<SYSTEM_TASK:>
Given the following text description, write Python code to implement the functionality described below step by step
<END_TASK>
<USER_TASK:>
Description:
 LocationDB object
The LocationDB is the Miasm object responsible of the symbols' management. A Location is an object representing a code or data (or anywhere else) position. As the name explicits it, the LocationDB is a database of locations. Here are some rules
Step1:  Note that
Step2:  Those locations are also used in intermediate representation
Step3:  In miasm, each expression embeds its size. The location doesn't have a size. To use a location in IR code, you have to wrap it in the Miasm word ExprLoc
<ASSISTANT_TASK:>
Python Code:
# Import and create a locationDB
from miasm.core.locationdb import LocationDB
loc_db = LocationDB()
print(repr(loc_db))
# Create a location with default attributes (no offset, no symbol name)
loc_a = loc_db.add_location()
print(loc_a)
# Create a second location with an offset
loc_b = loc_db.add_location(offset=112233)
print(loc_b)
# Add a location with a name
loc_c = loc_db.add_location(name="main")
# Add another alias name to this location
loc_db.add_location_name(loc_c, "_main_")
# Add another location
loc_d = loc_db.add_location()
# Display LocationDB
print(loc_db)
# Associate an offset to an existing location
loc_db.set_location_offset(loc_a, 0x5678)
print(loc_db)
# Remove a name from an existing location
loc_db.remove_location_name(loc_c, "_main_")
print(loc_db)
# Get the offset of a location
hex(loc_db.get_location_offset(loc_a))
# Location with no offset
print(loc_db.get_location_offset(loc_c))
# Display locations
loc_db.pretty_str(loc_a)
loc_db.pretty_str(loc_b)
loc_db.pretty_str(loc_c)
loc_db.pretty_str(loc_d)
Explanation: LocationDB object
The LocationDB is the Miasm object responsible of the symbols' management. A Location is an object representing a code or data (or anywhere else) position. As the name explicits it, the LocationDB is a database of locations. Here are some rules:
- each location has exactly one associated LocKey
- a LocKey is linked to a unique LocationDB (and must not be used in another LocationDB)
- a LocKey is very similar to primary key object in a database.
- a LocKey can have an optional offset.
- a LocKey can have multiple symbol names
- two Lockeys cannot share an identic offset
- two LocKeys cannot share a symbol name
Below are manipulations of the LocationDB
End of explanation
from miasm.analysis.binary import Container
from miasm.analysis.machine import Machine
# Create a LocationDB
loc_db = LocationDB()
# Create a container of bytes
cont = Container.from_string(
    b"\x83\xf8\x10\x74\x07\x89\xc6\x0f\x47\xc3\xeb\x08\x89\xc8\xe8\x31\x33\x22\x11\x40\xc3",
    loc_db
)
# Instantiate a x86 32 bit architecture
machine = Machine("x86_32")
# Instantiate a disassembler engine, using the previous bin_stream and its
# associated location DB.
mdis = machine.dis_engine(cont.bin_stream, loc_db=loc_db)
# Run a recursive traversal disassembling from address 0
asmcfg = mdis.dis_multiblock(0)
# Display each basic blocks
for block in asmcfg.blocks:
    print(block)
block = asmcfg.getby_offset(0)
print(block)
# The basic block is placed at a location, which can be retrieved using `.loc_key`
print(block.loc_key)
# We can add a name to this first location
loc_db.add_location_name(block.loc_key, "entry")
print(loc_db)
# And we can re-display the block:
print(block)
# We will give an arbitrary name to location at offset 0xC
loc_c = loc_db.get_offset_location(0xc)
loc_db.add_location_name(loc_c, "quiche")
print(block)
Explanation: Note that:
- if a location doesn't have an offset neither a name, its pretty form is loc_key_XXX
- if a location has an offset but no name, its pretty form is loc_OFFSET
- if a location has a name, its pretty form is name
Locations usage in Miasm
The locations are used everywhere in miasm. For example, let disassemble a simple shellcode:
End of explanation
# Get a lifter
lifter = machine.lifter_model_call(loc_db)
# Get the intermediate representation of the asmcfg
ircfg = lifter.new_ircfg_from_asmcfg(asmcfg)
# Get location at 0
loc_entry = loc_db.get_offset_location(0)
# Get irblock at this location
irblock = ircfg.blocks[loc_entry]
# Display IRBlock
print(irblock)
Explanation: Those locations are also used in intermediate representation:
End of explanation
# Get the irblock destination (IRDst value)
dst = irblock.dst
print(dst)
print(repr(dst))
# It's an ExprCond. We retrieve here the possible values
src1, src2 = dst.src1, dst.src2
print(repr(src1), repr(src2))
# Retrieve the location of the ExprLoc
loc = src1.loc_key
print(loc)
Explanation: In miasm, each expression embeds its size. The location doesn't have a size. To use a location in IR code, you have to wrap it in the Miasm word ExprLoc
End of explanation
<END_TASK>