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    Contents of /trunk/mkinitrd-magellan/busybox/util-linux/mkswap.c

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    Revision 816 - (show annotations) (download)
    Fri Apr 24 18:33:46 2009 UTC (15 years, 1 month ago) by niro
    File MIME type: text/plain
    File size: 3464 byte(s) 
    -updated to busybox-1.13.4
    1 /* vi: set sw=4 ts=4: */
    2 /* mkswap.c - format swap device (Linux v1 only)
    3 *
    4 * Copyright 2006 Rob Landley <rob@landley.net>
    5 *
    6 * Licensed under GPL version 2, see file LICENSE in this tarball for details.
    7 */
    8
    9 #include "libbb.h"
    10
    11 #if ENABLE_SELINUX
    12 static void mkswap_selinux_setcontext(int fd, const char *path)
    13 {
    14 struct stat stbuf;
    15
    16 if (!is_selinux_enabled())
    17 return;
    18
    19 if (fstat(fd, &stbuf) < 0)
    20 bb_perror_msg_and_die("fstat failed");
    21 if (S_ISREG(stbuf.st_mode)) {
    22 security_context_t newcon;
    23 security_context_t oldcon = NULL;
    24 context_t context;
    25
    26 if (fgetfilecon(fd, &oldcon) < 0) {
    27 if (errno != ENODATA)
    28 goto error;
    29 if (matchpathcon(path, stbuf.st_mode, &oldcon) < 0)
    30 goto error;
    31 }
    32 context = context_new(oldcon);
    33 if (!context || context_type_set(context, "swapfile_t"))
    34 goto error;
    35 newcon = context_str(context);
    36 if (!newcon)
    37 goto error;
    38 /* fsetfilecon_raw is hidden */
    39 if (strcmp(oldcon, newcon) != 0 && fsetfilecon(fd, newcon) < 0)
    40 goto error;
    41 if (ENABLE_FEATURE_CLEAN_UP) {
    42 context_free(context);
    43 freecon(oldcon);
    44 }
    45 }
    46 return;
    47 error:
    48 bb_perror_msg_and_die("SELinux relabeling failed");
    49 }
    50 #else
    51 #define mkswap_selinux_setcontext(fd, path) ((void)0)
    52 #endif
    53
    54 #if 0 /* from Linux 2.6.23 */
    55 /*
    56 * Magic header for a swap area. The first part of the union is
    57 * what the swap magic looks like for the old (limited to 128MB)
    58 * swap area format, the second part of the union adds - in the
    59 * old reserved area - some extra information. Note that the first
    60 * kilobyte is reserved for boot loader or disk label stuff...
    61 */
    62 union swap_header {
    63 struct {
    64 char reserved[PAGE_SIZE - 10];
    65 char magic[10]; /* SWAP-SPACE or SWAPSPACE2 */
    66 } magic;
    67 struct {
    68 char bootbits[1024]; /* Space for disklabel etc. */
    69 __u32 version; /* second kbyte, word 0 */
    70 __u32 last_page; /* 1 */
    71 __u32 nr_badpages; /* 2 */
    72 unsigned char sws_uuid[16]; /* 3,4,5,6 */
    73 unsigned char sws_volume[16]; /* 7,8,9,10 */
    74 __u32 padding[117]; /* 11..127 */
    75 __u32 badpages[1]; /* 128, total 129 32-bit words */
    76 } info;
    77 };
    78 #endif
    79
    80 #define NWORDS 129
    81 #define hdr ((uint32_t*)(&bb_common_bufsiz1))
    82
    83 struct BUG_bufsiz1_is_too_small {
    84 char BUG_bufsiz1_is_too_small[COMMON_BUFSIZE < (NWORDS * 4) ? -1 : 1];
    85 };
    86
    87 /* Stored without terminating NUL */
    88 static const char SWAPSPACE2[sizeof("SWAPSPACE2")-1] ALIGN1 = "SWAPSPACE2";
    89
    90 int mkswap_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
    91 int mkswap_main(int argc, char **argv)
    92 {
    93 int fd, pagesize;
    94 off_t len;
    95
    96 // No options supported.
    97
    98 if (argc != 2) bb_show_usage();
    99
    100 // Figure out how big the device is and announce our intentions.
    101
    102 fd = xopen(argv[1], O_RDWR);
    103 /* fdlength was reported to be unreliable - use seek */
    104 len = xlseek(fd, 0, SEEK_END);
    105 #if ENABLE_SELINUX
    106 xlseek(fd, 0, SEEK_SET);
    107 #endif
    108 pagesize = getpagesize();
    109 printf("Setting up swapspace version 1, size = %"OFF_FMT"u bytes\n",
    110 len - pagesize);
    111 mkswap_selinux_setcontext(fd, argv[1]);
    112
    113 // Make a header. hdr is zero-filled so far...
    114 hdr[0] = 1;
    115 hdr[1] = (len / pagesize) - 1;
    116
    117 // Write the header. Sync to disk because some kernel versions check
    118 // signature on disk (not in cache) during swapon.
    119
    120 xlseek(fd, 1024, SEEK_SET);
    121 xwrite(fd, hdr, NWORDS * 4);
    122 xlseek(fd, pagesize - 10, SEEK_SET);
    123 xwrite(fd, SWAPSPACE2, 10);
    124 fsync(fd);
    125
    126 if (ENABLE_FEATURE_CLEAN_UP) close(fd);
    127
    128 return 0;
    129 }