libstdc++: Fix filesystem::remove_all races [PR104161]

This fixes the remaining filesystem::remove_all race condition by using
POSIX openat to recurse into sub-directories and using POSIX unlinkat to
remove files. This avoids the remaining race where the directory being
removed is replaced with a symlink after the directory has been opened,
so that the filesystem::remove("subdir/file") resolves to "target/file"
instead, because "subdir" has been removed and replaced with a symlink.
The previous patch only fixed the case where the directory was replaced
with a symlink before we tried to open it, but it still used the full
(potentially compromised) path as an argument to filesystem::remove.

The first part of the fix is to use openat when recursing into a
sub-directory with recursive_directory_iterator. This means that opening
"dir/subdir" uses the file descriptor for "dir", and so is sure to open
"dir/subdir" and not "symlink/subdir". (The previous patch to use
O_NOFOLLOW already ensured we won't open "dir/symlink/" here.)

The second part of the fix is to use unlinkat for the remove_all
operation. Previously we used a directory_iterator to get the name of
each file in a directory and then used filesystem::remove(iter->path())
on that name. This meant that any checks (e.g. O_NOFOLLOW) done by the
iterator could be invalidated before the remove operation on that
pathname. The directory iterator contains an open DIR stream, which we
can use to obtain a file descriptor to pass to unlinkat. This ensures
that the file being deleted really is contained within the directory
we're iterating over, rather than using a pathname that could resolve to
some other file.

The filesystem::remove_all function previously used a (non-recursive)
filesystem::directory_iterator for each directory, and called itself
recursively for sub-directories. The new implementation uses a single
filesystem::recursive_directory_iterator object, and calls a new __erase
member function on that iterator. That new __erase member function does
the actual work of removing a file (or a directory after its contents
have been iterated over and removed) using unlinkat. That means we don't
need to expose the DIR stream or its file descriptor to the remove_all
function, it's still encapuslated by the iterator class.

It would be possible to add a __rewind member to directory iterators
too, to call rewinddir after each modification to the directory. That
would make it more likely for filesystem::remove_all to successfully
remove everything even if files are being written to the directory tree
while removing it. It's unclear if that is actually prefereable, or if
it's better to fail and report an error at the first opportunity.

The necessary APIs (openat, unlinkat, fdopendir, dirfd) are defined in
POSIX.1-2008, and in Glibc since 2.10. But if the target doesn't provide
them, the original code (with race conditions) is still used.

This also reduces the number of small memory allocations needed for
std::filesystem::remove_all, because we do not store the full path to
every directory entry that is iterated over. The new filename_only
option means we only store the filename in the directory entry, as that
is all we need in order to use openat or unlinkat.

Finally, rather than duplicating everything for the Filesystem TS, the
std::experimental::filesystem::remove_all implementation now just calls
std::filesystem::remove_all to do the work.

libstdc++-v3/ChangeLog:

	PR libstdc++/104161
	* acinclude.m4 (GLIBCXX_CHECK_FILESYSTEM_DEPS): Check for dirfd
	and unlinkat.
	* config.h.in: Regenerate.
	* configure: Regenerate.
	* include/bits/fs_dir.h (recursive_directory_iterator): Declare
	remove_all overloads as friends.
	(recursive_directory_iterator::__erase): Declare new member
	function.
	* include/bits/fs_fwd.h (remove, remove_all): Declare.
	* src/c++17/fs_dir.cc (_Dir): Add filename_only parameter to
	constructor. Pass file descriptor argument to base constructor.
	(_Dir::dir_and_pathname, _Dir::open_subdir, _Dir::do_unlink)
	(_Dir::unlink, _Dir::rmdir): Define new member functions.
	(directory_iterator): Pass filename_only argument to _Dir
	constructor.
	(recursive_directory_iterator::_Dir_stack): Adjust constructor
	parameters to take a _Dir rvalue instead of creating one.
	(_Dir_stack::orig): Add data member for storing original path.
	(_Dir_stack::report_error): Define new member function.
	(__directory_iterator_nofollow): Move here from dir-common.h and
	fix value to be a power of two.
	(__directory_iterator_filename_only): Define new constant.
	(recursive_directory_iterator): Construct _Dir object and move
	into _M_dirs stack. Pass skip_permission_denied argument to first
	advance call.
	(recursive_directory_iterator::increment): Use _Dir::open_subdir.
	(recursive_directory_iterator::__erase): Define new member
	function.
	* src/c++17/fs_ops.cc (ErrorReporter, do_remove_all): Remove.
	(fs::remove_all): Use new recursive_directory_iterator::__erase
	member function.
	* src/filesystem/dir-common.h (_Dir_base): Add int parameter to
	constructor and use openat to implement nofollow semantics.
	(_Dir_base::fdcwd, _Dir_base::set_close_on_exec, _Dir_base::openat):
	Define new member functions.
	(__directory_iterator_nofollow): Move to fs_dir.cc.
	* src/filesystem/dir.cc (_Dir): Pass file descriptor argument to
	base constructor.
	(_Dir::dir_and_pathname, _Dir::open_subdir): Define new member
	functions.
	(recursive_directory_iterator::_Dir_stack): Adjust constructor
	parameters to take a _Dir rvalue instead of creating one.
	(recursive_directory_iterator): Check for new nofollow option.
	Construct _Dir object and move into _M_dirs stack. Pass
	skip_permission_denied argument to first advance call.
	(recursive_directory_iterator::increment): Use _Dir::open_subdir.
	* src/filesystem/ops.cc (fs::remove_all): Use C++17 remove_all.
This commit is contained in:
Jonathan Wakely 2022-02-01 22:04:46 +00:00
parent b28b92bc00
commit ebf6175464
10 changed files with 573 additions and 231 deletions

View File

@ -4748,13 +4748,38 @@ dnl
glibcxx_cv_fdopendir, [dnl
GCC_TRY_COMPILE_OR_LINK(
[#include <dirent.h>],
[::fdopendir(1);],
[::DIR* dir = ::fdopendir(1);],
[glibcxx_cv_fdopendir=yes],
[glibcxx_cv_fdopendir=no])
])
if test $glibcxx_cv_fdopendir = yes; then
AC_DEFINE(HAVE_FDOPENDIR, 1, [Define if fdopendir is available in <dirent.h>.])
fi
dnl
AC_CACHE_CHECK([for dirfd],
glibcxx_cv_dirfd, [dnl
GCC_TRY_COMPILE_OR_LINK(
[#include <dirent.h>],
[int fd = ::dirfd((::DIR*)0);],
[glibcxx_cv_dirfd=yes],
[glibcxx_cv_dirfd=no])
])
if test $glibcxx_cv_dirfd = yes; then
AC_DEFINE(HAVE_DIRFD, 1, [Define if dirfd is available in <dirent.h>.])
fi
dnl
AC_CACHE_CHECK([for unlinkat],
glibcxx_cv_unlinkat, [dnl
GCC_TRY_COMPILE_OR_LINK(
[#include <fcntl.h>
#include <unistd.h>],
[::unlinkat(AT_FDCWD, "", AT_REMOVEDIR);],
[glibcxx_cv_unlinkat=yes],
[glibcxx_cv_unlinkat=no])
])
if test $glibcxx_cv_unlinkat = yes; then
AC_DEFINE(HAVE_UNLINKAT, 1, [Define if unlinkat is available in <fcntl.h>.])
fi
dnl
CXXFLAGS="$ac_save_CXXFLAGS"
AC_LANG_RESTORE

View File

@ -73,6 +73,9 @@
/* Define to 1 if you have the <dirent.h> header file. */
#undef HAVE_DIRENT_H
/* Define if dirfd is available in <dirent.h>. */
#undef HAVE_DIRFD
/* Define to 1 if you have the <dlfcn.h> header file. */
#undef HAVE_DLFCN_H
@ -486,6 +489,9 @@
/* Define to 1 if you have the <unistd.h> header file. */
#undef HAVE_UNISTD_H
/* Define if unlinkat is available in <fcntl.h>. */
#undef HAVE_UNLINKAT
/* Define to 1 if you have the `uselocale' function. */
#undef HAVE_USELOCALE

116
libstdc++-v3/configure vendored
View File

@ -77077,7 +77077,7 @@ else
int
main ()
{
::fdopendir(1);
::DIR* dir = ::fdopendir(1);
;
return 0;
}
@ -77098,7 +77098,7 @@ cat confdefs.h - <<_ACEOF >conftest.$ac_ext
int
main ()
{
::fdopendir(1);
::DIR* dir = ::fdopendir(1);
;
return 0;
}
@ -77119,6 +77119,118 @@ $as_echo "$glibcxx_cv_fdopendir" >&6; }
$as_echo "#define HAVE_FDOPENDIR 1" >>confdefs.h
fi
{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for dirfd" >&5
$as_echo_n "checking for dirfd... " >&6; }
if ${glibcxx_cv_dirfd+:} false; then :
$as_echo_n "(cached) " >&6
else
if test x$gcc_no_link = xyes; then
cat confdefs.h - <<_ACEOF >conftest.$ac_ext
/* end confdefs.h. */
#include <dirent.h>
int
main ()
{
int fd = ::dirfd((::DIR*)0);
;
return 0;
}
_ACEOF
if ac_fn_cxx_try_compile "$LINENO"; then :
glibcxx_cv_dirfd=yes
else
glibcxx_cv_dirfd=no
fi
rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
else
if test x$gcc_no_link = xyes; then
as_fn_error $? "Link tests are not allowed after GCC_NO_EXECUTABLES." "$LINENO" 5
fi
cat confdefs.h - <<_ACEOF >conftest.$ac_ext
/* end confdefs.h. */
#include <dirent.h>
int
main ()
{
int fd = ::dirfd((::DIR*)0);
;
return 0;
}
_ACEOF
if ac_fn_cxx_try_link "$LINENO"; then :
glibcxx_cv_dirfd=yes
else
glibcxx_cv_dirfd=no
fi
rm -f core conftest.err conftest.$ac_objext \
conftest$ac_exeext conftest.$ac_ext
fi
fi
{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $glibcxx_cv_dirfd" >&5
$as_echo "$glibcxx_cv_dirfd" >&6; }
if test $glibcxx_cv_dirfd = yes; then
$as_echo "#define HAVE_DIRFD 1" >>confdefs.h
fi
{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for unlinkat" >&5
$as_echo_n "checking for unlinkat... " >&6; }
if ${glibcxx_cv_unlinkat+:} false; then :
$as_echo_n "(cached) " >&6
else
if test x$gcc_no_link = xyes; then
cat confdefs.h - <<_ACEOF >conftest.$ac_ext
/* end confdefs.h. */
#include <fcntl.h>
#include <unistd.h>
int
main ()
{
::unlinkat(AT_FDCWD, "", AT_REMOVEDIR);
;
return 0;
}
_ACEOF
if ac_fn_cxx_try_compile "$LINENO"; then :
glibcxx_cv_unlinkat=yes
else
glibcxx_cv_unlinkat=no
fi
rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
else
if test x$gcc_no_link = xyes; then
as_fn_error $? "Link tests are not allowed after GCC_NO_EXECUTABLES." "$LINENO" 5
fi
cat confdefs.h - <<_ACEOF >conftest.$ac_ext
/* end confdefs.h. */
#include <fcntl.h>
#include <unistd.h>
int
main ()
{
::unlinkat(AT_FDCWD, "", AT_REMOVEDIR);
;
return 0;
}
_ACEOF
if ac_fn_cxx_try_link "$LINENO"; then :
glibcxx_cv_unlinkat=yes
else
glibcxx_cv_unlinkat=no
fi
rm -f core conftest.err conftest.$ac_objext \
conftest$ac_exeext conftest.$ac_ext
fi
fi
{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $glibcxx_cv_unlinkat" >&5
$as_echo "$glibcxx_cv_unlinkat" >&6; }
if test $glibcxx_cv_unlinkat = yes; then
$as_echo "#define HAVE_UNLINKAT 1" >>confdefs.h
fi
CXXFLAGS="$ac_save_CXXFLAGS"
ac_ext=c

View File

@ -537,6 +537,14 @@ _GLIBCXX_BEGIN_NAMESPACE_CXX11
struct _Dir_stack;
std::__shared_ptr<_Dir_stack> _M_dirs;
recursive_directory_iterator&
__erase(error_code* = nullptr);
friend uintmax_t
filesystem::remove_all(const path&, error_code&);
friend uintmax_t
filesystem::remove_all(const path&);
};
/// @relates std::filesystem::recursive_directory_iterator @{

View File

@ -354,6 +354,10 @@ _GLIBCXX_END_NAMESPACE_CXX11
bool is_regular_file(file_status) noexcept;
bool is_symlink(file_status) noexcept;
bool remove(const path&, error_code&) noexcept;
uintmax_t remove_all(const path&);
uintmax_t remove_all(const path&, error_code&);
/// @}
} // namespace filesystem
_GLIBCXX_END_NAMESPACE_VERSION

View File

@ -45,9 +45,14 @@ template class std::__shared_ptr<fs::recursive_directory_iterator::_Dir_stack>;
struct fs::_Dir : _Dir_base
{
_Dir(const fs::path& p, bool skip_permission_denied, bool nofollow,
error_code& ec)
: _Dir_base(p.c_str(), skip_permission_denied, nofollow, ec)
[[maybe_unused]] bool filename_only, error_code& ec)
: _Dir_base(fdcwd(), p.c_str(), skip_permission_denied, nofollow, ec)
{
#if _GLIBCXX_HAVE_DIRFD
if (filename_only)
return; // Do not store path p when we aren't going to use it.
#endif
if (!ec)
path = p;
}
@ -112,7 +117,63 @@ struct fs::_Dir : _Dir_base
return false;
}
fs::path path;
// Return a file descriptor for the directory and current entry's path.
// If dirfd is available, use it and return only the filename.
// Otherwise, return AT_FDCWD and return the full path.
pair<int, const posix::char_type*>
dir_and_pathname() const noexcept
{
const fs::path& p = entry.path();
#if _GLIBCXX_HAVE_DIRFD
if (!p.empty())
return {::dirfd(this->dirp), std::prev(p.end())->c_str()};
#endif
return {this->fdcwd(), p.c_str()};
}
// Create a new _Dir for the directory this->entry.path().
_Dir
open_subdir(bool skip_permission_denied, bool nofollow,
error_code& ec) const noexcept
{
auto [dirfd, pathname] = dir_and_pathname();
_Dir_base d(dirfd, pathname, skip_permission_denied, nofollow, ec);
// If this->path is empty, the new _Dir should have an empty path too.
const fs::path& p = this->path.empty() ? this->path : this->entry.path();
return _Dir(std::exchange(d.dirp, nullptr), p);
}
bool
do_unlink(bool is_directory, error_code& ec) const noexcept
{
#if _GLIBCXX_HAVE_UNLINKAT
auto [dirfd, pathname] = dir_and_pathname();
if (::unlinkat(dirfd, pathname, is_directory ? AT_REMOVEDIR : 0) == -1)
{
ec.assign(errno, std::generic_category());
return false;
}
else
{
ec.clear();
return true;
}
#else
return fs::remove(entry.path(), ec);
#endif
}
// Remove the non-directory that this->entry refers to.
bool
unlink(error_code& ec) const noexcept
{ return do_unlink(/* is_directory*/ false, ec); }
// Remove the directory that this->entry refers to.
bool
rmdir(error_code& ec) const noexcept
{ return do_unlink(/* is_directory*/ true, ec); }
fs::path path; // Empty if only using unlinkat with file descr.
directory_entry entry;
};
@ -124,6 +185,20 @@ namespace
{
return (obj & bits) != Bitmask::none;
}
// Non-standard directory option flags, currently only for internal use:
//
// Do not allow directory iterator to open a symlink.
// This might seem redundant given directory_options::follow_directory_symlink
// but that is only checked for recursing into sub-directories, and we need
// something that controls the initial opendir() call in the constructor.
constexpr fs::directory_options __directory_iterator_nofollow{64};
// Do not store full paths in std::filesystem::recursive_directory_iterator.
// When fs::remove_all uses recursive_directory_iterator::__erase and unlinkat
// is available in libc, we do not need the parent directory's path, only the
// filenames of the directory entries (and a file descriptor for the parent).
// This flag avoids allocating memory for full paths that won't be needed.
constexpr fs::directory_options __directory_iterator_filename_only{128};
}
fs::directory_iterator::
@ -132,12 +207,11 @@ directory_iterator(const path& p, directory_options options, error_code* ecptr)
// Do not report an error for permission denied errors.
const bool skip_permission_denied
= is_set(options, directory_options::skip_permission_denied);
// Do not allow opening a symlink (used by filesystem::remove_all)
const bool nofollow
= is_set(options, __directory_iterator_nofollow);
// Do not allow opening a symlink.
const bool nofollow = is_set(options, __directory_iterator_nofollow);
error_code ec;
_Dir dir(p, skip_permission_denied, nofollow, ec);
_Dir dir(p, skip_permission_denied, nofollow, /*filename only*/false, ec);
if (dir.dirp)
{
@ -185,48 +259,66 @@ fs::directory_iterator::increment(error_code& ec)
struct fs::recursive_directory_iterator::_Dir_stack : std::stack<_Dir>
{
_Dir_stack(directory_options opts, posix::DIR* dirp, const path& p)
_Dir_stack(directory_options opts, _Dir&& dir)
: options(opts), pending(true)
{
this->emplace(dirp, p);
this->push(std::move(dir));
}
path::string_type orig;
const directory_options options;
bool pending;
void clear() { c.clear(); }
path current_path() const
{
path p;
if (top().path.empty())
{
// Reconstruct path that failed from dir stack.
p = orig;
for (auto& d : this->c)
p /= d.entry.path();
}
else
p = top().entry.path();
return p;
}
};
fs::recursive_directory_iterator::
recursive_directory_iterator(const path& p, directory_options options,
error_code* ecptr)
{
if (posix::DIR* dirp = posix::opendir(p.c_str()))
// Do not report an error for permission denied errors.
const bool skip_permission_denied
= is_set(options, directory_options::skip_permission_denied);
// Do not allow opening a symlink as the starting directory.
const bool nofollow = is_set(options, __directory_iterator_nofollow);
// Prefer to store only filenames (not full paths) in directory_entry values.
const bool filename_only
= is_set(options, __directory_iterator_filename_only);
error_code ec;
_Dir dir(p, skip_permission_denied, nofollow, filename_only, ec);
if (dir.dirp)
{
if (ecptr)
ecptr->clear();
auto sp = std::__make_shared<_Dir_stack>(options, dirp, p);
if (ecptr ? sp->top().advance(*ecptr) : sp->top().advance())
_M_dirs.swap(sp);
}
else
{
const int err = errno;
if (fs::is_permission_denied_error(err)
&& is_set(options, fs::directory_options::skip_permission_denied))
auto sp = std::__make_shared<_Dir_stack>(options, std::move(dir));
if (ecptr ? sp->top().advance(skip_permission_denied, *ecptr)
: sp->top().advance(skip_permission_denied))
{
if (ecptr)
ecptr->clear();
return;
_M_dirs.swap(sp);
if (filename_only) // Need to save original path for error reporting.
_M_dirs->orig = p.native();
}
if (!ecptr)
_GLIBCXX_THROW_OR_ABORT(filesystem_error(
"recursive directory iterator cannot open directory", p,
std::error_code(err, std::generic_category())));
ecptr->assign(err, std::generic_category());
}
else if (ecptr)
*ecptr = ec;
else if (ec)
_GLIBCXX_THROW_OR_ABORT(fs::filesystem_error(
"recursive directory iterator cannot open directory", p, ec));
}
fs::recursive_directory_iterator::~recursive_directory_iterator() = default;
@ -292,14 +384,14 @@ fs::recursive_directory_iterator::increment(error_code& ec)
if (std::exchange(_M_dirs->pending, true) && top.should_recurse(follow, ec))
{
_Dir dir(top.entry.path(), skip_permission_denied, !follow, ec);
_Dir dir = top.open_subdir(skip_permission_denied, !follow, ec);
if (ec)
{
_M_dirs.reset();
return *this;
}
if (dir.dirp)
_M_dirs->push(std::move(dir));
_M_dirs->push(std::move(dir));
}
while (!_M_dirs->top().advance(skip_permission_denied, ec) && !ec)
@ -362,3 +454,96 @@ fs::recursive_directory_iterator::disable_recursion_pending() noexcept
{
_M_dirs->pending = false;
}
// Used to implement filesystem::remove_all.
fs::recursive_directory_iterator&
fs::recursive_directory_iterator::__erase(error_code* ecptr)
{
error_code ec;
if (!_M_dirs)
{
ec = std::make_error_code(errc::invalid_argument);
return *this;
}
// We never want to skip permission denied when removing files.
const bool skip_permission_denied = false;
// We never want to follow directory symlinks when removing files.
const bool nofollow = true;
// Loop until we find something we can remove.
while (!ec)
{
auto& top = _M_dirs->top();
if (top.entry._M_type == file_type::directory)
{
_Dir dir = top.open_subdir(skip_permission_denied, nofollow, ec);
if (!ec)
{
__glibcxx_assert(dir.dirp != nullptr);
if (dir.advance(skip_permission_denied, ec))
{
// Non-empty directory, recurse into it.
_M_dirs->push(std::move(dir));
continue;
}
if (!ec)
{
// Directory is empty so we can remove it.
if (top.rmdir(ec))
break; // Success
}
}
}
else if (top.unlink(ec))
break; // Success
else if (top.entry._M_type == file_type::none)
{
// We did not have a cached type, so it's possible that top.entry
// is actually a directory, and that's why the unlink above failed.
#ifdef EPERM
// POSIX.1-2017 says unlinking a directory returns EPERM,
// but LSB allows EISDIR too. Some targets don't even define EPERM.
if (ec.value() == EPERM || ec.value() == EISDIR)
#else
if (ec.value() == EISDIR)
#endif
{
// Retry, treating it as a directory.
top.entry._M_type = file_type::directory;
ec.clear();
continue;
}
}
}
if (!ec)
{
// We successfully removed the current entry, so advance to the next one.
if (_M_dirs->top().advance(skip_permission_denied, ec))
return *this;
else if (!ec)
{
// Reached the end of the current directory.
_M_dirs->pop();
if (_M_dirs->empty())
_M_dirs.reset();
return *this;
}
}
// Reset _M_dirs to empty.
auto dirs = std::move(_M_dirs);
// Need to report an error
if (ecptr)
*ecptr = ec;
else
_GLIBCXX_THROW_OR_ABORT(fs::filesystem_error("cannot remove all",
dirs->orig,
dirs->current_path(),
ec));
return *this;
}

View File

@ -1277,105 +1277,62 @@ fs::remove(const path& p, error_code& ec) noexcept
return false;
}
namespace std::filesystem
{
namespace
{
struct ErrorReporter
{
explicit
ErrorReporter(error_code& ec) : code(&ec)
{ }
explicit
ErrorReporter(const char* s, const path& p)
: code(nullptr), msg(s), path1(&p)
{ }
error_code* code;
const char* msg;
const path* path1;
void
report(const error_code& ec) const
{
if (code)
*code = ec;
else
_GLIBCXX_THROW_OR_ABORT(filesystem_error(msg, *path1, ec));
}
void
report(const error_code& ec, const path& path2) const
{
if (code)
*code = ec;
else if (path2 != *path1)
_GLIBCXX_THROW_OR_ABORT(filesystem_error(msg, *path1, path2, ec));
else
_GLIBCXX_THROW_OR_ABORT(filesystem_error(msg, *path1, ec));
}
};
uintmax_t
do_remove_all(const path& p, const ErrorReporter& err)
{
error_code ec;
const auto s = symlink_status(p, ec);
if (!status_known(s))
{
if (ec)
err.report(ec, p);
return -1;
}
ec.clear();
if (s.type() == file_type::not_found)
return 0;
uintmax_t count = 0;
if (s.type() == file_type::directory)
{
directory_iterator d(p, directory_options{99}, ec), end;
while (d != end)
{
const auto removed = fs::do_remove_all(d->path(), err);
if (removed == numeric_limits<uintmax_t>::max())
return -1;
count += removed;
d.increment(ec);
}
if (ec)
{
err.report(ec, p);
return -1;
}
}
if (fs::remove(p, ec))
++count;
if (ec)
{
err.report(ec, p);
return -1;
}
return count;
}
}
}
std::uintmax_t
fs::remove_all(const path& p)
{
return fs::do_remove_all(p, ErrorReporter{"cannot remove all", p});
uintmax_t count = 0;
auto st = filesystem::status(p);
if (!exists(st))
return 0;
if (is_directory(st))
{
recursive_directory_iterator dir(p, directory_options{64|128}), end;
path failed;
while (dir != end)
{
failed = dir->path();
dir.__erase();
++count;
}
}
return count + fs::remove(p);
}
std::uintmax_t
fs::remove_all(const path& p, error_code& ec)
{
ec.clear();
return fs::do_remove_all(p, ErrorReporter{ec});
uintmax_t count = 0;
recursive_directory_iterator dir(p, directory_options{64|128}, ec);
switch (ec.value())
{
case 0:
{
recursive_directory_iterator end;
while (dir != end)
{
dir.__erase(&ec);
if (ec)
return -1;
++count;
}
}
break;
case ENOENT:
// Our work here is done.
ec.clear();
return 0;
case ENOTDIR:
case ELOOP:
// Not a directory, will remove below.
break;
default:
// An error occurred.
return -1;
}
// Remove p itself, which is either a non-directory or is now empty.
if (int last = fs::remove(p, ec); !ec)
return count + last;
return -1;
}
void

View File

@ -34,11 +34,11 @@
# ifdef _GLIBCXX_HAVE_SYS_TYPES_H
# include <sys/types.h>
# endif
# include <dirent.h>
#endif
#ifdef _GLIBCXX_HAVE_FCNTL_H
# include <fcntl.h> // O_NOFOLLOW, O_DIRECTORY
# include <unistd.h> // close
# include <dirent.h> // opendir, readdir, fdopendir, dirfd
# ifdef _GLIBCXX_HAVE_FCNTL_H
# include <fcntl.h> // open, openat, fcntl, AT_FDCWD, O_NOFOLLOW etc.
# include <unistd.h> // close, unlinkat
# endif
#endif
namespace std _GLIBCXX_VISIBILITY(default)
@ -75,42 +75,32 @@ inline int closedir(DIR*) { return -1; }
namespace posix = __gnu_posix;
inline bool
is_permission_denied_error(int e)
{
if (e == EACCES)
return true;
#ifdef __APPLE__
if (e == EPERM) // See PR 99533
return true;
#endif
return false;
}
struct _Dir_base
{
_Dir_base(posix::DIR* dirp = nullptr) : dirp(dirp) { }
// If no error occurs then dirp is non-null,
// otherwise null (even if an EACCES error is ignored).
_Dir_base(const posix::char_type* pathname, bool skip_permission_denied,
[[maybe_unused]] bool nofollow, error_code& ec) noexcept
: dirp(nullptr)
// otherwise null (even if a permission denied error is ignored).
_Dir_base(int fd, const posix::char_type* pathname,
bool skip_permission_denied, bool nofollow,
error_code& ec) noexcept
: dirp(_Dir_base::openat(fd, pathname, nofollow))
{
#if defined O_RDONLY && O_NOFOLLOW && defined O_DIRECTORY && defined O_CLOEXEC \
&& defined _GLIBCXX_HAVE_FDOPENDIR && !_GLIBCXX_FILESYSTEM_IS_WINDOWS
if (nofollow)
{
// Do not allow opening a symlink (used by filesystem::remove_all)
const int flags = O_RDONLY | O_NOFOLLOW | O_DIRECTORY | O_CLOEXEC;
int fd = ::open(pathname, flags);
if (fd != -1)
{
if ((dirp = ::fdopendir(fd)))
{
ec.clear();
return;
}
}
if (errno == EACCES && skip_permission_denied)
ec.clear();
else
ec.assign(errno, std::generic_category());
return;
}
#endif
if ((dirp = posix::opendir(pathname)))
if (dirp)
ec.clear();
else if (errno == EACCES && skip_permission_denied)
else if (is_permission_denied_error(errno) && skip_permission_denied)
ec.clear();
else
ec.assign(errno, std::generic_category());
@ -153,6 +143,16 @@ struct _Dir_base
}
}
static constexpr int
fdcwd() noexcept
{
#ifdef AT_FDCWD
return AT_FDCWD;
#else
return -1; // Use invalid fd if AT_FDCWD isn't supported.
#endif
}
static bool is_dot_or_dotdot(const char* s) noexcept
{ return !strcmp(s, ".") || !strcmp(s, ".."); }
@ -161,21 +161,72 @@ struct _Dir_base
{ return !wcscmp(s, L".") || !wcscmp(s, L".."); }
#endif
// Set the close-on-exec flag if not already done via O_CLOEXEC.
static bool
set_close_on_exec([[maybe_unused]] int fd)
{
#if ! defined O_CLOEXEC && defined FD_CLOEXEC
int flags = ::fcntl(fd, F_GETFD);
if (flags == -1 || ::fcntl(fd, F_SETFD, flags | FD_CLOEXEC) == -1)
return false;
#endif
return true;
}
static ::DIR*
openat(int fd, const posix::char_type* pathname, bool nofollow)
{
#if _GLIBCXX_HAVE_FDOPENDIR && defined O_RDONLY && defined O_DIRECTORY \
&& ! _GLIBCXX_FILESYSTEM_IS_WINDOWS
// Any file descriptor we open here should be closed on exec.
#ifdef O_CLOEXEC
constexpr int close_on_exec = O_CLOEXEC;
#else
constexpr int close_on_exec = 0;
#endif
int flags = O_RDONLY | O_DIRECTORY | close_on_exec;
// Directory iterators are vulnerable to race conditions unless O_NOFOLLOW
// is supported, because a directory could be replaced with a symlink after
// checking is_directory(symlink_status(f)). O_NOFOLLOW avoids the race.
#ifdef O_NOFOLLOW
if (nofollow)
flags |= O_NOFOLLOW;
#else
nofollow = false;
#endif
#ifdef AT_FDCWD
fd = ::openat(fd, pathname, flags);
#else
// If we cannot use openat, there's no benefit to using posix::open unless
// we will use O_NOFOLLOW, so just use the simpler posix::opendir.
if (!nofollow)
return posix::opendir(pathname);
fd = ::open(pathname, flags);
#endif
if (fd == -1)
return nullptr;
if (set_close_on_exec(fd))
if (::DIR* dirp = ::fdopendir(fd))
return dirp;
int err = errno;
::close(fd);
errno = err;
return nullptr;
#else
return posix::opendir(pathname);
#endif
}
posix::DIR* dirp;
};
inline bool
is_permission_denied_error(int e)
{
if (e == EACCES)
return true;
#ifdef __APPLE__
if (e == EPERM) // See PR 99533
return true;
#endif
return false;
}
} // namespace filesystem
// BEGIN/END macros must be defined before including this file.
@ -211,8 +262,6 @@ get_file_type(const std::filesystem::__gnu_posix::dirent& d [[gnu::unused]])
#endif
}
constexpr directory_options __directory_iterator_nofollow{99};
_GLIBCXX_END_NAMESPACE_FILESYSTEM
_GLIBCXX_END_NAMESPACE_VERSION

View File

@ -53,7 +53,7 @@ struct fs::_Dir : std::filesystem::_Dir_base
{
_Dir(const fs::path& p, bool skip_permission_denied, bool nofollow,
error_code& ec)
: _Dir_base(p.c_str(), skip_permission_denied, nofollow, ec)
: _Dir_base(this->fdcwd(), p.c_str(), skip_permission_denied, nofollow, ec)
{
if (!ec)
path = p;
@ -113,6 +113,29 @@ struct fs::_Dir : std::filesystem::_Dir_base
return false;
}
// Return a file descriptor for the directory and current entry's path.
// If dirfd is available, use it and return only the filename.
// Otherwise, return AT_FDCWD and return the full path.
pair<int, const posix::char_type*>
dir_and_pathname() const noexcept
{
const fs::path& p = entry.path();
#if _GLIBCXX_HAVE_DIRFD
return {::dirfd(this->dirp), std::prev(p.end())->c_str()};
#endif
return {this->fdcwd(), p.c_str()};
}
// Create a new _Dir for the directory this->entry.path().
_Dir
open_subdir(bool skip_permission_denied, bool nofollow,
error_code& ec) noexcept
{
auto [dirfd, pathname] = dir_and_pathname();
_Dir_base d(dirfd, pathname, skip_permission_denied, nofollow, ec);
return _Dir(std::exchange(d.dirp, nullptr), entry.path());
}
fs::path path;
directory_entry entry;
file_type type = file_type::none;
@ -134,12 +157,9 @@ directory_iterator(const path& p, directory_options options, error_code* ecptr)
// Do not report an error for permission denied errors.
const bool skip_permission_denied
= is_set(options, directory_options::skip_permission_denied);
// Do not allow opening a symlink (used by filesystem::remove_all)
const bool nofollow
= is_set(options, __directory_iterator_nofollow);
error_code ec;
_Dir dir(p, skip_permission_denied, nofollow, ec);
_Dir dir(p, skip_permission_denied, /*nofollow*/false, ec);
if (dir.dirp)
{
@ -191,6 +211,11 @@ fs::directory_iterator::increment(error_code& ec) noexcept
struct fs::recursive_directory_iterator::_Dir_stack : std::stack<_Dir>
{
_Dir_stack(_Dir&& dir)
{
this->push(std::move(dir));
}
void clear() { c.clear(); }
};
@ -199,33 +224,27 @@ recursive_directory_iterator(const path& p, directory_options options,
error_code* ecptr)
: _M_options(options), _M_pending(true)
{
if (posix::DIR* dirp = posix::opendir(p.c_str()))
// Do not report an error for permission denied errors.
const bool skip_permission_denied
= is_set(options, directory_options::skip_permission_denied);
error_code ec;
_Dir dir(p, skip_permission_denied, /*nofollow*/false, ec);
if (dir.dirp)
{
if (ecptr)
ecptr->clear();
auto sp = std::make_shared<_Dir_stack>();
sp->push(_Dir{ dirp, p });
if (ecptr ? sp->top().advance(*ecptr) : sp->top().advance())
_M_dirs.swap(sp);
}
else
{
const int err = errno;
if (std::filesystem::is_permission_denied_error(err)
&& is_set(options, fs::directory_options::skip_permission_denied))
auto sp = std::__make_shared<_Dir_stack>(std::move(dir));
if (ecptr ? sp->top().advance(skip_permission_denied, *ecptr)
: sp->top().advance(skip_permission_denied))
{
if (ecptr)
ecptr->clear();
return;
_M_dirs.swap(sp);
}
if (!ecptr)
_GLIBCXX_THROW_OR_ABORT(filesystem_error(
"recursive directory iterator cannot open directory", p,
std::error_code(err, std::generic_category())));
ecptr->assign(err, std::generic_category());
}
else if (ecptr)
*ecptr = ec;
else if (ec)
_GLIBCXX_THROW_OR_ABORT(fs::filesystem_error(
"recursive directory iterator cannot open directory", p, ec));
}
fs::recursive_directory_iterator::~recursive_directory_iterator() = default;
@ -279,7 +298,7 @@ fs::recursive_directory_iterator::increment(error_code& ec) noexcept
if (std::exchange(_M_pending, true) && top.should_recurse(follow, ec))
{
_Dir dir(top.entry.path(), skip_permission_denied, !follow, ec);
_Dir dir = top.open_subdir(skip_permission_denied, !follow, ec);
if (ec)
{
_M_dirs.reset();

View File

@ -63,6 +63,8 @@
#define _GLIBCXX_END_NAMESPACE_FILESYSTEM } }
#include "ops-common.h"
#include <filesystem> // std::filesystem::remove_all
namespace fs = std::experimental::filesystem;
namespace posix = std::filesystem::__gnu_posix;
@ -1098,33 +1100,8 @@ fs::remove_all(const path& p)
std::uintmax_t
fs::remove_all(const path& p, error_code& ec) noexcept
{
const auto s = symlink_status(p, ec);
if (!status_known(s))
return -1;
ec.clear();
if (s.type() == file_type::not_found)
return 0;
uintmax_t count = 0;
if (s.type() == file_type::directory)
{
directory_iterator d(p, directory_options{99}, ec), end;
while (!ec && d != end)
{
const auto removed = fs::remove_all(d->path(), ec);
if (removed == numeric_limits<uintmax_t>::max())
return -1;
count += removed;
d.increment(ec);
}
if (ec)
return -1;
}
if (fs::remove(p, ec))
++count;
return ec ? -1 : count;
// Use the C++17 implementation.
return std::filesystem::remove_all(p.native(), ec);
}
void