File: env_file.c

package info (click to toggle)
db5.3 5.3.28-12+deb9u1
  • links: PTS, VCS
  • area: main
  • in suites: stretch
  • size: 163,332 kB
  • ctags: 82,990
  • sloc: ansic: 448,411; java: 111,824; tcl: 80,544; sh: 44,326; cs: 33,697; cpp: 21,604; perl: 14,557; xml: 10,799; makefile: 4,106; yacc: 1,003; awk: 965; sql: 801; erlang: 342; python: 216; php: 24; asm: 14
file content (137 lines) | stat: -rw-r--r-- 3,449 bytes parent folder | download | duplicates (5)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
/*-
 * See the file LICENSE for redistribution information.
 *
 * Copyright (c) 2002, 2013 Oracle and/or its affiliates.  All rights reserved.
 *
 * $Id$
 */

#include "db_config.h"

#include "db_int.h"

/*
 * __db_file_extend --
 *	Initialize a regular file by writing the last page of the file.
 *
 * PUBLIC: int __db_file_extend __P((ENV *, DB_FH *, size_t));
 */
int
__db_file_extend(env, fhp, size)
	ENV *env;
	DB_FH *fhp;
	size_t size;
{
	db_pgno_t pages;
	size_t nw;
	u_int32_t relative;
	int ret;
	char buf;

#ifdef HAVE_MMAP_EXTEND
	/*
	 * We have to ensure we extend a mmap'd segment a full memory page at
	 * a time or risk the end of the page not having any filesystem blocks
	 * associated resulting in the data loss.
	 */
	size = DB_ALIGN(size, getpagesize()) - 1;
#endif

	buf = '\0';
	/*
	 * Extend the file 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 we don't overflow -- (2^20 * 2^32 is bigger
	 * than any memory I expect to see for awhile).
	 */
	pages = (db_pgno_t)((size - sizeof(buf)) / MEGABYTE);
	relative = (u_int32_t)((size - sizeof(buf)) % MEGABYTE);
	if ((ret = __os_seek(env, fhp, pages, MEGABYTE, relative)) == 0)
		ret = __os_write(env, fhp, &buf, sizeof(buf), &nw);

	return (ret);
}

/*
 * __db_file_multi_write  --
 *	Overwrite a file with multiple passes to corrupt the data.
 *
 * PUBLIC: int __db_file_multi_write __P((ENV *, const char *));
 */
int
__db_file_multi_write(env, path)
	ENV *env;
	const char *path;
{
	DB_FH *fhp;
	u_int32_t mbytes, bytes;
	int ret;

	if ((ret = __os_open(env, path, 0, DB_OSO_REGION, 0, &fhp)) == 0 &&
	    (ret = __os_ioinfo(env, 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_file_write(env, fhp, mbytes, bytes, 255)) != 0)
			goto err;
		if ((ret =
		    __db_file_write(env, fhp, mbytes, bytes, 0)) != 0)
			goto err;
		if ((ret =
		    __db_file_write(env, fhp, mbytes, bytes, 255)) != 0)
			goto err;
	} else
		__db_err(env, ret, "%s", path);

err:	if (fhp != NULL)
		(void)__os_closehandle(env, fhp);
	return (ret);
}

/*
 * __db_file_write --
 *	A single pass over the file, writing the specified byte pattern.
 *
 * PUBLIC: int __db_file_write __P((ENV *,
 * PUBLIC:     DB_FH *, u_int32_t, u_int32_t, int));
 */
int
__db_file_write(env, fhp, mbytes, bytes, pattern)
	ENV *env;
	DB_FH *fhp;
	int pattern;
	u_int32_t mbytes, bytes;
{
	size_t len, nw;
	int i, ret;
	char *buf;

#undef	FILE_WRITE_IO_SIZE
#define	FILE_WRITE_IO_SIZE	(64 * 1024)
	if ((ret = __os_malloc(env, FILE_WRITE_IO_SIZE, &buf)) != 0)
		return (ret);
	memset(buf, pattern, FILE_WRITE_IO_SIZE);

	if ((ret = __os_seek(env, fhp, 0, 0, 0)) != 0)
		goto err;
	for (; mbytes > 0; --mbytes)
		for (i = MEGABYTE / FILE_WRITE_IO_SIZE; i > 0; --i)
			if ((ret = __os_write(
			    env, fhp, buf, FILE_WRITE_IO_SIZE, &nw)) != 0)
				goto err;
	for (; bytes > 0; bytes -= (u_int32_t)len) {
		len = bytes < FILE_WRITE_IO_SIZE ? bytes : FILE_WRITE_IO_SIZE;
		if ((ret = __os_write(env, fhp, buf, len, &nw)) != 0)
			goto err;
	}

	ret = __os_fsync(env, fhp);

err:	__os_free(env, buf);
	return (ret);
}