add new API pane for glibc and syscalls (#111)

This fixes all the issues with the context panes and it now works as it
did before the plugins were created.

In the GEF part, it was just a minor refactor and a new external API. 

In the gef-extras part, it was only necessary to call this new function!

I think the proposed solution is simple and it works.

gef code:
- hugsy/gef#1093

docs/install.md

@@ -64,6 +64,13 @@ Start with cloning this repo:
 git clone https://github.com/hugsy/gef-extras
 ```
 
+Add syscall_args and libc_function_args to context layout:
+
+```text
+gef➤  pi gef.config['context.layout'] += ' syscall_args'
+gef➤  pi gef.config['context.layout'] += ' libc_function_args'
+```
+
 Add the path to the external scripts to GEF's config:
 
 ```text
@@ -90,11 +97,13 @@ gef➤  gef config context.libc_args True
 gef➤  gef config context.libc_args_path /path/to/gef-extras/glibc-function-args
 ```
 
-Check out the [complete documentation](commands/glibc_function_args.md) on libc argument support.
-
+And don't forget to save your settings.
 
-Now run and enjoy all the fun!
+```text
+gef➤ gef save
+```
 
+Check out the [complete documentation](commands/glibc_function_args.md) on libc argument support.
 
 Note that it is possible to specify multiple directories, separating the paths with
 a semi-colon:
@@ -103,8 +112,4 @@ a semi-colon:
 gef➤  gef config gef.extra_plugins_dir /path/to/dir1;/path/to/dir2
 ```
 
-And don't forget to save your settings.
-
-```text
-gef➤ gef save
-```
+Now run and enjoy all the fun!

scripts/__init__.pyi

@@ -814,6 +814,11 @@ def register_external_context_pane(pane_name: str, display_pane_function: Callab
     def pane_title() -> str:  ...
 
 
+def register_external_context_layout_mapping(current_pane_name: str, display_pane_function: Callable[[], None], pane_title_function: Callable[[], Optional[str]], condition: Optional[Callable[[], bool]]) -> None:
+    def display_pane() -> None:  ...
+    def pane_title() -> str:  ...
+
+
 def register(cls: Union[Type["GenericCommand"], Type["GenericFunction"]]) -> Union[Type["GenericCommand"], Type["GenericFunction"]]: ...
 
 

scripts/libc_function_args/__init__.py

@@ -142,11 +142,11 @@ def extract_called_function_name() -> str:
 
         return function_name
 
-if GLIBC_FUNCTION_ARGS_CONTEXT_PANE_INDEX not in gef.config["context.layout"]:
+if GLIBC_FUNCTION_ARGS_CONTEXT_PANE_INDEX in gef.config["context.layout"]:
     #
     # Register the context pane
     #
-    register_external_context_pane(
+    register_external_context_layout_mapping(
         GLIBC_FUNCTION_ARGS_CONTEXT_PANE_INDEX,
         GlibcFunctionArguments.pane_content,
         pane_title_function=GlibcFunctionArguments.pane_title,

scripts/syscall_args/__init__.py

@@ -132,9 +132,9 @@ def __syscall_args_pane_content() -> None:
 def __syscall_args_pane_title() -> str:
     return CONTEXT_PANE_DESCRIPTION
 
-if CONTEXT_PANE_INDEX not in gef.config["context.layout"]:
+if CONTEXT_PANE_INDEX in gef.config["context.layout"]:
     #
     # Register a callback to `syscall-args` to automatically detect when a syscall is hit
     #
-    register_external_context_pane(
+    register_external_context_layout_mapping(
         CONTEXT_PANE_INDEX, __syscall_args_pane_content, pane_title_function=__syscall_args_pane_title, condition=__syscall_args_pane_condition)