1 files changed, 377 insertions, 0 deletions
diff --git a/appl/lib/disks.b b/appl/lib/disks.b
new file mode 100644
index 00000000..ac718af1
--- /dev/null
+++ b/appl/lib/disks.b
@@ -0,0 +1,377 @@
+implement Disks;
+
+# adapted from /sys/src/libdisk on Plan 9: subject to Lucent Public License 1.02
+
+include "sys.m";
+	sys: Sys;
+
+include "bufio.m";
+	bufio: Bufio;
+	Iobuf: import bufio;
+
+include "disks.m";
+
+scsiverbose := 0;
+
+Codefile: con "/lib/scsicodes";
+
+Code: adt {
+	v:	int;	# (asc<<8) | ascq
+	s:	string;
+};
+codes: array of Code;
+
+init()
+{
+	sys = load Sys Sys->PATH;
+	bufio = load Bufio Bufio->PATH;
+}
+
+#
+# Discover the disk geometry by various sleazeful means.
+# 
+# First, if there is a partition table in sector 0,
+# see if all the partitions have the same end head
+# and sector; if so, we'll assume that that's the 
+# right count.
+# 
+# If that fails, we'll try looking at the geometry that the ATA
+# driver supplied, if any, and translate that as a
+# BIOS might. 
+# 
+# If that too fails, which should only happen on a SCSI
+# disk with no currently defined partitions, we'll try
+# various common (h, s) pairs used by BIOSes when faking
+# the geometries.
+#
+
+# table entry:
+	Oactive,			# active flag
+	Ostarth,			# starting head
+	Ostarts,			# starting sector
+	Ostartc,			# starting cylinder
+	Otype,			# partition type
+	Oendh,			# ending head
+	Oends,			# ending sector
+	Oendc: con iota;		# ending cylinder
+	Oxlba: con Oendc+1;	# starting LBA from start of disc or partition [4]
+	Oxsize: con Oxlba+4;	# size in sectors[4]
+
+# Table: entry[NTentry][TentrySize] magic[2]
+Omagic: con NTentry*TentrySize;
+
+partitiongeometry(d: ref Disk): int
+{
+	buf := array[512] of byte;
+	t := buf[Toffset:];
+
+	#
+	# look for an MBR first in the /dev/sdXX/data partition, otherwise
+	# attempt to fall back on the current partition.
+	#
+	rawfd := sys->open(d.prefix+"data", Sys->OREAD);
+	if(rawfd != nil
+	&& sys->seek(rawfd, big 0, 0) == big 0
+	&& readn(rawfd, buf, 512) == 512
+	&& int t[Omagic] == Magic0
+	&& int t[Omagic+1] == Magic1) {
+		rawfd = nil;
+	}else{
+		rawfd = nil;
+		if(sys->seek(d.fd, big 0, 0) < big 0
+		|| readn(d.fd, buf, 512) != 512
+		|| int t[Omagic] != Magic0
+		|| int t[Omagic+1] != Magic1)
+			return -1;
+	}
+
+	h := s := -1;
+	for(i:=0; i<NTentry*TentrySize; i += TentrySize) {
+		if(t[i+Otype] == byte 0)
+			continue;
+
+		t[i+Oends] &= byte 63;
+		if(h == -1) {
+			h = int t[i+Oendh];
+			s = int t[i+Oends];
+		} else {
+			#
+			# Only accept the partition info if every
+			# partition is consistent.
+			#
+			if(h != int t[i+Oendh] || s != int t[i+Oends])
+				return -1;
+		}
+	}
+
+	if(h == -1)
+		return -1;
+
+	d.h = h+1;	# heads count from 0
+	d.s = s;	# sectors count from 1
+	d.c = int (d.secs / big (d.h*d.s));
+	d.chssrc = "part";
+	return 0;
+}
+
+#
+# If there is ATA geometry, use it, perhaps massaged
+#
+drivergeometry(d: ref Disk): int
+{
+	if(d.c == 0 || d.h == 0 || d.s == 0)
+		return -1;
+
+	d.chssrc = "disk";
+	if(d.c < 1024)
+		return 0;
+
+	case d.h {
+	15 =>
+		d.h = 255;
+		d.c /= 17;
+
+	* =>
+		for(m := 2; m*d.h < 256; m *= 2) {
+			if(d.c/m < 1024) {
+				d.c /= m;
+				d.h *= m;
+				return 0;
+			}
+		}
+
+		# set to 255, 63 and be done with it
+		d.h = 255;
+		d.s = 63;
+		d.c = int (d.secs / big(d.h * d.s));
+	}
+	return 0;
+}
+
+#
+# There's no ATA geometry and no partitions.
+# Our guess is as good as anyone's.
+#
+Guess: adt {
+	h:	int;
+	s:	int;
+};
+guess: array of Guess = array[] of {
+	(64, 32),
+	(64, 63),
+	(128, 63),
+	(255, 63),
+};
+
+guessgeometry(d: ref Disk)
+{
+	d.chssrc = "guess";
+	c := 1024;
+	for(i:=0; i<len guess; i++)
+		if(big(c*guess[i].h*guess[i].s) >= d.secs) {
+			d.h = guess[i].h;
+			d.s = guess[i].s;
+			d.c = int(d.secs / big(d.h * d.s));
+			return;
+		}
+
+	# use maximum values
+	d.h = 255;
+	d.s = 63;
+	d.c = int(d.secs / big(d.h * d.s));
+}
+
+findgeometry(disk: ref Disk)
+{
+	disk.h = disk.s = disk.c = 0;
+	if(partitiongeometry(disk) < 0 &&
+	   drivergeometry(disk) < 0)
+		guessgeometry(disk);
+}
+
+openfile(d: ref Disk): ref Disk
+{
+	(ok, db) := sys->fstat(d.fd);
+	if(ok < 0)
+		return nil;
+
+	d.secsize = 512;
+	d.size = db.length;
+	d.secs = d.size / big d.secsize;
+	d.offset = big 0;
+
+	findgeometry(d);
+	return mkwidth(d);
+}
+
+opensd(d: ref Disk): ref Disk
+{
+	b := bufio->fopen(d.ctlfd, Bufio->OREAD);
+	while((p := b.gets('\n')) != nil){
+		p = p[0:len p - 1];
+		(nf, f) := sys->tokenize(p, " \t");	# might need str->unquote
+		if(nf >= 3 && hd f == "geometry") {
+			d.secsize = int hd tl tl f;
+			if(nf >= 6) {
+				d.c = int hd tl tl tl f;
+				d.h = int hd tl tl tl tl f;
+				d.s = int hd tl tl tl tl tl f;
+			}
+		}
+		if(nf >= 4 && hd f == "part" && hd tl f == d.part) {
+			d.offset = big hd tl tl f;
+			d.secs = big hd tl tl tl f - d.offset;
+		}
+	}
+
+	
+	d.size = d.secs * big d.secsize;
+	if(d.size <= big 0) {
+		d.part = "";
+		d.dtype = "file";
+		return openfile(d);
+	}
+
+	findgeometry(d);
+	return mkwidth(d);
+}
+
+Disk.open(name: string, mode: int, noctl: int): ref Disk
+{
+	d := ref Disk;
+	d.rdonly = mode == Sys->OREAD;
+	d.fd = sys->open(name, Sys->OREAD);
+	if(d.fd == nil)
+		return nil;
+
+	if(mode != Sys->OREAD){
+		d.wfd = sys->open(name, Sys->OWRITE);
+		if(d.wfd == nil)
+			d.rdonly = 1;
+	}
+
+	if(noctl)
+		return openfile(d);
+
+	# check for floppy(3) disk
+	if(len name >= 7) {
+		q := name[len name-7:];
+		if(q[0] == 'f' && q[1] == 'd' && isdigit(q[2]) && q[3:] == "disk") {
+			if((d.ctlfd = sys->open(name[0:len name-4]+"ctl", Sys->ORDWR)) != nil) {
+				d.prefix = name[0:len name-4];	# fdN (unlike Plan 9)
+				d.dtype = "floppy";
+				return openfile(d);
+			}
+		}
+	}
+
+	# attempt to find sd(3) disk or partition
+	d.prefix = name;
+	for(i := len name; --i >= 0;)
+		if(name[i] == '/'){
+			d.prefix = name[0:i+1];
+			break;
+		}
+
+	if((d.ctlfd = sys->open(d.prefix+"ctl", Sys->ORDWR)) != nil) {
+		d.dtype = "sd";
+		d.part = name[len d.prefix:];
+		return opensd(d);
+	}
+
+	# assume we have just a normal file
+	d.dtype = "file";
+	return openfile(d);
+}
+
+mkwidth(d: ref Disk): ref Disk
+{
+	d.width = len sys->sprint("%bd", d.size);
+	return d;
+}
+
+isdigit(c: int): int
+{
+	return c >= '0' && c <= '9';
+}
+
+putchs(d: ref Disk, p: array of byte, lba: big)
+{
+	s := int (lba % big d.s);
+	h := int (lba / big d.s % big d.h);
+	c := int (lba / (big d.s * big d.h));
+
+	if(c >= 1024) {
+		c = 1023;
+		h = d.h - 1;
+		s = d.s - 1;
+	}
+
+	p[0] = byte h;
+	p[1] = byte (((s+1) & 16r3F) | ((c>>2) & 16rC0));
+	p[2] = byte c;
+}
+
+PCpart.bytes(p: self PCpart, d: ref Disk): array of byte
+{
+	a := array[TentrySize] of byte;
+	a[Oactive] = byte p.active;
+	a[Otype] = byte p.ptype;
+	putchs(d, a[Ostarth:], p.base+p.offset);
+	putchs(d, a[Oendh:], p.base+p.offset+p.size-big 1);
+	putle32(a[Oxlba:], p.offset);
+	putle32(a[Oxsize:], p.size);
+	return a;
+}
+
+PCpart.extract(a: array of byte, nil: ref Disk): PCpart
+{
+	p: PCpart;
+	p.active = int a[Oactive];
+	p.ptype = int a[Otype];
+	p.base = big 0;
+	p.offset = getle32(a[Oxlba:]);
+	p.size = getle32(a[Oxsize:]);
+	return p;
+}
+
+getle32(p: array of byte): big
+{
+	return (big p[3]<<24) | (big p[2]<<16) | (big p[1] << 8) | big p[0];
+}
+
+putle32(p: array of byte, i: big)
+{
+	p[0] = byte i;
+	p[1] = byte (i>>8);
+	p[2] = byte (i>>16);
+	p[3] = byte (i>>24);
+}
+
+Disk.readn(d: self ref Disk, buf: array of byte, nb: int): int
+{
+	return readn(d.fd, buf, nb);
+}
+
+chstext(p: array of byte): string
+{
+	h := int p[0];
+	c := int p[2];
+	c |= (int p[1]&16rC0)<<2;
+	s := (int p[1] & 16r3F);
+	return sys->sprint("%d/%d/%d", c, h, s);
+}
+
+readn(fd: ref Sys->FD, buf: array of byte, nb: int): int
+{
+	for(nr := 0; nr < nb;){
+		n := sys->read(fd, buf[nr:], nb-nr);
+		if(n <= 0){
+			if(nr == 0)
+				return n;
+			break;
+		}
+		nr += n;
+	}
+	return nr;
+}