env_file.c
上传用户:romrleung
上传日期:2022-05-23
资源大小:18897k
文件大小:4k
- /*-
- * 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);
- }