sdist_upip.py: Replacement for optimize_upip.py.

Unlike optimize_upip, which instantiates a separate distutils/setuptools
command to run after "sdist", sdist_upip overrides "sdist" implementation,
so it simplifies publishing workflow (no need to run adhoc commands).

Besides what optimize_upip did (post-porocessing to remove superfluous
files and recompressing with gzip 4K dictionary), sdist_upip also
adds pre-processing step of generation resource module (R.py) from
resource files.

So, now there's a single (and standard) command to generate a distrubution
package for MicroPython.

sdist_upip.py

@@ -0,0 +1,137 @@
+#
+# This module overrides distutils (also compatible with setuptools) "sdist"
+# command to perform pre- and post-processing as required for MicroPython's
+# upip package manager.
+#
+# Preprocessing steps:
+#  * Creation of Python resource module (R.py) from each top-level package's
+#    resources.
+# Postprocessing steps:
+#  * Removing metadata files not used by upip (this includes setup.py)
+#  * Recompressing gzip archive with 4K dictionary size so it can be
+#    installed even on low-heap targets.
+#
+import sys
+import os
+import zlib
+from subprocess import Popen, PIPE
+import glob
+import tarfile
+import re
+import io
+
+from distutils.filelist import FileList
+from distutils.command.sdist import sdist as _sdist
+
+
+def gzip_4k(inf, fname):
+    comp = zlib.compressobj(level=9, wbits=16 + 12)
+    with open(fname + ".out", "wb") as outf:
+        while 1:
+            data = inf.read(1024)
+            if not data:
+                break
+            outf.write(comp.compress(data))
+        outf.write(comp.flush())
+    os.rename(fname, fname + ".orig")
+    os.rename(fname + ".out", fname)
+
+
+FILTERS = [
+    # include, exclude, repeat
+    (r".+\.egg-info/(PKG-INFO|requires\.txt)", r"setup.py$"),
+    (r".+\.py$", r"[^/]+$"),
+    (None, r".+\.egg-info/.+"),
+]
+
+
+outbuf = io.BytesIO()
+
+def filter_tar(name):
+    fin = tarfile.open(name, "r:gz")
+    fout = tarfile.open(fileobj=outbuf, mode="w")
+    for info in fin:
+#        print(info)
+        if not "/" in info.name:
+            continue
+        fname = info.name.split("/", 1)[1]
+        include = None
+
+        for inc_re, exc_re in FILTERS:
+            if include is None and inc_re:
+                if re.match(inc_re, fname):
+                    include = True
+
+            if include is None and exc_re:
+                if re.match(exc_re, fname):
+                    include = False
+
+        if include is None:
+            include = True
+
+        if include:
+            print("including:", fname)
+        else:
+            print("excluding:", fname)
+            continue
+
+        farch = fin.extractfile(info)
+        fout.addfile(info, farch)
+    fout.close()
+    fin.close()
+
+
+def make_resource_module(manifest_files):
+        resources = []
+        # Any non-python file included in manifest is resource
+        for fname in manifest_files:
+            ext = fname.rsplit(".", 1)[1]
+            if ext != "py":
+                resources.append(fname)
+
+        if resources:
+            print("creating resource module R.py")
+            resources.sort()
+            last_pkg = None
+            r_file = None
+            for fname in resources:
+                pkg, res_name = fname.split("/", 1)
+                if last_pkg != pkg:
+                    last_pkg = pkg
+                    if r_file:
+                        r_file.write("}\n")
+                        r_file.close()
+                    r_file = open(pkg + "/R.py", "w")
+                    r_file.write("R = {\n")
+
+                with open(fname, "rb") as f:
+                    r_file.write("%r: %r,\n" % (res_name, f.read()))
+
+            if r_file:
+                r_file.write("}\n")
+                r_file.close()
+
+
+class sdist(_sdist):
+
+    def run(self):
+        self.filelist = FileList()
+        self.get_file_list()
+        make_resource_module(self.filelist.files)
+
+        r = super().run()
+
+        assert len(self.archive_files) == 1
+        print("filtering files and recompressing with 4K dictionary")
+        filter_tar(self.archive_files[0])
+        outbuf.seek(0)
+        gzip_4k(outbuf, self.archive_files[0])
+
+        return r
+
+
+# For testing only
+if __name__ == "__main__":
+    filter_tar(sys.argv[1])
+    outbuf.seek(0)
+    gzip_4k(outbuf, sys.argv[1])