back()
{
iterator pos = begin() + (cpos - begin());
if (pos + 1 != end())
std::move(pos + 1, end(), pos);
pos->~_Cmpt();
back().~_Cmpt();
--_M_size;
}
void erase(const_iterator cfirst, const_iterator clast)
void _M_erase_from(const_iterator pos)
{
iterator first = begin() + (cfirst - begin());
iterator last = begin() + (clast - begin());
if (last != end())
std::move(last, end(), first);
std::destroy(first + (end() - last), end());
iterator first = begin() + (pos - begin());
iterator last = end();
std::destroy(first, last);
_M_size -= last - first;
}
@ -288,7 +283,7 @@ path::_List::operator=(const _List& other)
impl->_M_size = newsize;
}
else if (newsize < oldsize)
impl->erase(impl->begin() + newsize, impl->end());
impl->_M_erase_from(impl->begin() + newsize);
std::copy_n(from, minsize, to);
type(_Type::_Multi);
}
@ -401,15 +396,16 @@ path::_List::back() const noexcept
}
inline void
path::_List::erase(const_iterator pos)
path::_List::pop_back()
{
_M_impl->erase(pos);
__glibcxx_assert(size() > 0);
_M_impl->pop_back();
}
inline void
path::_List::erase(const_iterator first, const_iterator last)
path::_List::_M_erase_from(const_iterator pos)
{
_M_impl->erase(first, last);
_M_impl->_M_erase_from(pos);
}
inline void
@ -591,7 +587,10 @@ path::operator/=(const path& __p)
{
// Remove empty final component
if (_M_cmpts._M_impl->back().empty())
_M_cmpts._M_impl->erase(--output);
{
_M_cmpts.pop_back();
--output;
}
}
else if (orig_pathlen != 0)
{
@ -629,7 +628,7 @@ path::operator/=(const path& __p)
{
_M_pathname.resize(orig_pathlen);
if (orig_type == _Type::_Multi)
_M_cmpts.erase(_M_cmpts.begin() + orig_size, _M_cmpts.end());
_M_cmpts._M_erase_from(_M_cmpts.begin() + orig_size);
else
_M_cmpts.clear();
_M_cmpts.type(orig_type);
@ -774,7 +773,10 @@ path::_M_append(basic_string_view<value_type> s)
{
// Remove empty final component
if (_M_cmpts._M_impl->back().empty())
_M_cmpts._M_impl->erase(--output);
{
_M_cmpts.pop_back();
--output;
}
}
else if (orig_pathlen != 0)
{
@ -818,7 +820,7 @@ path::_M_append(basic_string_view<value_type> s)
{
_M_pathname.resize(orig_pathlen);
if (orig_type == _Type::_Multi)
_M_cmpts.erase(_M_cmpts.begin() + orig_size, _M_cmpts.end());
_M_cmpts._M_erase_from(_M_cmpts.begin() + orig_size);
else
_M_cmpts.clear();
_M_cmpts.type(orig_type);
@ -945,7 +947,8 @@ path::operator+=(const path& p)
else if (orig_filenamelen == 0 && it != last)
{
// Remove empty filename at end of original path.
_M_cmpts.erase(--output);
_M_cmpts.pop_back();
--output;
}
if (it != last && it->_M_type() == _Type::_Root_name)
@ -995,7 +998,7 @@ path::operator+=(const path& p)
if (orig_type == _Type::_Multi)
{
if (_M_cmpts.size() > orig_size)
_M_cmpts.erase(_M_cmpts.begin() + orig_size, _M_cmpts.end());
_M_cmpts._M_erase_from(_M_cmpts.begin() + orig_size);
if (orig_filenamelen != -1)
{
if (_M_cmpts.size() == orig_size)
@ -1182,7 +1185,7 @@ path::_M_concat(basic_string_view<value_type> s)
_M_pathname.resize(orig_pathlen);
if (orig_type == _Type::_Multi)
{
_M_cmpts.erase(_M_cmpts.begin() + orig_size, _M_cmpts.end());
_M_cmpts._M_erase_from(_M_cmpts.begin() + orig_size);
if (orig_filenamelen != -1)
{
auto& back = _M_cmpts.back();
@ -1213,7 +1216,7 @@ path::remove_filename()
if (prev->_M_type() == _Type::_Root_dir
|| prev->_M_type() == _Type::_Root_name)
{
_M_cmpts.erase(cmpt);
_M_cmpts.pop_back();
if (_M_cmpts.size() == 1)
{
_M_cmpts.type(_M_cmpts.front()._M_type());
@ -1681,25 +1684,30 @@ path::lexically_normal() const
// Got a path with a relative path (i.e. at least one non-root
// element) and no filename at the end (i.e. empty last element),
// so must have a trailing slash. See what is before it.
auto elem = std::prev(ret.end(), 2);
auto elem = ret._M_cmpts.end() - 2;
if (elem->has_filename() && !is_dotdot(*elem))
{
// Remove the filename before the trailing slash
// (equiv. to ret = ret.parent_path().remove_filename())
if (elem == ret.begin())
if (elem == ret._M_cmpts.begin())
ret.clear();
else
{
ret._M_pathname.erase(elem._M_cur->_M_pos);
// Do we still have a trailing slash?
ret._M_pathname.erase(elem->_M_pos);
// Remove empty filename at the end:
ret._M_cmpts.pop_back();
// If we still have a trailing non-root dir separator
// then leave an empty filename at the end:
if (std::prev(elem)->_M_type() == _Type::_Filename)
ret._M_cmpts.erase(elem._M_cur);
else
ret._M_cmpts.erase(elem._M_cur, ret._M_cmpts.end());
elem->clear();
else // remove the component completely:
ret._M_cmpts.pop_back();
}
}
else // ???
else
// Append the ".." to something ending in "../" which happens
// when normalising paths like ".././.." and "../a/../.."
ret /= p;
}
}

2
libstdc++-v3/testsuite/27_io/filesystem/path/generation/normal.cc
View File

@ -125,6 +125,8 @@ test03()
{"../foo/../foo/.." , ".." },
{"../.f/../f" , "../f" },
{"../f/../.f" , "../.f" },
{"../.." , "../.." },
{"../../." , "../.." },
{".././../." , "../.." },
{".././.././" , "../.." },
{"/.." , "/" },

53
libstdc++-v3/testsuite/27_io/filesystem/path/generation/normal2.cc Normal file
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@ -0,0 +1,53 @@
// Copyright (C) 2019 Free Software Foundation, Inc.
//
// This file is part of the GNU ISO C++ Library. This library 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 3, or (at your option)
// any later version.
// This library 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 this library; see the file COPYING3. If not see
// <http://www.gnu.org/licenses/>.
// { dg-options "-std=gnu++17 -lstdc++fs" }
// { dg-do run { target c++17 } }
// { dg-require-filesystem-ts "" }
#undef _GLIBCXX_USE_CXX11_ABI
#define _GLIBCXX_USE_CXX11_ABI 0
#include <filesystem>
#include <testsuite_fs.h>
using std::filesystem::path;
void
compare_paths(path p, std::string expected)
{
#if defined(_WIN32) && !defined(__CYGWIN__)
for (auto& c : expected)
if (c == '/')
c = '\\';
#endif
__gnu_test::compare_paths(p, expected);
}
void
test02()
{
path p = "./a/b/c/../.././b/c";
// For the COW string this used to produce incorrect results:
auto norm = p.lexically_normal();
compare_paths( norm, "a/b/c" );
}
int
main()
{
test02();
}