busybox/mkswap.c

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/*
* 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]
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*
* -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.
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*
* The device may be a block device or an image of one, but this isn't
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* 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<EFBFBD>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.
*
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*/
#include "internal.h"
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#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>
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#include <sys/stat.h>
#include <asm/page.h> /* for PAGE_SIZE and PAGE_SHIFT */
/* we also get PAGE_SIZE via getpagesize() */
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static const char mkswap_usage[] = "mkswap [-c] [-v0|-v1] device [block-count]\n\n"
"Prepare a disk partition to be used as a swap partition.\n\n"
"Options:\n"
"\t-c\t\tCheck for read-ability.\n"
"\t-v0\t\tMake version 0 swap [max 128 Megs].\n"
"\t-v1\t\tMake version 1 swap [big!] (default for kernels > 2.1.117).\n"
"\tblock-count\tNumber of block to use (default is entire partition).\n";
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#ifndef _IO
/* pre-1.3.45 */
#define BLKGETSIZE 0x1260
#else
/* same on i386, m68k, arm; different on alpha, mips, sparc, ppc */
#define BLKGETSIZE _IO(0x12,96)
#endif
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static char * program_name = "mkswap";
static char * device_name = NULL;
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static int DEV = -1;
static long PAGES = 0;
static int check = 0;
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static int badpages = 0;
static int version = -1;
#define MAKE_VERSION(p,q,r) (65536*(p) + 256*(q) + (r))
static int
linux_version_code(void) {
struct utsname my_utsname;
int p, q, r;
if (uname(&my_utsname) == 0) {
p = atoi(strtok(my_utsname.release, "."));
q = atoi(strtok(NULL, "."));
r = atoi(strtok(NULL, "."));
return MAKE_VERSION(p,q,r);
}
return 0;
}
/*
* 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)
fprintf(stderr, "Assuming pages of size %d\n", pagesize);
#endif
signature_page = (int *) malloc(pagesize);
memset(signature_page,0,pagesize);
p = (struct swap_header_v1 *) signature_page;
}
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static void
write_signature(char *sig) {
char *sp = (char *) signature_page;
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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)
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{
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;
}
void
die(const char *str) {
fprintf(stderr, "%s: %s\n", program_name, str);
exit( FALSE);
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}
void
page_ok(int page) {
if (version==0)
bit_set(signature_page, page);
}
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void
page_bad(int page) {
if (version == 0)
bit_test_and_clear(signature_page, page);
else {
if (badpages == MAX_BADPAGES)
die("too many bad pages");
p->badpages[badpages] = page;
}
badpages++;
}
void
check_blocks(void) {
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unsigned int current_page;
int do_seek = 1;
char *buffer;
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buffer = malloc(pagesize);
if (!buffer)
die("Out of memory");
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current_page = 0;
while (current_page < PAGES) {
if (!check) {
page_ok(current_page++);
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continue;
}
if (do_seek && lseek(DEV,current_page*pagesize,SEEK_SET) !=
current_page*pagesize)
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die("seek failed in check_blocks");
if ((do_seek = (pagesize != read(DEV, buffer, pagesize)))) {
page_bad(current_page++);
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continue;
}
page_ok(current_page++);
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}
if (badpages == 1)
printf("one bad page\n");
else if (badpages > 1)
printf("%d bad pages\n", badpages);
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}
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)
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{
unsigned int high, low;
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low = 0;
for (high = 1; high > 0 && valid_offset (fd, high); high *= 2)
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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)
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{
int fd;
long size;
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fd = open(file, O_RDONLY);
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if (fd < 0) {
perror(file);
exit(1);
}
if (ioctl(fd, BLKGETSIZE, &size) >= 0) {
int sectors_per_page = pagesize/512;
size /= sectors_per_page;
} else {
size = find_size(fd) / pagesize;
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}
close(fd);
return size;
}
int mkswap_main(int argc, char ** argv)
{
char * tmp;
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struct stat statbuf;
int sz;
int maxpages;
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int goodpages;
int offset;
int force = 0;
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if (argc && *argv)
program_name = *argv;
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init_signature_page(); /* get pagesize */
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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) {
fprintf(stderr,
"%s: error: Nowhere to set up swap on?\n",
program_name);
usage( mkswap_usage);
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}
sz = get_size(device_name);
if (!PAGES) {
PAGES = sz;
} else if (PAGES > sz && !force) {
fprintf(stderr,
"%s: error: "
"size %ld is larger than device size %d\n",
program_name,
PAGES*(pagesize/1024), sz*(pagesize/1024));
exit( FALSE);
}
if (version == -1) {
if (PAGES <= V0_MAX_PAGES)
version = 0;
else if (linux_version_code() < MAKE_VERSION(2,1,117))
version = 0;
else if (pagesize < 2048)
version = 0;
else
version = 1;
}
if (version != 0 && version != 1) {
fprintf(stderr, "%s: error: unknown version %d\n",
program_name, version);
usage( mkswap_usage);
}
if (PAGES < 10) {
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fprintf(stderr,
"%s: error: swap area needs to be at least %ldkB\n",
program_name, (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 (linux_version_code() >= MAKE_VERSION(2,2,1))
maxpages = V1_MAX_PAGES;
else {
maxpages = V1_OLD_MAX_PAGES;
if (maxpages > V1_MAX_PAGES)
maxpages = V1_MAX_PAGES;
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}
#endif
if (PAGES > maxpages) {
PAGES = maxpages;
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fprintf(stderr, "%s: warning: truncating swap area to %ldkB\n",
program_name, PAGES * pagesize / 1024);
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}
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DEV = open(device_name,O_RDWR);
if (DEV < 0 || fstat(DEV, &statbuf) < 0) {
perror(device_name);
exit( FALSE);
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}
if (!S_ISBLK(statbuf.st_mode))
check=0;
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else if (statbuf.st_rdev == 0x0300 || statbuf.st_rdev == 0x0340)
die("Will not try to make swapdevice on '%s'");
#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)
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) {
fprintf(stderr, "\
%s: 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.\n",
program_name, device_name);
exit( FALSE);
}
}
}
#endif
if (version == 0 || check)
check_blocks();
if (version == 0 && !bit_test_and_clear(signature_page,0))
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die("fatal: first page unreadable");
if (version == 1) {
p->version = version;
p->last_page = PAGES-1;
p->nr_badpages = badpages;
}
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goodpages = PAGES - badpages - 1;
if (goodpages <= 0)
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)
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die("unable to rewind swap-device");
if (write(DEV,(char*)signature_page+offset, pagesize-offset)
!= pagesize-offset)
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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))
die("fsync failed");
exit ( TRUE);
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}