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/*-------------------------------------------------------------------------
*
* open.c
* Win32 open() replacement
*
*
* Portions Copyright (c) 1996-2020, PostgreSQL Global Development Group
*
* src/port/open.c
*
*-------------------------------------------------------------------------
*/
#ifdef WIN32
#ifndef FRONTEND
#include "postgres.h"
#else
#include "postgres_fe.h"
#endif
#include <fcntl.h>
#include <assert.h>
#include <sys/stat.h>
static int
openFlagsToCreateFileFlags(int openFlags)
{
switch (openFlags & (O_CREAT | O_TRUNC | O_EXCL))
{
/* O_EXCL is meaningless without O_CREAT */
case 0:
case O_EXCL:
return OPEN_EXISTING;
case O_CREAT:
return OPEN_ALWAYS;
/* O_EXCL is meaningless without O_CREAT */
case O_TRUNC:
case O_TRUNC | O_EXCL:
return TRUNCATE_EXISTING;
case O_CREAT | O_TRUNC:
return CREATE_ALWAYS;
/* O_TRUNC is meaningless with O_CREAT */
case O_CREAT | O_EXCL:
case O_CREAT | O_TRUNC | O_EXCL:
return CREATE_NEW;
}
/* will never get here */
return 0;
}
/*
* - file attribute setting, based on fileMode?
*/
int
pgwin32_open(const char *fileName, int fileFlags,...)
{
int fd;
HANDLE h = INVALID_HANDLE_VALUE;
SECURITY_ATTRIBUTES sa;
int loops = 0;
/* Check that we can handle the request */
assert((fileFlags & ((O_RDONLY | O_WRONLY | O_RDWR) | O_APPEND |
(O_RANDOM | O_SEQUENTIAL | O_TEMPORARY) |
_O_SHORT_LIVED | O_DSYNC | O_DIRECT |
(O_CREAT | O_TRUNC | O_EXCL) | (O_TEXT | O_BINARY))) == fileFlags);
#ifndef FRONTEND
Assert(pgwin32_signal_event != NULL); /* small chance of pg_usleep() */
#endif
#ifdef FRONTEND
/*
* Since PostgreSQL 12, those concurrent-safe versions of open() and
* fopen() can be used by frontends, having as side-effect to switch the
* file-translation mode from O_TEXT to O_BINARY if none is specified.
* Caller may want to enforce the binary or text mode, but if nothing is
* defined make sure that the default mode maps with what versions older
* than 12 have been doing.
*/
if ((fileFlags & O_BINARY) == 0)
fileFlags |= O_TEXT;
#endif
sa.nLength = sizeof(sa);
sa.bInheritHandle = TRUE;
sa.lpSecurityDescriptor = NULL;
while ((h = CreateFile(fileName,
/* cannot use O_RDONLY, as it == 0 */
(fileFlags & O_RDWR) ? (GENERIC_WRITE | GENERIC_READ) :
((fileFlags & O_WRONLY) ? GENERIC_WRITE : GENERIC_READ),
/* These flags allow concurrent rename/unlink */
(FILE_SHARE_READ | FILE_SHARE_WRITE | FILE_SHARE_DELETE),
&sa,
openFlagsToCreateFileFlags(fileFlags),
FILE_ATTRIBUTE_NORMAL |
((fileFlags & O_RANDOM) ? FILE_FLAG_RANDOM_ACCESS : 0) |
((fileFlags & O_SEQUENTIAL) ? FILE_FLAG_SEQUENTIAL_SCAN : 0) |
((fileFlags & _O_SHORT_LIVED) ? FILE_ATTRIBUTE_TEMPORARY : 0) |
((fileFlags & O_TEMPORARY) ? FILE_FLAG_DELETE_ON_CLOSE : 0) |
((fileFlags & O_DIRECT) ? FILE_FLAG_NO_BUFFERING : 0) |
((fileFlags & O_DSYNC) ? FILE_FLAG_WRITE_THROUGH : 0),
NULL)) == INVALID_HANDLE_VALUE)
{
/*
* Sharing violation or locking error can indicate antivirus, backup
* or similar software that's locking the file. Wait a bit and try
* again, giving up after 30 seconds.
*/
DWORD err = GetLastError();
if (err == ERROR_SHARING_VIOLATION ||
err == ERROR_LOCK_VIOLATION)
{
#ifndef FRONTEND
if (loops == 50)
ereport(LOG,
(errmsg("could not open file \"%s\": %s", fileName,
(err == ERROR_SHARING_VIOLATION) ? _("sharing violation") : _("lock violation")),
errdetail("Continuing to retry for 30 seconds."),
errhint("You might have antivirus, backup, or similar software interfering with the database system.")));
#endif
if (loops < 300)
{
pg_usleep(100000);
loops++;
continue;
}
}
/*
* 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)
{
if (loops < 10)
{
struct stat st;
if (stat(fileName, &st) != 0)
{
pg_usleep(100000);
loops++;
continue;
}
}
}
_dosmaperr(err);
return -1;
}
/* _open_osfhandle will, on error, set errno accordingly */
if ((fd = _open_osfhandle((intptr_t) h, fileFlags & O_APPEND)) < 0)
CloseHandle(h); /* will not affect errno */
else if (fileFlags & (O_TEXT | O_BINARY) &&
_setmode(fd, fileFlags & (O_TEXT | O_BINARY)) < 0)
{
_close(fd);
return -1;
}
return fd;
}
FILE *
pgwin32_fopen(const char *fileName, const char *mode)
{
int openmode = 0;
int fd;
if (strstr(mode, "r+"))
openmode |= O_RDWR;
else if (strchr(mode, 'r'))
openmode |= O_RDONLY;
if (strstr(mode, "w+"))
openmode |= O_RDWR | O_CREAT | O_TRUNC;
else if (strchr(mode, 'w'))
openmode |= O_WRONLY | O_CREAT | O_TRUNC;
if (strchr(mode, 'a'))
openmode |= O_WRONLY | O_CREAT | O_APPEND;
if (strchr(mode, 'b'))
openmode |= O_BINARY;
if (strchr(mode, 't'))
openmode |= O_TEXT;
fd = pgwin32_open(fileName, openmode);
if (fd == -1)
return NULL;
return _fdopen(fd, mode);
}
#endif
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