fix: macos hang and sector 0 corruption

Author: mikesmitty

src/machine/usb/msc/msc.go

@@ -288,7 +288,7 @@ func (m *msc) run(b []byte, isEpOut bool) bool {
 		m.sentBytes = 0
 		m.respStatus = csw.StatusPassed
 
-		m.scsiCmdBegin(b)
+		m.scsiCmdBegin()
 
 	case mscStateData:
 		// Transfer data
@@ -322,9 +322,8 @@ func (m *msc) run(b []byte, isEpOut bool) bool {
 		if m.totalBytes > m.sentBytes && m.cbw.isIn() {
 			// 6.7.2 The Thirteen Cases - Case 5 (Hi > Di): STALL before status
 			m.stallEndpoint(usb.MSC_ENDPOINT_IN)
-		} else if m.sendZLP || m.queuedBytes == m.maxPacketSize {
-			// If the last packet is wMaxPacketSize we need to first send a zero-length packet
-			// to indicate the end of the transfer before we can send a CSW
+		} else if m.sendZLP {
+			// Send a zero-length packet to force the end of the transfer before we send a CSW
 			m.queuedBytes = 0
 			m.sendZLP = false
 			m.sendUSBPacket(m.buf[:0])

src/machine/usb/msc/scsi.go

@@ -7,14 +7,14 @@ import (
 	"machine/usb/msc/scsi"
 )
 
-func (m *msc) scsiCmdBegin(b []byte) {
+func (m *msc) scsiCmdBegin() {
 	cmd := m.cbw.SCSICmd()
 	cmdType := cmd.CmdType()
 
 	// Handle multi-packet commands
 	switch cmdType {
 	case scsi.CmdRead, scsi.CmdWrite:
-		m.scsiCmdReadWrite(cmd, b)
+		m.scsiCmdReadWrite(cmd)
 		return
 	case scsi.CmdUnmap:
 		m.scsiCmdUnmap(cmd)

src/machine/usb/msc/scsi_readwrite.go

@@ -8,7 +8,7 @@ import (
 
 var invalidWriteError = errors.New("invalid write offset or length")
 
-func (m *msc) scsiCmdReadWrite(cmd scsi.Cmd, b []byte) {
+func (m *msc) scsiCmdReadWrite(cmd scsi.Cmd) {
 	status := m.validateScsiReadWrite(cmd)
 	if status != csw.StatusPassed {
 		m.sendScsiError(status, scsi.SenseIllegalRequest, scsi.SenseCodeInvalidCmdOpCode)
@@ -62,8 +62,9 @@ func (m *msc) validateScsiReadWrite(cmd scsi.Cmd) csw.Status {
 
 func (m *msc) usbToRawOffset(lba, offset uint32) (int64, int64) {
 	// Convert the emulated block address to the underlying hardware block's start and offset
-	byteOffset := lba*m.blockSizeUSB + m.blockOffset + offset
-	return int64(byteOffset), int64(byteOffset % m.blockSizeRaw)
+	rawLBA := (lba*m.blockSizeUSB + offset) / m.blockSizeRaw
+	rawBlockOffset := int64((lba*m.blockSizeUSB + offset) % m.blockSizeRaw)
+	return int64(m.blockOffset + rawLBA*m.blockSizeRaw), rawBlockOffset
 }
 
 func (m *msc) readBlock(b []byte, lba, offset uint32) (n int, err error) {