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Commit56b39cc

Browse files
macdiceadunstan
authored andcommitted
Check for STATUS_DELETE_PENDING on Windows.
1. Update our open() wrapper to check for NT's STATUS_DELETE_PENDINGand translate it to Unix-like errors. This is done withRtlGetLastNtStatus(), which is dynamically loaded from ntdll. A newfile win32ntdll.c centralizes lookup of NT functions, in case we decideto add more in the future.2. Remove non-working code that was trying to do something similar forstat(), and just reuse the open() wrapper code. As a side effect,stat() also gains resilience against "sharing violation" errors.3. Since stat() is used very early in process startup, remove therequirement that the Win32 signal event has been created beforepgwin32_open_handle() is reached. Instead, teach pg_usleep() to fallback to a non-interruptible sleep if reached before the signal event isavailable.This could be back-patched, but for now it's in master only. Theproblem has apparently been with us for a long time and generated only afew complaints. Proposed patches trigger it more often, which led tothis investigation and fix.Reviewed-by: Andres Freund <andres@anarazel.de>Reviewed-by: Alexander Lakhin <exclusion@gmail.com>Reviewed-by: Juan José Santamaría Flecha <juanjo.santamaria@gmail.com>Discussion:https://postgr.es/m/CA%2BhUKGJz_pZTF9mckn6XgSv69%2BjGwdgLkxZ6b3NWGLBCVjqUZA%40mail.gmail.com(cherry picked from commite2f0f8e)Author: Thomas Munro <tmunro@postgresql.org>Author: Alexandra Wang <alexandra.wang.oss@gmail.com>
1 parentb4363fc commit56b39cc

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9 files changed

+179
-122
lines changed

9 files changed

+179
-122
lines changed

‎configure

Lines changed: 6 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -16638,6 +16638,12 @@ esac
1663816638
;;
1663916639
esac
1664016640

16641+
case " $LIBOBJS " in
16642+
*" win32ntdll.$ac_objext "* ) ;;
16643+
*) LIBOBJS="$LIBOBJS win32ntdll.$ac_objext"
16644+
;;
16645+
esac
16646+
1664116647
case " $LIBOBJS " in
1664216648
*" win32security.$ac_objext "* ) ;;
1664316649
*) LIBOBJS="$LIBOBJS win32security.$ac_objext"

‎configure.in

Lines changed: 1 addition & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -1879,6 +1879,7 @@ if test "$PORTNAME" = "win32"; then
18791879
AC_LIBOBJ(system)
18801880
AC_LIBOBJ(win32env)
18811881
AC_LIBOBJ(win32error)
1882+
AC_LIBOBJ(win32ntdll)
18821883
AC_LIBOBJ(win32security)
18831884
AC_LIBOBJ(win32setlocale)
18841885
AC_LIBOBJ(win32stat)

‎src/backend/port/win32/signal.c

Lines changed: 11 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -52,7 +52,17 @@ static BOOL WINAPI pg_console_handler(DWORD dwCtrlType);
5252
void
5353
pg_usleep(longmicrosec)
5454
{
55-
Assert(pgwin32_signal_event!=NULL);
55+
if (unlikely(pgwin32_signal_event==NULL))
56+
{
57+
/*
58+
* If we're reached by pgwin32_open_handle() early in startup before
59+
* the signal event is set up, just fall back to a regular
60+
* non-interruptible sleep.
61+
*/
62+
SleepEx((microsec<500 ?1 : (microsec+500) /1000), FALSE);
63+
return;
64+
}
65+
5666
if (WaitForSingleObject(pgwin32_signal_event,
5767
(microsec<500 ?1 : (microsec+500) /1000))
5868
==WAIT_OBJECT_0)

‎src/include/port.h

Lines changed: 1 addition & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -280,6 +280,7 @@ extern bool rmtree(const char *path, bool rmtopdir);
280280
* passing of other special options.
281281
*/
282282
#defineO_DIRECT0x80000000
283+
externHANDLEpgwin32_open_handle(constchar*,int,bool);
283284
externintpgwin32_open(constchar*,int,...);
284285
externFILE*pgwin32_fopen(constchar*,constchar*);
285286
#defineopen(a,b,c) pgwin32_open(a,b,c)

‎src/include/port/win32ntdll.h

Lines changed: 27 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,27 @@
1+
/*-------------------------------------------------------------------------
2+
*
3+
* win32ntdll.h
4+
* Dynamically loaded Windows NT functions.
5+
*
6+
* Portions Copyright (c) 2021, PostgreSQL Global Development Group
7+
* Portions Copyright (c) 1994, Regents of the University of California
8+
*
9+
* src/include/port/win32ntdll.h
10+
*
11+
*-------------------------------------------------------------------------
12+
*/
13+
14+
/*
15+
* Because this includes NT headers that normally conflict with Win32 headers,
16+
* any translation unit that includes it should #define UMDF_USING_NTSTATUS
17+
* before including <windows.h>.
18+
*/
19+
20+
#include<ntstatus.h>
21+
#include<winternl.h>
22+
23+
typedefNTSTATUS (__stdcall*RtlGetLastNtStatus_t) (void);
24+
25+
externRtlGetLastNtStatus_tpg_RtlGetLastNtStatus;
26+
27+
externintinitialize_ntdll(void);

‎src/port/open.c

Lines changed: 56 additions & 48 deletions
Original file line numberDiff line numberDiff line change
@@ -13,17 +13,20 @@
1313

1414
#ifdefWIN32
1515

16+
#defineUMDF_USING_NTSTATUS
17+
1618
#ifndefFRONTEND
1719
#include"postgres.h"
1820
#else
1921
#include"postgres_fe.h"
2022
#endif
2123

24+
#include"port/win32ntdll.h"
25+
2226
#include<fcntl.h>
2327
#include<assert.h>
2428
#include<sys/stat.h>
2529

26-
2730
staticint
2831
openFlagsToCreateFileFlags(intopenFlags)
2932
{
@@ -56,38 +59,25 @@ openFlagsToCreateFileFlags(int openFlags)
5659
}
5760

5861
/*
59-
* - file attribute setting, based on fileMode?
62+
* Internal function used by pgwin32_open() and _pgstat64(). When
63+
* backup_semantics is true, directories may be opened (for limited uses). On
64+
* failure, INVALID_HANDLE_VALUE is returned and errno is set.
6065
*/
61-
int
62-
pgwin32_open(constchar*fileName,intfileFlags,...)
66+
HANDLE
67+
pgwin32_open_handle(constchar*fileName,intfileFlags,boolbackup_semantics)
6368
{
64-
intfd;
65-
HANDLEh=INVALID_HANDLE_VALUE;
69+
HANDLEh;
6670
SECURITY_ATTRIBUTESsa;
6771
intloops=0;
6872

73+
if (initialize_ntdll()<0)
74+
returnINVALID_HANDLE_VALUE;
75+
6976
/* Check that we can handle the request */
7077
assert((fileFlags& ((O_RDONLY |O_WRONLY |O_RDWR) |O_APPEND |
7178
(O_RANDOM |O_SEQUENTIAL |O_TEMPORARY) |
7279
_O_SHORT_LIVED |O_DSYNC |O_DIRECT |
7380
(O_CREAT |O_TRUNC |O_EXCL) | (O_TEXT |O_BINARY)))==fileFlags);
74-
#ifndefFRONTEND
75-
Assert(pgwin32_signal_event!=NULL);/* small chance of pg_usleep() */
76-
#endif
77-
78-
#ifdefFRONTEND
79-
80-
/*
81-
* Since PostgreSQL 12, those concurrent-safe versions of open() and
82-
* fopen() can be used by frontends, having as side-effect to switch the
83-
* file-translation mode from O_TEXT to O_BINARY if none is specified.
84-
* Caller may want to enforce the binary or text mode, but if nothing is
85-
* defined make sure that the default mode maps with what versions older
86-
* than 12 have been doing.
87-
*/
88-
if ((fileFlags&O_BINARY)==0)
89-
fileFlags |=O_TEXT;
90-
#endif
9181

9282
sa.nLength=sizeof(sa);
9383
sa.bInheritHandle= TRUE;
@@ -102,6 +92,7 @@ pgwin32_open(const char *fileName, int fileFlags,...)
10292
&sa,
10393
openFlagsToCreateFileFlags(fileFlags),
10494
FILE_ATTRIBUTE_NORMAL |
95+
(backup_semantics ?FILE_FLAG_BACKUP_SEMANTICS :0) |
10596
((fileFlags&O_RANDOM) ?FILE_FLAG_RANDOM_ACCESS :0) |
10697
((fileFlags&O_SEQUENTIAL) ?FILE_FLAG_SEQUENTIAL_SCAN :0) |
10798
((fileFlags&_O_SHORT_LIVED) ?FILE_ATTRIBUTE_TEMPORARY :0) |
@@ -140,38 +131,55 @@ pgwin32_open(const char *fileName, int fileFlags,...)
140131
/*
141132
* ERROR_ACCESS_DENIED is returned if the file is deleted but not yet
142133
* gone (Windows NT status code is STATUS_DELETE_PENDING). In that
143-
* case we want to wait a bit and try again, giving up after 1 second
144-
* (since this condition should never persist very long). However,
145-
* there are other commonly-hit cases that return ERROR_ACCESS_DENIED,
146-
* so care is needed. In particular that happens if we try to open a
147-
* directory, or of course if there's an actual file-permissions
148-
* problem. To distinguish these cases, try a stat(). In the
149-
* delete-pending case, it will either also get STATUS_DELETE_PENDING,
150-
* or it will see the file as gone and fail with ENOENT. In other
151-
* cases it will usually succeed. The only somewhat-likely case where
152-
* this coding will uselessly wait is if there's a permissions problem
153-
* with a containing directory, which we hope will never happen in any
154-
* performance-critical code paths.
134+
* case, we'd better ask for the NT status too so we can translate it
135+
* to a more Unix-like error. We hope that nothing clobbers the NT
136+
* status in between the internal NtCreateFile() call and CreateFile()
137+
* returning.
138+
*
139+
* If there's no O_CREAT flag, then we'll pretend the file is
140+
* invisible. With O_CREAT, we have no choice but to report that
141+
* there's a file in the way (which wouldn't happen on Unix).
155142
*/
156-
if (err==ERROR_ACCESS_DENIED)
143+
if (err==ERROR_ACCESS_DENIED&&
144+
pg_RtlGetLastNtStatus()==STATUS_DELETE_PENDING)
157145
{
158-
if (loops<10)
159-
{
160-
structmicrosoft_native_statst;
161-
162-
if (microsoft_native_stat(fileName,&st)!=0)
163-
{
164-
pg_usleep(100000);
165-
loops++;
166-
continue;
167-
}
168-
}
146+
if (fileFlags&O_CREAT)
147+
err=ERROR_FILE_EXISTS;
148+
else
149+
err=ERROR_FILE_NOT_FOUND;
169150
}
170151

171152
_dosmaperr(err);
172-
return-1;
153+
returnINVALID_HANDLE_VALUE;
173154
}
174155

156+
returnh;
157+
}
158+
159+
int
160+
pgwin32_open(constchar*fileName,intfileFlags,...)
161+
{
162+
HANDLEh;
163+
intfd;
164+
165+
h=pgwin32_open_handle(fileName,fileFlags, false);
166+
if (h==INVALID_HANDLE_VALUE)
167+
return-1;
168+
169+
#ifdefFRONTEND
170+
171+
/*
172+
* Since PostgreSQL 12, those concurrent-safe versions of open() and
173+
* fopen() can be used by frontends, having as side-effect to switch the
174+
* file-translation mode from O_TEXT to O_BINARY if none is specified.
175+
* Caller may want to enforce the binary or text mode, but if nothing is
176+
* defined make sure that the default mode maps with what versions older
177+
* than 12 have been doing.
178+
*/
179+
if ((fileFlags&O_BINARY)==0)
180+
fileFlags |=O_TEXT;
181+
#endif
182+
175183
/* _open_osfhandle will, on error, set errno accordingly */
176184
if ((fd=_open_osfhandle((intptr_t)h,fileFlags&O_APPEND))<0)
177185
CloseHandle(h);/* will not affect errno */

‎src/port/win32ntdll.c

Lines changed: 69 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,69 @@
1+
/*-------------------------------------------------------------------------
2+
*
3+
* win32ntdll.c
4+
* Dynamically loaded Windows NT functions.
5+
*
6+
* Portions Copyright (c) 2021, PostgreSQL Global Development Group
7+
* Portions Copyright (c) 1994, Regents of the University of California
8+
*
9+
*
10+
* IDENTIFICATION
11+
* src/port/win32ntdll.c
12+
*
13+
*-------------------------------------------------------------------------
14+
*/
15+
16+
#defineUMDF_USING_NTSTATUS
17+
18+
#include"c.h"
19+
20+
#include"port/win32ntdll.h"
21+
22+
RtlGetLastNtStatus_tpg_RtlGetLastNtStatus;
23+
24+
typedefstructNtDllRoutine
25+
{
26+
constchar*name;
27+
pg_funcptr_t*address;
28+
}NtDllRoutine;
29+
30+
staticconstNtDllRoutineroutines[]= {
31+
{"RtlGetLastNtStatus", (pg_funcptr_t*)&pg_RtlGetLastNtStatus}
32+
};
33+
34+
staticboolinitialized;
35+
36+
int
37+
initialize_ntdll(void)
38+
{
39+
HMODULEmodule;
40+
41+
if (initialized)
42+
return0;
43+
44+
if (!(module=LoadLibraryEx("ntdll.dll",NULL,0)))
45+
{
46+
_dosmaperr(GetLastError());
47+
return-1;
48+
}
49+
50+
for (inti=0;i<lengthof(routines);++i)
51+
{
52+
pg_funcptr_taddress;
53+
54+
address= (pg_funcptr_t)GetProcAddress(module,routines[i].name);
55+
if (!address)
56+
{
57+
_dosmaperr(GetLastError());
58+
FreeLibrary(module);
59+
60+
return-1;
61+
}
62+
63+
*(pg_funcptr_t*)routines[i].address=address;
64+
}
65+
66+
initialized= true;
67+
68+
return0;
69+
}

‎src/port/win32stat.c

Lines changed: 6 additions & 72 deletions
Original file line numberDiff line numberDiff line change
@@ -115,84 +115,18 @@ int
115115
_pgstat64(constchar*name,structstat*buf)
116116
{
117117
/*
118-
*We must use a handle so lstat() returns the information of the target
119-
*file. To have a reliable test for ERROR_DELETE_PENDING, this uses a
120-
*method similar to open() with a loop using stat() and some waits when
121-
*facing ERROR_ACCESS_DENIED.
118+
*Our open wrapper will report STATUS_DELETE_PENDING as ENOENT. We
119+
*request FILE_FLAG_BACKUP_SEMANTICS so that we can open directories too,
120+
*for limited purposes. We use the private handle-based version, so we
121+
*don't risk running out of fds.
122122
*/
123-
SECURITY_ATTRIBUTESsa;
124123
HANDLEhFile;
125124
intret;
126-
intloops=0;
127125

128-
if (name==NULL||buf==NULL)
129-
{
130-
errno=EINVAL;
131-
return-1;
132-
}
133-
/* fast not-exists check */
134-
if (GetFileAttributes(name)==INVALID_FILE_ATTRIBUTES)
135-
{
136-
DWORDerr=GetLastError();
137-
138-
if (err!=ERROR_ACCESS_DENIED)
139-
{
140-
_dosmaperr(err);
141-
return-1;
142-
}
143-
}
144-
145-
/* get a file handle as lightweight as we can */
146-
sa.nLength=sizeof(SECURITY_ATTRIBUTES);
147-
sa.bInheritHandle= TRUE;
148-
sa.lpSecurityDescriptor=NULL;
149-
while ((hFile=CreateFile(name,
150-
GENERIC_READ,
151-
(FILE_SHARE_READ |FILE_SHARE_WRITE |FILE_SHARE_DELETE),
152-
&sa,
153-
OPEN_EXISTING,
154-
(FILE_FLAG_NO_BUFFERING |FILE_FLAG_BACKUP_SEMANTICS |
155-
FILE_FLAG_OVERLAPPED),
156-
NULL))==INVALID_HANDLE_VALUE)
157-
{
158-
DWORDerr=GetLastError();
159-
160-
/*
161-
* ERROR_ACCESS_DENIED is returned if the file is deleted but not yet
162-
* gone (Windows NT status code is STATUS_DELETE_PENDING). In that
163-
* case we want to wait a bit and try again, giving up after 1 second
164-
* (since this condition should never persist very long). However,
165-
* there are other commonly-hit cases that return ERROR_ACCESS_DENIED,
166-
* so care is needed. In particular that happens if we try to open a
167-
* directory, or of course if there's an actual file-permissions
168-
* problem. To distinguish these cases, try a stat(). In the
169-
* delete-pending case, it will either also get STATUS_DELETE_PENDING,
170-
* or it will see the file as gone and fail with ENOENT. In other
171-
* cases it will usually succeed. The only somewhat-likely case where
172-
* this coding will uselessly wait is if there's a permissions problem
173-
* with a containing directory, which we hope will never happen in any
174-
* performance-critical code paths.
175-
*/
176-
if (err==ERROR_ACCESS_DENIED)
177-
{
178-
if (loops<10)
179-
{
180-
structmicrosoft_native_statst;
181-
182-
if (microsoft_native_stat(name,&st)!=0)
183-
{
184-
pg_usleep(100000);
185-
loops++;
186-
continue;
187-
}
188-
}
189-
}
190-
191-
_dosmaperr(err);
126+
hFile=pgwin32_open_handle(name,O_RDONLY, true);
127+
if (hFile==INVALID_HANDLE_VALUE)
192128
return-1;
193-
}
194129

195-
/* At last we can invoke fileinfo_to_stat */
196130
ret=fileinfo_to_stat(hFile,buf);
197131

198132
CloseHandle(hFile);

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