open.c

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/*-------------------------------------------------------------------------
 *
 * open.c
 *     Win32 open() replacement
 *
 *
 * Portions Copyright (c) 1996-2013, PostgreSQL Global Development Group
 *
 * src/port/open.c
 *
 *-------------------------------------------------------------------------
 */

#ifdef WIN32

#ifndef FRONTEND
#include "postgres.h"
#else
#include "postgres_fe.h"
#endif

#include <windows.h>
#include <fcntl.h>
#include <assert.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);

    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. Try again for 30
         * seconds before giving up.
         */
        DWORD       err = GetLastError();

        if (err == ERROR_SHARING_VIOLATION ||
            err == ERROR_LOCK_VIOLATION)
        {
            pg_usleep(100000);
            loops++;

#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)
                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