getsize.c revision b22ea17742b3e354c3ee1372d43630dda21a59f5 
1/*
2 * getsize.c --- get the size of a partition.
3 *
4 * Copyright (C) 1995, 1995 Theodore Ts'o.
5 *
6 * %Begin-Header%
7 * This file may be redistributed under the terms of the
8 * GNU Lesser General Public License.
9 * %End-Header%
10 */
11
12#define _LARGEFILE_SOURCE
13#define _LARGEFILE64_SOURCE
14
15/* include this before sys/queues.h! */
16#include "blkidP.h"
17
18#include <stdio.h>
19#if HAVE_UNISTD_H
20#include <unistd.h>
21#endif
22#if HAVE_ERRNO_H
23#include <errno.h>
24#endif
25#include <fcntl.h>
26#ifdef HAVE_SYS_IOCTL_H
27#include <sys/ioctl.h>
28#endif
29#ifdef HAVE_LINUX_FD_H
30#include <linux/fd.h>
31#endif
32#ifdef HAVE_SYS_DISKLABEL_H
33#include <sys/disklabel.h>
34#include <sys/stat.h>
35#endif
36#ifdef HAVE_SYS_DISK_H
37#ifdef HAVE_SYS_QUEUE_H
38#include <sys/queue.h> /* for LIST_HEAD */
39#endif
40#include <sys/disk.h>
41#endif
42#ifdef __linux__
43#include <sys/utsname.h>
44#endif
45
46#if defined(__linux__) && defined(_IO) && !defined(BLKGETSIZE)
47#define BLKGETSIZE _IO(0x12,96)	/* return device size */
48#endif
49
50#if defined(__linux__) && defined(_IOR) && !defined(BLKGETSIZE64)
51#define BLKGETSIZE64 _IOR(0x12,114,size_t)	/* return device size in bytes (u64 *arg) */
52#endif
53
54#ifdef APPLE_DARWIN
55#define BLKGETSIZE DKIOCGETBLOCKCOUNT32
56#endif /* APPLE_DARWIN */
57
58static int valid_offset(int fd, blkid_loff_t offset)
59{
60	char ch;
61
62	if (blkid_llseek(fd, offset, 0) < 0)
63		return 0;
64	if (read(fd, &ch, 1) < 1)
65		return 0;
66	return 1;
67}
68
69/*
70 * Returns the number of blocks in a partition
71 */
72blkid_loff_t blkid_get_dev_size(int fd)
73{
74	int valid_blkgetsize64 = 1;
75#ifdef __linux__
76	struct 		utsname ut;
77#endif
78	unsigned long long size64;
79	unsigned long size;
80	blkid_loff_t high, low;
81#ifdef FDGETPRM
82	struct floppy_struct this_floppy;
83#endif
84#ifdef HAVE_SYS_DISKLABEL_H
85	int part = -1;
86	struct disklabel lab;
87	struct partition *pp;
88	char ch;
89	struct stat st;
90#endif /* HAVE_SYS_DISKLABEL_H */
91
92#ifdef DKIOCGETBLOCKCOUNT	/* For Apple Darwin */
93	if (ioctl(fd, DKIOCGETBLOCKCOUNT, &size64) >= 0) {
94		if ((sizeof(blkid_loff_t) < sizeof(unsigned long long))
95		    && (size64 << 9 > 0xFFFFFFFF))
96			return 0; /* EFBIG */
97		return (blkid_loff_t) size64 << 9;
98	}
99#endif
100
101#ifdef BLKGETSIZE64
102#ifdef __linux__
103	if ((uname(&ut) == 0) &&
104	    ((ut.release[0] == '2') && (ut.release[1] == '.') &&
105	     (ut.release[2] < '6') && (ut.release[3] == '.')))
106		valid_blkgetsize64 = 0;
107#endif
108	if (valid_blkgetsize64 &&
109	    ioctl(fd, BLKGETSIZE64, &size64) >= 0) {
110		if ((sizeof(blkid_loff_t) < sizeof(unsigned long long))
111		    && ((size64) > 0xFFFFFFFF))
112			return 0; /* EFBIG */
113		return size64;
114	}
115#endif
116
117#ifdef BLKGETSIZE
118	if (ioctl(fd, BLKGETSIZE, &size) >= 0)
119		return (blkid_loff_t)size << 9;
120#endif
121
122#ifdef FDGETPRM
123	if (ioctl(fd, FDGETPRM, &this_floppy) >= 0)
124		return (blkid_loff_t)this_floppy.size << 9;
125#endif
126#ifdef HAVE_SYS_DISKLABEL_H
127#if 0
128	/*
129	 * This should work in theory but I haven't tested it.  Anyone
130	 * on a BSD system want to test this for me?  In the meantime,
131	 * binary search mechanism should work just fine.
132	 */
133	if ((fstat(fd, &st) >= 0) && S_ISBLK(st.st_mode))
134		part = st.st_rdev & 7;
135	if (part >= 0 && (ioctl(fd, DIOCGDINFO, (char *)&lab) >= 0)) {
136		pp = &lab.d_partitions[part];
137		if (pp->p_size)
138			return pp->p_size << 9;
139	}
140#endif
141#endif /* HAVE_SYS_DISKLABEL_H */
142
143	/*
144	 * OK, we couldn't figure it out by using a specialized ioctl,
145	 * which is generally the best way.  So do binary search to
146	 * find the size of the partition.
147	 */
148	low = 0;
149	for (high = 1024; valid_offset(fd, high); high *= 2)
150		low = high;
151	while (low < high - 1)
152	{
153		const blkid_loff_t mid = (low + high) / 2;
154
155		if (valid_offset(fd, mid))
156			low = mid;
157		else
158			high = mid;
159	}
160	return low + 1;
161}
162
163#ifdef TEST_PROGRAM
164int main(int argc, char **argv)
165{
166	blkid_loff_t bytes;
167	int	fd;
168
169	if (argc < 2) {
170		fprintf(stderr, "Usage: %s device\n"
171			"Determine the size of a device\n", argv[0]);
172		return 1;
173	}
174
175	if ((fd = open(argv[1], O_RDONLY)) < 0)
176		perror(argv[0]);
177
178	bytes = blkid_get_dev_size(fd);
179	printf("Device %s has %Ld 1k blocks.\n", argv[1], bytes >> 10);
180
181	return 0;
182}
183#endif
184