mmdebstrap: reimplement build hook recursively

Instead of writing a complex shell script in a limited sub-language of
shell, call out to ourselves and implement the build functionality in
Python.

1 files changed, 23 insertions, 17 deletions

diff --git a/mdbp/common.py b/mdbp/common.py
index 830aad7..eccefc1 100644
--- a/mdbp/common.py
+++ b/mdbp/common.py
@@ -119,6 +119,27 @@ def download(uri: str, checksums: typing.Dict[str, str],
             dest.unlink()
             raise
 
+def download_dsc(buildinput: JsonObject,
+                 destdir: pathlib.Path) -> pathlib.Path:
+    """Download the .input.dscuri including referenced components to the given
+    destination directory and return the path to the contained .dsc file.
+    """
+    dscuri = buildinput["dscuri"]
+    dscpath = destdir / dscuri.split("/")[-1]
+    # mypy doesn't grok this:
+    assert isinstance(dscpath, pathlib.Path)
+    download(dscuri, buildinput.get("checksums", {}), dscpath)
+    files: typing.Dict[str, typing.Dict[str, str]] = {}
+    with dscpath.open("r") as dscf:
+        for key, value in debian.deb822.Dsc(dscf).items():
+            if key.lower().startswith("checksums-"):
+                for entry in value:
+                    algo = key[10:].lower()
+                    files.setdefault(entry["name"], dict())[algo] = entry[algo]
+    for name, checksums in files.items():
+        download(urllib.parse.urljoin(dscuri, name), checksums, destdir / name)
+    return dscpath
+
 @contextlib.contextmanager
 def get_dsc(build: JsonObject) -> typing.Iterator[pathlib.Path]:
     """A context manager that provides a path pointing at the .dsc file for the
@@ -129,23 +150,8 @@ def get_dsc(build: JsonObject) -> typing.Iterator[pathlib.Path]:
     try:
         dscpath = build["input"]["dscpath"]
     except KeyError:
-        dscuri = build["input"]["dscuri"]
-        with tempfile.TemporaryDirectory() as tdirname:
-            tdir = pathlib.Path(tdirname)
-            dscpath = tdir / dscuri.split("/")[-1]
-            download(dscuri, build["input"].get("checksums", {}), dscpath)
-            files: typing.Dict[str, typing.Dict[str, str]] = {}
-            with dscpath.open("r") as dscf:
-                for key, value in debian.deb822.Dsc(dscf).items():
-                    if key.lower().startswith("checksums-"):
-                        for entry in value:
-                            algo = key[10:].lower()
-                            files.setdefault(entry["name"], dict())[algo] = \
-                                    entry[algo]
-            for name, checksums in files.items():
-                download(urllib.parse.urljoin(dscuri, name), checksums,
-                         tdir / name)
-            yield dscpath
+        with tempfile.TemporaryDirectory() as tdir:
+            yield download_dsc(build["input"], pathlib.Path(tdir))
     else:
         yield pathlib.Path(dscpath)