summaryrefslogtreecommitdiff
path: root/util-linux/mkswap.c
blob: 7d690ad99b5e7c6b18626211e5ed638d1cbd89e5 (plain)
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
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
/* vi: set sw=4 ts=4: */
/*
 * mkswap.c - set up a linux swap device
 *
 * (C) 1991 Linus Torvalds. This file may be redistributed as per
 * the Linux copyright.
 */

/*
 * 20.12.91  -	time began. Got VM working yesterday by doing this by hand.
 *
 * Usage: mkswap [-c] [-vN] [-f] device [size-in-blocks]
 *
 *	-c   for readability checking. (Use it unless you are SURE!)
 *	-vN  for swap areas version N. (Only N=0,1 known today.)
 *      -f   for forcing swap creation even if it would smash partition table.
 *
 * The device may be a block device or an image of one, but this isn't
 * enforced (but it's not much fun on a character device :-).
 *
 * Patches from jaggy@purplet.demon.co.uk (Mike Jagdis) to make the
 * size-in-blocks parameter optional added Wed Feb  8 10:33:43 1995.
 *
 * Version 1 swap area code (for kernel 2.1.117), aeb, 981010.
 *
 * Sparc fixes, jj@ultra.linux.cz (Jakub Jelinek), 981201 - mangled by aeb.
 * V1_MAX_PAGES fixes, jj, 990325.
 *
 * 1999-02-22 Arkadiusz Mi¶kiewicz <misiek@misiek.eu.org>
 * - added Native Language Support
 *
 *  from util-linux -- adapted for busybox by
 *  Erik Andersen <andersee@debian.org>. I ripped out Native Language
 *  Support, made some stuff smaller, and fitted for life in busybox.
 *
 */

#include "busybox.h"
#include <stdio.h>
#include <unistd.h>
#include <string.h>
#include <fcntl.h>
#include <stdlib.h>
#include <sys/ioctl.h>			/* for _IO */
#include <sys/utsname.h>
#include <asm/page.h>			/* for PAGE_SIZE and PAGE_SHIFT */
				/* we also get PAGE_SIZE via getpagesize() */

#ifndef _IO
/* pre-1.3.45 */
static const int BLKGETSIZE = 0x1260;
#else
/* same on i386, m68k, arm; different on alpha, mips, sparc, ppc */
#define BLKGETSIZE _IO(0x12,96)
#endif

static char *device_name = NULL;
static int DEV = -1;
static long PAGES = 0;
static int check = 0;
static int badpages = 0;
static int version = -1;

#define MAKE_VERSION(p,q,r)	(65536*(p) + 256*(q) + (r))

/*
 * The definition of the union swap_header uses the constant PAGE_SIZE.
 * Unfortunately, on some architectures this depends on the hardware model,
 * and can only be found at run time -- we use getpagesize().
 */

static int pagesize;
static int *signature_page;

struct swap_header_v1 {
	char bootbits[1024];		/* Space for disklabel etc. */
	unsigned int version;
	unsigned int last_page;
	unsigned int nr_badpages;
	unsigned int padding[125];
	unsigned int badpages[1];
} *p;

static void init_signature_page()
{
	pagesize = getpagesize();

#ifdef PAGE_SIZE
	if (pagesize != PAGE_SIZE)
		error_msg("Assuming pages of size %d", pagesize);
#endif
	signature_page = (int *) xmalloc(pagesize);
	memset(signature_page, 0, pagesize);
	p = (struct swap_header_v1 *) signature_page;
}

static void write_signature(char *sig)
{
	char *sp = (char *) signature_page;

	strncpy(sp + pagesize - 10, sig, 10);
}

#define V0_MAX_PAGES	(8 * (pagesize - 10))
/* Before 2.2.0pre9 */
#define V1_OLD_MAX_PAGES	((0x7fffffff / pagesize) - 1)
/* Since 2.2.0pre9:
   error if nr of pages >= SWP_OFFSET(SWP_ENTRY(0,~0UL))
   with variations on
	#define SWP_ENTRY(type,offset) (((type) << 1) | ((offset) << 8))
	#define SWP_OFFSET(entry) ((entry) >> 8)
   on the various architectures. Below the result - yuk.

   Machine	pagesize	SWP_ENTRY	SWP_OFFSET	bound+1	oldbound+2
   i386		2^12		o<<8		e>>8		1<<24	1<<19
   mips		2^12		o<<15		e>>15		1<<17	1<<19
   alpha	2^13		o<<40		e>>40		1<<24	1<<18
   m68k		2^12		o<<12		e>>12		1<<20	1<<19
   sparc	2^{12,13}	(o&0x3ffff)<<9	(e>>9)&0x3ffff	1<<18	1<<{19,18}
   sparc64	2^13		o<<13		e>>13		1<<51	1<<18
   ppc		2^12		o<<8		e>>8		1<<24	1<<19
   armo		2^{13,14,15}	o<<8		e>>8		1<<24	1<<{18,17,16}
   armv		2^12		o<<9		e>>9		1<<23	1<<19

   assuming that longs have 64 bits on alpha and sparc64 and 32 bits elsewhere.

   The bad part is that we need to know this since the kernel will
   refuse a swap space if it is too large.
*/
/* patch from jj - why does this differ from the above? */
#if defined(__alpha__)
#define V1_MAX_PAGES           ((1 << 24) - 1)
#elif defined(__mips__)
#define V1_MAX_PAGES           ((1 << 17) - 1)
#elif defined(__sparc_v9__)
#define V1_MAX_PAGES           ((3 << 29) - 1)
#elif defined(__sparc__)
#define V1_MAX_PAGES           (pagesize == 8192 ? ((3 << 29) - 1) : ((1 << 18) - 1))
#else
#define V1_MAX_PAGES           V1_OLD_MAX_PAGES
#endif
/* man page now says:
The maximum useful size of a swap area now depends on the architecture.
It is roughly 2GB on i386, PPC, m68k, ARM, 1GB on sparc, 512MB on mips,
128GB on alpha and 3TB on sparc64.
*/

#define MAX_BADPAGES	((pagesize-1024-128*sizeof(int)-10)/sizeof(int))

static void bit_set(unsigned int *addr, unsigned int nr)
{
	unsigned int r, m;

	addr += nr / (8 * sizeof(int));

	r = *addr;
	m = 1 << (nr & (8 * sizeof(int) - 1));

	*addr = r | m;
}

static int bit_test_and_clear(unsigned int *addr, unsigned int nr)
{
	unsigned int r, m;

	addr += nr / (8 * sizeof(int));

	r = *addr;
	m = 1 << (nr & (8 * sizeof(int) - 1));

	*addr = r & ~m;
	return (r & m) != 0;
}


static void page_ok(int page)
{
	if (version == 0)
		bit_set(signature_page, page);
}

static void page_bad(int page)
{
	if (version == 0)
		bit_test_and_clear(signature_page, page);
	else {
		if (badpages == MAX_BADPAGES)
			error_msg_and_die("too many bad pages");
		p->badpages[badpages] = page;
	}
	badpages++;
}

static void check_blocks(void)
{
	unsigned int current_page;
	int do_seek = 1;
	char *buffer;

	buffer = xmalloc(pagesize);
	current_page = 0;
	while (current_page < PAGES) {
		if (!check) {
			page_ok(current_page++);
			continue;
		}
		if (do_seek && lseek(DEV, current_page * pagesize, SEEK_SET) !=
			current_page * pagesize)
			error_msg_and_die("seek failed in check_blocks");
		if ((do_seek = (pagesize != read(DEV, buffer, pagesize)))) {
			page_bad(current_page++);
			continue;
		}
		page_ok(current_page++);
	}
	if (badpages == 1)
		printf("one bad page\n");
	else if (badpages > 1)
		printf("%d bad pages\n", badpages);
}

static long valid_offset(int fd, int offset)
{
	char ch;

	if (lseek(fd, offset, 0) < 0)
		return 0;
	if (read(fd, &ch, 1) < 1)
		return 0;
	return 1;
}

static int find_size(int fd)
{
	unsigned int high, low;

	low = 0;
	for (high = 1; high > 0 && valid_offset(fd, high); high *= 2)
		low = high;
	while (low < high - 1) {
		const int mid = (low + high) / 2;

		if (valid_offset(fd, mid))
			low = mid;
		else
			high = mid;
	}
	return (low + 1);
}

/* return size in pages, to avoid integer overflow */
static long get_size(const char *file)
{
	int fd;
	long size;

	if ((fd = open(file, O_RDONLY)) < 0)
		perror_msg_and_die("%s", file);
	if (ioctl(fd, BLKGETSIZE, &size) >= 0) {
		int sectors_per_page = pagesize / 512;

		size /= sectors_per_page;
	} else {
		size = find_size(fd) / pagesize;
	}
	close(fd);
	return size;
}

int mkswap_main(int argc, char **argv)
{
	char *tmp;
	struct stat statbuf;
	int sz;
	int maxpages;
	int goodpages;
	int offset;
	int force = 0;

	init_signature_page();		/* get pagesize */

	while (argc-- > 1) {
		argv++;
		if (argv[0][0] != '-') {
			if (device_name) {
				int blocks_per_page = pagesize / 1024;

				PAGES = strtol(argv[0], &tmp, 0) / blocks_per_page;
				if (*tmp)
					usage(mkswap_usage);
			} else
				device_name = argv[0];
		} else {
			switch (argv[0][1]) {
			case 'c':
				check = 1;
				break;
			case 'f':
				force = 1;
				break;
			case 'v':
				version = atoi(argv[0] + 2);
				break;
			default:
				usage(mkswap_usage);
			}
		}
	}
	if (!device_name) {
		error_msg("error: Nowhere to set up swap on?");
		usage(mkswap_usage);
	}
	sz = get_size(device_name);
	if (!PAGES) {
		PAGES = sz;
	} else if (PAGES > sz && !force) {
		error_msg("error: size %ld is larger than device size %d",
				PAGES * (pagesize / 1024), sz * (pagesize / 1024));
		return EXIT_FAILURE;
	}

	if (version == -1) {
		if (PAGES <= V0_MAX_PAGES)
			version = 0;
		else if (get_kernel_revision() < MAKE_VERSION(2, 1, 117))
			version = 0;
		else if (pagesize < 2048)
			version = 0;
		else
			version = 1;
	}
	if (version != 0 && version != 1) {
		error_msg("error: unknown version %d", version);
		usage(mkswap_usage);
	}
	if (PAGES < 10) {
		error_msg("error: swap area needs to be at least %ldkB",
				(long) (10 * pagesize / 1024));
		usage(mkswap_usage);
	}
#if 0
	maxpages = ((version == 0) ? V0_MAX_PAGES : V1_MAX_PAGES);
#else
	if (!version)
		maxpages = V0_MAX_PAGES;
	else if (get_kernel_revision() >= MAKE_VERSION(2, 2, 1))
		maxpages = V1_MAX_PAGES;
	else {
		maxpages = V1_OLD_MAX_PAGES;
		if (maxpages > V1_MAX_PAGES)
			maxpages = V1_MAX_PAGES;
	}
#endif
	if (PAGES > maxpages) {
		PAGES = maxpages;
		error_msg("warning: truncating swap area to %ldkB",
				PAGES * pagesize / 1024);
	}

	DEV = open(device_name, O_RDWR);
	if (DEV < 0 || fstat(DEV, &statbuf) < 0)
		perror_msg_and_die("%s", device_name);
	if (!S_ISBLK(statbuf.st_mode))
		check = 0;
	else if (statbuf.st_rdev == 0x0300 || statbuf.st_rdev == 0x0340)
		error_msg_and_die("Will not try to make swapdevice on '%s'", device_name);

#ifdef __sparc__
	if (!force && version == 0) {
		/* Don't overwrite partition table unless forced */
		unsigned char *buffer = (unsigned char *) signature_page;
		unsigned short *q, sum;

		if (read(DEV, buffer, 512) != 512)
			error_msg_and_die("fatal: first page unreadable");
		if (buffer[508] == 0xDA && buffer[509] == 0xBE) {
			q = (unsigned short *) (buffer + 510);
			for (sum = 0; q >= (unsigned short *) buffer;)
				sum ^= *q--;
			if (!sum) {
				error_msg("Device '%s' contains a valid Sun disklabel.\n"
"This probably means creating v0 swap would destroy your partition table\n"
"No swap created. If you really want to create swap v0 on that device, use\n"
"the -f option to force it.", device_name);
				return EXIT_FAILURE;
			}
		}
	}
#endif

	if (version == 0 || check)
		check_blocks();
	if (version == 0 && !bit_test_and_clear(signature_page, 0))
		error_msg_and_die("fatal: first page unreadable");
	if (version == 1) {
		p->version = version;
		p->last_page = PAGES - 1;
		p->nr_badpages = badpages;
	}

	goodpages = PAGES - badpages - 1;
	if (goodpages <= 0)
		error_msg_and_die("Unable to set up swap-space: unreadable");
	printf("Setting up swapspace version %d, size = %ld bytes\n",
		   version, (long) (goodpages * pagesize));
	write_signature((version == 0) ? "SWAP-SPACE" : "SWAPSPACE2");

	offset = ((version == 0) ? 0 : 1024);
	if (lseek(DEV, offset, SEEK_SET) != offset)
		error_msg_and_die("unable to rewind swap-device");
	if (write(DEV, (char *) signature_page + offset, pagesize - offset)
		!= pagesize - offset)
		error_msg_and_die("unable to write signature page");

	/*
	 * A subsequent swapon() will fail if the signature
	 * is not actually on disk. (This is a kernel bug.)
	 */
	if (fsync(DEV))
		error_msg_and_die("fsync failed");
	return EXIT_SUCCESS;
}