Prefer relative paths for vmmap output (#2822)

* prefer relpath in vmmap

* add configuration to turn off relative paths

* Add vmmap_prefer_relpaths to vmmap legend

* address some nits

* explain rel.startswith("../..")

* fix uitests

pwndbg/aglib/vmmap.py

@@ -7,6 +7,13 @@ import pwndbg.aglib.vmmap_custom
 import pwndbg.lib.cache
 import pwndbg.lib.memory
 
+pwndbg.config.add_param(
+    "vmmap-prefer-relpaths",
+    True,
+    "show relative paths by default in vmmap",
+    param_class=pwndbg.lib.config.PARAM_BOOLEAN,
+)
+
 
 @pwndbg.lib.cache.cache_until("start", "stop")
 def get() -> Tuple[pwndbg.lib.memory.Page, ...]:

pwndbg/commands/vmmap.py

@@ -46,8 +46,11 @@ def print_vmmap_table_header() -> None:
     """
     Prints the table header for the vmmap command.
     """
+    prefer_relpaths = "on" if pwndbg.config.vmmap_prefer_relpaths else "off"
+    width = 2 + 2 * pwndbg.aglib.arch.ptrsize
     print(
-        f"{'Start':>{2 + 2 * pwndbg.aglib.arch.ptrsize}} {'End':>{2 + 2 * pwndbg.aglib.arch.ptrsize}} {'Perm'} {'Size':>8} {'Offset':>6} {'File'}"
+        f"{'Start':>{width}} {'End':>{width}} {'Perm'} {'Size':>8} {'Offset':>6} "
+        f"{'File'} (set vmmap_prefer_relpaths {prefer_relpaths})"
     )
 
 

pwndbg/lib/memory.py

@@ -5,6 +5,7 @@ Reading, writing, and describing memory.
 from __future__ import annotations
 
 import os
+from os.path import relpath
 
 import pwndbg.aglib.arch
 
@@ -140,7 +141,15 @@ class Page:
         )
 
     def __str__(self) -> str:
-        return f"{self.vaddr:#{2 + 2 * pwndbg.aglib.arch.ptrsize}x} {self.vaddr + self.memsz:#{2 + 2 * pwndbg.aglib.arch.ptrsize}x} {self.permstr} {self.memsz:8x} {self.offset:6x} {self.objfile or ''}"
+        if pwndbg.config.vmmap_prefer_relpaths:
+            rel = relpath(self.objfile)
+            # Prefer absolute paths for system files (for example libc) since
+            # `os.path.relpath` returns longer relative paths with no clear benefits.
+            objfile = self.objfile if rel.startswith("../../") else rel
+        else:
+            objfile = self.objfile
+        width = 2 + 2 * pwndbg.aglib.arch.ptrsize
+        return f"{self.vaddr:#{width}x} {self.vaddr + self.memsz:#{width}x} {self.permstr} {self.memsz:8x} {self.offset:6x} {objfile or ''}"
 
     def __repr__(self) -> str:
         return f"{self.__class__.__name__}({self.__str__()!r})"

tests/gdb-tests/tests/test_command_vmmap.py

@@ -74,6 +74,7 @@ def test_command_vmmap_on_coredump_on_crash_simple_binary(start_binary, unload_f
 
     expected_maps = get_proc_maps()
 
+    gdb.execute("set vmmap-prefer-relpaths off")
     vmmaps = gdb.execute("vmmap", to_string=True).splitlines()
 
     # Basic asserts