From f85f39e662d494796d36f3c9fcb608f7042451b4 Mon Sep 17 00:00:00 2001
From: Kovid Goyal <kovid@kovidgoyal.net>
Date: Sat, 2 Oct 2021 07:22:33 +0530
Subject: [PATCH] Code to easily develop librsync bindings

---
 kittens/transfer/librsync.py | 17 +++++++++++++++++
 kittens/transfer/rsync.c     |  2 +-
 2 files changed, 18 insertions(+), 1 deletion(-)

diff --git a/kittens/transfer/librsync.py b/kittens/transfer/librsync.py
index 6777b285d..e8f6616c9 100644
--- a/kittens/transfer/librsync.py
+++ b/kittens/transfer/librsync.py
@@ -136,3 +136,20 @@ class PatchFile(StreamingJob):
 
     def __exit__(self, *a: object) -> None:
         self.close()
+
+
+def develop() -> None:
+    import sys
+    src = sys.argv[-1]
+    sig_loader = LoadSignature()
+    with open(src + '.sig', 'wb') as f:
+        for chunk in signature_of_file(src):
+            sig_loader(chunk)
+            f.write(chunk)
+    sig_loader()
+    with open(src + '.delta', 'wb') as f, PatchFile(src, src + '.output') as patcher:
+        for chunk in delta_for_file(src, sig_loader.signature):
+            f.write(chunk)
+            patcher.write(chunk)
+        if not patcher.finished:
+            patcher.write(b'')
diff --git a/kittens/transfer/rsync.c b/kittens/transfer/rsync.c
index 7c4572805..58f5116a1 100644
--- a/kittens/transfer/rsync.c
+++ b/kittens/transfer/rsync.c
@@ -156,7 +156,7 @@ copy_callback(void *opaque, rs_long_t pos, size_t *len, void **buf) {
     if (!mem) { PyErr_Clear(); return RS_MEM_ERROR; }
     PyObject *res = PyObject_CallFunction(callback, "OL", mem, p);
     Py_DECREF(mem);
-    if (res == NULL) { PyErr_Clear(); return RS_IO_ERROR; }
+    if (res == NULL) { PyErr_Print(); return RS_IO_ERROR; }
     rs_result r = RS_DONE;
     if (PyLong_Check(res)) { *len = PyLong_AsSize_t(res); }
     else { r = RS_INTERNAL_ERROR; }