Prefer errors.New for unformatted errors

command/command.go

@@ -4,6 +4,7 @@ package command
 
 import (
 	"bufio"
+	"errors"
 	"fmt"
 	"io"
 	"os"
@@ -103,7 +104,7 @@ func CommandFunc(fn func() error) cmdfunc {
 }
 
 func noCmdAvailable(p *proctl.DebuggedProcess, args ...string) error {
-	return fmt.Errorf("command not available")
+	return errors.New("command not available")
 }
 
 func nullCommand(p *proctl.DebuggedProcess, args ...string) error {
@@ -140,7 +141,7 @@ func threads(p *proctl.DebuggedProcess, args ...string) error {
 
 func thread(p *proctl.DebuggedProcess, args ...string) error {
 	if len(args) == 0 {
-		return fmt.Errorf("you must specify a thread")
+		return errors.New("you must specify a thread")
 	}
 	oldTid := p.CurrentThread.Id
 	tid, err := strconv.Atoi(args[0])
@@ -204,7 +205,7 @@ func next(p *proctl.DebuggedProcess, args ...string) error {
 
 func clear(p *proctl.DebuggedProcess, args ...string) error {
 	if len(args) == 0 {
-		return fmt.Errorf("not enough arguments")
+		return errors.New("not enough arguments")
 	}
 
 	bp, err := p.ClearByLocation(args[0])
@@ -250,7 +251,7 @@ func breakpoints(p *proctl.DebuggedProcess, args ...string) error {
 
 func breakpoint(p *proctl.DebuggedProcess, args ...string) error {
 	if len(args) == 0 {
-		return fmt.Errorf("not enough arguments")
+		return errors.New("not enough arguments")
 	}
 
 	bp, err := p.BreakByLocation(args[0])
@@ -265,7 +266,7 @@ func breakpoint(p *proctl.DebuggedProcess, args ...string) error {
 
 func printVar(p *proctl.DebuggedProcess, args ...string) error {
 	if len(args) == 0 {
-		return fmt.Errorf("not enough arguments")
+		return errors.New("not enough arguments")
 	}
 
 	val, err := p.EvalSymbol(args[0])
@@ -292,7 +293,7 @@ func filterVariables(vars []*proctl.Variable, filter *regexp.Regexp) []string {
 
 func info(p *proctl.DebuggedProcess, args ...string) error {
 	if len(args) == 0 {
-		return fmt.Errorf("not enough arguments. expected info type [regex].")
+		return errors.New("not enough arguments. expected info type [regex].")
 	}
 
 	// Allow for optional regex
@@ -345,7 +346,7 @@ func info(p *proctl.DebuggedProcess, args ...string) error {
 		data = filterVariables(vars, filter)
 
 	default:
-		return fmt.Errorf("unsupported info type, must be args, funcs, locals, sources, or vars")
+		return errors.New("unsupported info type, must be args, funcs, locals, sources, or vars")
 	}
 
 	// sort and output data

dwarf/reader/reader.go

@@ -2,7 +2,7 @@ package reader
 
 import (
 	"debug/dwarf"
-	"fmt"
+	"errors"
 )
 
 type Reader struct {
@@ -57,7 +57,7 @@ func (reader *Reader) SeekToFunction(pc uint64) (*dwarf.Entry, error) {
 		}
 	}
 
-	return nil, fmt.Errorf("unable to find function context")
+	return nil, errors.New("unable to find function context")
 }
 
 // SeekToType moves the reader to the type specified by the entry,
@@ -66,7 +66,7 @@ func (reader *Reader) SeekToFunction(pc uint64) (*dwarf.Entry, error) {
 func (reader *Reader) SeekToType(entry *dwarf.Entry, resolveTypedefs bool, resolvePointerTypes bool) (*dwarf.Entry, error) {
 	offset, ok := entry.Val(dwarf.AttrType).(dwarf.Offset)
 	if !ok {
-		return nil, fmt.Errorf("entry does not have a type attribute")
+		return nil, errors.New("entry does not have a type attribute")
 	}
 
 	// Seek to the first type offset
@@ -94,7 +94,7 @@ func (reader *Reader) SeekToType(entry *dwarf.Entry, resolveTypedefs bool, resol
 		reader.Seek(offset)
 	}
 
-	return nil, fmt.Errorf("no type entry found")
+	return nil, errors.New("no type entry found")
 }
 
 // NextScopeVariable moves the reader to the next debug entry that describes a local variable and returns the entry.

proctl/breakpoints_darwin_amd64.go

 package proctl
 
-import "fmt"
+import "errors"
 
 // TODO(darwin)
 func setHardwareBreakpoint(reg, tid int, addr uint64) error {
-	return fmt.Errorf("not implemented on darwin")
+	return errors.New("not implemented on darwin")
 }
 
 // TODO(darwin)
 func clearHardwareBreakpoint(reg, tid int) error {
-	return fmt.Errorf("not implemented on darwin")
+	return errors.New("not implemented on darwin")
 }

proctl/breakpoints_linux_amd64.go

@@ -15,7 +15,10 @@ int offset(int reg) {
 */
 import "C"
 
-import "fmt"
+import (
+	"errors"
+	"fmt"
+)
 
 // Sets a hardware breakpoint by setting the contents of the
 // debug register `reg` with the address of the instruction
@@ -23,7 +26,7 @@ import "fmt"
 // DR0-DR3. Debug register 7 is the control register.
 func setHardwareBreakpoint(reg, tid int, addr uint64) error {
 	if reg < 0 || reg > 3 {
-		return fmt.Errorf("invalid debug register value")
+		return errors.New("invalid debug register value")
 	}
 
 	var (

proctl/proctl.go

@@ -4,6 +4,7 @@ import (
 	"debug/dwarf"
 	"debug/gosym"
 	"encoding/binary"
+	"errors"
 	"fmt"
 	"os"
 	"path/filepath"
@@ -582,7 +583,7 @@ func (dbp *DebuggedProcess) handleBreakpointOnThread(id int) (*ThreadContext, er
 
 func (dbp *DebuggedProcess) run(fn func() error) error {
 	if dbp.exited {
-		return fmt.Errorf("process has already exited")
+		return errors.New("process has already exited")
 	}
 	dbp.running = true
 	dbp.halt = false

proctl/proctl_darwin.go

@@ -6,6 +6,7 @@ import "C"
 import (
 	"debug/gosym"
 	"debug/macho"
+	"errors"
 	"fmt"
 	"os"
 	"path/filepath"
@@ -49,7 +50,7 @@ func Launch(cmd []string) (*DebuggedProcess, error) {
 
 	pid := int(C.fork_exec(C.CString(argv0), &argv, &dbp.os.task, &dbp.os.portSet, &dbp.os.exceptionPort, &dbp.os.notificationPort))
 	if pid <= 0 {
-		return nil, fmt.Errorf("could not fork/exec")
+		return nil, errors.New("could not fork/exec")
 	}
 	dbp.Pid = pid
 
@@ -69,7 +70,7 @@ func (dbp *DebuggedProcess) requestManualStop() (err error) {
 	)
 	kret := C.raise_exception(task, thread, exceptionPort, C.EXC_BREAKPOINT)
 	if kret != C.KERN_SUCCESS {
-		return fmt.Errorf("could not raise mach exception")
+		return errors.New("could not raise mach exception")
 	}
 	return nil
 }
@@ -81,7 +82,7 @@ func (dbp *DebuggedProcess) updateThreadList() error {
 		count = C.thread_count(C.task_t(dbp.os.task))
 	)
 	if count == -1 {
-		return fmt.Errorf("could not get thread count")
+		return errors.New("could not get thread count")
 	}
 	list := make([]uint32, count)
 
@@ -89,10 +90,10 @@ func (dbp *DebuggedProcess) updateThreadList() error {
 	// instead of getting count above and passing in a slice
 	kret = C.get_threads(C.task_t(dbp.os.task), unsafe.Pointer(&list[0]))
 	if kret != C.KERN_SUCCESS {
-		return fmt.Errorf("could not get thread list")
+		return errors.New("could not get thread list")
 	}
 	if count < 0 {
-		return fmt.Errorf("could not get thread list")
+		return errors.New("could not get thread list")
 	}
 
 	for _, port := range list {
@@ -232,7 +233,7 @@ func (dbp *DebuggedProcess) trapWait(pid int) (*ThreadContext, error) {
 			}
 			return nil, ManualStopError{}
 		case 0:
-			return nil, fmt.Errorf("error while waiting for task")
+			return nil, errors.New("error while waiting for task")
 		}
 
 		// Since we cannot be notified of new threads on OS X

proctl/registers_darwin_amd64.go

@@ -2,7 +2,7 @@ package proctl
 
 // #include "threads_darwin.h"
 import "C"
-import "fmt"
+import "errors"
 
 type Regs struct {
 	pc, sp uint64
@@ -19,7 +19,7 @@ func (r *Regs) SP() uint64 {
 func (r *Regs) SetPC(thread *ThreadContext, pc uint64) error {
 	kret := C.set_pc(thread.os.thread_act, C.uint64_t(pc))
 	if kret != C.KERN_SUCCESS {
-		return fmt.Errorf("could not set pc")
+		return errors.New("could not set pc")
 	}
 	return nil
 }
@@ -28,7 +28,7 @@ func registers(thread *ThreadContext) (Registers, error) {
 	var state C.x86_thread_state64_t
 	kret := C.get_registers(C.mach_port_name_t(thread.os.thread_act), &state)
 	if kret != C.KERN_SUCCESS {
-		return nil, fmt.Errorf("could not get registers")
+		return nil, errors.New("could not get registers")
 	}
 	regs := &Regs{pc: uint64(state.__rip), sp: uint64(state.__rsp)}
 	return regs, nil

proctl/threads_darwin.go

@@ -3,6 +3,7 @@ package proctl
 // #include "threads_darwin.h"
 import "C"
 import (
+	"errors"
 	"fmt"
 	"unsafe"
 )
@@ -24,12 +25,12 @@ func (t *ThreadContext) Halt() error {
 func (t *ThreadContext) singleStep() error {
 	kret := C.single_step(t.os.thread_act)
 	if kret != C.KERN_SUCCESS {
-		return fmt.Errorf("could not single step")
+		return errors.New("could not single step")
 	}
 	t.Process.trapWait(0)
 	kret = C.clear_trap_flag(t.os.thread_act)
 	if kret != C.KERN_SUCCESS {
-		return fmt.Errorf("could not clear CPU trap flag")
+		return errors.New("could not clear CPU trap flag")
 	}
 	return nil
 }
@@ -41,7 +42,7 @@ func (t *ThreadContext) resume() error {
 	}
 	kret := C.resume_thread(t.os.thread_act)
 	if kret != C.KERN_SUCCESS {
-		return fmt.Errorf("could not continue thread")
+		return errors.New("could not continue thread")
 	}
 	return nil
 }
@@ -64,7 +65,7 @@ func writeMemory(thread *ThreadContext, addr uintptr, data []byte) (int, error)
 	)
 
 	if ret := C.write_memory(thread.Process.os.task, vm_addr, vm_data, length); ret < 0 {
-		return 0, fmt.Errorf("could not write memory")
+		return 0, errors.New("could not write memory")
 	}
 	return len(data), nil
 }
@@ -78,7 +79,7 @@ func readMemory(thread *ThreadContext, addr uintptr, data []byte) (int, error) {
 
 	ret := C.read_memory(thread.Process.os.task, vm_addr, vm_data, length)
 	if ret < 0 {
-		return 0, fmt.Errorf("could not read memory")
+		return 0, errors.New("could not read memory")
 	}
 	return len(data), nil
 }
@@ -86,7 +87,7 @@ func readMemory(thread *ThreadContext, addr uintptr, data []byte) (int, error) {
 func (thread *ThreadContext) saveRegisters() (Registers, error) {
 	kret := C.get_registers(C.mach_port_name_t(thread.os.thread_act), &thread.os.registers)
 	if kret != C.KERN_SUCCESS {
-		return nil, fmt.Errorf("could not save register contents")
+		return nil, errors.New("could not save register contents")
 	}
 	return &Regs{pc: uint64(thread.os.registers.__rip), sp: uint64(thread.os.registers.__rsp)}, nil
 }
@@ -94,7 +95,7 @@ func (thread *ThreadContext) saveRegisters() (Registers, error) {
 func (thread *ThreadContext) restoreRegisters() error {
 	kret := C.set_registers(C.mach_port_name_t(thread.os.thread_act), &thread.os.registers)
 	if kret != C.KERN_SUCCESS {
-		return fmt.Errorf("could not save register contents")
+		return errors.New("could not save register contents")
 	}
 	return nil
 }

proctl/threads_linux.go

 package proctl
 
 import (
+	"errors"
 	"fmt"
 
 	sys "golang.org/x/sys/unix"
@@ -52,7 +53,7 @@ func (t *ThreadContext) blocked() bool {
 
 func (thread *ThreadContext) saveRegisters() (Registers, error) {
 	if err := sys.PtraceGetRegs(thread.Id, &thread.os.registers); err != nil {
-		return nil, fmt.Errorf("could not save register contents")
+		return nil, errors.New("could not save register contents")
 	}
 	return &Regs{&thread.os.registers}, nil
 }

proctl/variables.go

@@ -5,6 +5,7 @@ import (
 	"debug/dwarf"
 	"debug/gosym"
 	"encoding/binary"
+	"errors"
 	"fmt"
 	"strconv"
 	"strings"
@@ -83,7 +84,7 @@ func (thread *ThreadContext) AllM() ([]*M, error) {
 	}
 	m := binary.LittleEndian.Uint64(mptr)
 	if m == 0 {
-		return nil, fmt.Errorf("allm contains no M pointers")
+		return nil, errors.New("allm contains no M pointers")
 	}
 
 	procidInstructions, err := instructionsFor("procid", thread.Process, reader, true)
@@ -190,7 +191,7 @@ func instructionsForEntry(entry *dwarf.Entry) ([]byte, error) {
 	if entry.Tag == dwarf.TagMember {
 		instructions, ok := entry.Val(dwarf.AttrDataMemberLoc).([]byte)
 		if !ok {
-			return nil, fmt.Errorf("member data has no data member location attribute")
+			return nil, errors.New("member data has no data member location attribute")
 		}
 		// clone slice to prevent stomping on the dwarf data
 		return append([]byte{}, instructions...), nil
@@ -199,7 +200,7 @@ func instructionsForEntry(entry *dwarf.Entry) ([]byte, error) {
 	// non-member
 	instructions, ok := entry.Val(dwarf.AttrLocation).([]byte)
 	if !ok {
-		return nil, fmt.Errorf("entry has no location attribute")
+		return nil, errors.New("entry has no location attribute")
 	}
 
 	// clone slice to prevent stomping on the dwarf data
@@ -224,7 +225,7 @@ func parseAllMPtr(dbp *DebuggedProcess, reader *dwarf.Reader) (uint64, error) {
 
 	instructions, ok := entry.Val(dwarf.AttrLocation).([]byte)
 	if !ok {
-		return 0, fmt.Errorf("type assertion failed")
+		return 0, errors.New("type assertion failed")
 	}
 	addr, err := op.ExecuteStackProgram(0, instructions)
 	if err != nil {
@@ -320,7 +321,7 @@ func allglenval(dbp *DebuggedProcess, reader *dwarf.Reader) (uint64, error) {
 
 	instructions, ok := entry.Val(dwarf.AttrLocation).([]byte)
 	if !ok {
-		return 0, fmt.Errorf("type assertion failed")
+		return 0, errors.New("type assertion failed")
 	}
 	addr, err := op.ExecuteStackProgram(0, instructions)
 	if err != nil {
@@ -341,7 +342,7 @@ func addressFor(dbp *DebuggedProcess, name string, reader *dwarf.Reader) (uint64
 
 	instructions, ok := entry.Val(dwarf.AttrLocation).([]byte)
 	if !ok {
-		return 0, fmt.Errorf("type assertion failed")
+		return 0, errors.New("type assertion failed")
 	}
 	addr, err := op.ExecuteStackProgram(0, instructions)
 	if err != nil {
@@ -358,7 +359,7 @@ func offsetFor(name string, reader *dwarf.Reader, parentinstr []byte) (uint64, e
 	}
 	instructions, ok := entry.Val(dwarf.AttrDataMemberLoc).([]byte)
 	if !ok {
-		return 0, fmt.Errorf("type assertion failed")
+		return 0, errors.New("type assertion failed")
 	}
 	offset, err := op.ExecuteStackProgram(0, append(parentinstr, instructions...))
 	if err != nil {
@@ -489,7 +490,7 @@ func (thread *ThreadContext) evaluateStructMember(parentEntry *dwarf.Entry, read
 	// Get parent variable name
 	parentName, ok := parentEntry.Val(dwarf.AttrName).(string)
 	if !ok {
-		return nil, fmt.Errorf("unable to retrive variable name")
+		return nil, errors.New("unable to retrive variable name")
 	}
 
 	// Seek reader to the type information so members can be iterated
@@ -522,7 +523,7 @@ func (thread *ThreadContext) evaluateStructMember(parentEntry *dwarf.Entry, read
 
 			offset, ok := memberEntry.Val(dwarf.AttrType).(dwarf.Offset)
 			if !ok {
-				return nil, fmt.Errorf("type assertion failed")
+				return nil, errors.New("type assertion failed")
 			}
 
 			data := thread.Process.dwarf
@@ -549,7 +550,7 @@ func (thread *ThreadContext) evaluateStructMember(parentEntry *dwarf.Entry, read
 // Extracts the name, type, and value of a variable from a dwarf entry
 func (thread *ThreadContext) extractVariableFromEntry(entry *dwarf.Entry) (*Variable, error) {
 	if entry == nil {
-		return nil, fmt.Errorf("invalid entry")
+		return nil, errors.New("invalid entry")
 	}
 
 	if entry.Tag != dwarf.TagFormalParameter && entry.Tag != dwarf.TagVariable {
@@ -558,12 +559,12 @@ func (thread *ThreadContext) extractVariableFromEntry(entry *dwarf.Entry) (*Vari
 
 	n, ok := entry.Val(dwarf.AttrName).(string)
 	if !ok {
-		return nil, fmt.Errorf("type assertion failed")
+		return nil, errors.New("type assertion failed")
 	}
 
 	offset, ok := entry.Val(dwarf.AttrType).(dwarf.Offset)
 	if !ok {
-		return nil, fmt.Errorf("type assertion failed")
+		return nil, errors.New("type assertion failed")
 	}
 
 	data := thread.Process.dwarf
@@ -574,7 +575,7 @@ func (thread *ThreadContext) extractVariableFromEntry(entry *dwarf.Entry) (*Vari
 
 	instructions, ok := entry.Val(dwarf.AttrLocation).([]byte)
 	if !ok {
-		return nil, fmt.Errorf("type assertion failed")
+		return nil, errors.New("type assertion failed")
 	}
 
 	val, err := thread.extractValue(instructions, 0, t, true)
@@ -910,7 +911,7 @@ func (thread *ThreadContext) readFloat(addr uintptr, size int64) (string, error)
 		return strconv.FormatFloat(n, 'f', -1, int(size)*8), nil
 	}
 
-	return "", fmt.Errorf("could not read float")
+	return "", errors.New("could not read float")
 }
 
 func (thread *ThreadContext) readBool(addr uintptr) (string, error) {
@@ -953,7 +954,7 @@ func (thread *ThreadContext) readFunctionPtr(addr uintptr) (string, error) {
 
 	n, ok := entry.Val(dwarf.AttrName).(string)
 	if !ok {
-		return "", fmt.Errorf("Unable to retrieve function name")
+		return "", errors.New("Unable to retrieve function name")
 	}
 
 	return n, nil

service/debugger/debugger.go

 package debugger
 
 import (
+	"errors"
 	"fmt"
 	"log"
 	"regexp"
@@ -65,7 +66,7 @@ func New(config *Config) *Debugger {
 // operation.
 func (d *Debugger) withProcess(f func(*proctl.DebuggedProcess) error) error {
 	if !d.running {
-		return fmt.Errorf("debugger isn't running")
+		return errors.New("debugger isn't running")
 	}
 
 	result := make(chan error)
@@ -161,7 +162,7 @@ func (d *Debugger) Run() error {
 // Detach stops the debugger.
 func (d *Debugger) Detach(kill bool) error {
 	if !d.running {
-		return fmt.Errorf("debugger isn't running")
+		return errors.New("debugger isn't running")
 	}
 
 	d.stop <- stopSignal{KillProcess: kill}
@@ -205,7 +206,7 @@ func (d *Debugger) CreateBreakPoint(requestedBp *api.BreakPoint) (*api.BreakPoin
 		case len(requestedBp.FunctionName) > 0:
 			loc = requestedBp.FunctionName
 		default:
-			return fmt.Errorf("no file or function name specified")
+			return errors.New("no file or function name specified")
 		}
 
 		bp, breakError := p.BreakByLocation(loc)

terminal/command.go

@@ -4,6 +4,7 @@ package terminal
 
 import (
 	"bufio"
+	"errors"
 	"fmt"
 	"io"
 	"os"
@@ -106,7 +107,7 @@ func CommandFunc(fn func() error) cmdfunc {
 }
 
 func noCmdAvailable(client service.Client, args ...string) error {
-	return fmt.Errorf("command not available")
+	return errors.New("command not available")
 }
 
 func nullCommand(client service.Client, args ...string) error {
@@ -220,7 +221,7 @@ func next(client service.Client, args ...string) error {
 
 func clear(client service.Client, args ...string) error {
 	if len(args) == 0 {
-		return fmt.Errorf("not enough arguments")
+		return errors.New("not enough arguments")
 	}
 
 	id, err := strconv.Atoi(args[0])
@@ -272,7 +273,7 @@ func breakpoints(client service.Client, args ...string) error {
 
 func breakpoint(client service.Client, args ...string) error {
 	if len(args) != 1 {
-		return fmt.Errorf("argument must be either a function name or <file:line>")
+		return errors.New("argument must be either a function name or <file:line>")
 	}
 	requestedBp := &api.BreakPoint{}
 	tokens := strings.Split(args[0], ":")
@@ -288,7 +289,7 @@ func breakpoint(client service.Client, args ...string) error {
 		requestedBp.File = file
 		requestedBp.Line = line
 	default:
-		return fmt.Errorf("invalid line reference")
+		return errors.New("invalid line reference")
 	}
 
 	bp, err := client.CreateBreakPoint(requestedBp)
@@ -302,7 +303,7 @@ func breakpoint(client service.Client, args ...string) error {
 
 func printVar(client service.Client, args ...string) error {
 	if len(args) == 0 {
-		return fmt.Errorf("not enough arguments")
+		return errors.New("not enough arguments")
 	}
 
 	val, err := client.EvalSymbol(args[0])
@@ -326,7 +327,7 @@ func filterVariables(vars []api.Variable, filter *regexp.Regexp) []string {
 
 func info(client service.Client, args ...string) error {
 	if len(args) == 0 {
-		return fmt.Errorf("not enough arguments. expected info type [regex].")
+		return errors.New("not enough arguments. expected info type [regex].")
 	}
 
 	// Allow for optional regex
@@ -397,7 +398,7 @@ func info(client service.Client, args ...string) error {
 		}
 
 	default:
-		return fmt.Errorf("unsupported info type, must be args, funcs, locals, sources, or vars")
+		return errors.New("unsupported info type, must be args, funcs, locals, sources, or vars")
 	}
 
 	// sort and output data

terminal/command_test.go

 package terminal
 
 import (
-	"fmt"
+	"errors"
 	"testing"
 
 	"github.com/derekparker/delve/service"
@@ -25,7 +25,7 @@ func TestCommandDefault(t *testing.T) {
 
 func TestCommandReplay(t *testing.T) {
 	cmds := DebugCommands(nil)
-	cmds.Register("foo", func(client service.Client, args ...string) error { return fmt.Errorf("registered command") }, "foo command")
+	cmds.Register("foo", func(client service.Client, args ...string) error { return errors.New("registered command") }, "foo command")
 	cmd := cmds.Find("foo")
 
 	err := cmd(nil)

terminal/terminal.go

 package terminal
 
 import (
+	"errors"
 	"fmt"
 	"io"
 	"os"
@@ -62,7 +63,7 @@ func (t *Term) Run() (error, int) {
 			if err == io.EOF {
 				err, status = handleExit(t.client, t)
 			}
-			err, status = fmt.Errorf("Prompt for input failed.\n"), 1
+			err, status = errors.New("Prompt for input failed.\n"), 1
 			break
 		}