gdb/testsuite: test for memory leaks in gdb.Inferior.read_memory()

diff --git a/gdb/testsuite/gdb.python/py-read-memory-leak.c b/gdb/testsuite/gdb.python/py-read-memory-leak.c
new file mode 100644
index 00000000000..75035cdbbe5
--- /dev/null
+++ b/gdb/testsuite/gdb.python/py-read-memory-leak.c
@@ -0,0 +1,27 @@ 
+/* This testcase is part of GDB, the GNU debugger.
+
+   Copyright 2014-2024 Free Software Foundation, Inc.
+
+   This program is free software; you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 3 of the License, or
+   (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
+
+static struct x
+{
+  char unsigned u[4096];
+} x, *px = &x;
+
+int
+main (void)
+{
+  return 0;
+}
diff --git a/gdb/testsuite/gdb.python/py-read-memory-leak.exp b/gdb/testsuite/gdb.python/py-read-memory-leak.exp
new file mode 100644
index 00000000000..52b072f34b3
--- /dev/null
+++ b/gdb/testsuite/gdb.python/py-read-memory-leak.exp
@@ -0,0 +1,44 @@ 
+# Copyright (C) 2024 Free Software Foundation, Inc.
+
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+# This file is part of the GDB testsuite.  It checks for memory leaks
+# associated with calling gdb.Inferior.read_memory().
+
+load_lib gdb-python.exp
+
+require allow_python_tests
+
+standard_testfile
+
+if { [prepare_for_testing "failed to prepare" ${testfile} ${srcfile}] } {
+    return -1
+}
+
+if ![runto_main] {
+   return -1
+}
+
+# Skip this test if the tracemalloc module is not available.
+if { ![gdb_py_module_available "tracemalloc"] } {
+    unsupported "tracemalloc module not available"
+    return
+}
+
+set pyfile [gdb_remote_download host ${srcdir}/${subdir}/${testfile}.py]
+
+# Source the Python script, this runs the test (which is written
+# completely in Python), and either prints PASS, or throws an
+# exception.
+gdb_test "source ${pyfile}" "PASS" "source python script"
diff --git a/gdb/testsuite/gdb.python/py-read-memory-leak.py b/gdb/testsuite/gdb.python/py-read-memory-leak.py
new file mode 100644
index 00000000000..62369b32ce2
--- /dev/null
+++ b/gdb/testsuite/gdb.python/py-read-memory-leak.py
@@ -0,0 +1,92 @@ 
+# Copyright (C) 2024 Free Software Foundation, Inc.
+
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+import os
+import tracemalloc
+import gdb
+
+# A global variable in which we store a reference to the memory buffer
+# returned from gdb.Inferior.read_memory().
+mem_buf = None
+
+
+# A global filters list, we only care about memory allocations
+# originating from this script.
+filters = [tracemalloc.Filter(True, "*" + os.path.basename(__file__))]
+
+
+# Run the test.  When CLEAR is True we clear the global INF variable
+# before comparing the before and after memory allocation traces.
+# When CLEAR is False we leave INF set to reference the gdb.Inferior
+# object, thus preventing the gdb.Inferior from being deallocated.
+def test(clear):
+    global filters, mem_buf
+
+    addr = gdb.parse_and_eval("px")
+    inf = gdb.inferiors()[0]
+
+    # Start tracing, and take a snapshot of the current allocations.
+    tracemalloc.start()
+    snapshot1 = tracemalloc.take_snapshot()
+
+    # Read from the inferior, this allocate a memory buffer object.
+    mem_buf = inf.read_memory(addr, 4096)
+
+    # Possibly clear the global INF variable.
+    if clear:
+        mem_buf = None
+
+    # Now grab a second snapshot of memory allocations, and stop
+    # tracing memory allocations.
+    snapshot2 = tracemalloc.take_snapshot()
+    tracemalloc.stop()
+
+    # Filter the snapshots; we only care about allocations originating
+    # from this file.
+    snapshot1 = snapshot1.filter_traces(filters)
+    snapshot2 = snapshot2.filter_traces(filters)
+
+    # Compare the snapshots, this leaves only things that were
+    # allocated, but not deallocated since the first snapshot.
+    stats = snapshot2.compare_to(snapshot1, "traceback")
+
+    # Total up all the allocated things.
+    total = 0
+    for stat in stats:
+        total += stat.size_diff
+    return total
+
+
+# The first time we run this some global state will be allocated which
+# shows up as memory that is allocated, but not released.  So, run the
+# test once and discard the result.
+test(True)
+
+# Now run the test twice, the first time we clear our global reference
+# to the memory buffer object, which should allow Python to deallocate
+# the object.  The second time we hold onto the global reference,
+# preventing Python from performing the deallocation.
+bytes_with_clear = test(True)
+bytes_without_clear = test(False)
+
+# The bug that used to exist in GDB was that even when we released the
+# global reference the gdb.Inferior object would not be deallocated.
+if bytes_with_clear > 0:
+    raise gdb.GdbError("memory leak when memory buffer should be released")
+if bytes_without_clear == 0:
+    raise gdb.GdbError("memory buffer object is no longer allocated")
+
+# Print a PASS message that the test script can see.
+print("PASS")