Merge the FreeType and Qhull download mechanisms.

Author: anntzer

.gitignore

@@ -105,5 +105,3 @@ lib/z.lib
 #########################
 lib/matplotlib/backends/web_backend/node_modules/
 lib/matplotlib/backends/web_backend/package-lock.json
-
-extern/qhull-*/

setup.py

@@ -28,7 +28,6 @@
 from pathlib import Path
 import shutil
 import subprocess
-import tarfile
 
 from setuptools import setup, find_packages, Extension
 from setuptools.command.build_ext import build_ext as BuildExtCommand
@@ -49,7 +48,7 @@
 
 import setupext
 from setupext import (
-    download_or_cache, print_raw, print_status, LOCAL_QHULL_VERSION)
+    get_and_extract_tarball, print_raw, print_status, LOCAL_QHULL_VERSION)
 
 # Get the version from versioneer
 import versioneer
@@ -87,24 +86,17 @@ def __init__(self, dist):
               "'python setup.py test'. Please run 'pytest'.")
 
 
-def _download_qhull_to(dest):
-    url = "http://www.qhull.org/download/qhull-2020-src-8.0.2.tgz"
-    sha = "b5c2d7eb833278881b952c8a52d20179eab87766b00b865000469a45c1838b7e"
-    if (dest / f"qhull-{LOCAL_QHULL_VERSION}").exists():
-        return
-    dest.mkdir(parents=True, exist_ok=True)
-    try:
-        buf = download_or_cache(url, sha)
-    except Exception:
-        raise IOError(f"Failed to download qhull.  Please download {url} and "
-                      f"extract it to {dest}.")
-    with tarfile.open(fileobj=buf, mode="r:gz") as tf:
-        tf.extractall(dest)
+def _download_qhull():
+    toplevel = get_and_extract_tarball(
+        urls=["http://www.qhull.org/download/qhull-2020-src-8.0.2.tgz"],
+        sha="b5c2d7eb833278881b952c8a52d20179eab87766b00b865000469a45c1838b7e",
+        dirname=f"qhull-{LOCAL_QHULL_VERSION}",
+    )
 
 
 class BuildExtraLibraries(BuildExtCommand):
     def finalize_options(self):
-        _download_qhull_to(Path("extern"))
+        _download_qhull()
         self.distribution.ext_modules[:] = [
             ext
             for package in good_packages

setupext.py

@@ -48,7 +48,7 @@ def _get_ssl_context():
     return ssl.create_default_context(cafile=certifi.where())
 
 
-def download_or_cache(url, sha):
+def get_from_cache_or_download(url, sha):
     """
     Get bytes from the given url or local cache.
 
@@ -86,7 +86,7 @@ def download_or_cache(url, sha):
     file_sha = _get_hash(data)
     if file_sha != sha:
         raise Exception(
-            f"The download file does not match the expected sha.  {url} was "
+            f"The downloaded file does not match the expected sha.  {url} was "
             f"expected to have {sha} but it had {file_sha}")
 
     if cache_dir is not None:  # Try to cache the downloaded file.
@@ -100,6 +100,45 @@ def download_or_cache(url, sha):
     return BytesIO(data)
 
 
+def get_and_extract_tarball(urls, sha, dirname):
+    """
+    Obtain a tarball (from cache or download) and extract it.
+
+    Parameters
+    ----------
+    urls : list[str]
+        URLs from which download is attempted (in order of attempt), if the
+        tarball is not in the cache yet.
+    sha : str
+        SHA256 hash of the tarball; used both as a cache key (by
+        `get_from_cache_or_download`) and to validate a downloaded tarball.
+    dirname : path-like
+        Directory where the tarball is extracted.
+    """
+    toplevel = Path("build", dirname)
+    if not toplevel.exists():  # Download it or load it from cache.
+        Path("build").mkdir(exist_ok=True)
+        for url in urls:
+            try:
+                tar_contents = get_from_cache_or_download(url, sha)
+                break
+            except Exception:
+                pass
+        else:
+            raise IOError(
+                f"Failed to download any of the following: {urls}.  "
+                f"Please download one of these urls and extract it into "
+                f"'build/' at the top-level of the source repository.")
+        print("Extracting {}".format(urllib.parse.urlparse(url).path))
+        with tarfile.open(fileobj=tar_contents, mode="r:gz") as tgz:
+            if os.path.commonpath(tgz.getnames()) != dirname:
+                raise IOError(
+                    f"The downloaded tgz file was expected to have {dirname} "
+                    f"as sole top-level directory, but that is not the case")
+            tgz.extractall("build")
+    return toplevel
+
+
 # SHA256 hashes of the FreeType tarballs
 _freetype_hashes = {
     '2.6.1':
@@ -515,7 +554,7 @@ def add_qhull_flags(ext):
     if options.get("system_qhull"):
         ext.libraries.append("qhull")
     else:
-        qhull_path = Path(f'extern/qhull-{LOCAL_QHULL_VERSION}/src')
+        qhull_path = Path(f'build/qhull-{LOCAL_QHULL_VERSION}/src')
         ext.include_dirs.insert(0, str(qhull_path))
         ext.sources.extend(map(str, sorted(qhull_path.glob('libqhull_r/*.c'))))
         if sysconfig.get_config_var("LIBM") == "-lm":
@@ -560,46 +599,24 @@ def do_custom_build(self, env):
         if options.get('system_freetype'):
             return
 
-        src_path = Path('build', f'freetype-{LOCAL_FREETYPE_VERSION}')
+        tarball = f'freetype-{LOCAL_FREETYPE_VERSION}.tar.gz'
+        src_path = get_and_extract_tarball(
+            urls=[
+                (f'https://downloads.sourceforge.net/project/freetype'
+                 f'/freetype2/{LOCAL_FREETYPE_VERSION}/{tarball}'),
+                (f'https://download.savannah.gnu.org/releases/freetype'
+                 f'/{tarball}')
+            ],
+            sha=LOCAL_FREETYPE_HASH,
+            dirname=f'freetype-{LOCAL_FREETYPE_VERSION}',
+        )
 
-        # We've already built freetype
         if sys.platform == 'win32':
             libfreetype = 'libfreetype.lib'
         else:
             libfreetype = 'libfreetype.a'
-
-        # bailing because it is already built
         if (src_path / 'objs' / '.libs' / libfreetype).is_file():
-            return
-
-        # do we need to download / load the source from cache?
-        if not src_path.exists():
-            os.makedirs('build', exist_ok=True)
-
-            tarball = f'freetype-{LOCAL_FREETYPE_VERSION}.tar.gz'
-            target_urls = [
-                (f'https://downloads.sourceforge.net/project/freetype'
-                 f'/freetype2/{LOCAL_FREETYPE_VERSION}/{tarball}'),
-                (f'https://download.savannah.gnu.org/releases/freetype'
-                 f'/{tarball}')
-            ]
-
-            for tarball_url in target_urls:
-                try:
-                    tar_contents = download_or_cache(tarball_url,
-                                                     LOCAL_FREETYPE_HASH)
-                    break
-                except Exception:
-                    pass
-            else:
-                raise IOError(
-                    f"Failed to download FreeType. Please download one of "
-                    f"{target_urls} and extract it into {src_path} at the "
-                    f"top-level of the source repository.")
-
-            print(f"Extracting {tarball}")
-            with tarfile.open(fileobj=tar_contents, mode="r:gz") as tgz:
-                tgz.extractall("build")
+            return  # Bail out because we have already built FreeType.
 
         print(f"Building freetype in {src_path}")
         if sys.platform != 'win32':  # compilation on non-windows