lib/ext2fs/getsectsize.c

   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 #ifndef _LARGEFILE_SOURCE
  14 #define _LARGEFILE_SOURCE
  15 #endif
  16 #ifndef _LARGEFILE64_SOURCE
  17 #define _LARGEFILE64_SOURCE
  18 #endif
  19
  20 #include "config.h"
  21 #include <stdio.h>
  22 #if HAVE_UNISTD_H
  23 #include <unistd.h>
  24 #endif
  25 #if HAVE_ERRNO_H
  26 #include <errno.h>
  27 #endif
  28 #include <fcntl.h>
  29 #ifdef HAVE_LINUX_FD_H
  30 #include <sys/ioctl.h>
  31 #include <linux/fd.h>
  32 #endif
  33
  34 #if defined(__linux__) && defined(_IO)
  35 #if !defined(BLKSSZGET)
  36 #define BLKSSZGET  _IO(0x12,104)/* get block device sector size */
  37 #endif
  38 #if !defined(BLKPBSZGET)
  39 #define BLKPBSZGET _IO(0x12,123)/* get block physical sector size */
  40 #endif
  41 #endif
  42
  43 #include "ext2_fs.h"
  44 #include "ext2fs.h"
  45
  46 /*
  47  * Returns the logical sector size of a device
  48  */
  49 errcode_t ext2fs_get_device_sectsize(const char *file, int *sectsize)
  50 {
  51         int     fd;
  52
  53         fd = ext2fs_open_file(file, O_RDONLY, 0);
  54         if (fd < 0)
  55                 return errno;
  56
  57 #ifdef BLKSSZGET
  58         if (ioctl(fd, BLKSSZGET, sectsize) >= 0) {
  59                 close(fd);
  60                 return 0;
  61         }
  62 #endif
  63         *sectsize = 0;
  64         close(fd);
  65         return 0;
  66 }
  67
  68 /*
  69  * Return desired alignment for direct I/O
  70  */
  71 int ext2fs_get_dio_alignment(int fd)
  72 {
  73         int align = 0;
  74
  75 #ifdef BLKSSZGET
  76         if (ioctl(fd, BLKSSZGET, &align) < 0)
  77                 align = 0;
  78 #endif
  79
  80 #ifdef _SC_PAGESIZE
  81         if (align <= 0)
  82                 align = sysconf(_SC_PAGESIZE);
  83 #endif
  84 #ifdef HAVE_GETPAGESIZE
  85         if (align <= 0)
  86                 align = getpagesize();
  87 #endif
  88         if (align <= 0)
  89                 align = 4096;
  90
  91         return align;
  92 }
  93
  94 /*
  95  * Returns the physical sector size of a device
  96  */
  97 errcode_t ext2fs_get_device_phys_sectsize(const char *file, int *sectsize)
  98 {
  99         int     fd;
 100
 101         fd = ext2fs_open_file(file, O_RDONLY, 0);
 102         if (fd < 0)
 103                 return errno;
 104
 105 #ifdef BLKPBSZGET
 106         if (ioctl(fd, BLKPBSZGET, sectsize) >= 0) {
 107                 close(fd);
 108                 return 0;
 109         }
 110 #endif
 111         *sectsize = 0;
 112         close(fd);
 113         return 0;
 114 }