release/src/router/busybox/util-linux/mkswap.c

   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 GPLv2, see file LICENSE in this source tree.
   7  */
   8
   9 //usage:#define mkswap_trivial_usage
  10 //usage:       "[-L LBL] BLOCKDEV [KBYTES]"
  11 //usage:#define mkswap_full_usage "\n\n"
  12 //usage:       "Prepare BLOCKDEV to be used as swap partition\n"
  13 //usage:     "\n        -L LBL  Label"
  14
  15 #include "libbb.h"
  16
  17 #if ENABLE_SELINUX
  18 static void mkswap_selinux_setcontext(int fd, const char *path)
  19 {
  20         struct stat stbuf;
  21
  22         if (!is_selinux_enabled())
  23                 return;
  24
  25         xfstat(fd, &stbuf, path);
  26         if (S_ISREG(stbuf.st_mode)) {
  27                 security_context_t newcon;
  28                 security_context_t oldcon = NULL;
  29                 context_t context;
  30
  31                 if (fgetfilecon(fd, &oldcon) < 0) {
  32                         if (errno != ENODATA)
  33                                 goto error;
  34                         if (matchpathcon(path, stbuf.st_mode, &oldcon) < 0)
  35                                 goto error;
  36                 }
  37                 context = context_new(oldcon);
  38                 if (!context || context_type_set(context, "swapfile_t"))
  39                         goto error;
  40                 newcon = context_str(context);
  41                 if (!newcon)
  42                         goto error;
  43                 /* fsetfilecon_raw is hidden */
  44                 if (strcmp(oldcon, newcon) != 0 && fsetfilecon(fd, newcon) < 0)
  45                         goto error;
  46                 if (ENABLE_FEATURE_CLEAN_UP) {
  47                         context_free(context);
  48                         freecon(oldcon);
  49                 }
  50         }
  51         return;
  52  error:
  53         bb_perror_msg_and_die("SELinux relabeling failed");
  54 }
  55 #else
  56 # define mkswap_selinux_setcontext(fd, path) ((void)0)
  57 #endif
  58
  59 /* from Linux 2.6.23 */
  60 /*
  61  * Magic header for a swap area. ... Note that the first
  62  * kilobyte is reserved for boot loader or disk label stuff.
  63  */
  64 struct swap_header_v1 {
  65 /*      char     bootbits[1024];    Space for disklabel etc. */
  66         uint32_t version;        /* second kbyte, word 0 */
  67         uint32_t last_page;      /* 1 */
  68         uint32_t nr_badpages;    /* 2 */
  69         char     sws_uuid[16];   /* 3,4,5,6 */
  70         char     sws_volume[16]; /* 7,8,9,10 */
  71         uint32_t padding[117];   /* 11..127 */
  72         uint32_t badpages[1];    /* 128 */
  73         /* total 129 32-bit words in 2nd kilobyte */
  74 } FIX_ALIASING;
  75
  76 #define NWORDS 129
  77 #define hdr ((struct swap_header_v1*)bb_common_bufsiz1)
  78
  79 struct BUG_sizes {
  80         char swap_header_v1_wrong[sizeof(*hdr)  != (NWORDS * 4) ? -1 : 1];
  81         char bufsiz1_is_too_small[COMMON_BUFSIZE < (NWORDS * 4) ? -1 : 1];
  82 };
  83
  84 /* Stored without terminating NUL */
  85 static const char SWAPSPACE2[sizeof("SWAPSPACE2")-1] ALIGN1 = "SWAPSPACE2";
  86
  87 int mkswap_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
  88 int mkswap_main(int argc UNUSED_PARAM, char **argv)
  89 {
  90         int fd;
  91         unsigned pagesize;
  92         off_t len;
  93         const char *label = "";
  94
  95         opt_complementary = "-1"; /* at least one param */
  96         /* TODO: -p PAGESZ, -U UUID */
  97         getopt32(argv, "L:", &label);
  98         argv += optind;
  99
 100         fd = xopen(argv[0], O_WRONLY);
 101
 102         /* Figure out how big the device is */
 103         len = get_volume_size_in_bytes(fd, argv[1], 1024, /*extend:*/ 1);
 104         pagesize = getpagesize();
 105         len -= pagesize;
 106
 107         /* Announce our intentions */
 108         printf("Setting up swapspace version 1, size = %"OFF_FMT"u bytes\n", len);
 109         mkswap_selinux_setcontext(fd, argv[0]);
 110
 111         /* hdr is zero-filled so far. Clear the first kbyte, or else
 112          * mkswap-ing former FAT partition does NOT erase its signature.
 113          *
 114          * util-linux-ng 2.17.2 claims to erase it only if it does not see
 115          * a partition table and is not run on whole disk. -f forces it.
 116          */
 117         xwrite(fd, hdr, 1024);
 118
 119         /* Fill the header. */
 120         hdr->version = 1;
 121         hdr->last_page = (uoff_t)len / pagesize;
 122
 123         if (ENABLE_FEATURE_MKSWAP_UUID) {
 124                 char uuid_string[37];
 125                 generate_uuid((void*)hdr->sws_uuid);
 126                 printf("UUID=%s\n", unparse_uuid((uint8_t *)hdr->sws_uuid, uuid_string));
 127         }
 128         safe_strncpy(hdr->sws_volume, label, 16);
 129
 130         /* Write the header.  Sync to disk because some kernel versions check
 131          * signature on disk (not in cache) during swapon. */
 132         xwrite(fd, hdr, NWORDS * 4);
 133         xlseek(fd, pagesize - 10, SEEK_SET);
 134         xwrite(fd, SWAPSPACE2, 10);
 135         fsync(fd);
 136
 137         if (ENABLE_FEATURE_CLEAN_UP)
 138                 close(fd);
 139
 140         return 0;
 141 }