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 #include "common_bufsiz.h"
  17
  18 #if ENABLE_SELINUX
  19 static void mkswap_selinux_setcontext(int fd, const char *path)
  20 {
  21         struct stat stbuf;
  22
  23         if (!is_selinux_enabled())
  24                 return;
  25
  26         xfstat(fd, &stbuf, path);
  27         if (S_ISREG(stbuf.st_mode)) {
  28                 security_context_t newcon;
  29                 security_context_t oldcon = NULL;
  30                 context_t context;
  31
  32                 if (fgetfilecon(fd, &oldcon) < 0) {
  33                         if (errno != ENODATA)
  34                                 goto error;
  35                         if (matchpathcon(path, stbuf.st_mode, &oldcon) < 0)
  36                                 goto error;
  37                 }
  38                 context = context_new(oldcon);
  39                 if (!context || context_type_set(context, "swapfile_t"))
  40                         goto error;
  41                 newcon = context_str(context);
  42                 if (!newcon)
  43                         goto error;
  44                 /* fsetfilecon_raw is hidden */
  45                 if (strcmp(oldcon, newcon) != 0 && fsetfilecon(fd, newcon) < 0)
  46                         goto error;
  47                 if (ENABLE_FEATURE_CLEAN_UP) {
  48                         context_free(context);
  49                         freecon(oldcon);
  50                 }
  51         }
  52         return;
  53  error:
  54         bb_perror_msg_and_die("SELinux relabeling failed");
  55 }
  56 #else
  57 # define mkswap_selinux_setcontext(fd, path) ((void)0)
  58 #endif
  59
  60 /* from Linux 2.6.23 */
  61 /*
  62  * Magic header for a swap area. ... Note that the first
  63  * kilobyte is reserved for boot loader or disk label stuff.
  64  */
  65 struct swap_header_v1 {
  66 /*      char     bootbits[1024];    Space for disklabel etc. */
  67         uint32_t version;        /* second kbyte, word 0 */
  68         uint32_t last_page;      /* 1 */
  69         uint32_t nr_badpages;    /* 2 */
  70         char     sws_uuid[16];   /* 3,4,5,6 */
  71         char     sws_volume[16]; /* 7,8,9,10 */
  72         uint32_t padding[117];   /* 11..127 */
  73         uint32_t badpages[1];    /* 128 */
  74         /* total 129 32-bit words in 2nd kilobyte */
  75 } FIX_ALIASING;
  76
  77 #define NWORDS 129
  78 #define hdr ((struct swap_header_v1*)bb_common_bufsiz1)
  79 #define INIT_G() do { setup_common_bufsiz(); } while (0)
  80
  81 struct BUG_sizes {
  82         char swap_header_v1_wrong[sizeof(*hdr)  != (NWORDS * 4) ? -1 : 1];
  83         char bufsiz1_is_too_small[COMMON_BUFSIZE < (NWORDS * 4) ? -1 : 1];
  84 };
  85
  86 /* Stored without terminating NUL */
  87 static const char SWAPSPACE2[sizeof("SWAPSPACE2")-1] ALIGN1 = "SWAPSPACE2";
  88
  89 int mkswap_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
  90 int mkswap_main(int argc UNUSED_PARAM, char **argv)
  91 {
  92         int fd;
  93         unsigned pagesize;
  94         off_t len;
  95         const char *label = "";
  96
  97         INIT_G();
  98
  99         opt_complementary = "-1"; /* at least one param */
 100         /* TODO: -p PAGESZ, -U UUID */
 101         getopt32(argv, "L:", &label);
 102         argv += optind;
 103
 104         fd = xopen(argv[0], O_WRONLY);
 105
 106         /* Figure out how big the device is */
 107         len = get_volume_size_in_bytes(fd, argv[1], 1024, /*extend:*/ 1);
 108         pagesize = getpagesize();
 109         len -= pagesize;
 110
 111         /* Announce our intentions */
 112         printf("Setting up swapspace version 1, size = %"OFF_FMT"u bytes\n", len);
 113         mkswap_selinux_setcontext(fd, argv[0]);
 114
 115         /* hdr is zero-filled so far. Clear the first kbyte, or else
 116          * mkswap-ing former FAT partition does NOT erase its signature.
 117          *
 118          * util-linux-ng 2.17.2 claims to erase it only if it does not see
 119          * a partition table and is not run on whole disk. -f forces it.
 120          */
 121         xwrite(fd, hdr, 1024);
 122
 123         /* Fill the header. */
 124         hdr->version = 1;
 125         hdr->last_page = (uoff_t)len / pagesize;
 126
 127         if (ENABLE_FEATURE_MKSWAP_UUID) {
 128                 char uuid_string[37];
 129                 generate_uuid((void*)hdr->sws_uuid);
 130                 printf("UUID=%s\n", unparse_uuid((uint8_t *)hdr->sws_uuid, uuid_string));
 131         }
 132         safe_strncpy(hdr->sws_volume, label, 16);
 133
 134         /* Write the header.  Sync to disk because some kernel versions check
 135          * signature on disk (not in cache) during swapon. */
 136         xwrite(fd, hdr, NWORDS * 4);
 137         xlseek(fd, pagesize - 10, SEEK_SET);
 138         xwrite(fd, SWAPSPACE2, 10);
 139         fsync(fd);
 140
 141         if (ENABLE_FEATURE_CLEAN_UP)
 142                 close(fd);
 143
 144         return 0;
 145 }