def show_sym(fname, data, endian, evtype, sym):
"""Show information about an evspy entry
Args:
fname (str): Filename of ELF file
data (bytes): Data for this symbol
endian (str): Endianness to use ('little', 'big', 'auto')
evtype (str): Event type, e.g. 'MISC_INIT_F'
sym (elf.Symbol): Symbol to show
"""
def _unpack_val(sym_data, offset):
start = offset * func_size
val_data = sym_data[start:start + func_size]
fmt = '%s%s' % ('>' if endian == 'big' else '<',
'L' if func_size == 4 else 'Q')
val = struct.unpack(fmt, val_data)[0]
return val
# Get the data, which is a struct evspy_info
sym_data = data[sym.offset:sym.offset + sym.size]
# Figure out the word size of the struct
func_size = 4 if sym.size < 16 else 8
# Read the function name for evspy_info->func
while True:
# Switch to big-endian if we see a failure
func_addr = _unpack_val(sym_data, 0)
func_name = elf.GetSymbolFromAddress(fname, func_addr)
if not func_name and endian == 'auto':
endian = 'big'
else:
break
has_id = sym.size in [12, 24]
if has_id:
# Find the address of evspy_info->id in the ELF
id_addr = _unpack_val(sym_data, 2)
# Get the file offset for that address
id_ofs = elf.GetFileOffset(fname, id_addr)
# Read out a nul-terminated string
id_data = data[id_ofs:id_ofs + 80]
pos = id_data.find(0)
if pos:
id_data = id_data[:pos]
id_str = id_data.decode('utf-8')
else:
id_str = None
# Find the file/line for the function
cmd = ['addr2line', '-e', fname, '%x' % func_addr]
out = tools.run(*cmd).strip()
# Drop the full path if it is the current directory
if out.startswith(src_path):
out = out[len(src_path) + 1:]
print('%-20s %-30s %s' % (evtype, id_str or f'f:{func_name}', out))
def test_get_file_offset_fail(self):
"""Test calling GetFileOffset() without elftools"""
try:
old_val = elf.ELF_TOOLS
elf.ELF_TOOLS = False
fname = self.ElfTestFile('embed_data')
with self.assertRaises(ValueError) as e:
elf.GetFileOffset(fname, 0)
self.assertIn("Python: No module named 'elftools'",
str(e.exception))
finally:
elf.ELF_TOOLS = old_val
def test_get_file_offset(self):
"""Test GetFileOffset() gives the correct file offset for a symbol"""
fname = self.ElfTestFile('embed_data')
syms = elf.GetSymbols(fname, ['embed'])
addr = syms['embed'].address
offset = elf.GetFileOffset(fname, addr)
data = tools.read_file(fname)
# Just use the first 4 bytes and assume it is little endian
embed_data = data[offset:offset + 4]
embed_value = struct.unpack('<I', embed_data)[0]
self.assertEqual(0x1234, embed_value)