packaging: split downloading code into own module

As we will introduce more code to support packaging, it will be
useful to have download code in its own module.

Differential Revision: https://phab.mercurial-scm.org/D6084

contrib/packaging/hgpackaging/downloads.py

@@ -1,4 +1,4 b''
-# util.py - Common packaging utility code.
+# downloads.py - Code for downloading dependencies.
 #
 # Copyright 2019 Gregory Szorc <[e-mail]>
 #
@@ -10,9 +10,7 b''
 import gzip
 import hashlib
 import pathlib
-import tarfile
 import urllib.request
-import zipfile
 
 
 def hash_path(p: pathlib.Path):
@@ -116,13 +114,3 b' def download_entry(entry: dict, dest_pat'
     download_to_path(url, local_path, entry['size'], entry['sha256'])
 
     return local_path
-
-
-def extract_tar_to_directory(source: pathlib.Path, dest: pathlib.Path):
-    with tarfile.open(source, 'r') as tf:
-        tf.extractall(dest)
-
-
-def extract_zip_to_directory(source: pathlib.Path, dest: pathlib.Path):
-    with zipfile.ZipFile(source, 'r') as zf:
-        zf.extractall(dest)

contrib/packaging/hgpackaging/util.py

@@ -7,117 +7,11 b''
 
 # no-check-code because Python 3 native.
 
-import gzip
-import hashlib
 import pathlib
 import tarfile
-import urllib.request
 import zipfile
 
 
-def hash_path(p: pathlib.Path):
-    h = hashlib.sha256()
-
-    with p.open('rb') as fh:
-        while True:
-            chunk = fh.read(65536)
-            if not chunk:
-                break
-
-            h.update(chunk)
-
-    return h.hexdigest()
-
-
-class IntegrityError(Exception):
-    """Represents an integrity error when downloading a URL."""
-
-
-def secure_download_stream(url, size, sha256):
-    """Securely download a URL to a stream of chunks.
-
-    If the integrity of the download fails, an IntegrityError is
-    raised.
-    """
-    h = hashlib.sha256()
-    length = 0
-
-    with urllib.request.urlopen(url) as fh:
-        if not url.endswith('.gz') and fh.info().get('Content-Encoding') == 'gzip':
-            fh = gzip.GzipFile(fileobj=fh)
-
-        while True:
-            chunk = fh.read(65536)
-            if not chunk:
-                break
-
-            h.update(chunk)
-            length += len(chunk)
-
-            yield chunk
-
-    digest = h.hexdigest()
-
-    if length != size:
-        raise IntegrityError('size mismatch on %s: wanted %d; got %d' % (
-            url, size, length))
-
-    if digest != sha256:
-        raise IntegrityError('sha256 mismatch on %s: wanted %s; got %s' % (
-            url, sha256, digest))
-
-
-def download_to_path(url: str, path: pathlib.Path, size: int, sha256: str):
-    """Download a URL to a filesystem path, possibly with verification."""
-
-    # We download to a temporary file and rename at the end so there's
-    # no chance of the final file being partially written or containing
-    # bad data.
-    print('downloading %s to %s' % (url, path))
-
-    if path.exists():
-        good = True
-
-        if path.stat().st_size != size:
-            print('existing file size is wrong; removing')
-            good = False
-
-        if good:
-            if hash_path(path) != sha256:
-                print('existing file hash is wrong; removing')
-                good = False
-
-        if good:
-            print('%s exists and passes integrity checks' % path)
-            return
-
-        path.unlink()
-
-    tmp = path.with_name('%s.tmp' % path.name)
-
-    try:
-        with tmp.open('wb') as fh:
-            for chunk in secure_download_stream(url, size, sha256):
-                fh.write(chunk)
-    except IntegrityError:
-        tmp.unlink()
-        raise
-
-    tmp.rename(path)
-    print('successfully downloaded %s' % url)
-
-
-def download_entry(entry: dict, dest_path: pathlib.Path, local_name=None) -> pathlib.Path:
-    url = entry['url']
-
-    local_name = local_name or url[url.rindex('/') + 1:]
-
-    local_path = dest_path / local_name
-    download_to_path(url, local_path, entry['size'], entry['sha256'])
-
-    return local_path
-
-
 def extract_tar_to_directory(source: pathlib.Path, dest: pathlib.Path):
     with tarfile.open(source, 'r') as tf:
         tf.extractall(dest)

contrib/packaging/inno/build.py

@@ -87,8 +87,10 b' def build(source_dir: pathlib.Path, buil'
     for finding the Python 2.7 toolchain. So, we require the environment
     to already be configured with an active toolchain.
     """
+    from hgpackaging.downloads import (
+        download_entry,
+    )
     from hgpackaging.util import (
-        download_entry,
         extract_tar_to_directory,
         extract_zip_to_directory,
     )

tests/test-check-code.t

@@ -12,6 +12,7 b' New errors are not allowed. Warnings are'
   > -X hgext/fsmonitor/pywatchman \
   > -X mercurial/thirdparty \
   > | sed 's-\\-/-g' | "$check_code" --warnings --per-file=0 - || false
+  Skipping contrib/packaging/hgpackaging/downloads.py it has no-che?k-code (glob)
   Skipping contrib/packaging/hgpackaging/util.py it has no-che?k-code (glob)
   Skipping contrib/packaging/inno/build.py it has no-che?k-code (glob)
   Skipping i18n/polib.py it has no-che?k-code (glob)