Dumpargs add --force to show all possible register arguments (#326)

* Added --all flag to dumpargs command

This gives possibility to dump all register argument even
if we failed to resolve arguments from metadatas.

* Display info when dumpargs not resolved call args

* Dumpargs: changed --all to --force

* Revert telescope changes as it fails when we are not on call instruction.

* Fix isort

pwndbg/arguments.py

@@ -52,8 +52,9 @@ ida_replacements = {
     '__userpurge': '',
 }
 
+
 def get_syscall_name(instruction):
-    if not CS_GRP_INT in instruction.groups:
+    if CS_GRP_INT not in instruction.groups:
         return None
 
     try:
@@ -65,6 +66,7 @@ def get_syscall_name(instruction):
     except:
         return None
 
+
 def get(instruction):
     """
     Returns an array containing the arguments to the current function,
@@ -109,7 +111,6 @@ def get(instruction):
         return []
 
     result = []
-    args = []
     name = name or ''
 
     sym   = gdb.lookup_symbol(name)
@@ -128,7 +129,6 @@ def get(instruction):
         except TypeError:
             pass
 
-
     # Try to grab the data out of IDA
     if not func and target:
         typename = pwndbg.ida.GetType(target)
@@ -139,17 +139,17 @@ def get(instruction):
             # GetType() does not include the name.
             typename = typename.replace('(', ' function_name(', 1)
 
-            for k,v in ida_replacements.items():
-                typename = typename.replace(k,v)
+            for k, v in ida_replacements.items():
+                typename = typename.replace(k, v)
 
-            func     = pwndbg.funcparser.ExtractFuncDeclFromSource(typename + ';')
+            func = pwndbg.funcparser.ExtractFuncDeclFromSource(typename + ';')
 
     if func:
         args = func.args
     else:
-        args = [pwndbg.functions.Argument('int',0,argname(i, abi)) for i in range(n_args_default)]
+        args = [pwndbg.functions.Argument('int', 0, argname(i, abi)) for i in range(n_args_default)]
 
-    for i,arg in enumerate(args):
+    for i, arg in enumerate(args):
         result.append((arg, argument(i, abi)))
 
     return result
@@ -164,6 +164,7 @@ def argname(n, abi=None):
 
     return 'arg[%i]' % n
 
+
 def argument(n, abi=None):
     """
     Returns the nth argument, as if $pc were a 'call' or 'bl' type
@@ -180,3 +181,14 @@ def argument(n, abi=None):
     sp = pwndbg.regs.sp + (n * pwndbg.arch.ptrsize)
 
     return int(pwndbg.memory.poi(pwndbg.typeinfo.ppvoid, sp))
+
+
+def arguments(abi=None):
+    """
+    Yields (arg_name, arg_value) tuples for arguments from a given ABI.
+    """
+    abi  = abi or pwndbg.abi.ABI.default()
+    regs = abi.register_arguments
+
+    for i in range(len(regs)):
+        yield argname(i, abi), argument(i, abi)

pwndbg/commands/dumpargs.py

@@ -5,24 +5,60 @@ from __future__ import division
 from __future__ import print_function
 from __future__ import unicode_literals
 
+import argparse
+
 import pwndbg.arguments
+import pwndbg.chain
 import pwndbg.commands
+import pwndbg.commands.telescope
 import pwndbg.disasm
 
+parser = argparse.ArgumentParser(
+    description='Prints determined arguments for call instruction. Pass --all to see all possible arguments.'
+)
+parser.add_argument('--force', action='store_true', help='Force displaying of all arguments.')
+
 
-@pwndbg.commands.Command
+@pwndbg.commands.ArgparsedCommand(parser)
 @pwndbg.commands.OnlyWhenRunning
-def dumpargs(*a):
+def dumpargs(force=False):
+    force_text = "Use `%s --force` to force the display." % dumpargs.__name__
+
+    if not pwndbg.disasm.is_call() and not force:
+        print("Cannot dump args as current instruction is not a call.\n" + force_text)
+        return
+
+    args = all_args() if force else call_args()
+
+    if args:
+        print('\n'.join(args))
+    else:
+        print("Couldn't resolve call arguments. Maybe the function doesn\'t take any?\n" + force_text)
+
+
+def call_args():
     """
-    If the current instruction is a call instruction, print that arguments.
+    Returns list of resolved call argument strings for display.
+    Attempts to resolve the target and determine the number of arguments.
+    Should be used only when being on a call instruction.
     """
-    result = []
+    results = []
 
-    # For call instructions, attempt to resolve the target and
-    # determine the number of arguments.
     for arg, value in pwndbg.arguments.get(pwndbg.disasm.one()):
         code   = False if arg.type == 'char' else True
         pretty = pwndbg.chain.format(value, code=code)
-        result.append('%8s%-10s %s' % ('',arg.name+':', pretty))
+        results.append('        %-10s %s' % (arg.name+':', pretty))
+
+    return results
+
+
+def all_args():
+    """
+    Returns list of all argument strings for display.
+    """
+    results = []
+
+    for name, value in pwndbg.arguments.arguments():
+        results.append('%4s = %s' % (name, pwndbg.chain.format(value)))
 
-    print('\n'.join(result))
+    return results

pwndbg/disasm/__init__.py

@@ -235,3 +235,10 @@ def near(address, instructions=1, emulate=False):
         del insns[-1]
 
     return insns
+
+
+def is_call(address=None):
+    """
+    Returns whether a given address contains call instruction.
+    """
+    return capstone.CS_GRP_CALL in one(address).groups