feature(telescope): option to set min repeating values before skipping

Buffer all repeating lines and check the minimum value when to start
marking them with skip lines. In case the minimum value is not hit, just
unroll the buffer.

To stop skipping any lines, there is the existing bool config
telescope-skip-repeat-val so we avoid adding special values to minimum
like -1 and keep the setting separated.

Fixes Gallopsled#803

pwndbg/commands/telescope.py

@@ -23,6 +23,8 @@
 telescope_lines = pwndbg.config.Parameter('telescope-lines', 8, 'number of lines to printed by the telescope command')
 skip_repeating_values = pwndbg.config.Parameter('telescope-skip-repeating-val', True,
                                                 'whether to skip repeating values of the telescope command')
+skip_repeating_values_minimum = pwndbg.config.Parameter('telescope-skip-repeating-val-minimum', 3,
+                                                        'minimum amount of repeated values before skipping lines')
 
 offset_separator = theme.Parameter('telescope-offset-separator', '│', 'offset separator of the telescope command')
 offset_delimiter = theme.Parameter('telescope-offset-delimiter', ':', 'offset delimiter of the telescope command')
@@ -94,28 +96,40 @@ def telescope(address=None, count=telescope_lines, to_string=False):
 
     # Print everything out
     result = []
-    last   = None
-    skip   = False
-    for i,addr in enumerate(range(start, stop, step)):
+    last = None
+    collapse_buffer = []
+
+    # Collapse repeating values exceeding minimum delta.
+    def collapse_repeating_values():
+        # The first line was already printed, hence increment by 1
+        if collapse_buffer and len(collapse_buffer) + 1 >= skip_repeating_values_minimum:
+            result.append(T.repeating_marker('%s' % repeating_marker))
+        else:
+            result.extend(collapse_buffer)
+        collapse_buffer.clear()
+
+    for i, addr in enumerate(range(start, stop, step)):
         if not pwndbg.memory.peek(addr):
+            collapse_repeating_values()
             result.append("<Could not read memory at %#x>" % addr)
             break
 
-        # Collapse repeating values.
-        value = pwndbg.memory.pvoid(addr)
-        if skip_repeating_values and last == value:
-            if not skip:
-                result.append(T.repeating_marker('%s' % repeating_marker))
-                skip = True
-            continue
-        last = value
-        skip = False
-
         line = ' '.join((T.offset("%02x%s%04x%s" % (i + telescope.offset, delimiter,
                                                     addr - start + (telescope.offset * ptrsize), separator)),
                          T.register(regs[addr].ljust(longest_regs)),
                          pwndbg.chain.format(addr)))
+
+        # Buffer repeating values.
+        if skip_repeating_values:
+            value = pwndbg.memory.pvoid(addr)
+            if last == value:
+                collapse_buffer.append(line)
+                continue
+            collapse_repeating_values()
+            last = value
+
         result.append(line)
+
     telescope.offset += i
     telescope.last_address = addr