Hello Michael,
12.07.2021 08:52, Michael Paquier wrote:
> On Mon, Jul 12, 2021 at 02:09:41PM +0900, Michael Paquier wrote:
>> And fairywren, that uses MinGW, is unhappy:
>> https://buildfarm.postgresql.org/cgi-bin/show_log.pl?nm=fairywren&dt=2021-07-12%2004%3A47%3A13
>> Looking at it now.
> I am not sure what to do here to cool down MinGW, so the patch has
> been reverted for now:
> - Plain stat() is not enough to do a proper detection of the files
> pending for deletion on MSVC, so reverting only the part with
> microsoft_native_stat() is not going to help.
> - We are going to need an evaluation of the stat() implementation in
> MinGW and check if is it possible to rely on it more. If yes, we
> could get away with more tweaks based on __MINGW32__/__MINGW64__.
I've managed to adapt open/win32stat for MinGW by preventing stat
overriding at the implementation level. Thus, the code that calls stat()
will use the overridden struct/function(s), but inside of
open/win32_stat we could access original stat and reference to
__pgstat64 where we want to use our.
Tested on MSVC, MinGW64 and MinGW32 — the fixed code compiles everywhere.
But when using perl from msys (not ActivePerl) while testing I've got
the same test failure due to another error condition:
In this case CreateFile() fails with ERROR_SHARING_VIOLATION (not
ERROR_ACCESS_DENIED) and it leads to the same "Permission denied" error.
This condition is handled in the pgwin32_open() but not in _pgstat64() yet.
I think I should develop another test for MSVC environment that will
demonstrate a such failure too.
But as it's not related to the DELETE_PENDING state, I wonder whether
this should be fixed in a separate patch.
Best regards,
Alexander
diff --git a/src/include/port/win32_port.h b/src/include/port/win32_port.h
index 05c5a53442..d72950880a 100644
--- a/src/include/port/win32_port.h
+++ b/src/include/port/win32_port.h
@@ -53,11 +53,13 @@
#undef near
/* needed before sys/stat hacking below: */
+#if !defined(NO_STAT_OVERRIDE)
#define fstat microsoft_native_fstat
#define stat microsoft_native_stat
#include <sys/stat.h>
#undef fstat
#undef stat
+#endif
/* Must be here to avoid conflicting with prototype in windows.h */
#define mkdir(a,b) mkdir(a)
@@ -253,7 +255,7 @@ typedef int pid_t;
* The struct stat is 32 bit in MSVC, so we redefine it as a copy of
* struct __stat64. This also fixes the struct size for MINGW builds.
*/
-struct stat /* This should match struct __stat64 */
+struct _pgstat64 /* This should match struct __stat64 */
{
_dev_t st_dev;
_ino_t st_ino;
@@ -268,12 +270,14 @@ struct stat /* This should match struct __stat64 */
__time64_t st_ctime;
};
-extern int _pgfstat64(int fileno, struct stat *buf);
-extern int _pgstat64(const char *name, struct stat *buf);
+extern int _pgfstat64(int fileno, struct _pgstat64 *buf);
+extern int _pgstat64(const char *name, struct _pgstat64 *buf);
+#if !defined(NO_STAT_OVERRIDE)
#define fstat(fileno, sb) _pgfstat64(fileno, sb)
-#define stat(path, sb) _pgstat64(path, sb)
+#define stat _pgstat64
#define lstat(path, sb) _pgstat64(path, sb)
+#endif
/* These macros are not provided by older MinGW, nor by MSVC */
#ifndef S_IRUSR
diff --git a/src/port/open.c b/src/port/open.c
index 14c6debba9..09144351a4 100644
--- a/src/port/open.c
+++ b/src/port/open.c
@@ -13,6 +13,7 @@
#ifdef WIN32
+#define NO_STAT_OVERRIDE
#ifndef FRONTEND
#include "postgres.h"
#else
diff --git a/src/port/win32stat.c b/src/port/win32stat.c
index 2ad8ee1359..1c9c01cc98 100644
--- a/src/port/win32stat.c
+++ b/src/port/win32stat.c
@@ -15,54 +15,10 @@
#ifdef WIN32
+#define NO_STAT_OVERRIDE
#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 */
+#include <sys/stat.h>
/*
@@ -112,7 +68,7 @@ fileattr_to_unixmode(int attr)
* Convert WIN32 file information (from a HANDLE) to a struct stat.
*/
static int
-fileinfo_to_stat(HANDLE hFile, struct stat *buf)
+fileinfo_to_stat(HANDLE hFile, struct _pgstat64 *buf)
{
BY_HANDLE_FILE_INFORMATION fiData;
@@ -159,119 +115,83 @@ fileinfo_to_stat(HANDLE hFile, struct stat *buf)
* This currently also implements lstat(), though perhaps that should change.
*/
int
-_pgstat64(const char *name, struct stat *buf)
+_pgstat64(const char *name, struct _pgstat64 *buf)
{
/*
* We must use a handle so lstat() returns the information of the target
- * file. To have a reliable test for ERROR_DELETE_PENDING, we use
- * NtQueryInformationFile from Windows 2000 or
- * GetFileInformationByHandleEx from Server 2008 / Vista.
+ * file. To have a reliable test for ERROR_DELETE_PENDING, this uses a
+ * method similar to open() with a loop using stat() and some waits when
+ * facing ERROR_ACCESS_DENIED.
*/
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;
- }
-
- /* 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)
{
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)
+ if (err != ERROR_ACCESS_DENIED)
{
- DWORD err = GetLastError();
-
- CloseHandle(hFile);
- _dosmaperr(err);
- return -1;
- }
-
- _NtQueryInformationFile = (PFN_NTQUERYINFORMATIONFILE) (pg_funcptr_t)
- GetProcAddress(ntdll, "NtQueryInformationFile");
- if (_NtQueryInformationFile == NULL)
- {
- DWORD err = GetLastError();
-
- CloseHandle(hFile);
_dosmaperr(err);
return -1;
}
}
- 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)))
+ /* get a file handle as lightweight as we can */
+ sa.nLength = sizeof(SECURITY_ATTRIBUTES);
+ sa.bInheritHandle = TRUE;
+ sa.lpSecurityDescriptor = NULL;
+ 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;
- }
-#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.
+ * 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.
*/
- CloseHandle(hFile);
- errno = ENOENT;
+ if (err == ERROR_ACCESS_DENIED)
+ {
+ if (loops < 10)
+ {
+ struct stat st;
+
+ if (stat(name, &st) != 0)
+ {
+ pg_usleep(100000);
+ loops++;
+ continue;
+ }
+ }
+ }
+
+ _dosmaperr(err);
return -1;
}
@@ -286,7 +206,7 @@ _pgstat64(const char *name, struct stat *buf)
* Windows implementation of fstat().
*/
int
-_pgfstat64(int fileno, struct stat *buf)
+_pgfstat64(int fileno, struct _pgstat64 *buf)
{
HANDLE hFile = (HANDLE) _get_osfhandle(fileno);
