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

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This follows the recommendations of the SD-card association.

Change-Id: Ie89a5972d086b3df9d92e631c394a521f807b016
Signed-off-by: Daniel Rosenberg <drosen@google.com>
This commit is contained in:
Daniel Rosenberg 2014-07-15 16:56:20 -07:00
parent cadd5bb70e
commit 052f275621
1 changed files with 69 additions and 31 deletions
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100
toolbox/newfs_msdos.c
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@ -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");
@ -536,36 +547,62 @@ 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;
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)
for (bpb.spc = howmany(fat == 16 ? DEFBLK16 : DEFBLK, bpb.bps);
bpb.spc < MAXSPC &&
bpb.res +
howmany((RESFTE + maxcls(fat)) * (fat / BPN),
bpb.bps * NPB) * bpb.nft +
rds +
(u_int64_t)(maxcls(fat) + 1) * bpb.spc <= bpb.bsec;
bpb.spc <<= 1);
if (fat != 32 && bpb.bspf > MAXU16)
errx(1, "too many sectors/FAT for FAT12/16");
x1 = bpb.res + rds;
x = bpb.bspf ? bpb.bspf : 1;
if (x1 + (u_int64_t)x * bpb.nft > bpb.bsec)
errx(1, "meta data exceeds file system size");
x1 += x * bpb.nft;
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) {
bpb.bspf = x2;
x1 += (bpb.bspf - 1) * bpb.nft;
}
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 (set_spc)
for (bpb.spc = howmany(fat == 16 ? DEFBLK16 : DEFBLK, bpb.bps);
bpb.spc < MAXSPC &&
bpb.res +
howmany((RESFTE + maxcls(fat)) * (fat / BPN),
bpb.bps * NPB) * bpb.nft +
rds +
(u_int64_t)(maxcls(fat) + 1) * bpb.spc <= bpb.bsec;
bpb.spc <<= 1);
if (fat != 32 && bpb.bspf > MAXU16)
errx(1, "too many sectors/FAT for FAT12/16");
x1 = bpb.res + rds;
x = bpb.bspf ? bpb.bspf : 1;
if (x1 + (u_int64_t)x * bpb.nft > bpb.bsec)
errx(1, "meta data exceeds file system size");
x1 += x * bpb.nft;
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 (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"