1 | /* vi: set sw=4 ts=4: */
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2 | /* mkswap.c - format swap device (Linux v1 only)
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3 | *
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4 | * Copyright 2006 Rob Landley <rob@landley.net>
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5 | *
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6 | * Licensed under GPL version 2, see file LICENSE in this tarball for details.
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7 | */
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8 |
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9 | #include "libbb.h"
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10 |
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11 | int mkswap_main(int argc, char **argv);
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12 | int mkswap_main(int argc, char **argv)
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13 | {
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14 | int fd, pagesize;
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15 | off_t len;
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16 | unsigned int hdr[129];
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17 |
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18 | // No options supported.
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19 |
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20 | if (argc != 2) bb_show_usage();
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21 |
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22 | // Figure out how big the device is and announce our intentions.
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23 |
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24 | fd = xopen(argv[1], O_RDWR);
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25 | len = fdlength(fd);
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26 | pagesize = getpagesize();
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27 | printf("Setting up swapspace version 1, size = %"OFF_FMT"d bytes\n",
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28 | len - pagesize);
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29 |
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30 | // Make a header.
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31 |
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32 | memset(hdr, 0, sizeof(hdr));
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33 | hdr[0] = 1;
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34 | hdr[1] = (len / pagesize) - 1;
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35 |
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36 | // Write the header. Sync to disk because some kernel versions check
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37 | // signature on disk (not in cache) during swapon.
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38 |
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39 | xlseek(fd, 1024, SEEK_SET);
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40 | xwrite(fd, hdr, sizeof(hdr));
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41 | xlseek(fd, pagesize-10, SEEK_SET);
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42 | xwrite(fd, "SWAPSPACE2", 10);
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43 | fsync(fd);
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44 |
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45 | if (ENABLE_FEATURE_CLEAN_UP) close(fd);
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46 |
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47 | return 0;
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48 | }
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