Refactor binding build

.readthedocs.yml

@@ -14,12 +14,11 @@ build:
     pre_install:
       - libtoolize
       - autoreconf --install
-      - mkdir ./install
-      - ./configure --prefix=`pwd`/install
+      - ./configure
       - make
-      - make install
-      - pip install cffi
-      - python ./python/src/libcpuid/_ffi_build_rtd.py ./libcpuid/libcpuid.h ./install
+      - pip install -e ./python
+      - export LD_LIBRARY_PATH=$LD_LIBRARY_PATH:$PWD/libcpuid/.libs
+      - ldconfig $PWD/libcpuid/.libs
 
 sphinx:
   configuration: python/docs/conf.py

python/src/libcpuid/_ffi_build.py

@@ -3,23 +3,96 @@
 """
 
 import os
-import sys
+import subprocess
+import tempfile
+import re
+from pathlib import Path
 from cffi import FFI
 
-sys.path.append(os.path.dirname(os.path.abspath(__file__)))
 
-from _ffi_build_utils import (  # pylint: disable=import-error, wrong-import-position
-    get_include_flags,
-    find_header_file,
-    preprocess_header,
-    eval_sizeofs,
+class FFIBuildException(Exception):
+    """Generic exception for errors occuring during the CFFI build."""
+
+
+def preprocess_header(header_path):
+    """
+    Preprocesses the header file (python-cffi only accepts preprocessed C definitions)
+    at the given path and returns it as a string.
+    """
+    try:
+        return subprocess.check_output(
+            ["gcc", "-U __GNUC__", "-E", header_path]
+        ).decode()
+    except subprocess.CalledProcessError as e:
+        if e.returncode == 127:
+            raise FFIBuildException(
+                "The gcc compiler is necessary to build python-libcpuid."
+            ) from e
+        raise FFIBuildException(
+            f"Error preprocessing the libcpuid header file: {e.stderr}"
+        ) from e
+
+
+def _get_sizeof_eval_source(sizeof):
+    return f"""
+#include <libcpuid.h>
+#include <stdio.h>
+
+int main() {{
+    printf("%ld", {sizeof});
+    return 0;
+}}
+"""
+
+
+def eval_sizeofs(header, cflags):
+    """
+    Evaluates each sizeof found in the given C header and replaces all
+    occurences of the sizeof with its computed value.
+    """
+    sizeofs = set(re.findall(r"sizeof\([^\)]*\)", header))
+    tmp_dir = tempfile.mkdtemp()
+    c_program_path = Path(tmp_dir, "sizeof.c")
+    executable_path = Path(tmp_dir, "sizeof")
+
+    for sizeof in sizeofs:
+        with open(c_program_path, "w", encoding="UTF-8") as c_program_file:
+            c_program_file.write(_get_sizeof_eval_source(sizeof))
+        subprocess.check_call(["gcc", c_program_path, *cflags, "-o", executable_path])
+        size = subprocess.check_output([executable_path]).decode()
+        header = header.replace(sizeof, size)
+
+    os.remove(c_program_path)
+    os.remove(executable_path)
+    os.rmdir(tmp_dir)
+    return header
+
+
+LIBCPUID_DIR = str(Path(*(Path(os.path.abspath(__file__)).parts[:-4])))
+LIBCPUID_INCLUDE_DIR = str(Path(LIBCPUID_DIR, "libcpuid"))
+LIBCPUID_LIBRARY_DIR = str(Path(LIBCPUID_DIR, "libcpuid", ".libs"))
+LIBCPUID_MAIN_HEADER_FILENAME = "libcpuid.h"
+LIBCPUID_MAIN_HEADER_PATH = str(
+    Path(LIBCPUID_INCLUDE_DIR, LIBCPUID_MAIN_HEADER_FILENAME)
+)
+LIBCPUID_LIBRARY_NAME = "cpuid"
+
+PREPROCESSED_HEADER = preprocess_header(LIBCPUID_MAIN_HEADER_PATH)
+NO_SIZEOF_HEADER = eval_sizeofs(
+    PREPROCESSED_HEADER,
+    [
+        f"-I{LIBCPUID_INCLUDE_DIR}",
+        f"-L{LIBCPUID_LIBRARY_DIR}",
+        f"-l{LIBCPUID_LIBRARY_NAME}",
+    ],
 )
 
-include_flags = get_include_flags()
-preprocessed_header = preprocess_header(find_header_file(include_flags))
-no_sizeof_header = eval_sizeofs(preprocessed_header, include_flags)
 ffibuilder = FFI()
-ffibuilder.cdef(no_sizeof_header)
-ffibuilder.set_source_pkgconfig(
-    "libcpuid._libcpuid_cffi", ["libcpuid"], "#include <libcpuid.h>"
+ffibuilder.cdef(NO_SIZEOF_HEADER)
+ffibuilder.set_source(
+    "libcpuid._libcpuid_cffi",
+    f"#include <{LIBCPUID_MAIN_HEADER_FILENAME}>",
+    libraries=[LIBCPUID_LIBRARY_NAME],
+    include_dirs=[LIBCPUID_INCLUDE_DIR],
+    library_dirs=[LIBCPUID_LIBRARY_DIR],
 )