[PATCH v7 14/59] perf python: Add wrapper for perf_data file abstraction

[Ian Rogers <irogers@google.com>]

The perf_data struct is needed for session supported.

Assisted-by: Gemini:gemini-3.1-pro-preview
Signed-off-by: Ian Rogers <irogers@google.com>
---
v2:
1. Fixed Memory & FD Leaks in pyrf_data__init : Added cleanup of old
   state (closing file and freeing path) if __init__ is called
   multiple times on the same object.

2. Fixed Invalid Free in pyrf_data__delete : Ensured pdata->data.path
   is always dynamically allocated via strdup() , even for the default
   "perf.data" . This avoids passing a static string literal to free().

3. Fixed NULL Pointer Dereference in pyrf_data__str : Added a check
   for NULL path to prevent segfaults if str() or repr() is called on
   an uninitialized object.

4. Guarded fd Argument Usage: Added a check to ensure that if an fd is
   provided, it corresponds to a pipe, failing gracefully with a
   ValueError otherwise.

v7:
- Added pyrf_data__new to zero-initialize pdata->data to fix
  crash on re-initialization.
---
 tools/perf/util/python.c | 103 ++++++++++++++++++++++++++++++++++++++-
 1 file changed, 102 insertions(+), 1 deletion(-)

diff --git a/tools/perf/util/python.c b/tools/perf/util/python.c
index 2ba3556c4f16..aa63c7ffe822 100644
--- a/tools/perf/util/python.c
+++ b/tools/perf/util/python.c
@@ -10,6 +10,7 @@
 
 #include "callchain.h"
 #include "counts.h"
+#include "data.h"
 #include "event.h"
 #include "evlist.h"
 #include "evsel.h"
@@ -2316,6 +2317,102 @@ static PyObject *pyrf__metrics(PyObject *self, PyObject *args)
 	return list;
 }
 
+struct pyrf_data {
+	PyObject_HEAD
+
+	struct perf_data data;
+};
+
+static int pyrf_data__init(struct pyrf_data *pdata, PyObject *args, PyObject *kwargs)
+{
+	static char *kwlist[] = { "path", "fd", NULL };
+	char *path = NULL;
+	int fd = -1;
+
+	if (!PyArg_ParseTupleAndKeywords(args, kwargs, "|si", kwlist, &path, &fd))
+		return -1;
+
+	if (pdata->data.open)
+		perf_data__close(&pdata->data);
+	free((char *)pdata->data.path);
+
+	if (!path)
+		path = "perf.data";
+
+	pdata->data.path = strdup(path);
+	if (!pdata->data.path) {
+		PyErr_NoMemory();
+		return -1;
+	}
+
+	if (fd != -1) {
+		struct stat st;
+
+		if (fstat(fd, &st) < 0 || !S_ISFIFO(st.st_mode)) {
+			PyErr_SetString(PyExc_ValueError,
+					"fd argument is only supported for pipes");
+			free((char *)pdata->data.path);
+			pdata->data.path = NULL;
+			return -1;
+		}
+	}
+
+	pdata->data.mode = PERF_DATA_MODE_READ;
+	pdata->data.file.fd = fd;
+	if (perf_data__open(&pdata->data) < 0) {
+		PyErr_Format(PyExc_IOError, "Failed to open perf data: %s",
+			     pdata->data.path ? pdata->data.path : "perf.data");
+		return -1;
+	}
+	return 0;
+}
+
+static void pyrf_data__delete(struct pyrf_data *pdata)
+{
+	perf_data__close(&pdata->data);
+	free((char *)pdata->data.path);
+	Py_TYPE(pdata)->tp_free((PyObject *)pdata);
+}
+
+static PyObject *pyrf_data__str(PyObject *self)
+{
+	const struct pyrf_data *pdata = (const struct pyrf_data *)self;
+
+	if (!pdata->data.path)
+		return PyUnicode_FromString("[uninitialized]");
+	return PyUnicode_FromString(pdata->data.path);
+}
+
+static PyObject *pyrf_data__new(PyTypeObject *type, PyObject *args, PyObject *kwargs)
+{
+	struct pyrf_data *pdata;
+
+	pdata = (struct pyrf_data *)PyType_GenericNew(type, args, kwargs);
+	if (pdata)
+		memset(&pdata->data, 0, sizeof(pdata->data));
+	return (PyObject *)pdata;
+}
+
+static const char pyrf_data__doc[] = PyDoc_STR("perf data file object.");
+
+static PyTypeObject pyrf_data__type = {
+	PyVarObject_HEAD_INIT(NULL, 0)
+	.tp_name	= "perf.data",
+	.tp_basicsize	= sizeof(struct pyrf_data),
+	.tp_dealloc	= (destructor)pyrf_data__delete,
+	.tp_flags	= Py_TPFLAGS_DEFAULT|Py_TPFLAGS_BASETYPE,
+	.tp_doc		= pyrf_data__doc,
+	.tp_init	= (initproc)pyrf_data__init,
+	.tp_repr	= pyrf_data__str,
+	.tp_str		= pyrf_data__str,
+};
+
+static int pyrf_data__setup_types(void)
+{
+	pyrf_data__type.tp_new = pyrf_data__new;
+	return PyType_Ready(&pyrf_data__type);
+}
+
 static PyMethodDef perf__methods[] = {
 	{
 		.ml_name  = "metrics",
@@ -2378,7 +2475,8 @@ PyMODINIT_FUNC PyInit_perf(void)
 	    pyrf_cpu_map__setup_types() < 0 ||
 	    pyrf_pmu_iterator__setup_types() < 0 ||
 	    pyrf_pmu__setup_types() < 0 ||
-	    pyrf_counts_values__setup_types() < 0)
+	    pyrf_counts_values__setup_types() < 0 ||
+	    pyrf_data__setup_types() < 0)
 		return module;
 
 	/* The page_size is placed in util object. */
@@ -2426,6 +2524,9 @@ PyMODINIT_FUNC PyInit_perf(void)
 	Py_INCREF(&pyrf_counts_values__type);
 	PyModule_AddObject(module, "counts_values", (PyObject *)&pyrf_counts_values__type);
 
+	Py_INCREF(&pyrf_data__type);
+	PyModule_AddObject(module, "data", (PyObject *)&pyrf_data__type);
+
 	dict = PyModule_GetDict(module);
 	if (dict == NULL)
 		goto error;
-- 
2.54.0.545.g6539524ca2-goog