08.07.2021 10:47, Michael Paquier wrote:
> On Thu, Jul 08, 2021 at 07:00:01AM +0300, Alexander Lakhin wrote:
>> As Tom Lane noted above, the code added with bed90759f is dubious
>> (_NtQueryInformationFile() can not be used to handle the "delete
>> pending" state as CreateFile() returns INVALID_HANDLE_VALUE in this case.)
>> Probably that change should be reverted. Should I do it along with the
>> proposed fix?
> Ah, I see. I have managed to miss your point. If
> _NtQueryInformationFile() cannot be used, then we'd actually miss the
> contents for standardInfo and the pending deletion. If you could send
> everything you have, that would be helpful! I'd like to test that
> stuff by myself, with all the contents discussed at disposal for a
> proper evaluation.
> --
Beside the aforementioned test I can only propose the extended patch,
that incorporates the undo of the changes brought by bed90759f.
With this patch that test is passed.
Best regards,
Alexander
diff --git a/src/backend/utils/adt/genfile.c b/src/backend/utils/adt/genfile.c
index c436d9318b..a8c22a81d0 100644
--- a/src/backend/utils/adt/genfile.c
+++ b/src/backend/utils/adt/genfile.c
@@ -28,6 +28,7 @@
#include "funcapi.h"
#include "mb/pg_wchar.h"
#include "miscadmin.h"
+#include "port.h"
#include "postmaster/syslogger.h"
#include "storage/fd.h"
#include "utils/acl.h"
diff --git a/src/port/win32stat.c b/src/port/win32stat.c
index 2ad8ee1359..6028ad809e 100644
--- a/src/port/win32stat.c
+++ b/src/port/win32stat.c
@@ -18,53 +18,6 @@
#include "c.h"
#include <windows.h>
-/*
- * In order to support MinGW and MSVC2013 we use NtQueryInformationFile as an
- * alternative for GetFileInformationByHandleEx. It is loaded from the ntdll
- * library.
- */
-#if _WIN32_WINNT < 0x0600
-#include <winternl.h>
-
-#if !defined(__MINGW32__) && !defined(__MINGW64__)
-/* MinGW includes this in <winternl.h>, but it is missing in MSVC */
-typedef struct _FILE_STANDARD_INFORMATION
-{
- LARGE_INTEGER AllocationSize;
- LARGE_INTEGER EndOfFile;
- ULONG NumberOfLinks;
- BOOLEAN DeletePending;
- BOOLEAN Directory;
-} FILE_STANDARD_INFORMATION;
-#define FileStandardInformation 5
-#endif /* !defined(__MINGW32__) &&
- * !defined(__MINGW64__) */
-
-typedef NTSTATUS (NTAPI * PFN_NTQUERYINFORMATIONFILE)
- (IN HANDLE FileHandle,
- OUT PIO_STATUS_BLOCK IoStatusBlock,
- OUT PVOID FileInformation,
- IN ULONG Length,
- IN FILE_INFORMATION_CLASS FileInformationClass);
-
-static PFN_NTQUERYINFORMATIONFILE _NtQueryInformationFile = NULL;
-
-static HMODULE ntdll = NULL;
-
-/*
- * Load DLL file just once regardless of how many functions we load/call in it.
- */
-static void
-LoadNtdll(void)
-{
- if (ntdll != NULL)
- return;
- ntdll = LoadLibraryEx("ntdll.dll", NULL, 0);
-}
-
-#endif /* _WIN32_WINNT < 0x0600 */
-
-
/*
* Convert a FILETIME struct into a 64 bit time_t.
*/
@@ -170,110 +123,73 @@ _pgstat64(const char *name, struct stat *buf)
SECURITY_ATTRIBUTES sa;
HANDLE hFile;
int ret;
-#if _WIN32_WINNT < 0x0600
- IO_STATUS_BLOCK ioStatus;
- FILE_STANDARD_INFORMATION standardInfo;
-#else
- FILE_STANDARD_INFO standardInfo;
-#endif
+ int loops = 0;
if (name == NULL || buf == NULL)
{
errno = EINVAL;
return -1;
}
-
/* fast not-exists check */
if (GetFileAttributes(name) == INVALID_FILE_ATTRIBUTES)
{
- _dosmaperr(GetLastError());
- return -1;
+ DWORD err = GetLastError();
+
+ if (err != ERROR_ACCESS_DENIED) {
+ _dosmaperr(err);
+ return -1;
+ }
}
/* get a file handle as lightweight as we can */
sa.nLength = sizeof(SECURITY_ATTRIBUTES);
sa.bInheritHandle = TRUE;
sa.lpSecurityDescriptor = NULL;
- hFile = CreateFile(name,
- GENERIC_READ,
- (FILE_SHARE_READ | FILE_SHARE_WRITE | FILE_SHARE_DELETE),
- &sa,
- OPEN_EXISTING,
- (FILE_FLAG_NO_BUFFERING | FILE_FLAG_BACKUP_SEMANTICS |
- FILE_FLAG_OVERLAPPED),
- NULL);
- if (hFile == INVALID_HANDLE_VALUE)
+ while ((hFile = CreateFile(name,
+ GENERIC_READ,
+ (FILE_SHARE_READ | FILE_SHARE_WRITE | FILE_SHARE_DELETE),
+ &sa,
+ OPEN_EXISTING,
+ (FILE_FLAG_NO_BUFFERING | FILE_FLAG_BACKUP_SEMANTICS |
+ FILE_FLAG_OVERLAPPED),
+ NULL)) == INVALID_HANDLE_VALUE)
{
DWORD err = GetLastError();
- CloseHandle(hFile);
- _dosmaperr(err);
- return -1;
- }
-
- memset(&standardInfo, 0, sizeof(standardInfo));
-
-#if _WIN32_WINNT < 0x0600
- if (_NtQueryInformationFile == NULL)
- {
- /* First time through: load ntdll.dll and find NtQueryInformationFile */
- LoadNtdll();
- if (ntdll == NULL)
- {
- DWORD err = GetLastError();
-
- CloseHandle(hFile);
- _dosmaperr(err);
- return -1;
- }
-
- _NtQueryInformationFile = (PFN_NTQUERYINFORMATIONFILE) (pg_funcptr_t)
- GetProcAddress(ntdll, "NtQueryInformationFile");
- if (_NtQueryInformationFile == NULL)
+ /*
+ * ERROR_ACCESS_DENIED is returned if the file is deleted but not yet
+ * gone (Windows NT status code is STATUS_DELETE_PENDING). In that
+ * case we want to wait a bit and try again, giving up after 1 second
+ * (since this condition should never persist very long). However,
+ * there are other commonly-hit cases that return ERROR_ACCESS_DENIED,
+ * so care is needed. In particular that happens if we try to open a
+ * directory, or of course if there's an actual file-permissions
+ * problem. To distinguish these cases, try a stat(). In the
+ * delete-pending case, it will either also get STATUS_DELETE_PENDING,
+ * or it will see the file as gone and fail with ENOENT. In other
+ * cases it will usually succeed. The only somewhat-likely case where
+ * this coding will uselessly wait is if there's a permissions problem
+ * with a containing directory, which we hope will never happen in any
+ * performance-critical code paths.
+ */
+ if (err == ERROR_ACCESS_DENIED)
{
- DWORD err = GetLastError();
-
- CloseHandle(hFile);
- _dosmaperr(err);
- return -1;
+ if (loops < 10)
+ {
+ struct microsoft_native_stat st;
+
+ if (microsoft_native_stat(name, &st) != 0)
+ {
+ pg_usleep(100000);
+ loops++;
+ continue;
+ }
+ }
}
- }
-
- if (!NT_SUCCESS(_NtQueryInformationFile(hFile, &ioStatus, &standardInfo,
- sizeof(standardInfo),
- FileStandardInformation)))
- {
- DWORD err = GetLastError();
-
- CloseHandle(hFile);
- _dosmaperr(err);
- return -1;
- }
-#else
- if (!GetFileInformationByHandleEx(hFile, FileStandardInfo, &standardInfo,
- sizeof(standardInfo)))
- {
- DWORD err = GetLastError();
- CloseHandle(hFile);
_dosmaperr(err);
return -1;
}
-#endif /* _WIN32_WINNT < 0x0600 */
-
- if (standardInfo.DeletePending)
- {
- /*
- * File has been deleted, but is not gone from the filesystem yet.
- * This can happen when some process with FILE_SHARE_DELETE has it
- * open, and it will be fully removed once that handle is closed.
- * Meanwhile, we can't open it, so indicate that the file just doesn't
- * exist.
- */
- CloseHandle(hFile);
- errno = ENOENT;
- return -1;
- }
/* At last we can invoke fileinfo_to_stat */
ret = fileinfo_to_stat(hFile, buf);
