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Implement LWG issue 2720. Replace perms::resolve_symlinks with perms::symlink_nofollow.

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This changes how filesystem::permissions(p, perms) handles symlinks. Previously
symlinks were not resolved by default instead only getting resolved when
"perms::resolve_symlinks" was used. After this change symlinks are resolved
by default and perms::symlink_nofollow must be given to change this.

This issue has not yet been moved to Ready status, and I will revert if it
doesn't get moved at the current meeting. However I feel confident that it
will and it's nice to have implementations when moving issues.


git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@273328 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Eric Fiselier
2016-06-21 22:42:42 +00:00
parent 756a6bd177
commit 7c96ddb563
4 changed files with 21 additions and 13 deletions
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8
src/experimental/filesystem/operations.cpp
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@@ -594,7 +594,7 @@ void __last_write_time(const path& p, file_time_type new_time,
void __permissions(const path& p, perms prms, std::error_code *ec)
{
const bool resolve_symlinks = bool(perms::resolve_symlinks & prms);
const bool resolve_symlinks = !bool(perms::symlink_nofollow & prms);
const bool add_perms = bool(perms::add_perms & prms);
const bool remove_perms = bool(perms::remove_perms & prms);
@@ -605,6 +605,8 @@ void __permissions(const path& p, perms prms, std::error_code *ec)
file_status st = detail::posix_lstat(p, &m_ec);
if (m_ec) return set_or_throw(m_ec, ec, "permissions", p);
// AT_SYMLINK_NOFOLLOW can only be used on symlinks, using it on a regular
// file will cause fchmodat to report an error on some systems.
const bool set_sym_perms = is_symlink(st) && !resolve_symlinks;
if ((resolve_symlinks && is_symlink(st)) && (add_perms || remove_perms)) {
@@ -622,14 +624,16 @@ void __permissions(const path& p, perms prms, std::error_code *ec)
# if defined(AT_SYMLINK_NOFOLLOW) && defined(AT_FDCWD)
const int flags = set_sym_perms ? AT_SYMLINK_NOFOLLOW : 0;
if (::fchmodat(AT_FDCWD, p.c_str(), real_perms, flags) == -1) {
return set_or_throw(ec, "permissions", p);
}
# else
if (set_sym_perms)
return set_or_throw(make_error_code(errc::operation_not_supported),
ec, "permissions", p);
if (::chmod(p.c_str(), real_perms) == -1) {
# endif
return set_or_throw(ec, "permissions", p);
}
# endif
if (ec) ec->clear();
}