| /* vi: set sw=4 ts=4: */ |
| /* mkswap.c - format swap device (Linux v1 only) |
| * |
| * 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(); |
| |
| 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[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); |
| |
| return 0; |
| } |