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0x08_CPython

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(277) 0x08. CPython

Specializations > System programming & Algorithm > Linux Programming

Project author

Julien Barbier

Assignment dates

03-25-2021 to 04-02-2021

Description

An investigation into how Python 3 is implemented in C and how to access it via its C API.

Requirements

Big O Notation in Answer File

  • O(1)
  • O(n)
  • O(n!)
  • n square -> O(n^2)
  • log(n) -> O(log(n))
  • n * log(n) -> O(nlog(n))
  • “short” notation (don’t use constants)

Provided file(s)

1-test_lists.py 2-tests.py 3-tests.py 4-tests.py 5-tests.py 100-tests.py

Mandatory Tasks

✅ 0. Lists big O

Write the big O notations for the following lists operations (one per line, in this exact order):

  • L1 - Assigning. Example: holberton[98] = 402
  • L2 - Appending. Example: holberton.append(98)
  • L3 - Concatenating a list of n elements. Example: holberton + [98, 402]
  • L4 - Inserting an item at a given position. Example: holberton.insert(98, 402)
  • L5 - Removing an element. Example: holberton.remove(98)
  • L6 - Removing and returning the last item in the list. Example: holberton.pop()
  • L7 - Poping an element at a given position. Example: holberton.pop(98)
  • L8 - Clearing a list. Example: holberton.clear()
  • L9 - Counting the list. Example: holberton.count()
  • L10 - Sorting the list. Example: holberton.sort()
  • L11 - Reversing the list. Example: holberton.reverse()
  • L12 - Deleting the list. Example: del holberton

File(s): 0-python_lists_bigO

✅ 1. CPython #0: Python lists

CPython is the reference implementation of the Python programming language. Written in C, CPython is the default and most widely used implementation of the language.

Create a C function that prints some basic info about Python lists.

  • Prototype: void print_python_list(PyObject *p);
  • Python version: 3.4
  • Your shared library will be compiled with this command line: gcc -Wall -Werror -Wextra -pedantic -std=c99 -shared -Wl,-soname,PyList -o libPyList.so -fPIC -I/usr/include/python3.4 1-python.c
  • OS: Ubuntu 14.04 LTS
  • Start by reading:

File(s): 1-python.c
Compiled: gcc -Wall -Werror -Wextra -pedantic -std=c99 -shared -Wl,-soname,PyList -o libPyList.so -fPIC -I/usr/include/python3.4 1-python.c

✅ 2. CPython #1: PyBytesObject

Create two C functions that print some basic info about Python lists and Python bytes objects.

Python lists:

  • Prototype: void print_python_list(PyObject *p);

Python bytes:

  • Prototype: void print_python_bytes(PyObject *p);
  • Line “first X bytes”: print a maximum of 10 bytes
  • If p is not a valid PyBytesObject, print an error message (see example)
  • Read /usr/include/python3.4/bytesobject.h

About:

  • Python version: 3.4
  • Your shared library will be compiled with this command line: gcc -Wall -Werror -Wextra -pedantic -std=c99 -shared -Wl,-soname,libPython.so -o libPython.so -fPIC -I/usr/include/python3.4 2-python.c
  • You are not allowed to use the following macros/functions:
    • Py_SIZE
    • Py_TYPE
    • PyList_GetItem
    • PyBytes_AS_STRING
    • PyBytes_GET_SIZE

File(s): 2-python.c
Compiled: gcc -Wall -Werror -Wextra -pedantic -std=c99 -shared -Wl,-soname,libPython.so -o libPython.so -fPIC -I/usr/include/python3.4 2-python.c

✅ 3. CPython #2: PyFloatObject

Create three C functions that print some basic info about Python lists, Python bytes an Python float objects.

Python lists:

  • Prototype: void print_python_list(PyObject *p);
  • If p is not a valid PyListObject, print an error message

Python bytes:

  • Prototype: void print_python_bytes(PyObject *p);
  • Line “first X bytes”: print a maximum of 10 bytes
  • If p is not a valid PyBytesObject, print an error message

Python float:

  • Prototype: void print_python_float(PyObject *p);
  • If p is not a valid PyFloatObject, print an error message
  • Read /usr/include/python3.4/floatobject.h

About:

  • Python version: 3.4
  • You are allowed to use the C standard library
  • Your shared library will be compiled with this command line: gcc -Wall -Werror -Wextra -pedantic -std=c99 -shared -Wl,-soname,libPython.so -o libPython.so -fPIC -I/usr/include/python3.4 3-python.c
  • You are not allowed to use the following macros/functions:
    • Py_SIZE
    • Py_TYPE
    • PyList_Size
    • PyList_GetItem
    • PyBytes_AS_STRING
    • PyBytes_GET_SIZE
    • PyBytes_AsString
    • PyFloat_AS_DOUBLE
    • PySequence_GetItem
    • PySequence_Fast_GET_SIZE
    • PySequence_Fast_GET_ITEM
    • PySequence_ITEM
    • PySequence_Fast_ITEMS

NOTE:

  • The Python script will be launched using the -u option (force stdout to be unbuffered).
  • It is strongly advised to either use setbuf(stdout, NULL); or fflush(stdout) in your C functions IF you choose to use printf. The reason to that is that Python's print and libC's printf don’t share the same buffer, and the output can appear disordered.

File(s): 3-python.c
Compiled: gcc -Wall -Werror -Wextra -pedantic -std=c99 -shared -Wl,-soname,libPython.so -o libPython.so -fPIC -I/usr/include/python3.4 3-python.c

✅ 4. CPython #3: Python Strings

Create a function that prints Python strings.

  • Prototype: void print_python_string(PyObject *p);
  • If p is not a valid string, print an error message
  • Read: Unicode HOWTO

About:

  • Python version: 3.4
  • You are allowed to use the C standard library
  • Your shared library will be compiled with this command line: gcc -Wall -Wextra -pedantic -Werror -std=c99 -shared -Wl,-soname,libPython.so -o libPython.so -fPIC -I/usr/include/python3.4 4-python.c

File(s): 4-python.c
Compiled: gcc -Wall -Wextra -pedantic -Werror -std=c99 -shared -Wl,-soname,libPython.so -o libPython.so -fPIC -I/usr/include/python3.4 4-python.c

✅ 5. CPython Integers

Create a C function that prints Python integers.

  • Prototype: void print_python_int(PyObject *p);
  • If p is not a valid string, print an error message
  • The function should first translate the Python int to a C unsigned long int and then use printf to print the number
    • If the absolute value of the number is too big to be stored in a C unsigned long int, print C unsigned long int overflow, followed by a new line
  • Read: /usr/include/python3.4/longintrepr.h

About:

  • Python version: 3.4
  • You are allowed to use the C standard library
  • You are only allowed to use the following Python macros / functions:
    • PyLong_SHIFT
    • PyLong_Check
  • Your shared library will be compiled with this command line: gcc -Wall -Wextra -pedantic -Werror -std=c99 -shared -Wl,-soname,libPython.so -o libPython.so -fPIC -I/usr/include/python3.4 5-python.c

File(s): 5-python.c
Compiled: gcc -Wall -Wextra -pedantic -Werror -std=c99 -shared -Wl,-soname,libPython.so -o libPython.so -fPIC -I/usr/include/python3.4 5-python.c

Advanced Tasks

✅ 6. CPython Integers

Create a C function that prints Python integers.

  • Prototype: void print_python_int(PyObject *p);
  • If p is not a valid string, print an error message
  • The function should be able to print any integer
  • Read: /usr/include/python3.4/longintrepr.h

About:

  • Python version: 3.4
  • You are allowed to use the C standard library
  • You are only allowed to use the following Python macros / functions:
    • PyLong_SHIFT
    • PyLong_Check
  • Your shared library will be compiled with this command line: gcc -Wall -Wextra -pedantic -Werror -std=c99 -shared -Wl,-soname,libPython.so.2 -o libPython.so.2 -fPIC -I/usr/include/python3.4 100-python.c

File(s): 100-python.c
Compiled: gcc -Wall -Wextra -pedantic -Werror -std=c99 -shared -Wl,-soname,libPython.so.2 -o libPython.so.2 -fPIC -I/usr/include/python3.4 100-python.c

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