From 1e8a534533acdd162399bd04e54db4189c1dd930 Mon Sep 17 00:00:00 2001
From: "Miss Islington (bot)"
 <31488909+miss-islington@users.noreply.github.com>
Date: Sun, 11 May 2025 01:02:44 +0200
Subject: [3.14] gh-132983: Make zstd types immutable (GH-133784) (#133857)

gh-132983: Make zstd types immutable (GH-133784)
(cherry picked from commit 1a87b6e9ae6da255f30465ed59a78913ebf2e898)

Co-authored-by: Adam Turner <9087854+AA-Turner@users.noreply.github.com>
---
 Modules/_zstd/_zstdmodule.c  | 3 +++
 Modules/_zstd/compressor.c   | 3 +++
 Modules/_zstd/decompressor.c | 3 ++-
 Modules/_zstd/zstddict.c     | 3 ++-
 4 files changed, 10 insertions(+), 2 deletions(-)

diff --git a/Modules/_zstd/_zstdmodule.c b/Modules/_zstd/_zstdmodule.c
index bddef0d..c3852fe 100644
--- a/Modules/_zstd/_zstdmodule.c
+++ b/Modules/_zstd/_zstdmodule.c
@@ -679,6 +679,9 @@ do {                                                                         \
     ADD_INT_CONST_TO_TYPE(mod_state->ZstdCompressor_type,
                           "FLUSH_FRAME", ZSTD_e_end);
 
+    /* Make ZstdCompressor immutable (set Py_TPFLAGS_IMMUTABLETYPE) */
+    PyType_Freeze(mod_state->ZstdCompressor_type);
+
 #undef ADD_TYPE
 #undef ADD_INT_MACRO
 #undef ADD_ZSTD_COMPRESSOR_INT_CONST
diff --git a/Modules/_zstd/compressor.c b/Modules/_zstd/compressor.c
index e70eb63..355a27d 100644
--- a/Modules/_zstd/compressor.c
+++ b/Modules/_zstd/compressor.c
@@ -729,6 +729,9 @@ static PyType_Slot zstdcompressor_slots[] = {
 PyType_Spec zstd_compressor_type_spec = {
     .name = "compression.zstd.ZstdCompressor",
     .basicsize = sizeof(ZstdCompressor),
+    // Py_TPFLAGS_IMMUTABLETYPE is not used here as several
+    // associated constants need to be added to the type.
+    // PyType_Freeze is called later to set the flag.
     .flags = Py_TPFLAGS_DEFAULT | Py_TPFLAGS_HAVE_GC,
     .slots = zstdcompressor_slots,
 };
diff --git a/Modules/_zstd/decompressor.c b/Modules/_zstd/decompressor.c
index 2ed88cd..a654a95 100644
--- a/Modules/_zstd/decompressor.c
+++ b/Modules/_zstd/decompressor.c
@@ -902,6 +902,7 @@ static PyType_Slot ZstdDecompressor_slots[] = {
 PyType_Spec zstd_decompressor_type_spec = {
     .name = "compression.zstd.ZstdDecompressor",
     .basicsize = sizeof(ZstdDecompressor),
-    .flags = Py_TPFLAGS_DEFAULT | Py_TPFLAGS_HAVE_GC,
+    .flags = Py_TPFLAGS_DEFAULT | Py_TPFLAGS_IMMUTABLETYPE
+             | Py_TPFLAGS_HAVE_GC,
     .slots = ZstdDecompressor_slots,
 };
diff --git a/Modules/_zstd/zstddict.c b/Modules/_zstd/zstddict.c
index 99976ce..47bc8a8 100644
--- a/Modules/_zstd/zstddict.c
+++ b/Modules/_zstd/zstddict.c
@@ -278,6 +278,7 @@ static PyType_Slot zstddict_slots[] = {
 PyType_Spec zstd_dict_type_spec = {
     .name = "compression.zstd.ZstdDict",
     .basicsize = sizeof(ZstdDict),
-    .flags = Py_TPFLAGS_DEFAULT | Py_TPFLAGS_HAVE_GC,
+    .flags = Py_TPFLAGS_DEFAULT | Py_TPFLAGS_IMMUTABLETYPE
+             | Py_TPFLAGS_HAVE_GC,
     .slots = zstddict_slots,
 };
-- 
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