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disk/format: create Fatinfo sector for fat32

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This commit is contained in:
cinap_lenrek 2015-06-04 03:58:03 +02:00
parent 137a762eca
commit e83ef3d1e2
1 changed files with 41 additions and 0 deletions
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41
sys/src/cmd/disk/format.c
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@ -72,6 +72,24 @@ struct Dosboot32
uchar type[8];
};
enum
{
FATINFOSIG1 = 0x41615252UL,
FATINFOSIG = 0x61417272UL,
};
typedef struct Fatinfo Fatinfo;
struct Fatinfo
{
uchar sig1[4];
uchar pad[480];
uchar sig[4];
uchar freeclust[4]; /* num frre clusters; -1 is unknown */
uchar nextfree[4]; /* most recently allocated cluster */
uchar resrv[4*3];
};
#define PUTSHORT(p, v) { (p)[1] = (v)>>8; (p)[0] = (v); }
#define PUTLONG(p, v) { PUTSHORT((p), (v)); PUTSHORT((p)+2, (v)>>16); }
#define GETSHORT(p) (((p)[1]<<8)|(p)[0])
@ -537,6 +555,8 @@ if(chatty) print("clustersize %d\n", clustersize);
*/
fatbits = 12;
Tryagain:
if(fatbits == 32)
nresrv++; /* for FatInfo */
volsecs = length/secsize;
/*
* here's a crock inside a crock. even having fixed fatbits,
@ -609,6 +629,8 @@ if(chatty) print("try %d fatbits => %d clusters of %d\n", fatbits, clusters, clu
bb = (Dosboot32*)buf;
PUTLONG(bb->fatsize, fatsecs);
PUTLONG(bb->rootclust, 2);
PUTSHORT(bb->fsinfo, nresrv-1);
PUTSHORT(bb->bootbak, 0);
bb->bootsig = 0x29;
bb->driveno = (t->media == 0xF8) ? getdriveno(disk) : 0;
memmove(bb->label, label, sizeof(bb->label));
@ -762,6 +784,25 @@ fprint(2, "add %s at clust %lux\n", d->name, x);
* write the fats and root
*/
if(commit) {
if(fatbits == 32){
Fatinfo *fi;
fi = malloc(secsize);
if(fi == nil)
fatal("out of memory");
memset(fi, 0, secsize);
PUTLONG(fi->sig1, FATINFOSIG1);
PUTLONG(fi->sig, FATINFOSIG);
PUTLONG(fi->freeclust, clusters - fatlast);
PUTLONG(fi->nextfree, fatlast);
if(seek(disk->wfd, (nresrv-1)*secsize, 0) < 0)
fatal("seek to fatinfo: %r\n");
if(write(disk->wfd, fi, secsize) < 0)
fatal("writing fat #1: %r");
free(fi);
}
if(seek(disk->wfd, nresrv*secsize, 0) < 0)
fatal("seek to fat #1: %r");
if(write(disk->wfd, fat, fatsecs*secsize) < 0)