Import sources from 2011-03-30 iso image

1 files changed, 584 insertions, 0 deletions

diff --git a/sys/src/boot/pc/dosboot.c b/sys/src/boot/pc/dosboot.c
new file mode 100755
index 000000000..9a0f5bc4f
--- /dev/null
+++ b/sys/src/boot/pc/dosboot.c
@@ -0,0 +1,584 @@
+#include	"u.h"
+#include	"lib.h"
+#include	"mem.h"
+#include	"dat.h"
+#include	"fns.h"
+#include	"fs.h"
+
+struct Dosboot{
+	uchar	magic[3];
+	uchar	version[8];
+	uchar	sectsize[2];
+	uchar	clustsize;
+	uchar	nresrv[2];
+	uchar	nfats;
+	uchar	rootsize[2];
+	uchar	volsize[2];
+	uchar	mediadesc;
+	uchar	fatsize[2];
+	uchar	trksize[2];
+	uchar	nheads[2];
+	uchar	nhidden[4];
+	uchar	bigvolsize[4];
+/* fat 32 */
+	uchar	bigfatsize[4];
+	uchar	extflags[2];
+	uchar	fsversion[2];
+	uchar	rootdirstartclust[4];
+	uchar	fsinfosect[2];
+	uchar	backupbootsect[2];
+/* ???
+	uchar	driveno;
+	uchar	reserved0;
+	uchar	bootsig;
+	uchar	volid[4];
+	uchar	label[11];
+	uchar	reserved1[8];
+*/
+};
+
+struct Dosdir{
+	uchar	name[8];
+	uchar	ext[3];
+	uchar	attr;
+	uchar	lowercase;
+	uchar	hundredth;
+	uchar	ctime[2];
+	uchar	cdate[2];
+	uchar	adate[2];
+	uchar	highstart[2];
+	uchar	mtime[2];
+	uchar	mdate[2];
+	uchar	start[2];
+	uchar	length[4];
+};
+
+#define	DOSRONLY	0x01
+#define	DOSHIDDEN	0x02
+#define	DOSSYSTEM	0x04
+#define	DOSVLABEL	0x08
+#define	DOSDIR	0x10
+#define	DOSARCH	0x20
+
+/*
+ *  predeclared
+ */
+static void	bootdump(Dosboot*);
+static void	setname(Dosfile*, char*);
+
+/*
+ *  debugging
+ */
+#define chatty	0
+#define chat	if(chatty)print
+
+/*
+ *  block io buffers
+ */
+enum
+{
+	Nbio=	16,
+};
+typedef struct	Clustbuf	Clustbuf;
+struct Clustbuf
+{
+	int	age;
+	long	sector;
+	uchar	*iobuf;
+	Dos	*dos;
+	int	size;
+};
+Clustbuf	bio[Nbio];
+
+/*
+ *  get an io block from an io buffer
+ */
+Clustbuf*
+getclust(Dos *dos, long sector)
+{
+	Fs *fs;
+	Clustbuf *p, *oldest;
+	int size;
+
+	chat("getclust @ %ld\n", sector);
+
+	/*
+	 *  if we have it, just return it
+	 */
+	for(p = bio; p < &bio[Nbio]; p++){
+		if(sector == p->sector && dos == p->dos){
+			p->age = m->ticks;
+			chat("getclust %ld in cache\n", sector);
+			return p;
+		}
+	}
+
+	/*
+	 *  otherwise, reuse the oldest entry
+	 */
+	oldest = bio;
+	for(p = &bio[1]; p < &bio[Nbio]; p++){
+		if(p->age <= oldest->age)
+			oldest = p;
+	}
+	p = oldest;
+
+	/*
+	 *  make sure the buffer is big enough
+	 */
+	size = dos->clustsize*dos->sectsize;
+	if(p->iobuf==0 || p->size < size)
+		p->iobuf = ialloc(size, 0);
+	p->size = size;
+
+	/*
+	 *  read in the cluster
+	 */
+	fs = (Fs*)dos;		/* assume dos is embedded at start of an Fs */
+	chat("getclust addr %lud %p %p %p\n", (ulong)((sector+dos->start)*(vlong)dos->sectsize),
+		fs, fs->diskseek, fs->diskread);
+	if(fs->diskseek(fs, (sector+dos->start)*(vlong)dos->sectsize) < 0){
+		chat("can't seek block\n");
+		return 0;
+	}
+	if(fs->diskread(fs, p->iobuf, size) != size){
+		chat("can't read block\n");
+		return 0;
+	}
+
+	p->age = m->ticks;
+	p->dos = dos;
+	p->sector = sector;
+	chat("getclust %ld read\n", sector);
+	return p;
+}
+
+/*
+ *  walk the fat one level ( n is a current cluster number ).
+ *  return the new cluster number or -1 if no more.
+ */
+static long
+fatwalk(Dos *dos, int n)
+{
+	ulong k, sect;
+	Clustbuf *p;
+	int o;
+
+	chat("fatwalk %d\n", n);
+
+	if(n < 2 || n >= dos->fatclusters)
+		return -1;
+
+	switch(dos->fatbits){
+	case 12:
+		k = (3*n)/2; break;
+	case 16:
+		k = 2*n; break;
+	case 32:
+		k = 4*n; break;
+	default:
+		return -1;
+	}
+	if(k >= dos->fatsize*dos->sectsize)
+		panic("getfat");
+
+	if (dos->sectsize == 0 || dos->clustsize == 0)
+		panic("fatwalk: zero sector or cluster size");
+	sect = (k/(dos->sectsize*dos->clustsize))*dos->clustsize + dos->fataddr;
+	o = k%(dos->sectsize*dos->clustsize);
+	p = getclust(dos, sect);
+	k = p->iobuf[o++];
+	if(o >= dos->sectsize*dos->clustsize){
+		p = getclust(dos, sect+dos->clustsize);
+		o = 0;
+	}
+	k |= p->iobuf[o++]<<8;
+	if(dos->fatbits == 12){
+		if(n&1)
+			k >>= 4;
+		else
+			k &= 0xfff;
+		if(k >= 0xff8)
+			k = -1;
+	}
+	else if (dos->fatbits == 32){
+		if(o >= dos->sectsize*dos->clustsize){
+			p = getclust(dos, sect+dos->clustsize);
+			o = 0;
+		}
+		k |= p->iobuf[o++]<<16;
+		k |= p->iobuf[o]<<24;
+		if (k >= 0xfffffff8)
+			k = -1;
+	}
+	else
+		k = k < 0xfff8 ? k : -1;
+	chat("fatwalk %d -> %lud\n", n, k);
+	return k;
+}
+
+/*
+ *  map a file's logical cluster address to a physical sector address
+ */
+static long
+fileaddr(Dosfile *fp, long ltarget)
+{
+	Dos *dos = fp->dos;
+	long l;
+	long p;
+
+	chat("fileaddr %8.8s %ld\n", fp->name, ltarget);
+	/*
+	 *  root directory is contiguous and easy (unless FAT32)
+	 */
+	if(fp->pstart == 0 && dos->rootsize != 0) {
+		if(ltarget*dos->sectsize*dos->clustsize >= dos->rootsize*sizeof(Dosdir))
+			return -1;
+		l = dos->rootaddr + ltarget*dos->clustsize;
+		chat("fileaddr %ld -> %ld\n", ltarget, l);
+		return l;
+	}
+
+	/*
+	 *  anything else requires a walk through the fat
+	 */
+	if(ltarget >= fp->lcurrent && fp->pcurrent){
+		/* start at the currrent point */
+		l = fp->lcurrent;
+		p = fp->pcurrent;
+	} else {
+		/* go back to the beginning */
+		l = 0;
+		p = fp->pstart;
+	}
+	while(l != ltarget){
+		/* walk the fat */
+		p = fatwalk(dos, p);
+		if(p < 0)
+			return -1;
+		l++;
+	}
+	fp->lcurrent = l;
+	fp->pcurrent = p;
+
+	/*
+	 *  clusters start at 2 instead of 0 (why? - presotto)
+	 */
+	l =  dos->dataaddr + (p-2)*dos->clustsize;
+	chat("fileaddr %ld -> %ld\n", ltarget, l);
+	return l;
+}
+
+/*
+ *  read from a dos file
+ */
+long
+dosread(Dosfile *fp, void *a, long n)
+{
+	long addr;
+	long rv;
+	int i;
+	int off;
+	Clustbuf *p;
+	uchar *from, *to;
+
+	if((fp->attr & DOSDIR) == 0){
+		if(fp->offset >= fp->length)
+			return 0;
+		if(fp->offset+n > fp->length)
+			n = fp->length - fp->offset;
+	}
+
+	to = a;
+	for(rv = 0; rv < n; rv+=i){
+		/*
+		 *  read the cluster
+		 */
+		addr = fileaddr(fp, fp->offset/fp->dos->clustbytes);
+		if(addr < 0)
+			return -1;
+		p = getclust(fp->dos, addr);
+		if(p == 0)
+			return -1;
+
+		/*
+		 *  copy the bytes we need
+		 */
+		off = fp->offset % fp->dos->clustbytes;
+		from = &p->iobuf[off];
+		i = n - rv;
+		if(i > fp->dos->clustbytes - off)
+			i = fp->dos->clustbytes - off;
+		memmove(to, from, i);
+		to += i;
+		fp->offset += i;
+	}
+
+	return rv;
+}
+
+/*
+ *  walk a directory returns
+ * 	-1 if something went wrong
+ *	 0 if not found
+ *	 1 if found
+ */
+int
+doswalk(File *f, char *name)
+{
+	Dosdir d;
+	long n;
+	Dosfile *file;
+
+	chat("doswalk %s\n", name);
+
+	file = &f->dos;
+
+	if((file->attr & DOSDIR) == 0){
+		chat("walking non-directory!\n");
+		return -1;
+	}
+
+	setname(file, name);
+
+	file->offset = 0;	/* start at the beginning */
+	while((n = dosread(file, &d, sizeof(d))) == sizeof(d)){
+		chat("comparing to %8.8s.%3.3s\n", (char*)d.name, (char*)d.ext);
+		if(memcmp(file->name, d.name, sizeof(d.name)) != 0)
+			continue;
+		if(memcmp(file->ext, d.ext, sizeof(d.ext)) != 0)
+			continue;
+		if(d.attr & DOSVLABEL){
+			chat("%8.8s.%3.3s is a LABEL\n", (char*)d.name, (char*)d.ext);
+			continue;
+		}
+		file->attr = d.attr;
+		file->pstart = GSHORT(d.start);
+		if (file->dos->fatbits == 32)
+			file->pstart |= GSHORT(d.highstart) << 16;
+		file->length = GLONG(d.length);
+		file->pcurrent = 0;
+		file->lcurrent = 0;
+		file->offset = 0;
+		return 1;
+	}
+	return n >= 0 ? 0 : -1;
+}
+
+/*
+ *  instructions that boot blocks can start with
+ */
+#define	JMPSHORT	0xeb
+#define JMPNEAR		0xe9
+
+/*
+ *  read in a segment
+ */
+long
+dosreadseg(File *f, void *va, long len)
+{
+	char *a;
+	long n, sofar;
+	Dosfile *fp;
+
+	fp = &f->dos;
+	a = va;
+	for(sofar = 0; sofar < len; sofar += n){
+		n = 8*1024;
+		if(len - sofar < n)
+			n = len - sofar;
+		n = dosread(fp, a + sofar, n);
+		if(n <= 0)
+			break;
+		print(".");
+	}
+	return sofar;
+}
+
+int
+dosinit(Fs *fs)
+{
+	Clustbuf *p;
+	Dosboot *b;
+	int i;
+	Dos *dos;
+	Dosfile *root;
+
+chat("dosinit0 %p %p %p\n", fs, fs->diskseek, fs->diskread);
+
+	dos = &fs->dos;
+	/* defaults till we know better */
+	dos->sectsize = 512;
+	dos->clustsize = 1;
+
+	/* get first sector */
+	p = getclust(dos, 0);
+	if(p == 0){
+		chat("can't read boot block\n");
+		return -1;
+	}
+
+chat("dosinit0a\n");
+
+	p->dos = 0;				/* don't cache this block */
+	b = (Dosboot *)p->iobuf;
+	if(b->magic[0] != JMPNEAR && (b->magic[0] != JMPSHORT || b->magic[2] != 0x90)){
+		chat("no dos file system %x %x %x %x\n",
+			b->magic[0], b->magic[1], b->magic[2], b->magic[3]);
+		return -1;
+	}
+
+	if(chatty)
+		bootdump(b);
+
+	if(b->clustsize == 0) {
+unreasonable:
+		if(chatty){
+			print("unreasonable FAT BPB: ");
+			for(i=0; i<3+8+2+1; i++)
+				print(" %.2ux", p->iobuf[i]);
+			print("\n");
+		}
+		return -1;
+	}
+
+chat("dosinit1\n");
+
+	/*
+	 * Determine the systems' wondrous properties.
+	 * There are heuristics here, but there's no real way
+	 * of knowing if this is a reasonable FAT.
+	 */
+	dos->fatbits = 0;
+	dos->sectsize = GSHORT(b->sectsize);
+	if(dos->sectsize & 0xFF)
+		goto unreasonable;
+	dos->clustsize = b->clustsize;
+	dos->clustbytes = dos->sectsize*dos->clustsize;
+	dos->nresrv = GSHORT(b->nresrv);
+	dos->nfats = b->nfats;
+	dos->fatsize = GSHORT(b->fatsize);
+	dos->rootsize = GSHORT(b->rootsize);
+	dos->volsize = GSHORT(b->volsize);
+	if(dos->volsize == 0)
+		dos->volsize = GLONG(b->bigvolsize);
+	dos->mediadesc = b->mediadesc;
+	if(dos->fatsize == 0) {
+		chat("fat32\n");
+		dos->rootsize = 0;
+		dos->fatsize = GLONG(b->bigfatsize);
+		dos->fatbits = 32;
+	}
+	dos->fataddr = dos->nresrv;
+	if (dos->rootsize == 0) {
+		dos->rootaddr = 0;
+		dos->rootclust = GLONG(b->rootdirstartclust);
+		dos->dataaddr = dos->fataddr + dos->nfats*dos->fatsize;
+	} else {
+		dos->rootaddr = dos->fataddr + dos->nfats*dos->fatsize;
+		i = dos->rootsize*sizeof(Dosdir) + dos->sectsize - 1;
+		i = i/dos->sectsize;
+		dos->dataaddr = dos->rootaddr + i;
+	}
+	dos->fatclusters = 2+(dos->volsize - dos->dataaddr)/dos->clustsize;
+	if(dos->fatbits != 32) {
+		if(dos->fatclusters < 4087)
+			dos->fatbits = 12;
+		else
+			dos->fatbits = 16;
+	}
+	dos->freeptr = 2;
+
+	if(dos->clustbytes < 512 || dos->clustbytes > 64*1024)
+		goto unreasonable;
+
+chat("dosinit2\n");
+
+	/*
+	 *  set up the root
+	 */
+
+	fs->root.fs = fs;
+	root = &fs->root.dos;
+	root->dos = dos;
+	root->pstart = dos->rootsize == 0 ? dos->rootclust : 0;
+	root->pcurrent = root->lcurrent = 0;
+	root->offset = 0;
+	root->attr = DOSDIR;
+	root->length = dos->rootsize*sizeof(Dosdir);
+
+chat("dosinit3\n");
+
+	fs->read = dosreadseg;
+	fs->walk = doswalk;
+	return 0;
+}
+
+static void
+bootdump(Dosboot *b)
+{
+	if(chatty == 0)
+		return;
+	print("magic: 0x%2.2x 0x%2.2x 0x%2.2x ",
+		b->magic[0], b->magic[1], b->magic[2]);
+	print("version: \"%8.8s\"\n", (char*)b->version);
+	print("sectsize: %d ", GSHORT(b->sectsize));
+	print("allocsize: %d ", b->clustsize);
+	print("nresrv: %d ", GSHORT(b->nresrv));
+	print("nfats: %d\n", b->nfats);
+	print("rootsize: %d ", GSHORT(b->rootsize));
+	print("volsize: %d ", GSHORT(b->volsize));
+	print("mediadesc: 0x%2.2x\n", b->mediadesc);
+	print("fatsize: %d ", GSHORT(b->fatsize));
+	print("trksize: %d ", GSHORT(b->trksize));
+	print("nheads: %d ", GSHORT(b->nheads));
+	print("nhidden: %d ", GLONG(b->nhidden));
+	print("bigvolsize: %d\n", GLONG(b->bigvolsize));
+/*
+	print("driveno: %d\n", b->driveno);
+	print("reserved0: 0x%2.2x\n", b->reserved0);
+	print("bootsig: 0x%2.2x\n", b->bootsig);
+	print("volid: 0x%8.8x\n", GLONG(b->volid));
+	print("label: \"%11.11s\"\n", b->label);
+*/
+}
+
+
+/*
+ *  set up a dos file name
+ */
+static void
+setname(Dosfile *fp, char *from)
+{
+	char *to;
+
+	to = fp->name;
+	for(; *from && to-fp->name < 8; from++, to++){
+		if(*from == '.'){
+			from++;
+			break;
+		}
+		if(*from >= 'a' && *from <= 'z')
+			*to = *from + 'A' - 'a';
+		else
+			*to = *from;
+	}
+	while(to - fp->name < 8)
+		*to++ = ' ';
+	
+	/* from might be 12345678.123: don't save the '.' in ext */
+	if(*from == '.')
+		from++;
+
+	to = fp->ext;
+	for(; *from && to-fp->ext < 3; from++, to++){
+		if(*from >= 'a' && *from <= 'z')
+			*to = *from + 'A' - 'a';
+		else
+			*to = *from;
+	}
+	while(to-fp->ext < 3)
+		*to++ = ' ';
+
+	chat("name is %8.8s.%3.3s\n", fp->name, fp->ext);
+}