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mkswap.c

/*
 * 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.
 * sparc64 fixes, jj, 000219.
 *
 * 1999-02-22 Arkadiusz Mi¶kiewicz <misiek@pld.ORG.PL>
 * - added Native Language Support
 * 
 */

#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 <sys/stat.h>
#include "../defines.h"
#include "swapheader.h"
#include "xstrncpy.h"
#include "nls.h"

#ifdef HAVE_uuid_uuid_h
#include <uuid/uuid.h>
#endif

/* Try to get PAGE_SIZE from libc or kernel includes */
#ifdef HAVE_sys_user_h
                        /* Note: <sys/user.h> says: for gdb only */
#include <sys/user.h>         /* for PAGE_SIZE and PAGE_SHIFT */
#else
#ifdef HAVE_asm_page_h
#include <asm/page.h>         /* for PAGE_SIZE and PAGE_SHIFT */
                        /* we also get PAGE_SIZE via getpagesize() */
#endif
#endif

#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

static char * program_name = "mkswap";
static char * device_name = NULL;
static int DEV = -1;
static unsigned long PAGES = 0;
static unsigned long badpages = 0;
static int check = 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;
}

#ifdef __sparc__
# ifdef __arch64__
#  define is_sparc64() 1
#  define is_be64() 1
# else /* sparc32 */
static int
is_sparc64(void) {
      struct utsname un;
      static int sparc64 = -1;

      if (sparc64 != -1) return sparc64;
      sparc64 = 0;

      if (uname(&un) < 0) return 0;
      if (! strcmp(un.machine, "sparc64")) {
            sparc64 = 1;
            return 1;
      }
      if (strcmp(un.machine, "sparc"))
            return 0; /* Should not happen */

#ifdef HAVE_personality
      {
            extern int personality(unsigned long);
            int oldpers;
#define PERS_LINUX          0x00000000
#define PERS_LINUX_32BIT    0x00800000
#define PERS_LINUX32        0x00000008

            oldpers = personality(PERS_LINUX_32BIT);
            if (oldpers != -1) {
                  if (personality(PERS_LINUX) != -1) {
                        uname(&un);
                        if (! strcmp(un.machine, "sparc64")) {
                              sparc64 = 1;
                              oldpers = PERS_LINUX32;
                        }
                  }
                  personality(oldpers);
            }
      }
#endif

      return sparc64;
}
#  define is_be64() is_sparc64()
# endif /* sparc32 */
#else /* !sparc */
# define is_be64() 0
#endif

/*
 * 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(), so that
 * we do not need separate binaries e.g. for sun4, sun4c/d/m and sun4u.
 *
 * Even more unfortunately, getpagesize() does not always return
 * the right information. For example, libc4 and libc5 do not use
 * the system call but invent a value themselves
 * (EXEC_PAGESIZE or NBPG * CLSIZE or NBPC), and thus it may happen
 * that e.g. on a sparc PAGE_SIZE=4096 and getpagesize() returns 8192.
 * What to do? Let us allow the user to specify the pagesize explicitly.
 */

static int user_pagesize = 0;
static int kernel_pagesize;      /* obtained via getpagesize(); */
static int defined_pagesize = 0;   /* PAGE_SIZE, when that exists */
static int pagesize;
static long *signature_page;
struct swap_header_v1 *p;

static void
init_signature_page(void) {

#ifdef PAGE_SIZE
      defined_pagesize = PAGE_SIZE;
#endif
      kernel_pagesize = getpagesize();
      pagesize = kernel_pagesize;

      if (user_pagesize) {
            if ((user_pagesize & (user_pagesize-1)) ||
                user_pagesize < 1024) {
                  fprintf(stderr, _("Bad user-specified page size %d\n"),
                        user_pagesize);
                  exit(1);
            }
            pagesize = user_pagesize;
      }

      if (user_pagesize && user_pagesize != kernel_pagesize &&
          user_pagesize != defined_pagesize)
            fprintf(stderr, _("Using user-specified page size %d, "
                          "instead of the system values %d/%d\n"),
                  pagesize, kernel_pagesize, defined_pagesize);
      else if (defined_pagesize && pagesize != defined_pagesize)
            fprintf(stderr, _("Assuming pages of size %d (not %d)\n"),
                  pagesize, defined_pagesize);

      signature_page = (long *) malloc(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);
}

#if 0
static int
tohex(int a) {
      return ((a < 10) ? '0'+a : 'a'+a-10);
}

static void
uuid_unparse(unsigned char *uuid, char *s) {
      int i;

      for (i=0; i<16; i++) {
            if (i == 4 || i == 6 || i == 8 || i == 10)
                  *s++ = '-';
            *s++ = tohex((uuid[i] >> 4) & 0xf);
            *s++ = tohex(uuid[i] & 0xf);
      }
      *s = 0;
}
#endif

static void
write_uuid_and_label(char *uuid, char *volume_name) {
      struct swap_header_v1_2 *h;

      /* Sanity check */
      if (sizeof(struct swap_header_v1) !=
          sizeof(struct swap_header_v1_2)) {
            fprintf(stderr,
                  _("Bad swap header size, no label written.\n"));
            return;
      }

      h = (struct swap_header_v1_2 *) signature_page;
      if (uuid)
            memcpy(h->uuid, uuid, sizeof(h->uuid));
      if (volume_name) {
            xstrncpy(h->volume_name, volume_name, sizeof(h->volume_name));
            if (strlen(volume_name) > strlen(h->volume_name))
                  fprintf(stderr, _("Label was truncated.\n"));
      }
      if (uuid || volume_name) {
            if (volume_name)
                  printf("LABEL=%s, ", h->volume_name);
            else
                  printf(_("no label, "));
#ifdef HAVE_uuid_uuid_h
            if (uuid) {
                  char uuid_string[37];
                  uuid_unparse(uuid, uuid_string);
                  printf("UUID=%s\n", uuid_string);
            } else
#endif
                  printf(_("no uuid\n"));
      }
}

/*
 * Find out what the maximum amount of swap space is that the kernel will
 * handle.  This wouldn't matter if the kernel just used as much of the
 * swap space as it can handle, but until 2.3.4 it would return an error
 * to swapon() if the swapspace was too large.
 */
#define V0_MAX_PAGES    (8 * (pagesize - 10))
/* Before 2.2.0pre9 */
#define V1_OLD_MAX_PAGES      ((0x7fffffff / pagesize) - 1)
/* Since 2.2.0pre9, before 2.3.4:
   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? */
/* 32bit kernels have a second limitation of 2GB, sparc64 is limited by
   the size of virtual address space allocation for vmalloc */
#if defined(__alpha__)
#define V1_MAX_PAGES           ((1 << 24) - 1)
#elif defined(__mips__)
#define V1_MAX_PAGES           ((1 << 17) - 1)
#elif defined(__sparc__)
#define V1_MAX_PAGES           (is_sparc64() ? ((3 << 29) - 1) : ((1 << 18) - 1))
#elif defined(__ia64__)
/* 
 * The actual size will depend on the amount of virtual address space
 * available to vmalloc the swap map.
 */
#define V1_MAX_PAGES          ((1UL << 54) - 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))

/*
 * One more point of lossage - Linux swapspace really is a mess.
 * The definition of the bitmap used is architecture dependent,
 * and requires one to know whether the machine is bigendian,
 * and if so, whether it will use 32-bit or 64-bit units in
 * test_bit().
 * davem writes: "... is based upon an unsigned long type of
 * the cpu and the native endianness".
 * So, it seems we can write `unsigned long' below.
 * However, sparc64 uses 64-bit units in the kernel, while
 * mkswap may have been translated with 32-bit longs. Thus,
 * we need an explicit test for version 0 swap on sparc64.
 */

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

      if(is_be64()) {
            unsigned long long *bitmap = (unsigned long long *) addr;
            unsigned long long bitnum = (unsigned long long) nr;
            unsigned long long rl, ml;

            bitmap += bitnum / (8 * sizeof(long long));
            rl = *bitmap;
            ml = 1ULL << (bitnum & (8ULL * sizeof(long long) - 1ULL));
            *bitmap = rl | ml;
            return;
      }

      addr += nr / (8 * sizeof(unsigned long));
      r = *addr;
      m = 1 << (nr & (8 * sizeof(unsigned long) - 1));
      *addr = r | m;
}

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

      if(is_be64()) {
            unsigned long long *bitmap = (unsigned long long *) addr;
            unsigned long long bitnum = (unsigned long long) nr;
            unsigned long long rl, ml;

            bitmap += bitnum / (8 * sizeof(long long));
            rl = *bitmap;
            ml = 1ULL << (bitnum & (8ULL * sizeof(long long) - 1ULL));
            *bitmap = rl & ~ml;
            return ((rl & ml) != 0ULL);
      }

      addr += nr / (8 * sizeof(unsigned long));
      r = *addr;
      m = 1 << (nr & (8 * sizeof(unsigned long) - 1));
      *addr = r & ~m;
      return (r & m) != 0;
}

static void
usage(void) {
      fprintf(stderr,
            _("Usage: %s [-c] [-v0|-v1] [-pPAGESZ] [-L label] /dev/name [blocks]\n"),
            program_name);
      exit(1);
}

static void
die(const char *str) {
      fprintf(stderr, "%s: %s\n", program_name, str);
      exit(1);
}

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)
                  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 = malloc(pagesize);
      if (!buffer)
            die(_("Out of memory"));
      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)
                  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(_("%lu bad pages\n"), badpages);
}

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

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

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

      low = 0;
      for (high = 1; high > 0 && valid_offset (fd, high); high *= 2)
            low = high;
      while (low < high - 1) {
            const off_t 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 unsigned long
get_size(const char  *file) {
      int   fd;
      unsigned long     size;

      fd = open(file, O_RDONLY);
      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;
      }
      close(fd);
      return size;
}

static int
isnzdigit(char c) {
      return (c >= '1' && c <= '9');
}

int
main(int argc, char ** argv) {
      struct stat statbuf;
      int i;
      unsigned long maxpages;
      unsigned long goodpages;
      unsigned long sz;
      off_t offset;
      int force = 0;
      char *block_count = 0;
      char *pp;
      char *opt_label = NULL;
      char *uuid = NULL;
#ifdef HAVE_uuid_uuid_h
      uuid_t uuid_dat;
#endif

      program_name = (argc && *argv) ? argv[0] : "mkswap";
      if ((pp = strrchr(program_name, '/')) != NULL)
            program_name = pp+1;

      setlocale(LC_ALL, "");
      bindtextdomain(PACKAGE, LOCALEDIR);
      textdomain(PACKAGE);

      if (argc == 2 &&
          (!strcmp(argv[1], "-V") || !strcmp(argv[1], "--version"))) {
            printf(_("%s from %s\n"), program_name, util_linux_version);
            exit(0);
      }

      for (i=1; i<argc; i++) {
            if (argv[i][0] == '-') {
                  switch (argv[i][1]) {
                        case 'c':
                              check=1;
                              break;
                        case 'f':
                              force=1;
                              break;
                        case 'p':
                              pp = argv[i]+2;
                              if (!*pp && i+1 < argc)
                                    pp = argv[++i];
                              if (isnzdigit(*pp))
                                    user_pagesize = atoi(pp);
                              else
                                    usage();
                              break;
                          case 'L':
                              pp = argv[i]+2;
                              if (!*pp && i+1 < argc)
                                    pp = argv[++i];
                              opt_label = pp;
                                break;
                        case 'v':
                              version = atoi(argv[i]+2);
                              break;
                        default:
                              usage();
                  }
            } else if (!device_name) {
                  device_name = argv[i];
            } else if (!block_count) {
                  block_count = argv[i];
            } else
                  usage();
      }

#ifdef HAVE_uuid_uuid_h
      uuid_generate(uuid_dat);
      uuid = uuid_dat;
#endif

      init_signature_page();  /* get pagesize */

      if (!device_name) {
            fprintf(stderr,
                  _("%s: error: Nowhere to set up swap on?\n"),
                  program_name);
            usage();
      }
      if (block_count) {
            /* this silly user specified the number of blocks
               explicitly */
            char *tmp;
            int blocks_per_page = pagesize/1024;
            PAGES = strtoul(block_count,&tmp,0)/blocks_per_page;
            if (*tmp)
                  usage();
      }
      sz = get_size(device_name);
      if (!PAGES) {
            PAGES = sz;
      } else if (PAGES > sz && !force) {
            fprintf(stderr,
                  _("%s: error: "
                    "size %lu is larger than device size %lu\n"),
                  program_name,
                  PAGES*(pagesize/1024), sz*(pagesize/1024));
            exit(1);
      }

      if (version == -1) {
            /* labels only for v1 */
            if (opt_label)
                  version = 1;
            else
            /* use version 1 as default, if possible */
            if (PAGES <= V0_MAX_PAGES && PAGES > V1_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();
      }

      if (PAGES < 10) {
            fprintf(stderr,
                  _("%s: error: swap area needs to be at least %ldkB\n"),
                  program_name, (long)(10 * pagesize / 1000));
            usage();
      }

      if (version == 0)
            maxpages = V0_MAX_PAGES;
      else if (linux_version_code() >= MAKE_VERSION(2,3,4))
            maxpages = PAGES;
      else if (linux_version_code() >= MAKE_VERSION(2,2,1))
            maxpages = V1_MAX_PAGES;
      else
            maxpages = V1_OLD_MAX_PAGES;

      if (PAGES > maxpages) {
            PAGES = maxpages;
            fprintf(stderr,
                  _("%s: warning: truncating swap area to %ldkB\n"),
                  program_name, PAGES * pagesize / 1000);
      }

      if (opt_label && version == 0) {
            fprintf(stderr,
                  _("%s: error: label only with v1 swap area\n"),
                  program_name);
            usage();
      }

      DEV = open(device_name,O_RDWR);
      if (DEV < 0 || fstat(DEV, &statbuf) < 0) {
            perror(device_name);
            exit(1);
      }

      /* Want a block device. Probably not /dev/hda or /dev/hdb. */
      if (!S_ISBLK(statbuf.st_mode))
            check=0;
      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(1);
                  }
            }
      }
#endif

      if (version == 0 || check)
            check_blocks();
      if (version == 0 && !bit_test_and_clear(signature_page,0))
            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 ((long) goodpages <= 0)
            die(_("Unable to set up swap-space: unreadable"));
      printf(_("Setting up swapspace version %d, size = %llu kB\n"),
            version, (unsigned long long)goodpages * pagesize / 1000);
      write_signature((version == 0) ? "SWAP-SPACE" : "SWAPSPACE2");

      if (version == 1)
            write_uuid_and_label(uuid, opt_label);

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

      /*
       * A subsequent swapon() will fail if the signature
       * is not actually on disk. (This is a kernel bug.)
       */
#ifdef HAVE_fsync
      if (fsync(DEV))
             die(_("fsync failed"));
#endif
      return 0;
}

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