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