Meta: Add file download and archive extraction tools to gn build

Use them to download and extract the TZDB files

Meta/gn/build/extract_archive_contents.py

@@ -0,0 +1,100 @@
+#!/usr/bin/env python3
+r"""Extracts files from an archive for use in the build
+
+It's intended to be used for files that are cached between runs.
+
+"""
+
+import argparse
+import pathlib
+import tarfile
+import zipfile
+import sys
+
+
+def extract_member(file, destination, path):
+    """
+    Extract a single file from a ZipFile or TarFile
+
+    :param ZipFile|TarFile file: Archive object to extract from
+    :param Path destination: Location to write the file
+    :param str path: Filename to extract from archive.
+    """
+    destination_path = destination / path
+    if destination_path.exists():
+        return
+    destination_path.parent.mkdir(parents=True, exist_ok=True)
+    if isinstance(file, tarfile.TarFile):
+        with file.extractfile(path) as member:
+            destination_path.write_text(member.read().decode('utf-8'))
+    else:
+        assert isinstance(file, zipfile.ZipFile)
+        with file.open(path) as member:
+            destination_path.write_text(member.read().decode('utf-8'))
+
+
+def extract_directory(file, destination, path):
+    """
+    Extract a directory from a ZipFile or TarFile
+
+    :param ZipFile|TarFile file: Archive object to extract from
+    :param Path destination: Location to write the files
+    :param str path: Directory name to extract from archive.
+    """
+    destination_path = destination / path
+    if destination_path.exists():
+        return
+    destination_path.mkdir(parents=True, exist_ok=True)
+    if not isinstance(file, zipfile.ZipFile):
+        raise NotImplementedError
+    # FIXME: This loops over the entire archive len(args.paths) times. Decrease complexity
+    for entry in file.namelist():
+        if entry.startswith(path):
+            entry_destination = destination / entry
+            if entry.endswith('/'):
+                entry_destination.mkdir(exist_ok=True)
+                continue
+            with file.open(entry) as member:
+                entry_destination.write_text(member.read().decode('utf-8'))
+
+
+def main():
+    parser = argparse.ArgumentParser(
+                 epilog=__doc__,
+                 formatter_class=argparse.RawDescriptionHelpFormatter)
+    parser.add_argument('archive', help='input archive')
+    parser.add_argument('paths', nargs='*', help='paths to extract from the archive')
+    parser.add_argument('-s', "--stamp", required=False,
+                        help='stamp file name to create after operation is done')
+    parser.add_argument('-d', "--destination", required=True,
+                        help='directory to write the extracted file to')
+    args = parser.parse_args()
+
+    archive = pathlib.Path(args.archive)
+    destination = pathlib.Path(args.destination)
+
+    def extract_paths(file, paths):
+        for path in paths:
+            if path.endswith('/'):
+                extract_directory(file, destination, path)
+            else:
+                extract_member(file, destination, path)
+
+    if tarfile.is_tarfile(archive):
+        with tarfile.open(archive) as f:
+            extract_paths(f, args.paths)
+    elif zipfile.is_zipfile(archive):
+        with zipfile.ZipFile(archive) as f:
+            extract_paths(f, args.paths)
+    else:
+        print(f"Unknown file type for {archive}, unable to extract {args.path}")
+        return 1
+
+    if args.stamp:
+        pathlib.Path(args.stamp).touch()
+
+    return 0
+
+
+if __name__ == '__main__':
+    sys.exit(main())