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disk/format, 9boot: fix alignment issues

--- a/sys/src/boot/pc/fat.c

+++ b/sys/src/boot/pc/fat.c

@@ -16,6 +16,7 @@

 typedef struct File File;

 typedef struct Dir Dir;

 typedef struct Pbs Pbs;

+typedef struct Pbs32 Pbs32;

 typedef struct Fat Fat;

 struct Fat

@@ -75,36 +76,32 @@

 	uchar nheads[2];

 	uchar nhidden[4];

 	uchar bigvolsize[4];

-	union

-	{

-		struct

-		{

-			uchar driveno;

-			uchar reserved0;

-			uchar bootsig;

-			uchar volid[4];

-			uchar label[11];

-			uchar type[8];

-		};

-		struct

-		{

-			uchar fatsize[4];

-			uchar flags[2];

-			uchar ver[2];

-			uchar rootclust[4];

-			uchar fsinfo[2];

-			uchar bootbak[2];

-			uchar reserved0[12];

-			uchar driveno;

-			uchar reserved1;

-			uchar bootsig;

-			uchar volid[4];

-			uchar label[11];

-			uchar type[8];

-		} fat32;

-	};

+	uchar driveno;

+	uchar reserved0;

+	uchar bootsig;

+	uchar volid[4];

+	uchar label[11];

+	uchar type[8];

 };

+struct Pbs32

+{

+	uchar common[36];

+	uchar fatsize[4];

+	uchar flags[2];

+	uchar ver[2];

+	uchar rootclust[4];

+	uchar fsinfo[2];

+	uchar bootbak[2];

+	uchar reserved0[12];

+	uchar driveno;

+	uchar reserved1;

+	uchar bootsig;

+	uchar volid[4];

+	uchar label[11];

+	uchar type[8];

+};

+

 int readsect(ulong drive, ulong lba, void *buf);

 void

@@ -278,7 +275,7 @@

 	if(GETSHORT(p->sectsize) != Sectsz)

 		return -1;

-	if(memcmp(p->type, "FAT", 3) && memcmp(p->fat32.type, "FAT", 3))

+	if(memcmp(p->type, "FAT", 3) && memcmp(((Pbs32*)buf)->type, "FAT", 3))

 		return -1;

 	/* load values from fat */

@@ -285,7 +282,7 @@

 	ver = 0;

 	fatsize = GETSHORT(p->fatsize);

 	if(fatsize == 0){

-		fatsize = GETLONG(p->fat32.fatsize);

+		fatsize = GETLONG(((Pbs32*)buf)->fatsize);

 		ver = Fat32;

 	}

 	volsize = GETSHORT(p->volsize);

@@ -310,7 +307,7 @@

 	fat->dirstart  = fat->fatlba + fatsize * p->nfats;

 	if(ver == Fat32){

 		fat->datalba = fat->dirstart;

-		fat->dirstart  = GETLONG(p->fat32.rootclust);

+		fat->dirstart  = GETLONG(((Pbs32*)buf)->rootclust);

 		fat->eofmark = 0xffffff7;

 	}else{

 		fat->datalba = fat->dirstart + dirsize;

--- a/sys/src/cmd/disk/format.c

+++ b/sys/src/cmd/disk/format.c

@@ -45,33 +45,33 @@

 	uchar	nheads[2];

 	uchar	nhidden[4];

 	uchar	bigvolsize[4];

-	union {

-		struct {

-			uchar	driveno;

-			uchar	reserved0;

-			uchar	bootsig;

-			uchar	volid[4];

-			uchar	label[11];

-			uchar	type[8];

-		};

-		struct {

-			uchar	fatsize[4];

-			uchar	flags[2];

-			uchar	ver[2];

-			uchar	rootclust[4];

-			uchar	fsinfo[2];

-			uchar	bootbak[2];

-			uchar	reserved0[12];

-			uchar	driveno;

-			uchar	reserved1;

-			uchar	bootsig;

-			uchar	volid[4];

-			uchar	label[11];

-			uchar	type[8];

-		} fat32;

-	};

+	uchar	driveno;

+	uchar	reserved0;

+	uchar	bootsig;

+	uchar	volid[4];

+	uchar	label[11];

+	uchar	type[8];

 };

+typedef struct Dosboot32 Dosboot32;

+struct Dosboot32

+{

+	uchar	common[36];

+	uchar	fatsize[4];

+	uchar	flags[2];

+	uchar	ver[2];

+	uchar	rootclust[4];

+	uchar	fsinfo[2];

+	uchar	bootbak[2];

+	uchar	reserved0[12];

+	uchar	driveno;

+	uchar	reserved1;

+	uchar	bootsig;

+	uchar	volid[4];

+	uchar	label[11];

+	uchar	type[8];

+};

+

 #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])

@@ -604,12 +604,15 @@

 		sprint(r, "FAT%d    ", fatbits);

 		if(fatbits == 32){

-			PUTLONG(b->fat32.fatsize, fatsecs);

-			PUTLONG(b->fat32.rootclust, 2);

-			b->fat32.bootsig = 0x29;

-			b->fat32.driveno = (t->media == 0xF8) ? getdriveno(disk) : 0;

-			memmove(b->fat32.label, label, sizeof(b->fat32.label));

-			memmove(b->fat32.type, r, sizeof(b->fat32.type));

+			Dosboot32 *bb;

+

+			bb = (Dosboot32*)buf;

+			PUTLONG(bb->fatsize, fatsecs);

+			PUTLONG(bb->rootclust, 2);

+			bb->bootsig = 0x29;

+			bb->driveno = (t->media == 0xF8) ? getdriveno(disk) : 0;

+			memmove(bb->label, label, sizeof(bb->label));

+			memmove(bb->type, r, sizeof(bb->type));

 		} else {

 			b->bootsig = 0x29;

 			b->driveno = (t->media == 0xF8) ? getdriveno(disk) : 0;