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/*-
* See the file LICENSE for redistribution information.
*
* Copyright (c) 2002
* Sleepycat Software. All rights reserved.
*/
#include "db_config.h"
#ifndef lint
static const char revid[] = "$Id: env_file.c,v 1.5 2002/03/08 17:47:18 sue Exp $";
#endif /* not lint */
#ifndef NO_SYSTEM_INCLUDES
#include <sys/types.h>
#include <string.h>
#endif
#include "db_int.h"
static int __db_overwrite_pass __P((DB_ENV *,
const char *, DB_FH *, u_int32_t, u_int32_t, u_int32_t));
/*
* __db_fileinit --
* Initialize a regular file, optionally zero-filling it as well.
*
* PUBLIC: int __db_fileinit __P((DB_ENV *, DB_FH *, size_t, int));
*/
int
__db_fileinit(dbenv, fhp, size, zerofill)
DB_ENV *dbenv;
DB_FH *fhp;
size_t size;
int zerofill;
{
db_pgno_t pages;
size_t i;
size_t nw;
u_int32_t relative;
int ret;
char buf[OS_VMPAGESIZE];
/* Write nuls to the new bytes. */
memset(buf, 0, sizeof(buf));
/*
* Extend the region by writing the last page. If the region is >4Gb,
* increment may be larger than the maximum possible seek "relative"
* argument, as it's an unsigned 32-bit value. Break the offset into
* pages of 1MB each so that we don't overflow (2^20 + 2^32 is bigger
* than any memory I expect to see for awhile).
*/
if ((ret = __os_seek(dbenv, fhp, 0, 0, 0, 0, DB_OS_SEEK_END)) != 0)
return (ret);
pages = (db_pgno_t)((size - OS_VMPAGESIZE) / MEGABYTE);
relative = (u_int32_t)((size - OS_VMPAGESIZE) % MEGABYTE);
if ((ret = __os_seek(dbenv,
fhp, MEGABYTE, pages, relative, 0, DB_OS_SEEK_CUR)) != 0)
return (ret);
if ((ret = __os_write(dbenv, fhp, buf, sizeof(buf), &nw)) != 0)
return (ret);
/*
* We may want to guarantee that there is enough disk space for the
* file, so we also write a byte to each page. We write the byte
* because reading it is insufficient on systems smart enough not to
* instantiate disk pages to satisfy a read (e.g., Solaris).
*/
if (zerofill) {
pages = (db_pgno_t)(size / MEGABYTE);
relative = (u_int32_t)(size % MEGABYTE);
if ((ret = __os_seek(dbenv, fhp,
MEGABYTE, pages, relative, 1, DB_OS_SEEK_END)) != 0)
return (ret);
/* Write a byte to each page. */
for (i = 0; i < size; i += OS_VMPAGESIZE) {
if ((ret = __os_write(dbenv, fhp, buf, 1, &nw)) != 0)
return (ret);
if ((ret = __os_seek(dbenv, fhp,
0, 0, OS_VMPAGESIZE - 1, 0, DB_OS_SEEK_CUR)) != 0)
return (ret);
}
}
return (0);
}
/*
* __db_overwrite --
* Overwrite a file.
*
* PUBLIC: int __db_overwrite __P((DB_ENV *, const char *));
*/
int
__db_overwrite(dbenv, path)
DB_ENV *dbenv;
const char *path;
{
DB_FH fh, *fhp;
u_int32_t mbytes, bytes;
int ret;
fhp = &fh;
if ((ret = __os_open(dbenv, path, DB_OSO_REGION, 0, fhp)) == 0 &&
(ret = __os_ioinfo(dbenv, path, fhp, &mbytes, &bytes, NULL)) == 0) {
/*
* !!!
* Overwrite a regular file with alternating 0xff, 0x00 and 0xff
* byte patterns. Implies a fixed-block filesystem, journaling
* or logging filesystems will require operating system support.
*/
if ((ret = __db_overwrite_pass(
dbenv, path, fhp, mbytes, bytes, 0xff)) != 0)
goto err;
if ((ret = __db_overwrite_pass(
dbenv, path, fhp, mbytes, bytes, 0x00)) != 0)
goto err;
if ((ret = __db_overwrite_pass(
dbenv, path, fhp, mbytes, bytes, 0xff)) != 0)
goto err;
} else
__db_err(dbenv, "%s: %s", path, db_strerror(ret));
err: if (F_ISSET(fhp, DB_FH_VALID))
__os_closehandle(dbenv, fhp);
return (ret);
}
/*
* __db_overwrite_pass --
* A single pass over the file, writing the specified byte pattern.
*/
static int
__db_overwrite_pass(dbenv, path, fhp, mbytes, bytes, pattern)
DB_ENV *dbenv;
const char *path;
DB_FH *fhp;
u_int32_t mbytes, bytes, pattern;
{
size_t len, nw;
int i, ret;
char buf[8 * 1024];
if ((ret = __os_seek(dbenv, fhp, 0, 0, 0, 0, DB_OS_SEEK_SET)) != 0)
goto err;
memset(buf, pattern, sizeof(buf));
for (; mbytes > 0; --mbytes)
for (i = MEGABYTE / sizeof(buf); i > 0; --i)
if ((ret =
__os_write(dbenv, fhp, buf, sizeof(buf), &nw)) != 0)
goto err;
for (; bytes > 0; bytes -= (u_int32_t)len) {
len = bytes < sizeof(buf) ? bytes : sizeof(buf);
if ((ret = __os_write(dbenv, fhp, buf, len, &nw)) != 0)
goto err;
}
if ((ret = __os_fsync(dbenv, fhp)) != 0)
err: __db_err(dbenv, "%s: %s", path, db_strerror(ret));
return (ret);
}
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