Update imports to use direct namespace imports

WARNING: OLD STYLE IMPORTS DO NOT WORK The old style of importing the
full module and using pb.* prefixes has been replaced with direct
imports of the needed names. This makes the code more explicit about
what is being used and removes the unnecessary pb prefix.

Author: varun-r-mallya

README.md

@@ -13,25 +13,25 @@ This is an LLVM IR generator for eBPF programs in Python. We use llvmlite to gen
 ## Usage
 ```python
 # pythonbpf_example.py
-import pythonbpf as pb
+from pythonbpf import bpf, map, bpfglobal, section, compile
 from pythonbpf.helpers import bpf_ktime_get_ns
 from pythonbpf.maps import HashMap
 
 from ctypes import c_void_p, c_int64, c_int32, c_uint64
 
-@pb.bpf
-@pb.map
+@bpf
+@map
 def last() -> HashMap:
     return HashMap(key_type=c_uint64, value_type=c_uint64, max_entries=1)
 
-@pb.bpf
-@pb.section("tracepoint/syscalls/sys_enter_execve")
+@bpf
+@section("tracepoint/syscalls/sys_enter_execve")
 def hello(ctx: c_void_p) -> c_int32:
     print("entered")
     return c_int32(0)
 
-@pb.bpf
-@pb.section("tracepoint/syscalls/sys_exit_execve")
+@bpf
+@section("tracepoint/syscalls/sys_exit_execve")
 def hello_again(ctx: c_void_p) -> c_int64:
     print("exited")
     key = 0
@@ -40,16 +40,16 @@ def hello_again(ctx: c_void_p) -> c_int64:
     ts = bpf_ktime_get_ns()
     return c_int64(0)
 
-@pb.bpf
-@pb.bpfglobal
+@bpf
+@bpfglobal
 def LICENSE() -> str:
     return "GPL"
 
 def some_normal_function():
     print("normal function")
 
 # compiles and dumps object file in the same directory
-pb.compile()
+compile()
 ```
 - Run `python pythonbpf_example.py` to get the compiled object file that can be then loaded into the kernel.
 

examples/execve3.py

@@ -1,25 +1,25 @@
-import pythonbpf as pb
+from pythonbpf import bpf, map, section, bpfglobal, compile
 from pythonbpf.helpers import bpf_ktime_get_ns
 from pythonbpf.maps import HashMap
 
 from ctypes import c_void_p, c_int64, c_int32, c_uint64
 
-@pb.bpf
-@pb.map
+@bpf
+@map
 def last() -> HashMap:
     return HashMap(key_type=c_uint64, value_type=c_uint64, max_entries=1)
 
 
-@pb.bpf
-@pb.section("tracepoint/syscalls/sys_enter_execve")
+@bpf
+@section("tracepoint/syscalls/sys_enter_execve")
 def hello(ctx: c_void_p) -> c_int32:
     print("entered")
     print("multi constant support")
     return c_int32(0)
 
 
-@pb.bpf
-@pb.section("tracepoint/syscalls/sys_exit_execve")
+@bpf
+@section("tracepoint/syscalls/sys_exit_execve")
 def hello_again(ctx: c_void_p) -> c_int64:
     print("exited")
     key = 0
@@ -34,9 +34,9 @@ def hello_again(ctx: c_void_p) -> c_int64:
     return c_int64(0)
 
 
-@pb.bpf
-@pb.bpfglobal
+@bpf
+@bpfglobal
 def LICENSE() -> str:
     return "GPL"
 
-pb.compile()
+compile()

pythonbpf/codegen.py

@@ -6,8 +6,8 @@
 from .globals_pass import globals_processing
 import os
 import subprocess
-import pathlib
-import __main__
+import inspect
+from pathlib import Path
 
 def find_bpf_chunks(tree):
     """Find all functions decorated with @bpf in the AST."""
@@ -96,12 +96,14 @@ def compile_to_ir(filename: str, output: str):
     return output
 
 def compile():
-    main_file = pathlib.Path(__main__.__file__).resolve()
+    # Look one level up the stack to the caller of this function
+    caller_frame = inspect.stack()[1]
+    caller_file = Path(caller_frame.filename).resolve()
 
-    ll_file = pathlib.Path("/tmp") / main_file.with_suffix(".ll").name
-    o_file = main_file.with_suffix(".o")
+    ll_file = Path("/tmp") / caller_file.with_suffix(".ll").name
+    o_file = caller_file.with_suffix(".o")
 
-    compile_to_ir(str(main_file), str(ll_file))
+    compile_to_ir(str(caller_file), str(ll_file))
 
     subprocess.run([
         "llc", "-march=bpf", "-filetype=obj", "-O2",