txscript: Remove unused parseScriptTemplate func.

Also remove tests associated with the func accordingly.

txscript/opcode.go

@@ -618,79 +618,6 @@ type parsedOpcode struct {
 	data   []byte
 }
 
-// checkParseableInScript checks whether or not the current opcode is able to be
-// parsed at a certain position in a script.
-// This returns the position of the next opcode to be parsed in the script.
-func (pop *parsedOpcode) checkParseableInScript(script []byte, scriptPos int) (int, error) {
-	// Parse data out of instruction.
-	switch {
-	// No additional data.  Note that some of the opcodes, notably
-	// OP_1NEGATE, OP_0, and OP_[1-16] represent the data
-	// themselves.
-	case pop.opcode.length == 1:
-		scriptPos++
-
-	// Data pushes of specific lengths -- OP_DATA_[1-75].
-	case pop.opcode.length > 1:
-		if len(script[scriptPos:]) < pop.opcode.length {
-			str := fmt.Sprintf("opcode %s requires %d "+
-				"bytes, but script only has %d remaining",
-				pop.opcode.name, pop.opcode.length, len(script[scriptPos:]))
-			return 0, scriptError(ErrMalformedPush, str)
-		}
-
-		// Slice out the data.
-		pop.data = script[scriptPos+1 : scriptPos+pop.opcode.length]
-		scriptPos += pop.opcode.length
-
-	// Data pushes with parsed lengths -- OP_PUSHDATAP{1,2,4}.
-	case pop.opcode.length < 0:
-		var l uint
-		off := scriptPos + 1
-
-		if len(script[off:]) < -pop.opcode.length {
-			str := fmt.Sprintf("opcode %s requires %d "+
-				"bytes, but script only has %d remaining",
-				pop.opcode.name, -pop.opcode.length, len(script[off:]))
-			return 0, scriptError(ErrMalformedPush, str)
-		}
-
-		// Next -length bytes are little endian length of data.
-		switch pop.opcode.length {
-		case -1:
-			l = uint(script[off])
-		case -2:
-			l = ((uint(script[off+1]) << 8) |
-				uint(script[off]))
-		case -4:
-			l = ((uint(script[off+3]) << 24) |
-				(uint(script[off+2]) << 16) |
-				(uint(script[off+1]) << 8) |
-				uint(script[off]))
-		default:
-			str := fmt.Sprintf("invalid opcode length %d",
-				pop.opcode.length)
-			return 0, scriptError(ErrMalformedPush, str)
-		}
-
-		// Move offset to beginning of the data.
-		off += -pop.opcode.length
-
-		// Disallow entries that do not fit script or were
-		// sign extended.
-		if int(l) > len(script[off:]) || int(l) < 0 {
-			str := fmt.Sprintf("opcode %s pushes %d bytes, "+
-				"but script only has %d remaining",
-				pop.opcode.name, int(l), len(script[off:]))
-			return 0, scriptError(ErrMalformedPush, str)
-		}
-
-		pop.data = script[off : off+int(l)]
-		scriptPos += 1 - pop.opcode.length + int(l)
-	}
-	return scriptPos, nil
-}
-
 // disasmOpcode writes a human-readable disassembly of the provided opcode and
 // data into the provided buffer.  The compact flag indicates the disassembly
 // should print a more compact representation of data-carrying and small integer

txscript/script.go

@@ -143,65 +143,6 @@ func IsPushOnlyScript(script []byte) bool {
 	return tokenizer.Err() == nil
 }
 
-// parseScriptTemplate is the same as parseScript but allows the passing of the
-// template list for testing purposes.  When there are parse errors, it returns
-// the list of parsed opcodes up to the point of failure along with the error.
-func parseScriptTemplate(script []byte, opcodes *[256]opcode) ([]parsedOpcode, error) {
-	retScript := make([]parsedOpcode, 0, len(script))
-	var err error
-	for i := 0; i < len(script); {
-		instr := script[i]
-		op := &opcodes[instr]
-		pop := parsedOpcode{opcode: op}
-		i, err = pop.checkParseableInScript(script, i)
-		if err != nil {
-			return retScript, err
-		}
-
-		retScript = append(retScript, pop)
-	}
-
-	return retScript, nil
-}
-
-// checkScriptTemplateParseable is the same as parseScriptTemplate but does not
-// return the list of opcodes up until the point of failure so that this can be
-// used in functions which do not necessarily have a need for the failed list of
-// opcodes, such as IsUnspendable.
-//
-// This function returns a pointer to a byte. This byte is nil if the parsing
-// has an error, or if the script length is zero. If the script length is not
-// zero and parsing succeeds, then the first opcode parsed will be returned.
-//
-// Not returning the full opcode list up until failure also has the benefit of
-// reducing GC pressure, as the list would get immediately thrown away.
-func checkScriptTemplateParseable(script []byte, opcodes *[256]opcode) (*byte, error) {
-	var err error
-
-	// A script of length zero is an unspendable script but it is parseable.
-	var firstOpcode byte
-	var numParsedInstr uint = 0
-
-	for i := 0; i < len(script); {
-		instr := script[i]
-		op := &opcodes[instr]
-		pop := parsedOpcode{opcode: op}
-		i, err = pop.checkParseableInScript(script, i)
-		if err != nil {
-			return nil, err
-		}
-
-		// if this is a op_return then it is unspendable so we set the first
-		// parsed instruction in case it's an op_return
-		if numParsedInstr == 0 {
-			firstOpcode = pop.opcode.value
-		}
-		numParsedInstr++
-	}
-
-	return &firstOpcode, nil
-}
-
 // DisasmString formats a disassembled script for one line printing.  When the
 // script fails to parse, the returned string will contain the disassembled
 // script up to the point the failure occurred along with the string '[error]'

txscript/script_test.go

@@ -12,22 +12,6 @@ import (
 	"github.com/btcsuite/btcd/wire"
 )
 
-// TestParseOpcode tests for opcode parsing with bad data templates.
-func TestParseOpcode(t *testing.T) {
-	// Deep copy the array and make one of the opcodes invalid by setting it
-	// to the wrong length.
-	fakeArray := opcodeArray
-	fakeArray[OP_PUSHDATA4] = opcode{value: OP_PUSHDATA4,
-		name: "OP_PUSHDATA4", length: -8, opfunc: opcodePushData}
-
-	// This script would be fine if -8 was a valid length.
-	_, err := parseScriptTemplate([]byte{OP_PUSHDATA4, 0x1, 0x00, 0x00,
-		0x00, 0x00, 0x00, 0x00, 0x00}, &fakeArray)
-	if err == nil {
-		t.Errorf("no error with dodgy opcode array!")
-	}
-}
-
 // TestPushedData ensured the PushedData function extracts the expected data out
 // of various scripts.
 func TestPushedData(t *testing.T) {