Currently the _Dir::open_subdir function decides whether to construct a
_Dir_base with just a pathname, or a file descriptor and pathname. But
that means it is tightly coupled to the implementation of
_Dir_base::openat, which is what actually decides whether to use a file
descriptor or not. If the derived class passes a file descriptor and
filename, but the base class expects a full path and ignores the file
descriptor, then recursive_directory_iterator cannot recurse.
This change introduces a new type that provides the union of all the
information available to the derived class (the full pathname, as well
as a file descriptor for a directory and another pathname relative to
that directory). This allows the derived class to be agnostic to how the
base class will use that information.
libstdc++-v3/ChangeLog:
* src/c++17/fs_dir.cc (_Dir::dir_and_pathname):: Replace with
current() returning _At_path.
(_Dir::_Dir, _Dir::open_subdir, _Dir::do_unlink): Adjust.
* src/filesystem/dir-common.h (_Dir_base::_At_path): New class.
(_Dir_base::_Dir_Base, _Dir_base::openat): Use _At_path.
* src/filesystem/dir.cc (_Dir::dir_and_pathname): Replace with
current() returning _At_path.
(_Dir::_Dir, _Dir::open_subdir): Adjust.
(cherry picked from commit
198781144f33b0ef17dd2094580b5c77ad97d6e8)
{
_Dir(const fs::path& p, bool skip_permission_denied, bool nofollow,
[[maybe_unused]] bool filename_only, error_code& ec)
- : _Dir_base(fdcwd(), p.c_str(), skip_permission_denied, nofollow, ec)
+ : _Dir_base(p.c_str(), skip_permission_denied, nofollow, ec)
{
#if _GLIBCXX_HAVE_DIRFD && _GLIBCXX_HAVE_OPENAT && _GLIBCXX_HAVE_UNLINKAT
if (filename_only)
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
+ // Return a pathname for the current directory entry, as an _At_path.
+ _Dir_base::_At_path
+ current() const noexcept
{
const fs::path& p = entry.path();
-#if _GLIBCXX_HAVE_DIRFD && _GLIBCXX_HAVE_OPENAT
- if (!p.empty())
- return {::dirfd(this->dirp), std::prev(p.end())->c_str()};
+#if _GLIBCXX_HAVE_DIRFD
+ if (!p.empty()) [[__likely__]]
+ {
+ auto len = std::prev(p.end())->native().size();
+ return {::dirfd(this->dirp), p.c_str(), p.native().size() - len};
+ }
#endif
- return {this->fdcwd(), p.c_str()};
+ return p.c_str();
}
// Create a new _Dir for the directory this->entry.path().
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);
+ _Dir_base d(current(), 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::move(d), p);
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)
+ const auto atp = current();
+ if (::unlinkat(atp.dir(), atp.path_at_dir(),
+ is_directory ? AT_REMOVEDIR : 0) == -1)
{
ec.assign(errno, std::generic_category());
return false;
#ifndef _GLIBCXX_DIR_COMMON_H
#define _GLIBCXX_DIR_COMMON_H 1
+#include <stdint.h> // uint32_t
#include <string.h> // strcmp
#include <errno.h>
#if _GLIBCXX_FILESYSTEM_IS_WINDOWS
struct _Dir_base
{
+ // As well as the full pathname (including the directory iterator's path)
+ // this type contains a file descriptor for a directory and a second pathname
+ // relative to that directory. The file descriptor and relative pathname
+ // can be used with POSIX openat and unlinkat.
+ struct _At_path
+ {
+ // No file descriptor given, so interpret the pathname relative to the CWD.
+ _At_path(const posix::char_type* p) noexcept
+ : pathname(p), dir_fd(fdcwd()), offset(0)
+ { }
+
+ _At_path(int fd, const posix::char_type* p, size_t offset) noexcept
+ : pathname(p), dir_fd(fd), offset(offset)
+ { }
+
+ const posix::char_type*
+ path() const noexcept { return pathname; }
+
+ int
+ dir() const noexcept { return dir_fd; }
+
+ const posix::char_type*
+ path_at_dir() const noexcept { return pathname + offset; }
+
+ private:
+ const posix::char_type* pathname; // Full path relative to CWD.
+ int dir_fd; // A directory descriptor (either the parent dir, or AT_FDCWD).
+ uint32_t offset; // Offset into pathname for the part relative to dir_fd.
+
+ // Special value representing the current working directory.
+ // Not a valid file descriptor for an open directory stream.
+ static constexpr int
+ fdcwd() noexcept
+ {
+#ifdef AT_FDCWD
+ return AT_FDCWD;
+#else
+ return -1; // Use invalid fd if AT_FDCWD isn't supported.
+#endif
+ }
+ };
+
// If no error occurs then dirp is non-null,
// otherwise null (even if a permission denied error is ignored).
- _Dir_base(int fd, const posix::char_type* pathname,
+ _Dir_base(const _At_path& atp,
bool skip_permission_denied, bool nofollow,
error_code& ec) noexcept
- : dirp(_Dir_base::openat(fd, pathname, nofollow))
+ : dirp(_Dir_base::openat(atp, nofollow))
{
if (dirp)
ec.clear();
}
}
- 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, ".."); }
}
static posix::DIR*
- openat(int fd, const posix::char_type* pathname, bool nofollow)
+ openat(const _At_path& atp, bool nofollow)
{
#if _GLIBCXX_HAVE_FDOPENDIR && defined O_RDONLY && defined O_DIRECTORY \
&& ! _GLIBCXX_FILESYSTEM_IS_WINDOWS
nofollow = false;
#endif
+ int fd;
-#if _GLIBCXX_HAVE_OPENAT && defined AT_FDCWD
- fd = ::openat(fd, pathname, flags);
+#if _GLIBCXX_HAVE_OPENAT
+ fd = ::openat(atp.dir(), atp.path_at_dir(), 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);
+ return posix::opendir(atp.path());
- fd = ::open(pathname, flags);
+ fd = ::open(atp.path(), flags);
#endif
if (fd == -1)
errno = err;
return nullptr;
#else
- return posix::opendir(pathname);
+ return posix::opendir(atp.path());
#endif
}
{
_Dir(const fs::path& p, bool skip_permission_denied, bool nofollow,
error_code& ec)
- : _Dir_base(this->fdcwd(), p.c_str(), skip_permission_denied, nofollow, ec)
+ : _Dir_base(p.c_str(), skip_permission_denied, nofollow, ec)
{
if (!ec)
path = p;
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
+ // Return a pathname for the current directory entry, as an _At_path.
+ _Dir_base::_At_path
+ current() const noexcept
{
const fs::path& p = entry.path();
-#if _GLIBCXX_HAVE_DIRFD && _GLIBCXX_HAVE_OPENAT
- return {::dirfd(this->dirp), std::prev(p.end())->c_str()};
+#if _GLIBCXX_HAVE_DIRFD
+ auto len = std::prev(p.end())->native().size();
+ return {::dirfd(this->dirp), p.c_str(), p.native().size() - len};
+#else
+ return p.c_str();
#endif
- return {this->fdcwd(), p.c_str()};
}
// Create a new _Dir for the directory this->entry.path().
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);
+ _Dir_base d(current(), skip_permission_denied, nofollow, ec);
return _Dir(std::move(d), entry.path());
}
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