fix(emulate): refix emulate, let it works correct on unicorn-1.0.2rc1 ~ unicorn-1.0.2

pwndbg/disasm/__init__.py

@@ -218,6 +218,8 @@ def near(address, instructions=1, emulate=False, show_prev_insns=True):
     # If we hit the current instruction, we can do emulation going forward from there.
     if address == pc and emulate:
         emu = pwndbg.emu.emulator.Emulator()
+        # skip current line
+        emu.single_step()
 
     # Now find all of the instructions moving forward.
     #
@@ -225,8 +227,6 @@ def near(address, instructions=1, emulate=False, show_prev_insns=True):
     # and the instruction at 'address'.
     insn = current
     total_instructions = 1 + (2*instructions)
-    last_emu_target = None
-    target_candidate = address
 
     while insn and len(insns) < total_instructions:
         target = insn.target
@@ -239,14 +239,7 @@ def near(address, instructions=1, emulate=False, show_prev_insns=True):
         # If we initialized the emulator and emulation is still enabled, we can use it
         # to figure out the next instruction.
         if emu:
-            # For whatever reason, the first instruction is emulated twice on
-            # unicorn-1.0.2rc1~unicorn-1.0.2rc3, but not on >= unicorn-1.0.2rc4.
-            # If the address is equal with the last one, skip it
-            last_emu_target = target_candidate
-            while last_emu_target == target_candidate:
-                target_candidate, size_candidate = emu.single_step()
-                if not target_candidate:
-                    break
+            target_candidate, size_candidate = emu.single_step()
 
             if None not in (target_candidate, size_candidate):
                 target = target_candidate

pwndbg/emu/emulator.py

@@ -432,6 +432,7 @@ class Emulator:
         debug("# Single-stepping at %#x: %s %s" % (pc, insn.mnemonic, insn.op_str))
 
         try:
+            self.single_step_hook_hit_count = 0
             self.emulate_with_hook(self.single_step_hook_code, count=1)
         except U.unicorn.UcError as e:
             self._single_step = (None, None)
@@ -446,8 +447,13 @@ class Emulator:
             a = self.single_step(pc)
 
     def single_step_hook_code(self, _uc, address, instruction_size, _user_data):
-        debug("# single_step: %#-8x" % address)
-        self._single_step = (address, instruction_size)
+        # For whatever reason, the hook will hit twice on
+        # unicorn >= 1.0.2rc4, but not on unicorn-1.0.2rc1~unicorn-1.0.2rc3,
+        # So we use a counter to ensure the code run only once
+        if self.single_step_hook_hit_count == 0:
+            debug("# single_step: %#-8x" % address)
+            self._single_step = (address, instruction_size)
+            self.single_step_hook_hit_count += 1
 
     def dumpregs(self):
         for reg in list(self.regs.retaddr) + list(self.regs.misc) + list(self.regs.common) + list(self.regs.flags):