os_seek.c
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上传日期:2022-05-23
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文件大小:1k
- /*-
- * See the file LICENSE for redistribution information.
- *
- * Copyright (c) 1997-2002
- * Sleepycat Software. All rights reserved.
- */
- #include "db_config.h"
- #ifndef lint
- static const char revid[] = "$Id: os_seek.c,v 11.18 2002/07/12 18:56:52 bostic Exp $";
- #endif /* not lint */
- #ifndef NO_SYSTEM_INCLUDES
- #include <sys/types.h>
- #include <stdlib.h>
- #include <string.h>
- #include <unistd.h>
- #endif
- #include "db_int.h"
- /*
- * __os_seek --
- * Seek to a page/byte offset in the file.
- *
- * PUBLIC: int __os_seek __P((DB_ENV *,
- * PUBLIC: DB_FH *, size_t, db_pgno_t, u_int32_t, int, DB_OS_SEEK));
- */
- int
- __os_seek(dbenv, fhp, pgsize, pageno, relative, isrewind, db_whence)
- DB_ENV *dbenv;
- DB_FH *fhp;
- size_t pgsize;
- db_pgno_t pageno;
- u_int32_t relative;
- int isrewind;
- DB_OS_SEEK db_whence;
- {
- off_t offset;
- int ret, whence;
- switch (db_whence) {
- case DB_OS_SEEK_CUR:
- whence = SEEK_CUR;
- break;
- case DB_OS_SEEK_END:
- whence = SEEK_END;
- break;
- case DB_OS_SEEK_SET:
- whence = SEEK_SET;
- break;
- default:
- return (EINVAL);
- }
- if (DB_GLOBAL(j_seek) != NULL)
- ret = DB_GLOBAL(j_seek)(fhp->fd,
- pgsize, pageno, relative, isrewind, whence);
- else {
- offset = (off_t)pgsize * pageno + relative;
- if (isrewind)
- offset = -offset;
- do {
- ret = lseek(fhp->fd, offset, whence) == -1 ?
- __os_get_errno() : 0;
- } while (ret == EINTR);
- }
- if (ret != 0)
- __db_err(dbenv, "seek: %lu %d %d: %s",
- (u_long)pgsize * pageno + relative,
- isrewind, db_whence, strerror(ret));
- return (ret);
- }