os_open.c
上传用户:tsgydb
上传日期:2007-04-14
资源大小:10674k
文件大小:5k
- /*-
- * See the file LICENSE for redistribution information.
- *
- * Copyright (c) 1997, 1998, 1999, 2000
- * Sleepycat Software. All rights reserved.
- */
- #include "db_config.h"
- #ifndef lint
- static const char revid[] = "$Id: os_open.c,v 11.9 2000/11/30 00:58:43 ubell Exp $";
- #endif /* not lint */
- #ifndef NO_SYSTEM_INCLUDES
- #include <sys/types.h>
- #include <fcntl.h>
- #include <signal.h>
- #include <string.h>
- #include <unistd.h>
- #endif
- #include "db_int.h"
- #include "os_jump.h"
- int __os_win32_errno __P((void));
- /*
- * __os_open --
- * Open a file descriptor.
- */
- int
- __os_open(dbenv, name, flags, mode, fhp)
- DB_ENV *dbenv;
- const char *name;
- u_int32_t flags;
- int mode;
- DB_FH *fhp;
- {
- DWORD bytesWritten;
- HANDLE wh;
- u_int32_t log_size;
- int access, attr, oflags, share, createflag;
- int ret, nrepeat;
- /*
- * The "public" interface to the __os_open routine passes around POSIX
- * 1003.1 flags, not DB flags. If the user has defined their own open
- * interface, use the POSIX flags.
- */
- if (__db_jump.j_open != NULL) {
- oflags = O_BINARY | O_NOINHERIT;
- if (LF_ISSET(DB_OSO_CREATE))
- oflags |= O_CREAT;
- if (LF_ISSET(DB_OSO_EXCL))
- oflags |= O_EXCL;
- if (LF_ISSET(DB_OSO_RDONLY))
- oflags |= O_RDONLY;
- else
- oflags |= O_RDWR;
- if (LF_ISSET(DB_OSO_SEQ))
- oflags |= _O_SEQUENTIAL;
- else
- oflags |= _O_RANDOM;
- if (LF_ISSET(DB_OSO_TEMP))
- oflags |= _O_TEMPORARY;
- if (LF_ISSET(DB_OSO_TRUNC))
- oflags |= O_TRUNC;
- return (__os_openhandle(dbenv, name, oflags, mode, fhp));
- }
- if (LF_ISSET(DB_OSO_LOG))
- log_size = fhp->log_size; /* XXX: Gag. */
- memset(fhp, 0, sizeof(*fhp));
- /*
- * Otherwise, use the Windows/32 CreateFile interface so that we can
- * play magic games with log files to get data flush effects similar
- * to the POSIX O_DSYNC flag.
- *
- * !!!
- * We currently ignore the 'mode' argument. It would be possible
- * to construct a set of security attributes that we could pass to
- * CreateFile that would accurately represents the mode. In worst
- * case, this would require looking up user and all group names and
- * creating an entry for each. Alternatively, we could call the
- * _chmod (partial emulation) function after file creation, although
- * this leaves us with an obvious race. However, these efforts are
- * largely meaningless on FAT, the most common file system, which
- * only has a "readable" and "writeable" flag, applying to all users.
- */
- wh = INVALID_HANDLE_VALUE;
- access = GENERIC_READ;
- if (!LF_ISSET(DB_OSO_RDONLY))
- access |= GENERIC_WRITE;
- share = FILE_SHARE_READ | FILE_SHARE_WRITE;
- attr = FILE_ATTRIBUTE_NORMAL;
- /*
- * Reproduce POSIX 1003.1 semantics: if O_CREATE and O_EXCL are both
- * specified, fail, returning EEXIST, unless we create the file.
- */
- if (LF_ISSET(DB_OSO_CREATE) && LF_ISSET(DB_OSO_EXCL))
- createflag = CREATE_NEW; /* create only if !exist*/
- else if (!LF_ISSET(DB_OSO_CREATE) && LF_ISSET(DB_OSO_TRUNC))
- createflag = TRUNCATE_EXISTING; /* truncate, fail if !exist */
- else if (LF_ISSET(DB_OSO_TRUNC))
- createflag = CREATE_ALWAYS; /* create and truncate */
- else if (LF_ISSET(DB_OSO_CREATE))
- createflag = OPEN_ALWAYS; /* open or create */
- else
- createflag = OPEN_EXISTING; /* open only if existing */
- if (LF_ISSET(DB_OSO_LOG)) {
- F_SET(fhp, DB_FH_NOSYNC);
- attr |= FILE_FLAG_WRITE_THROUGH;
- }
- if (LF_ISSET(DB_OSO_SEQ))
- attr |= FILE_FLAG_SEQUENTIAL_SCAN;
- else
- attr |= FILE_FLAG_RANDOM_ACCESS;
- if (LF_ISSET(DB_OSO_TEMP))
- attr |= FILE_FLAG_DELETE_ON_CLOSE;
- for (nrepeat = 1; nrepeat < 4; ++nrepeat) {
- ret = 0;
- __os_set_errno(0);
- wh = CreateFile(name, access, share, NULL, createflag, attr, 0);
- if (wh == INVALID_HANDLE_VALUE) {
- /*
- * If it's a "temporary" error, we retry up to 3 times,
- * waiting up to 12 seconds. While it's not a problem
- * if we can't open a database, an inability to open a
- * log file is cause for serious dismay.
- */
- ret = __os_win32_errno();
- if (ret == ENFILE || ret == EMFILE || ret == ENOSPC) {
- (void)__os_sleep(dbenv, nrepeat * 2, 0);
- continue;
- }
- goto err;
- }
- break;
- }
- /*
- * Special handling needed for log files. To get Windows to not update
- * the MFT metadata on each write, extend the file to its maximum size.
- * Windows will allocate all the data blocks and store them in the MFT
- * (inode) area. In addition, flush the MFT area to disk.
- * This strategy only works for Win/NT; Win/9X does not
- * guarantee that the logs will be zero filled.
- */
- if (LF_ISSET(DB_OSO_LOG) && log_size != 0 &&
- __os_is_winnt()) {
- if (SetFilePointer(wh,
- log_size - 1, NULL, FILE_BEGIN) == (DWORD)-1)
- goto err;
- if (WriteFile(wh, "x00", 1, &bytesWritten, NULL) == 0)
- goto err;
- if (bytesWritten != 1)
- goto err;
- if (SetEndOfFile(wh) == 0)
- goto err;
- if (SetFilePointer(wh, 0, NULL, FILE_BEGIN) == (DWORD)-1)
- goto err;
- if (FlushFileBuffers(wh) == 0)
- goto err;
- }
- /*
- * We acquire a POSIX file descriptor as this allows us to use the
- * general UNIX I/O routines instead of writing Windows specific
- * ones. Closing that file descriptor is sufficient to close the
- * Windows HANDLE.
- */
- fhp->fd =
- _open_osfhandle((long)wh, LF_ISSET(DB_OSO_RDONLY) ? O_RDONLY : 0);
- fhp->handle = wh;
- F_SET(fhp, DB_FH_VALID);
- return (0);
- err: if (ret == 0)
- ret = __os_win32_errno();
- if (wh != INVALID_HANDLE_VALUE)
- (void)CloseHandle(wh);
- return (ret);
- }