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Commit 052f2756 authored by Daniel Rosenberg's avatar Daniel Rosenberg
Browse files

newfs_msdos: Added option to cluster-align the start of the root directory 



This follows the recommendations of the SD-card association.

Change-Id: Ie89a5972d086b3df9d92e631c394a521f807b016
Signed-off-by: default avatarDaniel Rosenberg <drosen@google.com>
parent cadd5bb7

toolbox/newfs_msdos.c

+69 −31
Original line number Diff line number Diff line
@@ -238,11 +238,12 @@ static void usage(void); 
 */

int newfs_msdos_main(int argc, char *argv[])

{

    static const char opts[] = "@:NB:C:F:I:L:O:S:a:b:c:e:f:h:i:k:m:n:o:r:s:u:";

    static const char opts[] = "@:NAB:C:F:I:L:O:S:a:b:c:e:f:h:i:k:m:n:o:r:s:u:";

    const char *opt_B = NULL, *opt_L = NULL, *opt_O = NULL, *opt_f = NULL;

    u_int opt_F = 0, opt_I = 0, opt_S = 0, opt_a = 0, opt_b = 0, opt_c = 0;

    u_int opt_e = 0, opt_h = 0, opt_i = 0, opt_k = 0, opt_m = 0, opt_n = 0;

    u_int opt_o = 0, opt_r = 0, opt_s = 0, opt_u = 0;

    u_int opt_A = 0;

    int opt_N = 0;

    int Iflag = 0, mflag = 0, oflag = 0;

    char buf[MAXPATHLEN];
@@ -260,6 +261,7 @@ int newfs_msdos_main(int argc, char *argv[]) 
    ssize_t n;

    time_t now;

    u_int fat, bss, rds, cls, dir, lsn, x, x1, x2;

    u_int extra_res, alignment=0, set_res, set_spf, set_spc, tempx, attempts=0;

    int ch, fd, fd1;

    off_t opt_create = 0, opt_ofs = 0;
@@ -271,6 +273,9 @@ int newfs_msdos_main(int argc, char *argv[]) 
        case 'N':

            opt_N = 1;

            break;

        case 'A':

            opt_A = 1;

            break;

        case 'B':

            opt_B = optarg;

            break;
@@ -359,6 +364,12 @@ int newfs_msdos_main(int argc, char *argv[]) 
            err(1, "%s", buf);

    }

    dtype = *argv;

    if (opt_A) {

        if (opt_r)

            errx(1, "align (-A) is incompatible with -r");

        if (opt_N)

            errx(1, "align (-A) is incompatible with -N");

    }

    if (opt_create) {

        if (opt_N)

            errx(1, "create (-C) is incompatible with -N");
@@ -536,14 +547,30 @@ int newfs_msdos_main(int argc, char *argv[]) 
        if (bpb.bkbs != MAXU16 && x <= bpb.bkbs)

            x = bpb.bkbs + 1;

    }

    if (!bpb.res)

        bpb.res = fat == 32 ? MAX(x, MAX(16384 / bpb.bps, 4)) : x;



    extra_res = 0;

    set_res = !bpb.res;

    set_spf = !bpb.bspf;

    set_spc = !bpb.spc;

    tempx = x;

    /*

     * Attempt to align if opt_A is set. This is done by increasing the number

     * of reserved blocks. This can cause other factors to change, which can in

     * turn change the alignment. This should take at most 2 iterations, as

     * increasing the reserved amount may cause the FAT size to decrease by 1,

     * requiring another nft reserved blocks. If spc changes, it will

     * be half of its previous size, and thus will not throw off alignment.

     */

    do {

        x = tempx;

        if (set_res)

            bpb.res = (fat == 32 ? MAX(x, MAX(16384 / bpb.bps, 4)) : x) + extra_res;

        else if (bpb.res < x)

            errx(1, "too few reserved sectors");

        if (fat != 32 && !bpb.rde)

            bpb.rde = DEFRDE;

        rds = howmany(bpb.rde, bpb.bps / sizeof(struct de));

    if (!bpb.spc)

        if (set_spc)

            for (bpb.spc = howmany(fat == 16 ? DEFBLK16 : DEFBLK, bpb.bps);

                    bpb.spc < MAXSPC &&

                    bpb.res +
@@ -562,10 +589,20 @@ int newfs_msdos_main(int argc, char *argv[]) 
        x = (u_int64_t)(bpb.bsec - x1) * bpb.bps * NPB /

                (bpb.spc * bpb.bps * NPB + fat / BPN * bpb.nft);

        x2 = howmany((RESFTE + MIN(x, maxcls(fat))) * (fat / BPN), bpb.bps * NPB);

    if (!bpb.bspf) {

        if (set_spf) {

            bpb.bspf = x2;

            x1 += (bpb.bspf - 1) * bpb.nft;

        }

        if(set_res) {

            /* attempt to align root directory */

            alignment = (bpb.res + bpb.bspf * bpb.nft) % bpb.spc;

            extra_res += bpb.spc - alignment;

        }

        attempts++;

    } while(opt_A && alignment != 0 && attempts < 2);

    if (alignment != 0)

        warnx("warning: Alignment failed.");



    cls = (bpb.bsec - x1) / bpb.spc;

    x = (u_int64_t)bpb.bspf * bpb.bps * NPB / (fat / BPN) - RESFTE;

    if (cls > x)
@@ -1024,6 +1061,7 @@ static void usage(void) 
            "usage: newfs_msdos [ -options ] special [disktype]\n"

            "where the options are:\n"

            "\t-@ create file system at specified offset\n"

            "\t-A Attempt to cluster align root directory\n"

            "\t-B get bootstrap from file\n"

            "\t-C create image file with specified size\n"

            "\t-F FAT type (12, 16, or 32)\n"