machine: fix usb truncation?

Remove the sendUSBPacket maxLen param because this greatly confused the compiler.
It also fixes a bug where the length provided to the hardware may not match the length of the packet.
sendUSBPacket now panics if the sent packet is too big.

I also fixed some of the string descriptor logic where we could create a packet without fully populating it.

RP2* systems might require some more work since they are implemented very differently?
I don't have any of those to test with yet, so maybe someone can deal with them in a seperate PR?

builder/sizes_test.go

@@ -44,7 +44,7 @@ func TestBinarySize(t *testing.T) {
 		// microcontrollers
 		{"hifive1b", "examples/echo", 3668, 280, 0, 2244},
 		{"microbit", "examples/serial", 2694, 342, 8, 2248},
-		{"wioterminal", "examples/pininterrupt", 7187, 1489, 116, 6888},
+		{"wioterminal", "examples/pininterrupt", 6833, 1491, 120, 6888},
 
 		// TODO: also check wasm. Right now this is difficult, because
 		// wasm binaries are run through wasm-opt and therefore the

compiler/compiler.go

@@ -1599,7 +1599,8 @@ func (b *builder) createBuiltin(argTypes []types.Type, argValues []llvm.Value, c
 		elemsLen := b.CreateExtractValue(elems, 1, "append.elemsLen")
 		elemType := b.getLLVMType(argTypes[0].Underlying().(*types.Slice).Elem())
 		elemSize := llvm.ConstInt(b.uintptrType, b.targetData.TypeAllocSize(elemType), false)
-		result := b.createRuntimeCall("sliceAppend", []llvm.Value{srcBuf, elemsBuf, srcLen, srcCap, elemsLen, elemSize}, "append.new")
+		elemLayout := b.createObjectLayout(elemType, pos)
+		result := b.createRuntimeCall("sliceAppend", []llvm.Value{srcBuf, elemsBuf, srcLen, srcCap, elemsLen, elemSize, elemLayout}, "append.new")
 		newPtr := b.CreateExtractValue(result, 0, "append.newPtr")
 		newLen := b.CreateExtractValue(result, 1, "append.newLen")
 		newCap := b.CreateExtractValue(result, 2, "append.newCap")

compiler/testdata/slice.ll

@@ -55,7 +55,7 @@ entry:
   store i32 2, ptr %0, align 4
   %1 = getelementptr inbounds nuw i8, ptr %varargs, i32 8
   store i32 3, ptr %1, align 4
-  %append.new = call { ptr, i32, i32 } @runtime.sliceAppend(ptr %ints.data, ptr nonnull %varargs, i32 %ints.len, i32 %ints.cap, i32 3, i32 4, ptr undef) #3
+  %append.new = call { ptr, i32, i32 } @runtime.sliceAppend(ptr %ints.data, ptr nonnull %varargs, i32 %ints.len, i32 %ints.cap, i32 3, i32 4, ptr nonnull inttoptr (i32 3 to ptr), ptr undef) #3
   %append.newPtr = extractvalue { ptr, i32, i32 } %append.new, 0
   %append.newLen = extractvalue { ptr, i32, i32 } %append.new, 1
   %append.newCap = extractvalue { ptr, i32, i32 } %append.new, 2
@@ -66,13 +66,13 @@ entry:
   ret { ptr, i32, i32 } %4
 }
 
-declare { ptr, i32, i32 } @runtime.sliceAppend(ptr, ptr nocapture readonly, i32, i32, i32, i32, ptr) #1
+declare { ptr, i32, i32 } @runtime.sliceAppend(ptr, ptr nocapture readonly, i32, i32, i32, i32, ptr, ptr) #1
 
 ; Function Attrs: nounwind
 define hidden { ptr, i32, i32 } @main.sliceAppendSlice(ptr %ints.data, i32 %ints.len, i32 %ints.cap, ptr %added.data, i32 %added.len, i32 %added.cap, ptr %context) unnamed_addr #2 {
 entry:
   %stackalloc = alloca i8, align 1
-  %append.new = call { ptr, i32, i32 } @runtime.sliceAppend(ptr %ints.data, ptr %added.data, i32 %ints.len, i32 %ints.cap, i32 %added.len, i32 4, ptr undef) #3
+  %append.new = call { ptr, i32, i32 } @runtime.sliceAppend(ptr %ints.data, ptr %added.data, i32 %ints.len, i32 %ints.cap, i32 %added.len, i32 4, ptr nonnull inttoptr (i32 3 to ptr), ptr undef) #3
   %append.newPtr = extractvalue { ptr, i32, i32 } %append.new, 0
   %append.newLen = extractvalue { ptr, i32, i32 } %append.new, 1
   %append.newCap = extractvalue { ptr, i32, i32 } %append.new, 2

src/internal/reflectlite/value.go

@@ -1745,7 +1745,7 @@ func memzero(ptr unsafe.Pointer, size uintptr)
 func alloc(size uintptr, layout unsafe.Pointer) unsafe.Pointer
 
 //go:linkname sliceAppend runtime.sliceAppend
-func sliceAppend(srcBuf, elemsBuf unsafe.Pointer, srcLen, srcCap, elemsLen uintptr, elemSize uintptr) (unsafe.Pointer, uintptr, uintptr)
+func sliceAppend(srcBuf, elemsBuf unsafe.Pointer, srcLen, srcCap, elemsLen uintptr, elemSize uintptr, layout unsafe.Pointer) (unsafe.Pointer, uintptr, uintptr)
 
 //go:linkname sliceCopy runtime.sliceCopy
 func sliceCopy(dst, src unsafe.Pointer, dstLen, srcLen uintptr, elemSize uintptr) int
@@ -1810,7 +1810,7 @@ func buflen(v Value) (unsafe.Pointer, uintptr) {
 }
 
 //go:linkname sliceGrow runtime.sliceGrow
-func sliceGrow(buf unsafe.Pointer, oldLen, oldCap, newCap, elemSize uintptr) (unsafe.Pointer, uintptr, uintptr)
+func sliceGrow(buf unsafe.Pointer, oldLen, oldCap, newCap, elemSize uintptr, layout unsafe.Pointer) (unsafe.Pointer, uintptr, uintptr)
 
 // extend slice to hold n new elements
 func extendSlice(v Value, n int) sliceHeader {
@@ -1823,7 +1823,10 @@ func extendSlice(v Value, n int) sliceHeader {
 		old = *(*sliceHeader)(v.value)
 	}
 
-	nbuf, nlen, ncap := sliceGrow(old.data, old.len, old.cap, old.len+uintptr(n), v.typecode.elem().Size())
+	elem := v.typecode.elem()
+	elemSize := elem.Size()
+	elemLayout := elem.gcLayout()
+	nbuf, nlen, ncap := sliceGrow(old.data, old.len, old.cap, old.len+uintptr(n), elemSize, elemLayout)
 
 	return sliceHeader{
 		data: nbuf,
@@ -1862,8 +1865,10 @@ func AppendSlice(s, t Value) Value {
 	}
 	sSlice := (*sliceHeader)(s.value)
 	tSlice := (*sliceHeader)(t.value)
-	elemSize := s.typecode.elem().Size()
+	elem := s.typecode.elem()
-	ptr, len, cap := sliceAppend(sSlice.data, tSlice.data, sSlice.len, sSlice.cap, tSlice.len, elemSize)
+	elemSize := elem.Size()
+	elemLayout := elem.gcLayout()
+	ptr, len, cap := sliceAppend(sSlice.data, tSlice.data, sSlice.len, sSlice.cap, tSlice.len, elemSize, elemLayout)
 	result := &sliceHeader{
 		data: ptr,
 		len:  len,

src/machine/machine_atsamd21_usb.go

@@ -337,7 +337,7 @@ func handleUSBSetAddress(setup usb.Setup) bool {
 
 // SendUSBInPacket sends a packet for USB (interrupt in / bulk in).
 func SendUSBInPacket(ep uint32, data []byte) bool {
-	sendUSBPacket(ep, data, 0)
+	sendUSBPacket(ep, data)
 
 	// clear transfer complete flag
 	setEPINTFLAG(ep, sam.USB_DEVICE_EPINTFLAG_TRCPT1)
@@ -351,27 +351,28 @@ func SendUSBInPacket(ep uint32, data []byte) bool {
 // Prevent file size increases: https://github.com/tinygo-org/tinygo/pull/998
 //
 //go:noinline
-func sendUSBPacket(ep uint32, data []byte, maxsize uint16) {
+func sendUSBPacket(ep uint32, data []byte) {
-	l := uint16(len(data))
+	// Select the corresponding buffer.
-	if 0 < maxsize && maxsize < l {
+	buffer := udd_ep_control_cache_buffer[:]
-		l = maxsize
+	if ep != 0 {
+		buffer = udd_ep_in_cache_buffer[ep][:]
 	}
 
-	// Set endpoint address for sending data
+	// Copy the packet to the buffer.
-	if ep == 0 {
+	copy(buffer[:len(data)], data)
-		copy(udd_ep_control_cache_buffer[:], data[:l])
+
-		usbEndpointDescriptors[ep].DeviceDescBank[1].ADDR.Set(uint32(uintptr(unsafe.Pointer(&udd_ep_control_cache_buffer))))
+	// Select the corresponding endpoint descriptor.
-	} else {
+	endpoint := &usbEndpointDescriptors[ep].DeviceDescBank[1]
-		copy(udd_ep_in_cache_buffer[ep][:], data[:l])
+
-		usbEndpointDescriptors[ep].DeviceDescBank[1].ADDR.Set(uint32(uintptr(unsafe.Pointer(&udd_ep_in_cache_buffer[ep]))))
+	// Set the endpoint address.
-	}
+	endpoint.ADDR.Set(uint32(uintptr(unsafe.Pointer(unsafe.SliceData(buffer)))))
 
 	// clear multi-packet size which is total bytes already sent
-	usbEndpointDescriptors[ep].DeviceDescBank[1].PCKSIZE.ClearBits(usb_DEVICE_PCKSIZE_MULTI_PACKET_SIZE_Mask << usb_DEVICE_PCKSIZE_MULTI_PACKET_SIZE_Pos)
+	endpoint.PCKSIZE.ClearBits(usb_DEVICE_PCKSIZE_MULTI_PACKET_SIZE_Mask << usb_DEVICE_PCKSIZE_MULTI_PACKET_SIZE_Pos)
 
 	// set byte count, which is total number of bytes to be sent
-	usbEndpointDescriptors[ep].DeviceDescBank[1].PCKSIZE.ClearBits(usb_DEVICE_PCKSIZE_BYTE_COUNT_Mask << usb_DEVICE_PCKSIZE_BYTE_COUNT_Pos)
+	endpoint.PCKSIZE.ClearBits(usb_DEVICE_PCKSIZE_BYTE_COUNT_Mask << usb_DEVICE_PCKSIZE_BYTE_COUNT_Pos)
-	usbEndpointDescriptors[ep].DeviceDescBank[1].PCKSIZE.SetBits((uint32(l) & usb_DEVICE_PCKSIZE_BYTE_COUNT_Mask) << usb_DEVICE_PCKSIZE_BYTE_COUNT_Pos)
+	endpoint.PCKSIZE.SetBits((uint32(len(data)) & usb_DEVICE_PCKSIZE_BYTE_COUNT_Mask) << usb_DEVICE_PCKSIZE_BYTE_COUNT_Pos)
 }
 
 func ReceiveUSBControlPacket() ([cdcLineInfoSize]byte, error) {

src/machine/machine_atsamd51_usb.go

@@ -340,7 +340,7 @@ func handleUSBSetAddress(setup usb.Setup) bool {
 
 // SendUSBInPacket sends a packet for USB (interrupt in / bulk in).
 func SendUSBInPacket(ep uint32, data []byte) bool {
-	sendUSBPacket(ep, data, 0)
+	sendUSBPacket(ep, data)
 
 	// clear transfer complete flag
 	setEPINTFLAG(ep, sam.USB_DEVICE_ENDPOINT_EPINTFLAG_TRCPT1)
@@ -354,27 +354,28 @@ func SendUSBInPacket(ep uint32, data []byte) bool {
 // Prevent file size increases: https://github.com/tinygo-org/tinygo/pull/998
 //
 //go:noinline
-func sendUSBPacket(ep uint32, data []byte, maxsize uint16) {
+func sendUSBPacket(ep uint32, data []byte) {
-	l := uint16(len(data))
+	// Select the corresponding buffer.
-	if 0 < maxsize && maxsize < l {
+	buffer := udd_ep_control_cache_buffer[:]
-		l = maxsize
+	if ep != 0 {
+		buffer = udd_ep_in_cache_buffer[ep][:]
 	}
 
-	// Set endpoint address for sending data
+	// Copy the packet to the buffer.
-	if ep == 0 {
+	copy(buffer[:len(data)], data)
-		copy(udd_ep_control_cache_buffer[:], data[:l])
+
-		usbEndpointDescriptors[ep].DeviceDescBank[1].ADDR.Set(uint32(uintptr(unsafe.Pointer(&udd_ep_control_cache_buffer))))
+	// Select the corresponding endpoint descriptor.
-	} else {
+	endpoint := &usbEndpointDescriptors[ep].DeviceDescBank[1]
-		copy(udd_ep_in_cache_buffer[ep][:], data[:l])
+
-		usbEndpointDescriptors[ep].DeviceDescBank[1].ADDR.Set(uint32(uintptr(unsafe.Pointer(&udd_ep_in_cache_buffer[ep]))))
+	// Set the endpoint address.
-	}
+	endpoint.ADDR.Set(uint32(uintptr(unsafe.Pointer(unsafe.SliceData(buffer)))))
 
 	// clear multi-packet size which is total bytes already sent
-	usbEndpointDescriptors[ep].DeviceDescBank[1].PCKSIZE.ClearBits(usb_DEVICE_PCKSIZE_MULTI_PACKET_SIZE_Mask << usb_DEVICE_PCKSIZE_MULTI_PACKET_SIZE_Pos)
+	endpoint.PCKSIZE.ClearBits(usb_DEVICE_PCKSIZE_MULTI_PACKET_SIZE_Mask << usb_DEVICE_PCKSIZE_MULTI_PACKET_SIZE_Pos)
 
 	// set byte count, which is total number of bytes to be sent
-	usbEndpointDescriptors[ep].DeviceDescBank[1].PCKSIZE.ClearBits(usb_DEVICE_PCKSIZE_BYTE_COUNT_Mask << usb_DEVICE_PCKSIZE_BYTE_COUNT_Pos)
+	endpoint.PCKSIZE.ClearBits(usb_DEVICE_PCKSIZE_BYTE_COUNT_Mask << usb_DEVICE_PCKSIZE_BYTE_COUNT_Pos)
-	usbEndpointDescriptors[ep].DeviceDescBank[1].PCKSIZE.SetBits((uint32(l) & usb_DEVICE_PCKSIZE_BYTE_COUNT_Mask) << usb_DEVICE_PCKSIZE_BYTE_COUNT_Pos)
+	endpoint.PCKSIZE.SetBits((uint32(len(data)) & usb_DEVICE_PCKSIZE_BYTE_COUNT_Mask) << usb_DEVICE_PCKSIZE_BYTE_COUNT_Pos)
 }
 
 func ReceiveUSBControlPacket() ([cdcLineInfoSize]byte, error) {

src/machine/machine_nrf52840_usb.go

@@ -256,7 +256,7 @@ func initEndpoint(ep, config uint32) {
 
 // SendUSBInPacket sends a packet for USBHID (interrupt in / bulk in).
 func SendUSBInPacket(ep uint32, data []byte) bool {
-	sendUSBPacket(ep, data, 0)
+	sendUSBPacket(ep, data)
 
 	// clear transfer complete flag
 	nrf.USBD.INTENCLR.Set(nrf.USBD_INTENCLR_ENDEPOUT0 << 4)
@@ -267,33 +267,32 @@ func SendUSBInPacket(ep uint32, data []byte) bool {
 // Prevent file size increases: https://github.com/tinygo-org/tinygo/pull/998
 //
 //go:noinline
-func sendUSBPacket(ep uint32, data []byte, maxsize uint16) {
+func sendUSBPacket(ep uint32, data []byte) {
+	// Select the corresponding buffer.
 	count := len(data)
-	if 0 < int(maxsize) && int(maxsize) < count {
+	var buffer []byte
-		count = int(maxsize)
-	}
-
 	if ep == 0 {
-		copy(udd_ep_control_cache_buffer[:], data[:count])
+		buffer = udd_ep_control_cache_buffer[:]
 		if count > usb.EndpointPacketSize {
+			// The packet must be sent in chunks.
 			sendOnEP0DATADONE.offset = usb.EndpointPacketSize
-			sendOnEP0DATADONE.ptr = &udd_ep_control_cache_buffer[sendOnEP0DATADONE.offset]
+			sendOnEP0DATADONE.ptr = &udd_ep_control_cache_buffer[usb.EndpointPacketSize]
 			sendOnEP0DATADONE.count = count - usb.EndpointPacketSize
 			count = usb.EndpointPacketSize
 		}
-		sendViaEPIn(
-			ep,
-			&udd_ep_control_cache_buffer[0],
-			count,
-		)
 	} else {
-		copy(udd_ep_in_cache_buffer[ep][:], data[:count])
+		buffer = udd_ep_in_cache_buffer[ep][:]
-		sendViaEPIn(
-			ep,
-			&udd_ep_in_cache_buffer[ep][0],
-			count,
-		)
 	}
+
+	// Copy the packet to the buffer.
+	copy(buffer[:len(data)], data)
+
+	// Send the first chunk of the packet.
+	sendViaEPIn(
+		ep,
+		&buffer[0],
+		count,
+	)
 }
 
 func handleEndpointRx(ep uint32) []byte {

src/machine/machine_rp2040_usb.go

@@ -128,7 +128,7 @@ func handleUSBSetAddress(setup usb.Setup) bool {
 	const ackTimeout = 570
 
 	rp.USBCTRL_REGS.SIE_STATUS.Set(rp.USBCTRL_REGS_SIE_STATUS_ACK_REC)
-	sendUSBPacket(0, []byte{}, 0)
+	sendUSBPacket(0, []byte{})
 
 	// Wait for transfer to complete with a timeout.
 	t := timer.timeElapsed()

src/machine/machine_rp2350_usb.go

@@ -131,7 +131,7 @@ func handleUSBSetAddress(setup usb.Setup) bool {
 	const ackTimeout = 570
 
 	rp.USB.SIE_STATUS.Set(rp.USB_SIE_STATUS_ACK_REC)
-	sendUSBPacket(0, []byte{}, 0)
+	sendUSBPacket(0, []byte{})
 
 	// Wait for transfer to complete with a timeout.
 	t := timer.timeElapsed()

src/machine/machine_rp2_usb.go

@@ -72,19 +72,15 @@ func initEndpoint(ep, config uint32) {
 
 // SendUSBInPacket sends a packet for USB (interrupt in / bulk in).
 func SendUSBInPacket(ep uint32, data []byte) bool {
-	sendUSBPacket(ep, data, 0)
+	sendUSBPacket(ep, data)
 	return true
 }
 
 // Prevent file size increases: https://github.com/tinygo-org/tinygo/pull/998
 //
 //go:noinline
-func sendUSBPacket(ep uint32, data []byte, maxsize uint16) {
+func sendUSBPacket(ep uint32, data []byte) {
 	count := len(data)
-	if 0 < int(maxsize) && int(maxsize) < count {
-		count = int(maxsize)
-	}
-
 	if ep == 0 {
 		if count > usb.EndpointPacketSize {
 			count = usb.EndpointPacketSize
@@ -145,7 +141,7 @@ func setEPDataPID(ep uint32, dataOne bool) {
 }
 
 func SendZlp() {
-	sendUSBPacket(0, []byte{}, 0)
+	sendUSBPacket(0, []byte{})
 }
 
 func sendViaEPIn(ep uint32, data []byte, count int) {

src/machine/usb.go

@@ -81,21 +81,6 @@ func usbSerial() string {
 	return ""
 }
 
-// strToUTF16LEDescriptor converts a utf8 string into a string descriptor
-// note: the following code only converts ascii characters to UTF16LE. In order
-// to do a "proper" conversion, we would need to pull in the 'unicode/utf16'
-// package, which at the time this was written added 512 bytes to the compiled
-// binary.
-func strToUTF16LEDescriptor(in string, out []byte) {
-	out[0] = byte(len(out))
-	out[1] = descriptor.TypeString
-	for i, rune := range in {
-		out[(i<<1)+2] = byte(rune)
-		out[(i<<1)+3] = 0
-	}
-	return
-}
-
 const cdcLineInfoSize = 7
 
 var (
@@ -137,51 +122,53 @@ var (
 	usbStallHandler [NumberOfUSBEndpoints]func(usb.Setup) bool
 )
 
+var usbLangInfo = [4]byte{
+	// length = 4 bytes
+	0x04,
+	// descriptor type = string
+	0x03,
+	// language codes
+	// 0x0409 = English (United States)
+	0x09, 0x04,
+}
+
 // sendDescriptor creates and sends the various USB descriptor types that
 // can be requested by the host.
 func sendDescriptor(setup usb.Setup) {
 	switch setup.WValueH {
 	case descriptor.TypeConfiguration:
-		sendUSBPacket(0, usbDescriptor.Configuration, setup.WLength)
+		sendDescriptorData(usbDescriptor.Configuration, setup.WLength)
 		return
+
 	case descriptor.TypeDevice:
 		usbDescriptor.Configure(usbVendorID(), usbProductID())
-		sendUSBPacket(0, usbDescriptor.Device, setup.WLength)
+		sendDescriptorData(usbDescriptor.Device, setup.WLength)
 		return
 
 	case descriptor.TypeString:
 		switch setup.WValueL {
 		case 0:
-			usb_trans_buffer[0] = 0x04
+			sendDescriptorData(usbLangInfo[:], setup.WLength)
-			usb_trans_buffer[1] = 0x03
-			usb_trans_buffer[2] = 0x09
-			usb_trans_buffer[3] = 0x04
-			sendUSBPacket(0, usb_trans_buffer[:4], setup.WLength)
 
 		case usb.IPRODUCT:
-			b := usb_trans_buffer[:(len(usbProduct())<<1)+2]
+			sendDescriptorString(usbProduct(), setup.WLength)
-			strToUTF16LEDescriptor(usbProduct(), b)
-			sendUSBPacket(0, b, setup.WLength)
 
 		case usb.IMANUFACTURER:
-			b := usb_trans_buffer[:(len(usbManufacturer())<<1)+2]
+			sendDescriptorString(usbManufacturer(), setup.WLength)
-			strToUTF16LEDescriptor(usbManufacturer(), b)
-			sendUSBPacket(0, b, setup.WLength)
 
 		case usb.ISERIAL:
-			sz := len(usbSerial())
+			serial := usbSerial()
-			if sz == 0 {
+			if len(serial) == 0 {
 				SendZlp()
 			} else {
-				b := usb_trans_buffer[:(sz<<1)+2]
+				sendDescriptorString(serial, setup.WLength)
-				strToUTF16LEDescriptor(usbSerial(), b)
-				sendUSBPacket(0, b, setup.WLength)
 			}
 		}
+		// TODO: why do we do this when WValueL is unknown?
 		return
 	case descriptor.TypeHIDReport:
 		if h, ok := usbDescriptor.HID[setup.WIndex]; ok {
-			sendUSBPacket(0, h, setup.WLength)
+			sendDescriptorData(h, setup.WLength)
 			return
 		}
 	case descriptor.TypeDeviceQualifier:
@@ -194,6 +181,39 @@ func sendDescriptor(setup usb.Setup) {
 	return
 }
 
+// sendDescriptorString sends a string descriptor, truncating it to fit maxLen or the buffer size.
+// note: the following code only converts ascii characters to UTF16LE. In order
+// to do a "proper" conversion, we would need to pull in the 'unicode/utf16'
+// package, which at the time this was written added 512 bytes to the compiled
+// binary.
+// TODO: old comment, re-evaluate
+func sendDescriptorString(data string, maxLen uint16) {
+	if maxLen < 2 {
+		// Something has gone horribly wrong.
+		SendZlp()
+		return
+	}
+
+	// Clamp the length.
+	maxEncBytes := min(len(usb_trans_buffer), len(udd_ep_control_cache_buffer), int(maxLen))
+	data = data[:min(len(data), (maxEncBytes-2)/2)]
+
+	// Write the header.
+	buf := usb_trans_buffer[:2*len(data)+2]
+	hdr, body := buf[:2], buf[2:]
+	hdr[0] = byte(len(buf))
+	hdr[1] = descriptor.TypeString
+
+	// Convert the string to UTF16.
+	// NOTE: Using range here would cause the length to disagree when multibyte codepoints are present.
+	for i := 0; i < len(data); i++ {
+		body[2*i] = byte(data[i])
+		body[2*i+1] = 0
+	}
+
+	sendUSBPacket(0, buf)
+}
+
 func handleStandardSetup(setup usb.Setup) bool {
 	switch setup.BRequest {
 	case usb.GET_STATUS:
@@ -206,7 +226,7 @@ func handleStandardSetup(setup usb.Setup) bool {
 			}
 		}
 
-		sendUSBPacket(0, usb_trans_buffer[:2], setup.WLength)
+		sendDescriptorData(usb_trans_buffer[:2], setup.WLength)
 		return true
 
 	case usb.CLEAR_FEATURE:
@@ -251,7 +271,7 @@ func handleStandardSetup(setup usb.Setup) bool {
 
 	case usb.GET_CONFIGURATION:
 		usb_trans_buffer[0] = usbConfiguration
-		sendUSBPacket(0, usb_trans_buffer[:1], setup.WLength)
+		sendDescriptorData(usb_trans_buffer[:1], setup.WLength)
 		return true
 
 	case usb.SET_CONFIGURATION:
@@ -271,7 +291,7 @@ func handleStandardSetup(setup usb.Setup) bool {
 
 	case usb.GET_INTERFACE:
 		usb_trans_buffer[0] = usbSetInterface
-		sendUSBPacket(0, usb_trans_buffer[:1], setup.WLength)
+		sendDescriptorData(usb_trans_buffer[:1], setup.WLength)
 		return true
 
 	case usb.SET_INTERFACE:
@@ -285,6 +305,21 @@ func handleStandardSetup(setup usb.Setup) bool {
 	}
 }
 
+// sendDescriptorData sends a descriptor, truncating it to fit maxLen or the buffer size.
+func sendDescriptorData(data []byte, maxLen uint16) {
+	data = lenToCap(data)
+	data = data[:min(len(data), len(udd_ep_control_cache_buffer), int(maxLen))]
+	sendUSBPacket(0, data)
+}
+
+// Set the cap of the slice to the length.
+// This is safe, but cannot be proven by the compiler.
+//
+//go:nobounds
+func lenToCap(b []byte) []byte {
+	return b[:len(b):len(b)]
+}
+
 func EnableCDC(txHandler func(), rxHandler func([]byte), setupHandler func(usb.Setup) bool) {
 	if len(usbDescriptor.Device) == 0 {
 		usbDescriptor = descriptor.CDC

src/runtime/slice.go

@@ -3,19 +3,18 @@ package runtime
 // This file implements compiler builtins for slices: append() and copy().
 
 import (
-	"internal/gclayout"
 	"math/bits"
 	"unsafe"
 )
 
 // Builtin append(src, elements...) function: append elements to src and return
 // the modified (possibly expanded) slice.
-func sliceAppend(srcBuf, elemsBuf unsafe.Pointer, srcLen, srcCap, elemsLen, elemSize uintptr) (unsafe.Pointer, uintptr, uintptr) {
+func sliceAppend(srcBuf, elemsBuf unsafe.Pointer, srcLen, srcCap, elemsLen, elemSize uintptr, layout unsafe.Pointer) (unsafe.Pointer, uintptr, uintptr) {
 	newLen := srcLen + elemsLen
 	if elemsLen > 0 {
 		// Allocate a new slice with capacity for elemsLen more elements, if necessary;
 		// otherwise, reuse the passed slice.
-		srcBuf, _, srcCap = sliceGrow(srcBuf, srcLen, srcCap, newLen, elemSize)
+		srcBuf, _, srcCap = sliceGrow(srcBuf, srcLen, srcCap, newLen, elemSize, layout)
 
 		// Append the new elements in-place.
 		memmove(unsafe.Add(srcBuf, srcLen*elemSize), elemsBuf, elemsLen*elemSize)
@@ -36,7 +35,7 @@ func sliceCopy(dst, src unsafe.Pointer, dstLen, srcLen uintptr, elemSize uintptr
 }
 
 // sliceGrow returns a new slice with space for at least newCap elements
-func sliceGrow(oldBuf unsafe.Pointer, oldLen, oldCap, newCap, elemSize uintptr) (unsafe.Pointer, uintptr, uintptr) {
+func sliceGrow(oldBuf unsafe.Pointer, oldLen, oldCap, newCap, elemSize uintptr, layout unsafe.Pointer) (unsafe.Pointer, uintptr, uintptr) {
 	if oldCap >= newCap {
 		// No need to grow, return the input slice.
 		return oldBuf, oldLen, oldCap
@@ -48,12 +47,6 @@ func sliceGrow(oldBuf unsafe.Pointer, oldLen, oldCap, newCap, elemSize uintptr)
 	// memory allocators, this causes some difficult to debug issues.
 	newCap = 1 << bits.Len(uint(newCap))
 
-	var layout unsafe.Pointer
-	// less type info here; can only go off element size
-	if elemSize < unsafe.Sizeof(uintptr(0)) {
-		layout = gclayout.NoPtrs.AsPtr()
-	}
-
 	buf := alloc(newCap*elemSize, layout)
 	if oldLen > 0 {
 		// copy any data to new slice

testdata/corpus.yaml

@@ -190,6 +190,7 @@
   - pkg: tiff
 - repo: github.com/golang/geo
   subdirs:
+  - pkg: earth
   - pkg: r1
   - pkg: r2
   - pkg: r3
@@ -285,3 +286,6 @@
 - repo: github.com/julienschmidt/httprouter
 - repo: github.com/openhistogram/circonusllhist
   skipwasi: true #  math.MaxInt64 (untyped int constant 9223372036854775807) overflows int
+- repo: github.com/philhofer/fwd
+- repo: github.com/blevesearch/sear
+- repo: github.com/steveyen/gtreap