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92 lines
1.7 KiB
C
92 lines
1.7 KiB
C
/*-
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* See the file LICENSE for redistribution information.
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*
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* Copyright (c) 1997-2005
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* Sleepycat Software. All rights reserved.
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*
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* $Id: os_seek.c,v 12.1 2005/06/16 20:23:30 bostic Exp $
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*/
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#include "db_config.h"
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#include "db_int.h"
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/*
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* __os_seek --
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* Seek to a page/byte offset in the file.
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*/
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int
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__os_seek(dbenv, fhp, pgsize, pageno, relative, isrewind, db_whence)
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DB_ENV *dbenv;
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DB_FH *fhp;
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u_int32_t pgsize;
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db_pgno_t pageno;
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u_int32_t relative;
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int isrewind;
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DB_OS_SEEK db_whence;
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{
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/* Yes, this really is how Microsoft have designed their API */
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union {
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__int64 bigint;
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struct {
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unsigned long low;
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long high;
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};
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} offbytes;
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off_t offset;
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int ret, whence;
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DWORD from;
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offset = (off_t)pgsize * pageno + relative;
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if (isrewind)
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offset = -offset;
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if (DB_GLOBAL(j_seek) != NULL) {
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switch (db_whence) {
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case DB_OS_SEEK_CUR:
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whence = SEEK_CUR;
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break;
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case DB_OS_SEEK_END:
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whence = SEEK_END;
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break;
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case DB_OS_SEEK_SET:
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whence = SEEK_SET;
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break;
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default:
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return (EINVAL);
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}
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ret = DB_GLOBAL(j_seek)(fhp->fd, offset, whence);
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} else {
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switch (db_whence) {
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case DB_OS_SEEK_CUR:
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from = FILE_CURRENT;
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break;
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case DB_OS_SEEK_END:
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from = FILE_END;
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break;
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case DB_OS_SEEK_SET:
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from = FILE_BEGIN;
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break;
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default:
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return (EINVAL);
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}
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offbytes.bigint = offset;
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ret = (SetFilePointer(fhp->handle,
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offbytes.low, &offbytes.high, from) == (DWORD) - 1) ?
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__os_get_errno() : 0;
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}
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if (ret == 0) {
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fhp->pgsize = pgsize;
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fhp->pgno = pageno;
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fhp->offset = relative;
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} else {
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__db_err(dbenv, "seek: %lu %d %d: %s",
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(u_long)pgsize * pageno + relative,
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isrewind, db_whence, strerror(ret));
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}
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return (ret);
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}
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