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To fix issue #137, support racy directory enumerations.
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@ned14
ned14 committed Jul 30, 2024
1 parent 3ebfc74 commit a25485e
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Showing 3 changed files with 118 additions and 85 deletions.
4 changes: 2 additions & 2 deletions .github/workflows/unittests_macos.yml
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Expand Up @@ -11,8 +11,8 @@ on:

jobs:
MacOS:
name: Mac OS 12
runs-on: macos-12
name: Mac OS 13
runs-on: macos-13
strategy:
fail-fast: false
matrix:
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6 changes: 3 additions & 3 deletions include/llfio/revision.hpp
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@@ -1,4 +1,4 @@
// Note the second line of this file must ALWAYS be the git SHA, third line ALWAYS the git SHA update time
#define LLFIO_PREVIOUS_COMMIT_REF c3acf3e42c7f84954d99e4901ad66a3d9d6eb755
#define LLFIO_PREVIOUS_COMMIT_DATE "2024-06-11 17:16:03 +00:00"
#define LLFIO_PREVIOUS_COMMIT_UNIQUE c3acf3e4
#define LLFIO_PREVIOUS_COMMIT_REF 3ebfc74763d7a5048bbe0719472190efce4cda85
#define LLFIO_PREVIOUS_COMMIT_DATE "2024-07-30 13:20:31 +00:00"
#define LLFIO_PREVIOUS_COMMIT_UNIQUE 3ebfc747
193 changes: 113 additions & 80 deletions include/llfio/v2.0/detail/impl/windows/directory_handle.ipp
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Expand Up @@ -326,7 +326,7 @@ result<directory_handle::buffers_type> directory_handle::read(io_request<buffers
directory for all entries + stat structures as a single snapshot.
*/
retry:
size_t kernelbuffertoallocate = 0;
size_t kernelbuffertoallocate = 1024; // starting slop
while(_lock.exchange(1, std::memory_order_relaxed) != 0)
{
std::this_thread::yield();
Expand All @@ -340,21 +340,24 @@ result<directory_handle::buffers_type> directory_handle::read(io_request<buffers
for(;;)
{
IO_STATUS_BLOCK isb = make_iostatus();
memset(_buffer, 0, sizeof(FILE_NAMES_INFORMATION));
NTSTATUS ntstat = NtQueryDirectoryFile(_v.h, nullptr, nullptr, nullptr, &isb, buffer_, sizeof(_buffer), FileNamesInformation, FALSE,
req.glob.empty() ? nullptr : &_glob, first);
if(STATUS_PENDING == ntstat)
{
ntstat = ntwait(_v.h, isb, deadline());
}
if((NTSTATUS) 0x80000006l /*STATUS_NO_MORE_FILES*/ == ntstat || (buffer_->FileNameLength == 0 && buffer_->NextEntryOffset == 0))
{
break;
}
if(ntstat < 0)
{
if((NTSTATUS) 0x80000006l /*STATUS_NO_MORE_FILES*/ == ntstat)
{
break;
}
return ntkernel_error(ntstat);
}
if(isb.Information == 0)
{
break;
}
first = false;
done = false;
for(FILE_NAMES_INFORMATION *fni = buffer_; !done;
Expand Down Expand Up @@ -389,91 +392,121 @@ result<directory_handle::buffers_type> directory_handle::read(io_request<buffers
reinterpret_cast<what_to_enumerate_type *>(req.kernelbuffer.data());
max_bytes = req.kernelbuffer.empty() ? static_cast<ULONG>(req.buffers._kernel_buffer_size) : static_cast<ULONG>(req.kernelbuffer.size());
bytes = std::min(max_bytes, (ULONG) kernelbuffertoallocate);
IO_STATUS_BLOCK isb = make_iostatus();
NTSTATUS ntstat =
NtQueryDirectoryFile(_v.h, nullptr, nullptr, nullptr, &isb, buffer, bytes, what_to_enumerate, FALSE, req.glob.empty() ? nullptr : &_glob, TRUE);
if(STATUS_PENDING == ntstat)
{
ntstat = ntwait(_v.h, isb, deadline());
}
if(ntstat < 0)
{
return ntkernel_error(ntstat);
}
auto *buffer_ = buffer;
size_t entries_parsed = 0;
for(size_t count = 0;; count++)
{
char _buffer[65536 + sizeof(what_to_enumerate_type)];
auto *buffer_ = (what_to_enumerate_type *) _buffer;
isb = make_iostatus();
memset(_buffer, 0, sizeof(what_to_enumerate_type));
ntstat = NtQueryDirectoryFile(_v.h, nullptr, nullptr, nullptr, &isb, buffer_, sizeof(_buffer), what_to_enumerate, TRUE,
req.glob.empty() ? nullptr : &_glob, FALSE);
if(ntstat != (NTSTATUS) 0x80000006 /*STATUS_NO_MORE_FILES*/ && !(buffer_->FileNameLength == 0 && buffer_->NextEntryOffset == 0))
IO_STATUS_BLOCK isb = make_iostatus();
NTSTATUS ntstat =
NtQueryDirectoryFile(_v.h, nullptr, nullptr, nullptr, &isb, buffer_, bytes, what_to_enumerate, FALSE, req.glob.empty() ? nullptr : &_glob, count == 0);
if(STATUS_PENDING == ntstat)
{
ntstat = ntwait(_v.h, isb, deadline());
}
if(ntstat < 0)
{
if(ntstat != (NTSTATUS) 0x80000006 /*STATUS_NO_MORE_FILES*/)
{
return ntkernel_error(ntstat);
}
if(count <= 1)
{
assert(isb.Information == 0);
}
else
{
if(req.flags & flags::permit_racy_reads)
{
req.buffers._snapshot = false;
}
else
{
// The directory has changed since we initially read it, need a bigger buffer
LLFIO_DEADLINE_TO_TIMEOUT_LOOP(d);
goto retry;
}
}
// Fill is complete
req.buffers._resize(entries_parsed);
req.buffers._metadata = default_stat_contents;
req.buffers._done = true;
return std::move(req.buffers);
}
if(count >= 1 && !(req.flags & flags::permit_racy_reads))
{
return errc::operation_would_block;
}
if(isb.Information > bytes - 1024)
{
// The directory has changed since we initially read it, need a bigger buffer
LLFIO_DEADLINE_TO_TIMEOUT_LOOP(d);
goto retry;
}
}
}

size_t n = 0;
bool done = false;
for(what_to_enumerate_type *ffdi = buffer; !done;
ffdi = reinterpret_cast<what_to_enumerate_type *>(reinterpret_cast<uintptr_t>(ffdi) + ffdi->NextEntryOffset))
{
size_t length = ffdi->FileNameLength / sizeof(wchar_t);
done = (ffdi->NextEntryOffset == 0);
if(length <= 2 && '.' == ffdi->FileName[0])
{
if(1 == length || '.' == ffdi->FileName[1])
/* https://github.com/ned14/llfio/issues/137 reports that NT doesn't always fully fill
the buffer supplied for non-obvious reasons, and requires repeated additional enumerations
to get the whole directory.
*/
bool done = false;
for(what_to_enumerate_type *ffdi = buffer_; !done;
ffdi = reinterpret_cast<what_to_enumerate_type *>(reinterpret_cast<uintptr_t>(ffdi) + ffdi->NextEntryOffset))
{
continue;
}
}
directory_entry &item = req.buffers[n];
// Try to zero terminate leafnames where possible for later efficiency
if(reinterpret_cast<uintptr_t>(ffdi->FileName + length) + sizeof(wchar_t) <= reinterpret_cast<uintptr_t>(ffdi) + ffdi->NextEntryOffset)
{
ffdi->FileName[length] = 0;
item.leafname = path_view_type(ffdi->FileName, length, path_view::zero_terminated);
}
else
{
item.leafname = path_view_type(ffdi->FileName, length, path_view::not_zero_terminated);
}
if(req.filtering == filter::fastdeleted && item.leafname.is_llfio_deleted())
{
continue;
}
item.stat = stat_t(nullptr);
size_t length = ffdi->FileNameLength / sizeof(wchar_t);
done = (ffdi->NextEntryOffset == 0);
if(length <= 2 && '.' == ffdi->FileName[0])
{
if(1 == length || '.' == ffdi->FileName[1])
{
continue;
}
}
directory_entry &item = req.buffers[entries_parsed];
// Try to zero terminate leafnames where possible for later efficiency
if(reinterpret_cast<uintptr_t>(ffdi->FileName + length) + sizeof(wchar_t) <= reinterpret_cast<uintptr_t>(ffdi) + ffdi->NextEntryOffset)
{
ffdi->FileName[length] = 0;
item.leafname = path_view_type(ffdi->FileName, length, path_view::zero_terminated);
}
else
{
item.leafname = path_view_type(ffdi->FileName, length, path_view::not_zero_terminated);
}
if(req.filtering == filter::fastdeleted && item.leafname.is_llfio_deleted())
{
continue;
}
item.stat = stat_t(nullptr);
#ifndef LLFIO_DIRECTORY_HANDLE_ENUMERATE_LESS_INFO
item.stat.st_ino = ffdi->FileId.QuadPart;
item.stat.st_type = to_st_type(ffdi->FileAttributes, ffdi->ReparsePointTag);
item.stat.st_ino = ffdi->FileId.QuadPart;
item.stat.st_type = to_st_type(ffdi->FileAttributes, ffdi->ReparsePointTag);
#else
item.stat.st_type = to_st_type(ffdi->FileAttributes, IO_REPARSE_TAG_SYMLINK /* not accurate, but best we can do */);
item.stat.st_type = to_st_type(ffdi->FileAttributes, IO_REPARSE_TAG_SYMLINK /* not accurate, but best we can do */);
#endif
item.stat.st_atim = to_timepoint(ffdi->LastAccessTime);
item.stat.st_mtim = to_timepoint(ffdi->LastWriteTime);
item.stat.st_ctim = to_timepoint(ffdi->ChangeTime);
item.stat.st_size = ffdi->EndOfFile.QuadPart;
item.stat.st_allocated = ffdi->AllocationSize.QuadPart;
item.stat.st_birthtim = to_timepoint(ffdi->CreationTime);
item.stat.st_sparse = static_cast<unsigned int>((ffdi->FileAttributes & FILE_ATTRIBUTE_SPARSE_FILE) != 0u);
item.stat.st_compressed = static_cast<unsigned int>((ffdi->FileAttributes & FILE_ATTRIBUTE_COMPRESSED) != 0u);
item.stat.st_reparse_point = static_cast<unsigned int>((ffdi->FileAttributes & FILE_ATTRIBUTE_REPARSE_POINT) != 0u);
n++;
if(!done && n >= req.buffers.size())
{
// Fill is incomplete
req.buffers._metadata = default_stat_contents;
req.buffers._done = false;
return std::move(req.buffers);
item.stat.st_atim = to_timepoint(ffdi->LastAccessTime);
item.stat.st_mtim = to_timepoint(ffdi->LastWriteTime);
item.stat.st_ctim = to_timepoint(ffdi->ChangeTime);
item.stat.st_size = ffdi->EndOfFile.QuadPart;
item.stat.st_allocated = ffdi->AllocationSize.QuadPart;
item.stat.st_birthtim = to_timepoint(ffdi->CreationTime);
item.stat.st_sparse = static_cast<unsigned int>((ffdi->FileAttributes & FILE_ATTRIBUTE_SPARSE_FILE) != 0u);
item.stat.st_compressed = static_cast<unsigned int>((ffdi->FileAttributes & FILE_ATTRIBUTE_COMPRESSED) != 0u);
item.stat.st_reparse_point = static_cast<unsigned int>((ffdi->FileAttributes & FILE_ATTRIBUTE_REPARSE_POINT) != 0u);
entries_parsed++;
if(!done && entries_parsed >= req.buffers.size())
{
// Fill is incomplete
req.buffers._metadata = default_stat_contents;
req.buffers._done = false;
return std::move(req.buffers);
}
if(done)
{
auto whattoadd = (7 + offsetof(what_to_enumerate_type, FileName) + ffdi->FileNameLength) & ~7;
buffer_ = reinterpret_cast<what_to_enumerate_type *>(reinterpret_cast<uintptr_t>(ffdi) + whattoadd);
bytes -= whattoadd;
}
}
}
}
// Fill is complete
req.buffers._resize(n);
req.buffers._metadata = default_stat_contents;
req.buffers._done = true;
return std::move(req.buffers);
}

LLFIO_V2_NAMESPACE_END

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