source: MondoRescue/branches/3.3/mindi-busybox/util-linux/mkswap.c@ 3625

/* 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.
 */

//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;
}