mallocng: add ng-slots command (#3144)

* move slot printing out to a func; add ng-slots

* make ng-find use this now

docs/commands/index.md

@@ -261,6 +261,7 @@
 -  [mallocng-find](musl/mallocng-find.md) - Find slot which contains the given address.
 -  [mallocng-group](musl/mallocng-group.md) - Print out information about a mallocng group at the given address.
 -  [mallocng-meta](musl/mallocng-meta.md) - Print out information about a mallocng group given the address of its meta.
+-  [mallocng-slot-start](musl/mallocng-slot-start.md) - Dump information about a mallocng slot, given its start address.
 -  [mallocng-slot-user](musl/mallocng-slot-user.md) - Dump information about a mallocng slot, given its user address.
 
 <!-- END OF AUTOGENERATED PART. Do not modify this line or the line below, they mark the end of the auto-generated part of the file. If you want to extend the documentation in a way which cannot easily be done by adding to the command help description, write below the following line. -->

docs/commands/musl/mallocng-slot-start.md

@@ -0,0 +1,26 @@
+<!-- THIS PART OF THIS FILE IS AUTOGENERATED. DO NOT MODIFY IT. See scripts/generate-docs.sh -->
+# mallocng-slot-start
+
+```text
+usage: mallocng-slot-start [-h] [-a] address
+
+```
+
+Dump information about a mallocng slot, given its start address.
+
+**Alias:** ng-slots
+### Positional arguments
+
+|Positional Argument|Help|
+| :--- | :--- |
+|address|The start of the slot (not including IB).|
+
+### Optional arguments
+
+|Short|Long|Help|
+| :--- | :--- | :--- |
+|-h|--help|show this help message and exit|
+|-a|--all|Print out all information. Including meta and group data.|
+
+<!-- END OF AUTOGENERATED PART. Do not modify this line or the line below, they mark the end of the auto-generated part of the file. If you want to extend the documentation in a way which cannot easily be done by adding to the command help description, write below the following line. -->
+<!-- ------------\>8---- ----\>8---- ----\>8------------ -->

pwndbg/commands/mallocng.py

@@ -331,42 +331,12 @@ def dump_meta(meta: mallocng.Meta) -> str:
     return output
 
 
-parser = argparse.ArgumentParser(
-    description="""
-Dump information about a mallocng slot, given its user address.
-    """,
-)
-parser.add_argument(
-    "address",
-    type=int,
-    help="The start of user memory. Referred to as `p` in the source.",
-)
-parser.add_argument(
-    "-a",
-    "--all",
-    action="store_true",
-    help="Print out all information. Including meta and group data.",
-)
-
-
-@pwndbg.commands.Command(
-    parser,
-    category=CommandCategory.MUSL,
-    aliases=["ng-slotu"],
-)
-@pwndbg.commands.OnlyWhenRunning
-def mallocng_slot_user(address: int, all: bool) -> None:
-    if not memory.is_readable_address(address):
-        print(message.error(f"Address {address:#x} not readable."))
-        return
-
-    slot = mallocng.Slot(address)
-
+def dump_slot(slot: mallocng.Slot, all: bool) -> str:
     try:
         slot.preload()
     except pwndbg.dbg_mod.Error as e:
         print(message.error(f"Error while reading slot: {e}"))
-        return
+        return ""
 
     read_success: bool = True
 
@@ -483,11 +453,79 @@ def mallocng_slot_user(address: int, all: bool) -> None:
     pp.add(inband_group)
     pp.end_section()
 
-    pp.print()
+    output = pp.dump()
 
     if all:
-        print(dump_group(slot.group), end="")
-        print(dump_meta(slot.meta), end="")
+        output += dump_group(slot.group)
+        output += dump_meta(slot.meta)
+
+    return output
+
+
+parser = argparse.ArgumentParser(
+    description="""
+Dump information about a mallocng slot, given its user address.
+    """,
+)
+parser.add_argument(
+    "address",
+    type=int,
+    help="The start of user memory. Referred to as `p` in the source.",
+)
+parser.add_argument(
+    "-a",
+    "--all",
+    action="store_true",
+    help="Print out all information. Including meta and group data.",
+)
+
+
+@pwndbg.commands.Command(
+    parser,
+    category=CommandCategory.MUSL,
+    aliases=["ng-slotu"],
+)
+@pwndbg.commands.OnlyWhenRunning
+def mallocng_slot_user(address: int, all: bool) -> None:
+    if not memory.is_readable_address(address):
+        print(message.error(f"Address {address:#x} not readable."))
+        return
+
+    slot = mallocng.Slot(address)
+    print(dump_slot(slot, all), end="")
+
+
+parser = argparse.ArgumentParser(
+    description="""
+Dump information about a mallocng slot, given its start address.
+    """,
+)
+parser.add_argument(
+    "address",
+    type=int,
+    help="The start of the slot (not including IB).",
+)
+parser.add_argument(
+    "-a",
+    "--all",
+    action="store_true",
+    help="Print out all information. Including meta and group data.",
+)
+
+
+@pwndbg.commands.Command(
+    parser,
+    category=CommandCategory.MUSL,
+    aliases=["ng-slots"],
+)
+@pwndbg.commands.OnlyWhenRunning
+def mallocng_slot_start(address: int, all: bool) -> None:
+    if not memory.is_readable_address(address):
+        print(message.error(f"Address {address:#x} not readable."))
+        return
+
+    slot = mallocng.Slot.from_start(address)
+    print(dump_slot(slot, all), end="")
 
 
 parser = argparse.ArgumentParser(
@@ -630,4 +668,4 @@ def mallocng_find(
         print(message.info("No slot found containing that address."))
         return
 
-    mallocng_slot_user(mallocng.Slot.from_start(slot_start).p, all=all)
+    mallocng_slot_start(slot_start, all=all)