delve/pkg/proc/interface.go
Alessandro Arzilli 1a9e38aa0c
proc,terminal: Implement reverse step, next and stepout (#1785)
* proc: move defer breakpoint code into a function

Moves the code that sets a breakpoint on the first deferred function,
used by both next and StepOut, to its function.

* proc: implement reverse step/next/stepout

When the direction of execution is reversed (on a recording) Step, Next and
StepOut will behave similarly to their forward version. However there are
some subtle interactions between their behavior, prologue skipping, deferred
calls and normal calls. Specifically:

- when stepping backwards we need to set a breakpoint on the first
  instruction after each CALL instruction, once this breakpoint is reached we
  need to execute a single StepInstruction operation to reverse step into the
  CALL.
- to insure that the prologue is skipped reverse next needs to check if it
  is on the first instruction after the prologue, and if it is behave like
  reverse stepout.
- there is no reason to set breakpoints on deferred calls when reverse
  nexting or reverse stepping out, they will never be hit.
- reverse step out should generally place its breakpoint on the CALL
  instruction that created the current stack frame (which will be the CALL
  instruction immediately preceding the instruction at the return address).
- reverse step out needs to treat panic calls and deferreturn calls
  specially.

* service,terminal: implement reverse step, next, stepout
2020-03-11 15:40:41 -07:00

112 lines
3.6 KiB
Go

package proc
import (
"go/ast"
)
// Process represents the target of the debugger. This
// target could be a system process, core file, etc.
//
// Implementations of Process are not required to be thread safe and users
// of Process should not assume they are.
// There is one exception to this rule: it is safe to call RequestManualStop
// concurrently with ContinueOnce.
type Process interface {
Info
ProcessManipulation
BreakpointManipulation
RecordingManipulation
}
// ProcessInternal holds a set of methods that are not meant to be called by
// anyone except for an instance of `proc.Target`. These methods are not
// safe to use by themselves and should never be called directly outside of
// the `proc` package.
// This is temporary and in support of an ongoing refactor.
type ProcessInternal interface {
SetCurrentThread(Thread)
// Restart restarts the recording from the specified position, or from the
// last checkpoint if pos == "".
// If pos starts with 'c' it's a checkpoint ID, otherwise it's an event
// number.
Restart(pos string) error
Detach(bool) error
ContinueOnce() (trapthread Thread, stopReason StopReason, err error)
}
// RecordingManipulation is an interface for manipulating process recordings.
type RecordingManipulation interface {
// Recorded returns true if the current process is a recording and the path
// to the trace directory.
Recorded() (recorded bool, tracedir string)
// Direction changes execution direction.
ChangeDirection(Direction) error
// GetDirection returns the current direction of execution.
GetDirection() Direction
// When returns current recording position.
When() (string, error)
// Checkpoint sets a checkpoint at the current position.
Checkpoint(where string) (id int, err error)
// Checkpoints returns the list of currently set checkpoint.
Checkpoints() ([]Checkpoint, error)
// ClearCheckpoint removes a checkpoint.
ClearCheckpoint(id int) error
}
// Direction is the direction of execution for the target process.
type Direction int8
const (
// Forward direction executes the target normally.
Forward Direction = 0
// Backward direction executes the target in reverse.
Backward Direction = 1
)
// Checkpoint is a checkpoint
type Checkpoint struct {
ID int
When string
Where string
}
// Info is an interface that provides general information on the target.
type Info interface {
Pid() int
// ResumeNotify specifies a channel that will be closed the next time
// ContinueOnce finishes resuming the target.
ResumeNotify(chan<- struct{})
// Valid returns true if this Process can be used. When it returns false it
// also returns an error describing why the Process is invalid (either
// ErrProcessExited or ProcessDetachedError).
Valid() (bool, error)
BinInfo() *BinaryInfo
EntryPoint() (uint64, error)
ThreadInfo
}
// ThreadInfo is an interface for getting information on active threads
// in the process.
type ThreadInfo interface {
FindThread(threadID int) (Thread, bool)
ThreadList() []Thread
CurrentThread() Thread
}
// ProcessManipulation is an interface for changing the execution state of a process.
type ProcessManipulation interface {
RequestManualStop() error
// CheckAndClearManualStopRequest returns true the first time it's called
// after a call to RequestManualStop.
CheckAndClearManualStopRequest() bool
}
// BreakpointManipulation is an interface for managing breakpoints.
type BreakpointManipulation interface {
Breakpoints() *BreakpointMap
SetBreakpoint(addr uint64, kind BreakpointKind, cond ast.Expr) (*Breakpoint, error)
ClearBreakpoint(addr uint64) (*Breakpoint, error)
ClearInternalBreakpoints() error
}