From 36e74c1b57e56a45fbe6713aa5a90e7c0a0f2ae0 Mon Sep 17 00:00:00 2001
From: Jim Mussared <jim.mussared@gmail.com>
Date: Tue, 27 Jun 2023 00:30:45 +1000
Subject: [PATCH] zlib: Add zlib module.

This is a replacement for the `zlib` module that used to be built-in and
has been replaced by the MicroPython-specific `deflate` module.

Also updates the `gzip` module in a similar fashion and provide the
`gzip.GzipFile` class and `gzip.open` function.

This work was funded through GitHub Sponsors.

Signed-off-by: Jim Mussared <jim.mussared@gmail.com>
---
 python-stdlib/gzip/gzip.py     | 50 +++++++++++++++++-----------------
 python-stdlib/gzip/manifest.py |  2 +-
 python-stdlib/zlib/manifest.py |  3 ++
 python-stdlib/zlib/zlib.py     | 39 ++++++++++++++++++++++++++
 4 files changed, 68 insertions(+), 26 deletions(-)
 create mode 100644 python-stdlib/zlib/manifest.py
 create mode 100644 python-stdlib/zlib/zlib.py

diff --git a/python-stdlib/gzip/gzip.py b/python-stdlib/gzip/gzip.py
index 6d6c967a..c4473bec 100644
--- a/python-stdlib/gzip/gzip.py
+++ b/python-stdlib/gzip/gzip.py
@@ -1,29 +1,29 @@
-# import zlib
-import uzlib as zlib
+# MicroPython gzip module
+# MIT license; Copyright (c) 2023 Jim Mussared
 
-FTEXT = 1
-FHCRC = 2
-FEXTRA = 4
-FNAME = 8
-FCOMMENT = 16
+_WBITS = const(15)
+
+import io, deflate
+
+
+def GzipFile(fileobj):
+    return deflate.DeflateIO(fileobj, deflate.GZIP, _WBITS)
+
+
+def open(filename, mode):
+    return deflate.DeflateIO(open(filename, mode), deflate.GZIP, _WBITS, True)
+
+
+if hasattr(deflate.DeflateIO, "write"):
+
+    def compress(data):
+        f = io.BytesIO()
+        with GzipFile(fileobj=f) as g:
+            g.write(data)
+        return f.getvalue()
 
 
 def decompress(data):
-    assert data[0] == 0x1F and data[1] == 0x8B
-    assert data[2] == 8
-    flg = data[3]
-    assert flg & 0xE0 == 0
-    i = 10
-    if flg & FEXTRA:
-        i += data[11] << 8 + data[10] + 2
-    if flg & FNAME:
-        while data[i]:
-            i += 1
-        i += 1
-    if flg & FCOMMENT:
-        while data[i]:
-            i += 1
-        i += 1
-    if flg & FHCRC:
-        i += 2
-    return zlib.decompress(memoryview(data)[i:], -15)
+    f = io.BytesIO(data)
+    with GzipFile(fileobj=f) as g:
+        return g.read()
diff --git a/python-stdlib/gzip/manifest.py b/python-stdlib/gzip/manifest.py
index eab70e56..006b538c 100644
--- a/python-stdlib/gzip/manifest.py
+++ b/python-stdlib/gzip/manifest.py
@@ -1,3 +1,3 @@
-metadata(version="0.1.1")
+metadata(version="1.0.0")
 
 module("gzip.py")
diff --git a/python-stdlib/zlib/manifest.py b/python-stdlib/zlib/manifest.py
new file mode 100644
index 00000000..f95602f2
--- /dev/null
+++ b/python-stdlib/zlib/manifest.py
@@ -0,0 +1,3 @@
+metadata(version="1.0.0", description="Compression and decompression using the deflate algorithm")
+
+module("zlib.py")
diff --git a/python-stdlib/zlib/zlib.py b/python-stdlib/zlib/zlib.py
new file mode 100644
index 00000000..e6c342ef
--- /dev/null
+++ b/python-stdlib/zlib/zlib.py
@@ -0,0 +1,39 @@
+# MicroPython zlib module
+# MIT license; Copyright (c) 2023 Jim Mussared
+
+import io, deflate
+
+_MAX_WBITS = const(15)
+
+
+def _decode_wbits(wbits, decompress):
+    if -15 <= wbits <= -5:
+        return (
+            deflate.RAW,
+            -wbits,
+        )
+    elif 5 <= wbits <= 15:
+        return (deflate.ZLIB, wbits)
+    elif decompress and wbits == 0:
+        return (deflate.ZLIB,)
+    elif 21 <= wbits <= 31:
+        return (deflate.GZIP, wbits - 16)
+    elif decompress and 35 <= wbits <= 47:
+        return (deflate.AUTO, wbits - 32)
+    else:
+        raise ValueError("wbits")
+
+
+if hasattr(deflate.DeflateIO, "write"):
+
+    def compress(data, wbits=_MAX_WBITS):
+        f = io.BytesIO()
+        with deflate.DeflateIO(f, *_decode_wbits(wbits, False)) as g:
+            g.write(data)
+        return f.getvalue()
+
+
+def decompress(data, wbits=_MAX_WBITS):
+    f = io.BytesIO(data)
+    with deflate.DeflateIO(f, *_decode_wbits(wbits, True)) as g:
+        return g.read()