gh-127350: Add Py_fopen() and Py_fclose() functions (#127821)

3 files changed, 87 insertions, 4 deletions

diff --git a/Modules/_testcapi/clinic/file.c.h b/Modules/_testcapi/clinic/file.c.h
new file mode 100644
index 0000000..2ca21ff
--- /dev/null
+++ b/Modules/_testcapi/clinic/file.c.h
@@ -0,0 +1,48 @@
+/*[clinic input]
+preserve
+[clinic start generated code]*/
+
+#include "pycore_modsupport.h"    // _PyArg_CheckPositional()
+
+PyDoc_STRVAR(_testcapi_py_fopen__doc__,
+"py_fopen($module, path, mode, /)\n"
+"--\n"
+"\n"
+"Call Py_fopen(), fread(256) and Py_fclose(). Return read bytes.");
+
+#define _TESTCAPI_PY_FOPEN_METHODDEF    \
+    {"py_fopen", _PyCFunction_CAST(_testcapi_py_fopen), METH_FASTCALL, _testcapi_py_fopen__doc__},
+
+static PyObject *
+_testcapi_py_fopen_impl(PyObject *module, PyObject *path, const char *mode);
+
+static PyObject *
+_testcapi_py_fopen(PyObject *module, PyObject *const *args, Py_ssize_t nargs)
+{
+    PyObject *return_value = NULL;
+    PyObject *path;
+    const char *mode;
+
+    if (!_PyArg_CheckPositional("py_fopen", nargs, 2, 2)) {
+        goto exit;
+    }
+    path = args[0];
+    if (!PyUnicode_Check(args[1])) {
+        _PyArg_BadArgument("py_fopen", "argument 2", "str", args[1]);
+        goto exit;
+    }
+    Py_ssize_t mode_length;
+    mode = PyUnicode_AsUTF8AndSize(args[1], &mode_length);
+    if (mode == NULL) {
+        goto exit;
+    }
+    if (strlen(mode) != (size_t)mode_length) {
+        PyErr_SetString(PyExc_ValueError, "embedded null character");
+        goto exit;
+    }
+    return_value = _testcapi_py_fopen_impl(module, path, mode);
+
+exit:
+    return return_value;
+}
+/*[clinic end generated code: output=c9fe964c3e5a0c32 input=a9049054013a1b77]*/
diff --git a/Modules/_testcapi/file.c b/Modules/_testcapi/file.c
index 634563f..4bad430 100644
--- a/Modules/_testcapi/file.c
+++ b/Modules/_testcapi/file.c
@@ -1,8 +1,43 @@
+// clinic/file.c.h uses internal pycore_modsupport.h API
+#define PYTESTCAPI_NEED_INTERNAL_API
+
 #include "parts.h"
 #include "util.h"
+#include "clinic/file.c.h"
+
+/*[clinic input]
+module _testcapi
+[clinic start generated code]*/
+/*[clinic end generated code: output=da39a3ee5e6b4b0d input=6361033e795369fc]*/
+
+/*[clinic input]
+_testcapi.py_fopen
+
+    path: object
+    mode: str
+    /
+
+Call Py_fopen(), fread(256) and Py_fclose(). Return read bytes.
+[clinic start generated code]*/
 
+static PyObject *
+_testcapi_py_fopen_impl(PyObject *module, PyObject *path, const char *mode)
+/*[clinic end generated code: output=5a900af000f759de input=d7e7b8f0fd151953]*/
+{
+    FILE *fp = Py_fopen(path, mode);
+    if (fp == NULL) {
+        return NULL;
+    }
+
+    char buffer[256];
+    size_t size = fread(buffer, 1, Py_ARRAY_LENGTH(buffer), fp);
+    Py_fclose(fp);
+
+    return PyBytes_FromStringAndSize(buffer, size);
+}
 
 static PyMethodDef test_methods[] = {
+    _TESTCAPI_PY_FOPEN_METHODDEF
     {NULL},
 };
 
diff --git a/Modules/_testcapi/object.c b/Modules/_testcapi/object.c
index 3af5429..841410c 100644
--- a/Modules/_testcapi/object.c
+++ b/Modules/_testcapi/object.c
@@ -15,7 +15,7 @@ call_pyobject_print(PyObject *self, PyObject * args)
         return NULL;
     }
 
-    fp = _Py_fopen_obj(filename, "w+");
+    fp = Py_fopen(filename, "w+");
 
     if (Py_IsTrue(print_raw)) {
         flags = Py_PRINT_RAW;
@@ -41,7 +41,7 @@ pyobject_print_null(PyObject *self, PyObject *args)
         return NULL;
     }
 
-    fp = _Py_fopen_obj(filename, "w+");
+    fp = Py_fopen(filename, "w+");
 
     if (PyObject_Print(NULL, fp, 0) < 0) {
         fclose(fp);
@@ -72,7 +72,7 @@ pyobject_print_noref_object(PyObject *self, PyObject *args)
         return NULL;
     }
 
-    fp = _Py_fopen_obj(filename, "w+");
+    fp = Py_fopen(filename, "w+");
 
     if (PyObject_Print(test_string, fp, 0) < 0){
         fclose(fp);
@@ -103,7 +103,7 @@ pyobject_print_os_error(PyObject *self, PyObject *args)
     }
 
     // open file in read mode to induce OSError
-    fp = _Py_fopen_obj(filename, "r");
+    fp = Py_fopen(filename, "r");
 
     if (PyObject_Print(test_string, fp, 0) < 0) {
         fclose(fp);