text: /* vi: set sw=4 ts=4: */
  /* mkswap.c - format swap device (Linux v1 only)
   *
   * Copyright 2006 Rob Landley <rob@landley.net>
   *
   * Licensed under GPL version 2, see file LICENSE in this tarball for details.
   */
  #include "libbb.h"
  
  #if ENABLE_SELINUX
  static void mkswap_selinux_setcontext(int fd, const char *path)
  {
  	struct stat stbuf;
  
  	if (!is_selinux_enabled())
  		return;
  
  	if (fstat(fd, &stbuf) < 0)
  		bb_perror_msg_and_die("fstat failed");
  	if (S_ISREG(stbuf.st_mode)) {
  		security_context_t newcon;
  		security_context_t oldcon = NULL;
  		context_t context;
  
  		if (fgetfilecon(fd, &oldcon) < 0) {
  			if (errno != ENODATA)
  				goto error;
  			if (matchpathcon(path, stbuf.st_mode, &oldcon) < 0)
  				goto error;
  		}
  		context = context_new(oldcon);
  		if (!context || context_type_set(context, "swapfile_t"))
  			goto error;
  		newcon = context_str(context);
  		if (!newcon)
  			goto error;
  		/* fsetfilecon_raw is hidden */
  		if (strcmp(oldcon, newcon) != 0 && fsetfilecon(fd, newcon) < 0)
  			goto error;
  		if (ENABLE_FEATURE_CLEAN_UP) {
  			context_free(context);
  			freecon(oldcon);
  		}
  	}
  	return;
   error:
  	bb_perror_msg_and_die("SELinux relabeling failed");
  }
  #else
  # define mkswap_selinux_setcontext(fd, path) ((void)0)
  #endif
  
  /* from Linux 2.6.23 */
  /*
   * Magic header for a swap area. ... Note that the first
   * kilobyte is reserved for boot loader or disk label stuff.
   */
  struct swap_header_v1 {
  /*	char     bootbits[1024];    Space for disklabel etc. */
  	uint32_t version;        /* second kbyte, word 0 */
  	uint32_t last_page;      /* 1 */
  	uint32_t nr_badpages;    /* 2 */
  	char     sws_uuid[16];   /* 3,4,5,6 */
  	char     sws_volume[16]; /* 7,8,9,10 */
  	uint32_t padding[117];   /* 11..127 */
  	uint32_t badpages[1];    /* 128 */
  	/* total 129 32-bit words in 2nd kilobyte */
  } FIX_ALIASING;
  
  #define NWORDS 129
  #define hdr ((struct swap_header_v1*)bb_common_bufsiz1)
  
  struct BUG_sizes {
  	char swap_header_v1_wrong[sizeof(*hdr)  != (NWORDS * 4) ? -1 : 1];
  	char bufsiz1_is_too_small[COMMON_BUFSIZE < (NWORDS * 4) ? -1 : 1];
  };
  
  /* Stored without terminating NUL */
  static const char SWAPSPACE2[sizeof("SWAPSPACE2")-1] ALIGN1 = "SWAPSPACE2";
  
  int mkswap_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
  int mkswap_main(int argc UNUSED_PARAM, char **argv)
  {
  	int fd;
  	unsigned pagesize;
  	off_t len;
  	const char *label = "";
  
  	opt_complementary = "-1"; /* at least one param */
  	/* TODO: -p PAGESZ, -U UUID */
  	getopt32(argv, "L:", &label);
  	argv += optind;
  
  	fd = xopen(argv[0], O_WRONLY);
  
  	/* Figure out how big the device is */
  	len = get_volume_size_in_bytes(fd, argv[1], 1024, /*extend:*/ 1);
  	pagesize = getpagesize();
  	len -= pagesize;
  
  	/* Announce our intentions */
  	printf("Setting up swapspace version 1, size = %"OFF_FMT"u bytes\n", len);
  	mkswap_selinux_setcontext(fd, argv[0]);
  
  	/* hdr is zero-filled so far. Clear the first kbyte, or else
  	 * mkswap-ing former FAT partition does NOT erase its signature.
  	 *
  	 * util-linux-ng 2.17.2 claims to erase it only if it does not see
  	 * a partition table and is not run on whole disk. -f forces it.
  	 */
  	xwrite(fd, hdr, 1024);
  
  	/* Fill the header. */
  	hdr->version = 1;
  	hdr->last_page = (uoff_t)len / pagesize;
  
  	if (ENABLE_FEATURE_MKSWAP_UUID) {
  		char uuid_string[37];
  		generate_uuid((void*)hdr->sws_uuid);
  		printf("UUID=%s\n", unparse_uuid((uint8_t *)hdr->sws_uuid, uuid_string));
  	}
  	safe_strncpy(hdr->sws_volume, label, 16);
  
  	/* Write the header.  Sync to disk because some kernel versions check
  	 * signature on disk (not in cache) during swapon. */
  	xwrite(fd, hdr, NWORDS * 4);
  	xlseek(fd, pagesize - 10, SEEK_SET);
  	xwrite(fd, SWAPSPACE2, 10);
  	fsync(fd);
  
  	if (ENABLE_FEATURE_CLEAN_UP)
  		close(fd);
  
  	return 0;
  }
  