getsectsize.c revision e0ed7404719a9ddd2ba427a80db5365c8bad18c0 
1/*
2 * getsectsize.c --- get the sector size of a device.
3 *
4 * Copyright (C) 1995, 1995 Theodore Ts'o.
5 * Copyright (C) 2003 VMware, Inc.
6 *
7 * %Begin-Header%
8 * This file may be redistributed under the terms of the GNU Library
9 * General Public License, version 2.
10 * %End-Header%
11 */
12
13#define _LARGEFILE_SOURCE
14#define _LARGEFILE64_SOURCE
15
16#include <stdio.h>
17#if HAVE_UNISTD_H
18#include <unistd.h>
19#endif
20#if HAVE_ERRNO_H
21#include <errno.h>
22#endif
23#include <fcntl.h>
24#ifdef HAVE_LINUX_FD_H
25#include <sys/ioctl.h>
26#include <linux/fd.h>
27#endif
28
29#if defined(__linux__) && defined(_IO)
30#if !defined(BLKSSZGET)
31#define BLKSSZGET  _IO(0x12,104)/* get block device sector size */
32#endif
33#if !defined(BLKPBSZGET)
34#define BLKPBSZGET _IO(0x12,123)/* get block physical sector size */
35#endif
36#endif
37
38#include "ext2_fs.h"
39#include "ext2fs.h"
40
41/*
42 * Returns the logical sector size of a device
43 */
44errcode_t ext2fs_get_device_sectsize(const char *file, int *sectsize)
45{
46	int	fd;
47
48	fd = ext2fs_open_file(file, O_RDONLY, 0);
49	if (fd < 0)
50		return errno;
51
52#ifdef BLKSSZGET
53	if (ioctl(fd, BLKSSZGET, sectsize) >= 0) {
54		close(fd);
55		return 0;
56	}
57#endif
58	*sectsize = 0;
59	close(fd);
60	return 0;
61}
62
63/*
64 * Return desired alignment for direct I/O
65 */
66int ext2fs_get_dio_alignment(int fd)
67{
68	int align = 0;
69
70#ifdef BLKSSZGET
71	if (ioctl(fd, BLKSSZGET, &align) < 0)
72		align = 0;
73#endif
74
75#ifdef _SC_PAGESIZE
76	if (align <= 0)
77		align = sysconf(_SC_PAGESIZE);
78#endif
79#ifdef HAVE_GETPAGESIZE
80	if (align <= 0)
81		align = getpagesize();
82#endif
83	if (align <= 0)
84		align = 4096;
85
86	return align;
87}
88
89/*
90 * Returns the physical sector size of a device
91 */
92errcode_t ext2fs_get_device_phys_sectsize(const char *file, int *sectsize)
93{
94	int	fd;
95
96	fd = ext2fs_open_file(file, O_RDONLY, 0);
97	if (fd < 0)
98		return errno;
99
100#ifdef BLKPBSZGET
101	if (ioctl(fd, BLKPBSZGET, sectsize) >= 0) {
102		close(fd);
103		return 0;
104	}
105#endif
106	*sectsize = 0;
107	close(fd);
108	return 0;
109}
110