99 lines
2.6 KiB
C
99 lines
2.6 KiB
C
/*-
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* See the file LICENSE for redistribution information.
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*
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* Copyright (c) 2004,2008 Oracle. All rights reserved.
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*
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* $Id: os_truncate.c 63573 2008-05-23 21:43:21Z trent.nelson $
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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_truncate --
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* Truncate the file.
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*/
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int
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__os_truncate(env, fhp, pgno, pgsize)
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ENV *env;
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DB_FH *fhp;
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db_pgno_t pgno;
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u_int32_t pgsize;
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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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} off;
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DB_ENV *dbenv;
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off_t offset;
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int ret;
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dbenv = env == NULL ? NULL : env->dbenv;
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offset = (off_t)pgsize * pgno;
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ret = 0;
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if (dbenv != NULL &&
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FLD_ISSET(dbenv->verbose, DB_VERB_FILEOPS | DB_VERB_FILEOPS_ALL))
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__db_msg(env,
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"fileops: truncate %s to %lu", fhp->name, (u_long)offset);
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#ifdef HAVE_FILESYSTEM_NOTZERO
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/*
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* If the filesystem doesn't zero fill, it isn't safe to extend the
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* file, or we end up with junk blocks. Just return in that case.
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*/
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if (__os_fs_notzero()) {
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off_t stat_offset;
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u_int32_t mbytes, bytes;
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/* Stat the file. */
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if ((ret =
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__os_ioinfo(env, NULL, fhp, &mbytes, &bytes, NULL)) != 0)
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return (ret);
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stat_offset = (off_t)mbytes * MEGABYTE + bytes;
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if (offset > stat_offset)
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return (0);
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}
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#endif
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LAST_PANIC_CHECK_BEFORE_IO(env);
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/*
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* Windows doesn't provide truncate directly. Instead, it has
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* SetEndOfFile, which truncates to the current position. To
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* deal with that, we open a duplicate file handle for truncating.
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*
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* We want to retry the truncate call, which involves a SetFilePointer
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* and a SetEndOfFile, but there are several complications:
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*
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* 1) since the Windows API deals in 32-bit values, it's possible that
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* the return from SetFilePointer (the low 32-bits) is
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* INVALID_SET_FILE_POINTER even when the call has succeeded. So we
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* have to also check whether GetLastError() returns NO_ERROR.
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*
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* 2) when it returns, SetFilePointer overwrites the high bits of the
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* offset, so if we need to retry, we have to reset the offset each
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* time.
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*
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* We can't switch to SetFilePointerEx, which knows about 64-bit
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* offsets, because it isn't supported on Win9x/ME.
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*/
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RETRY_CHK((off.bigint = (__int64)pgsize * pgno,
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(SetFilePointer(fhp->trunc_handle, off.low, &off.high, FILE_BEGIN)
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== INVALID_SET_FILE_POINTER && GetLastError() != NO_ERROR) ||
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!SetEndOfFile(fhp->trunc_handle)), ret);
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if (ret != 0) {
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__db_syserr(env, ret, "SetFilePointer: %lu", pgno * pgsize);
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ret = __os_posix_err(ret);
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}
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return (ret);
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}
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