busybox/util-linux/mkswap.c

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/* vi: set sw=4 ts=4: */
/* mkswap.c - format swap device (Linux v1 only)
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*
* Copyright 2006 Rob Landley <rob@landley.net>
*
* Licensed under GPLv2, see file LICENSE in this source tree.
*/
//config:config MKSWAP
//config: bool "mkswap (5.8 kb)"
//config: default y
//config: help
//config: The mkswap utility is used to configure a file or disk partition as
//config: Linux swap space. This allows Linux to use the entire file or
//config: partition as if it were additional RAM, which can greatly increase
//config: the capability of low-memory machines. This additional memory is
//config: much slower than real RAM, but can be very helpful at preventing your
//config: applications being killed by the Linux out of memory (OOM) killer.
//config: Once you have created swap space using 'mkswap' you need to enable
//config: the swap space using the 'swapon' utility.
//config:
//config:config FEATURE_MKSWAP_UUID
//config: bool "UUID support"
//config: default y
//config: depends on MKSWAP
//config: help
//config: Generate swap spaces with universally unique identifiers.
//applet:IF_MKSWAP(APPLET(mkswap, BB_DIR_SBIN, BB_SUID_DROP))
//kbuild:lib-$(CONFIG_MKSWAP) += mkswap.o
//usage:#define mkswap_trivial_usage
//usage: "[-L LBL] BLOCKDEV [KBYTES]"
//usage:#define mkswap_full_usage "\n\n"
//usage: "Prepare BLOCKDEV to be used as swap partition\n"
//usage: "\n -L LBL Label"
#include "libbb.h"
#include "common_bufsiz.h"
#if ENABLE_SELINUX
static void mkswap_selinux_setcontext(int fd, const char *path)
{
struct stat stbuf;
if (!is_selinux_enabled())
return;
xfstat(fd, &stbuf, path);
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)
#define INIT_G() do { setup_common_bufsiz(); } while (0)
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 = "";
INIT_G();
/* TODO: -p PAGESZ, -U UUID */
getopt32: remove opt_complementary function old new delta vgetopt32 1318 1392 +74 runsvdir_main 703 713 +10 bb_make_directory 423 425 +2 collect_cpu 546 545 -1 opt_chars 3 - -3 opt_complementary 4 - -4 tftpd_main 567 562 -5 ntp_init 476 471 -5 zcip_main 1266 1256 -10 xxd_main 428 418 -10 whois_main 140 130 -10 who_main 463 453 -10 which_main 212 202 -10 wget_main 2535 2525 -10 watchdog_main 291 281 -10 watch_main 222 212 -10 vlock_main 399 389 -10 uuencode_main 332 322 -10 uudecode_main 316 306 -10 unlink_main 45 35 -10 udhcpd_main 1482 1472 -10 udhcpc_main 2762 2752 -10 tune2fs_main 290 280 -10 tunctl_main 366 356 -10 truncate_main 218 208 -10 tr_main 518 508 -10 time_main 1134 1124 -10 tftp_main 286 276 -10 telnetd_main 1873 1863 -10 tcpudpsvd_main 1785 1775 -10 taskset_main 521 511 -10 tar_main 1009 999 -10 tail_main 1644 1634 -10 syslogd_main 1967 1957 -10 switch_root_main 368 358 -10 svlogd_main 1454 1444 -10 sv 1296 1286 -10 stat_main 104 94 -10 start_stop_daemon_main 1028 1018 -10 split_main 542 532 -10 sort_main 796 786 -10 slattach_main 624 614 -10 shuf_main 504 494 -10 setsid_main 96 86 -10 setserial_main 1132 1122 -10 setfont_main 388 378 -10 setconsole_main 78 68 -10 sendmail_main 1209 1199 -10 sed_main 677 667 -10 script_main 1077 1067 -10 run_parts_main 325 315 -10 rtcwake_main 454 444 -10 rm_main 175 165 -10 reformime_main 119 109 -10 readlink_main 123 113 -10 rdate_main 246 236 -10 pwdx_main 189 179 -10 pstree_main 317 307 -10 pscan_main 663 653 -10 popmaildir_main 818 808 -10 pmap_main 80 70 -10 nc_main 1042 1032 -10 mv_main 558 548 -10 mountpoint_main 477 467 -10 mount_main 1264 1254 -10 modprobe_main 768 758 -10 modinfo_main 333 323 -10 mktemp_main 200 190 -10 mkswap_main 324 314 -10 mkfs_vfat_main 1489 1479 -10 microcom_main 715 705 -10 md5_sha1_sum_main 521 511 -10 man_main 867 857 -10 makedevs_main 1052 1042 -10 ls_main 563 553 -10 losetup_main 432 422 -10 loadfont_main 89 79 -10 ln_main 524 514 -10 link_main 75 65 -10 ipcalc_main 544 534 -10 iostat_main 2397 2387 -10 install_main 768 758 -10 id_main 480 470 -10 i2cset_main 1239 1229 -10 i2cget_main 380 370 -10 i2cdump_main 1482 1472 -10 i2cdetect_main 682 672 -10 hwclock_main 406 396 -10 httpd_main 741 731 -10 grep_main 837 827 -10 getty_main 1559 1549 -10 fuser_main 297 287 -10 ftpgetput_main 345 335 -10 ftpd_main 2232 2222 -10 fstrim_main 251 241 -10 fsfreeze_main 77 67 -10 fsck_minix_main 2921 2911 -10 flock_main 314 304 -10 flashcp_main 740 730 -10 flash_eraseall_main 833 823 -10 fdformat_main 532 522 -10 expand_main 680 670 -10 eject_main 335 325 -10 dumpleases_main 630 620 -10 du_main 314 304 -10 dos2unix_main 441 431 -10 diff_main 1350 1340 -10 df_main 1064 1054 -10 date_main 1095 1085 -10 cut_main 961 951 -10 cryptpw_main 228 218 -10 crontab_main 575 565 -10 crond_main 1149 1139 -10 cp_main 370 360 -10 common_traceroute_main 3834 3824 -10 common_ping_main 1767 1757 -10 comm_main 239 229 -10 cmp_main 655 645 -10 chrt_main 379 369 -10 chpst_main 704 694 -10 chpasswd_main 308 298 -10 chown_main 171 161 -10 chmod_main 158 148 -10 cat_main 428 418 -10 bzip2_main 120 110 -10 blkdiscard_main 264 254 -10 base64_main 221 211 -10 arping_main 1665 1655 -10 ar_main 556 546 -10 adjtimex_main 406 396 -10 adduser_main 882 872 -10 addgroup_main 411 401 -10 acpid_main 1198 1188 -10 optstring 11 - -11 opt_string 18 - -18 OPT_STR 25 - -25 ubi_tools_main 1288 1258 -30 ls_options 31 - -31 ------------------------------------------------------------------------------ (add/remove: 0/6 grow/shrink: 3/129 up/down: 86/-1383) Total: -1297 bytes text data bss dec hex filename 915428 485 6876 922789 e14a5 busybox_old 914629 485 6872 921986 e1182 busybox_unstripped Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
2017-08-09 01:25:02 +05:30
getopt32(argv, "^" "L:" "\0" "-1"/*at least one arg*/, &label);
argv += optind;
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fd = xopen(argv[0], O_WRONLY);
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/* 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[32];
generate_uuid((void*)hdr->sws_uuid);
bin2hex(uuid_string, hdr->sws_uuid, 16);
/* f.e. UUID=dfd9c173-be52-4d27-99a5-c34c6c2ff55f */
printf("UUID=%.8s" "-%.4s-%.4s-%.4s-%.12s\n",
uuid_string,
uuid_string+8,
uuid_string+8+4,
uuid_string+8+4+4,
uuid_string+8+4+4+4
);
}
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);
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return 0;
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}