flipperzero-firmware/debug/flipperapps.py

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from dataclasses import dataclass
from typing import Tuple, Dict
import struct
import posixpath
import os
import zlib
import gdb
def get_file_crc32(filename):
with open(filename, "rb") as f:
return zlib.crc32(f.read())
@dataclass
class AppState:
name: str
text_address: int = 0
entry_address: int = 0
other_sections: Dict[str, int] = None
debug_link_elf: str = ""
debug_link_crc: int = 0
def __post_init__(self):
if self.other_sections is None:
self.other_sections = {}
def get_original_elf_path(self, elf_path="build/latest/.extapps") -> str:
return (
posixpath.join(elf_path, self.debug_link_elf)
if elf_path
else self.debug_link_elf
)
def is_debug_available(self) -> bool:
have_debug_info = bool(self.debug_link_elf and self.debug_link_crc)
if not have_debug_info:
print("No debug info available for this app")
return False
debug_elf_path = self.get_original_elf_path()
debug_elf_crc32 = get_file_crc32(debug_elf_path)
if self.debug_link_crc != debug_elf_crc32:
print(
f"Debug info ({debug_elf_path}) CRC mismatch: {self.debug_link_crc:08x} != {debug_elf_crc32:08x}, rebuild app"
)
return False
return True
def get_gdb_load_command(self) -> str:
load_path = self.get_original_elf_path()
print(f"Loading debug information from {load_path}")
load_command = (
f"add-symbol-file -readnow {load_path} 0x{self.text_address:08x} "
)
load_command += " ".join(
f"-s {name} 0x{address:08x}"
for name, address in self.other_sections.items()
)
return load_command
def get_gdb_unload_command(self) -> str:
return f"remove-symbol-file -a 0x{self.text_address:08x}"
def is_loaded_in_gdb(self, gdb_app) -> bool:
# Avoid constructing full app wrapper for comparison
return self.entry_address == int(gdb_app["state"]["entry"])
@staticmethod
def parse_debug_link_data(section_data: bytes) -> Tuple[str, int]:
# Debug link format: a null-terminated string with debuggable file name
# Padded with 0's to multiple of 4 bytes
# Followed by 4 bytes of CRC32 checksum of that file
elf_name = section_data[:-4].decode("utf-8").split("\x00")[0]
crc32 = struct.unpack("<I", section_data[-4:])[0]
return (elf_name, crc32)
@staticmethod
def from_gdb(gdb_app: "AppState") -> "AppState":
state = AppState(str(gdb_app["manifest"]["name"].string()))
state.entry_address = int(gdb_app["state"]["entry"])
app_state = gdb_app["state"]
if debug_link_size := int(app_state["debug_link_info"]["debug_link_size"]):
debug_link_data = (
gdb.selected_inferior()
.read_memory(int(app_state["debug_link_info"]["debug_link"]), debug_link_size)
.tobytes()
)
state.debug_link_elf, state.debug_link_crc = AppState.parse_debug_link_data(
debug_link_data
)
for idx in range(app_state["mmap_entry_count"]):
mmap_entry = app_state["mmap_entries"][idx]
section_name = mmap_entry["name"].string()
section_addr = int(mmap_entry["address"])
if section_name == ".text":
state.text_address = section_addr
else:
state.other_sections[section_name] = section_addr
return state
class FlipperAppDebugHelper:
def __init__(self):
self.app_ptr = None
self.app_type_ptr = None
self.current_app: AppState = None
def attach_fw(self) -> None:
self.app_ptr = gdb.lookup_global_symbol("last_loaded_app")
self.app_type_ptr = gdb.lookup_type("FlipperApplication").pointer()
self._check_app_state()
def _check_app_state(self) -> None:
app_ptr_value = self.app_ptr.value()
if not app_ptr_value and self.current_app:
# There is an ELF loaded in GDB, but nothing is running on the device
self._unload_debug_elf()
elif app_ptr_value:
# There is an app running on the device
loaded_app = app_ptr_value.cast(self.app_type_ptr).dereference()
if self.current_app and not self.current_app.is_loaded_in_gdb(loaded_app):
# Currently loaded ELF is not the one running on the device
self._unload_debug_elf()
if not self.current_app:
# Load ELF for the app running on the device
self._load_debug_elf(loaded_app)
def _unload_debug_elf(self) -> None:
try:
gdb.execute(self.current_app.get_gdb_unload_command())
except gdb.error as e:
print(f"Failed to unload debug ELF: {e} (might not be an error)")
self.current_app = None
def _load_debug_elf(self, app_object) -> None:
self.current_app = AppState.from_gdb(app_object)
if self.current_app.is_debug_available():
gdb.execute(self.current_app.get_gdb_load_command())
def handle_stop(self, event) -> None:
self._check_app_state()
helper = FlipperAppDebugHelper()
try:
helper.attach_fw()
print("Support for Flipper external apps debug is enabled")
gdb.events.stop.connect(helper.handle_stop)
except gdb.error as e:
print(f"Support for Flipper external apps debug is not available: {e}")