From b3b778ddcfae0b6bb19d6c05584720dd7a6c68dc Mon Sep 17 00:00:00 2001
From: rome-xi <rome-xi@users.noreply.github.com>
Date: Mon, 24 Aug 2026 02:22:55 +0000
Subject: [PATCH] fix: use BrotliDecoderAttachDictionary for custom
 dictionaries

Signed-off-by: rome-xi <rome-xi@users.noreply.github.com>
---
 src/brotlicffi/_api.py         |  5 ++++-
 src/brotlicffi/_build.py       | 11 +++++++++++
 test/test_custom_dictionary.py | 22 ++++++++++++++++++++++
 3 files changed, 37 insertions(+), 1 deletion(-)
 create mode 100644 test/test_custom_dictionary.py

diff --git a/src/brotlicffi/_api.py b/src/brotlicffi/_api.py
index 75a5182..002f68c 100644
--- a/src/brotlicffi/_api.py
+++ b/src/brotlicffi/_api.py
@@ -390,11 +390,14 @@ def __init__(self, dictionary=b''):
         if dictionary:
             self._dictionary = ffi.new("uint8_t []", dictionary)
             self._dictionary_size = len(dictionary)
-            lib.BrotliDecoderSetCustomDictionary(
+            attached = lib.BrotliDecoderAttachDictionary(
                 self._decoder,
+                lib.BROTLI_SHARED_DICTIONARY_RAW,
                 self._dictionary_size,
                 self._dictionary
             )
+            if attached != lib.BROTLI_TRUE:
+                raise error("Error attaching custom dictionary.")
 
     @staticmethod
     def _calculate_buffer_size(
diff --git a/src/brotlicffi/_build.py b/src/brotlicffi/_build.py
index 115be2e..8ddb000 100644
--- a/src/brotlicffi/_build.py
+++ b/src/brotlicffi/_build.py
@@ -19,6 +19,7 @@
     "_brotlicffi",
     """#include <brotli/decode.h>
        #include <brotli/encode.h>
+       #include <brotli/shared_dictionary.h>
     """,
     libraries=libraries,
     include_dirs=["libbrotli/c", "libbrotli/c/include", "libbrotli/c/common"]
@@ -112,6 +113,16 @@
 
     const char* BrotliDecoderErrorString(BrotliDecoderErrorCode c);
 
+    typedef enum BrotliSharedDictionaryType {
+      BROTLI_SHARED_DICTIONARY_RAW = 0,
+      BROTLI_SHARED_DICTIONARY_SERIALIZED = 1
+    } BrotliSharedDictionaryType;
+
+    BROTLI_BOOL BrotliDecoderAttachDictionary(BrotliDecoderState* state,
+                                              BrotliSharedDictionaryType type,
+                                              size_t data_size,
+                                              const uint8_t* data);
+
     /* enc/encode.h */
     typedef ... BrotliEncoderState;
 
diff --git a/test/test_custom_dictionary.py b/test/test_custom_dictionary.py
new file mode 100644
index 0000000..d50bd8c
--- /dev/null
+++ b/test/test_custom_dictionary.py
@@ -0,0 +1,22 @@
+# -*- coding: utf-8 -*-
+"""
+Regression tests for Decompressor custom dictionary support (#215).
+"""
+import brotlicffi
+
+
+def test_decompressor_accepts_custom_dictionary():
+    """
+    Constructing Decompressor(dictionary=...) must not raise AttributeError
+    for the removed BrotliDecoderSetCustomDictionary API.
+    """
+    decompressor = brotlicffi.Decompressor(dictionary=b"custom dictionary")
+    assert decompressor is not None
+
+
+def test_decompressor_without_dictionary_still_works():
+    """Attaching no dictionary leaves ordinary decompression working."""
+    payload = b"hello world from brotlicffi custom dictionary regression"
+    compressed = brotlicffi.compress(payload)
+    decompressor = brotlicffi.Decompressor()
+    assert decompressor.decompress(compressed) + decompressor.finish() == payload