| /* |
| * getsize.c --- get the size of a partition. |
| * |
| * Copyright (C) 1995, 1995 Theodore Ts'o. |
| * |
| * %Begin-Header% |
| * This file may be redistributed under the terms of the GNU Public |
| * License. |
| * %End-Header% |
| */ |
| |
| #include <stdio.h> |
| #if HAVE_UNISTD_H |
| #include <unistd.h> |
| #endif |
| #include <fcntl.h> |
| #ifdef HAVE_LINUX_FS_H |
| #include <linux/fs.h> |
| #endif |
| #ifdef HAVE_LINUX_FD_H |
| #include <sys/ioctl.h> |
| #include <linux/fd.h> |
| #endif |
| #ifdef HAVE_SYS_DISKLABEL_H |
| #include <sys/ioctl.h> |
| #include <sys/disklabel.h> |
| #endif /* HAVE_SYS_DISKLABEL_H */ |
| |
| #if EXT2_FLAT_INCLUDES |
| #include "ext2_fs.h" |
| #else |
| #include <linux/ext2_fs.h> |
| #endif |
| |
| #include "ext2fs.h" |
| |
| static int valid_offset (int fd, ext2_loff_t offset) |
| { |
| char ch; |
| |
| if (ext2fs_llseek (fd, offset, 0) < 0) |
| return 0; |
| if (read (fd, &ch, 1) < 1) |
| return 0; |
| return 1; |
| } |
| |
| /* |
| * Returns the number of blocks in a partition |
| */ |
| errcode_t ext2fs_get_device_size(const char *file, int blocksize, |
| blk_t *retblocks) |
| { |
| int fd; |
| #ifdef BLKGETSIZE |
| long size; |
| #endif |
| ext2_loff_t high, low; |
| #ifdef FDGETPRM |
| struct floppy_struct this_floppy; |
| #endif |
| #ifdef HAVE_SYS_DISKLABEL_H |
| int part; |
| struct disklabel lab; |
| struct partition *pp; |
| char ch; |
| #endif /* HAVE_SYS_DISKLABEL_H */ |
| |
| fd = open(file, O_RDONLY); |
| if (fd < 0) |
| return errno; |
| |
| #ifdef BLKGETSIZE |
| if (ioctl(fd, BLKGETSIZE, &size) >= 0) { |
| close(fd); |
| *retblocks = size / (blocksize / 512); |
| return 0; |
| } |
| #endif |
| #ifdef FDGETPRM |
| if (ioctl(fd, FDGETPRM, &this_floppy) >= 0) { |
| close(fd); |
| *retblocks = this_floppy.size / (blocksize / 512); |
| return 0; |
| } |
| #endif |
| #ifdef HAVE_SYS_DISKLABEL_H |
| part = strlen(file) - 1; |
| if (part >= 0) { |
| ch = file[part]; |
| if (isdigit(ch)) |
| part = 0; |
| else if (ch >= 'a' && ch <= 'h') |
| part = ch - 'a'; |
| else |
| part = -1; |
| } |
| if (part >= 0 && (ioctl(fd, DIOCGDINFO, (char *)&lab) >= 0)) { |
| pp = &lab.d_partitions[part]; |
| if (pp->p_size) { |
| close(fd); |
| *retblocks = pp->p_size / (blocksize / 512); |
| return 0; |
| } |
| } |
| #endif /* HAVE_SYS_DISKLABEL_H */ |
| |
| /* |
| * OK, we couldn't figure it out by using a specialized ioctl, |
| * which is generally the best way. So do binary search to |
| * find the size of the partition. |
| */ |
| low = 0; |
| for (high = 1024; valid_offset (fd, high); high *= 2) |
| low = high; |
| while (low < high - 1) |
| { |
| const ext2_loff_t mid = (low + high) / 2; |
| |
| if (valid_offset (fd, mid)) |
| low = mid; |
| else |
| high = mid; |
| } |
| valid_offset (fd, 0); |
| close(fd); |
| *retblocks = (low + 1) / blocksize; |
| return 0; |
| } |