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-rw-r--r--mkswap.c422
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diff --git a/mkswap.c b/mkswap.c
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--- a/mkswap.c
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-/* 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 <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() */
-#include "busybox.h"
-
-#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;
-
-static 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(void)
-{
- 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)
- show_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:
- show_usage();
- }
- }
- }
- if (!device_name) {
- error_msg("error: Nowhere to set up swap on?");
- show_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);
- show_usage();
- }
- if (PAGES < 10) {
- error_msg("error: swap area needs to be at least %ldkB",
- (long) (10 * pagesize / 1024));
- show_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;
-}
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