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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()
+{
+ 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 (!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;
+ }
+ 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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