From 10bd43664948708717c06b55ff5ac341d79da1b5 Mon Sep 17 00:00:00 2001
From: godoy <95002561+herniqeu@users.noreply.github.com>
Date: Sun, 1 Nov 2026 02:30:54 -0300
Subject: [PATCH 1/2] Pass a full-width size_t to the compat setparam/getparam

libmagic reads and writes the value of magic_setparam/magic_getparam as a
size_t, but magic/compat.py built a c_int buffer instead. On 64-bit that
truncated values above 32 bits before they reached libmagic (and
getparam let libmagic write 8 bytes into a 4-byte buffer).
magic/__init__.py already uses c_size_t; only the compat layer was left
behind.
---
 magic/compat.py | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/magic/compat.py b/magic/compat.py
index 32a7b93b..dbac9dfc 100644
--- a/magic/compat.py
+++ b/magic/compat.py
@@ -244,7 +244,7 @@ def getparam(self, param):
         Returns the param value if successful and -1 if the parameter
         was unknown.
         """
-        v = c_int()
+        v = c_size_t()
         i = _getparam(self._magic_t, param, byref(v))
         if i == -1:
             return -1
@@ -254,7 +254,7 @@ def setparam(self, param, value):
         """
         Returns 0 if successful and -1 if the parameter was unknown.
         """
-        v = c_int(value)
+        v = c_size_t(value)
         return _setparam(self._magic_t, param, byref(v))
 
 

From 29b292f37e5693e1c75444340487765865342e61 Mon Sep 17 00:00:00 2001
From: godoy <95002561+herniqeu@users.noreply.github.com>
Date: Sun, 1 Nov 2026 02:30:55 -0300
Subject: [PATCH 2/2] Test that compat setparam/getparam keep 64-bit values

---
 test/python_magic_test.py | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/test/python_magic_test.py b/test/python_magic_test.py
index 26398614..48d9e558 100755
--- a/test/python_magic_test.py
+++ b/test/python_magic_test.py
@@ -191,6 +191,14 @@ def test_version(self):
         except NotImplementedError:
             pass
 
+
+    def test_compat_params_use_size_t(self):
+        # libmagic reads and writes setparam/getparam values as a size_t,
+        # so the compat module must not truncate them to 32 bits.
+        m = magic.compat.open(magic.compat.MAGIC_NONE)
+        self.assertEqual(0, m.setparam(magic.compat.PARAM_BYTES_MAX, 2**33))
+        self.assertEqual(2**33, m.getparam(magic.compat.PARAM_BYTES_MAX))
+
     def test_fs_encoding(self):
         self.assertEqual("utf-8", sys.getfilesystemencoding().lower())