git: 9front

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ref: 6459fcff761a53c534f48106deee25a230022ad3
parent: 4c64c5023f8250a3d5b816f53223f30b6b8aa8cf
author: cinap_lenrek <cinap_lenrek@gmx.de>
date: Tue May 8 12:30:18 EDT 2012 

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;
-- 
⑨