From: Michael Tremer <michael.tremer@ipfire.org>
Date: Wed, 2 Aug 2023 15:08:15 +0000 (+0000)
Subject: _pakfire: util: Refactor PyObject_AsFileHandle using fmemcookie
X-Git-Tag: 0.9.29~80
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=3dca9fd03fe30f9610613d83e28d51fa2c4fee86;p=pakfire.git

_pakfire: util: Refactor PyObject_AsFileHandle using fmemcookie

Python is not very good at handling file objects, so we wrap them into
this little tool.

Signed-off-by: Michael Tremer <michael.tremer@ipfire.org>
---

diff --git a/src/_pakfire/util.c b/src/_pakfire/util.c
index 3fda33ed4..fb2b1f133 100644
--- a/src/_pakfire/util.c
+++ b/src/_pakfire/util.c
@@ -112,21 +112,109 @@ PyObject* PyDateTime_FromTime_t(const time_t* t) {
 	);
 }
 
-FILE* PyObject_AsFileHandle(PyObject* object, const char* mode) {
-	// Get a file descriptor
-	int fd = PyObject_AsFileDescriptor(object);
-	if (fd < 0)
-		return NULL;
+static ssize_t PyObject_AsFileHandle_read(void* cookie, char* buffer, size_t size) {
+	PyObject* object = (PyObject*)cookie;
+	PyObject* pybuffer = NULL;
+	const char* bytes = NULL;
+	Py_ssize_t bytes_read = -1;
+
+	// Make sure we acquired the GIL
+	PyGILState_STATE state = PyGILState_Ensure();
+
+	// Read data from the object
+	pybuffer = PyObject_CallMethod(object, "read", "i", size);
+	if (!pybuffer)
+		goto ERROR;
+
+	// Handle strings
+	if (PyUnicode_Check(pybuffer)) {
+		bytes = PyUnicode_AsUTF8AndSize(pybuffer, &bytes_read);
+		if (!bytes)
+			goto ERROR;
 
-	// Duplicate the file handle
-	fd = dup(fd);
+	// Handle bytes
+	} else if (PyBytes_Check(pybuffer)) {
+		bytes = PyBytes_AsString(pybuffer);
+		if (!bytes)
+			goto ERROR;
+
+		bytes_read = PyBytes_Size(pybuffer);
+
+	// Fail on anything else
+	} else {
+		PyErr_SetString(PyExc_TypeError, "read() returned an unexpected data type\n");
+		goto ERROR;
+	}
 
-	// Convert to file handle
-	FILE* f = fdopen(fd, mode);
-	if (!f) {
-		PyErr_SetFromErrno(PyExc_OSError);
+	// Copy the data into the target buffer
+	memcpy(buffer, bytes, bytes_read);
+
+ERROR:
+	Py_DECREF(pybuffer);
+
+	// Release the GIL
+	PyGILState_Release(state);
+
+	return bytes_read;
+}
+
+static ssize_t PyObject_AsFileHandle_write(void* cookie, const char* buffer, size_t size) {
+	PyObject* object = (PyObject*)cookie;
+	ssize_t r = 0;
+
+	// Make sure we acquired the GIL
+	PyGILState_STATE state = PyGILState_Ensure();
+
+	PyObject* pybuffer = PyBytes_FromStringAndSize(buffer, size);
+	if (!pybuffer)
+		goto ERROR;
+
+	PyObject* result = PyObject_CallMethod(object, "write", "b", pybuffer);
+	if (!result)
+		goto ERROR;
+
+	// It looks like we successfully wrote the data
+	r = size;
+
+ERROR:
+	Py_XDECREF(pybuffer);
+
+	// Release the GIL
+	PyGILState_Release(state);
+
+	return r;
+}
+
+static int PyObject_AsFileHandle_close(void* cookie) {
+	PyObject* object = (PyObject*)cookie;
+
+	// Make sure we acquired the GIL
+	PyGILState_STATE state = PyGILState_Ensure();
+
+	// Decrement the reference counter for the object
+	Py_DECREF(object);
+
+	// Release the GIL
+	PyGILState_Release(state);
+
+	return 0;
+}
+
+static cookie_io_functions_t PyFileHandleMethods = {
+	.read = PyObject_AsFileHandle_read,
+	.write = PyObject_AsFileHandle_write,
+	.close = PyObject_AsFileHandle_close,
+};
+
+FILE* PyObject_AsFileHandle(PyObject* object, const char* mode) {
+	// We only support reading files
+	if (!mode || *mode != 'r') {
+		errno = ENOTSUP;
 		return NULL;
 	}
 
-	return f;
+	// Increment the reference counter for the object
+	Py_INCREF(object);
+
+	return fopencookie(object, mode, PyFileHandleMethods);
 }